Earbud case with charging system

Abstract

The present invention provides a case for a pair of earbuds, comprising: a housing having cavities for receiving the pair of earbuds; and a charging circuit system configured to initiate charging of the earbuds when an earbud detector detects that the pair of earbuds are inserted into the cavities.

Description

Earbud case with a charging system The described embodiments generally relate to portable listening devices such as earbuds and other types of headphones, and to cases for storing and charging such devices. The portable listening devices are usable with a wide variety of electronic devices such as portable media players, smartphones, tablet computers, laptop computers, stereo systems, and other types of devices. Historically, portable listening devices have included one or more small speakers configured to be placed on, in, or near the user's ear, structural components for holding the speakers in place, and a cable for electrically connecting the portable listening device to an audio source. Other portable listening devices can be wireless devices that do not include a cable and instead receive an audio data stream from a wireless audio source wirelessly. While wireless portable listening devices have many advantages over wired devices, they also have some potential disadvantages. For example, wireless portable listening devices typically require one or more batteries to supply power to the wireless communication circuitry and other components of the device, such as rechargeable batteries. Disposable batteries need to be replaced when their charge is depleted, and rechargeable batteries need to be recharged periodically. Also, if the portable wireless listening device is a pair of wireless earbuds, the earbuds can be relatively small and prone to being lost when not in use. Additionally, achieving high-end acoustic performance with relatively small earbuds presents a challenge to manufacturers due to the reduced amount of space available within each earbud. Some embodiments of the present invention relate to a case for storing and charging a portable listening device (such as a pair of wireless earbuds or other types of headphones). In various embodiments, the case may include one or more features that can improve the user experience associated with using the case and the portable listening device. For example, some embodiments of the present invention relate to a case for wireless earbuds that includes a detector for detecting whether the earbuds are stored in the case, along with a detector for detecting whether the lid of the case is open or closed. The circuitry within the case can use the information from the detectors to improve the user experience associated with: charging the earbuds; pairing the earbuds with a host device (such as a portable media player or other audio signal source); and / or turning off one or more features of the earbuds to extend the life of any battery used to power the earbuds. In other embodiments, a case for a portable listening device may include a lid that encloses the listening device within the case when closed and exposes the stored listening device when open, such that the user can remove the listening device from the case. The lid may be pivotally coupled to the outer shell of the case by a bistable hinge having an over-center configuration, where the lid is in a stable position when closed or fully open and unstable at intermediate positions such that the lid tends to move to the open or closed position. The bistable operation of the lid can provide the user with a positive experience when opening and closing the lid, as the lid easily and with minimal effort moves between the closed position and the fully open position. In other embodiments, a case for a portable listening device may be configured to magnetically attract and hold the listening device within the case. Still other embodiments facilitate the pairing of the wireless portable listening device with a host device, and / or automatically turn off the radio frequency of the wireless portable listening device when the device is stored and fully enclosed within the case and automatically turn on the radio frequency immediately after opening the lid of the case. Various embodiments of the present invention may include all of the above features together or only some of these features. Earbud Case with Charging System : In some embodiments, there is provided a case for transporting and charging a portable listening device that includes a rechargeable battery and electrical contacts. The portable listening device case may include: an outer shell configured to house the portable listening device; a lid attached to the outer shell and operable between a closed position where the lid hides the listening device within the case and an open position where the lid is displaced from the outer shell such that the user can remove the listening device from the case; a detector configured to generate a detection signal when the listening device is placed in the outer shell; and a charging circuitry configured to initiate charging of the rechargeable battery in response to receiving the detection signal. Case with Magnetic Over-Center Mechanism : Some embodiments of the present invention relate to a case that can be used to store a portable listening device or another type of electronic device. The case may include: a housing having a cavity for accommodating the electronic device and an accommodation opening, the cavity being in communication with the accommodation opening; a lid fastened to the housing by a pivotable joint, the lid being operable between an open position where the accommodation opening is exposed and a closed position where the lid covers the accommodation opening; and a plurality of magnetic elements disposed in the housing and the lid, the plurality of magnetic elements being configured to establish an over-center position for the lid such that when the lid is then attracted to the closed position, the lid resists rotation from the open position to the closed position until the lid moves past the over-center position. Earbud case with radio frequency off feature : Some embodiments relate to a case for a portable listening device having radio frequency, wherein the case includes: a housing having a cavity configured to accommodate the portable listening device; a lid attached to the housing and operable between a closed position where the lid hides the portable listening device inside the case and an open position where the lid is displaced from the housing such that a user can remove the portable listening device from the case; a lid sensor for detecting whether the lid is in the closed position or the open position; and a circuit system configured to turn on the radio frequency when the lid sensor detects that the lid has moved from the closed position to the open position. The lid sensor can generate an open signal when the lid moves from the closed position to the open position, and the circuit system can be configured to turn on the radio frequency in response to the open signal. In some cases, the case may further include an electrical connector having a first contact positioned in the cavity to electrically connect to a second contact on the portable listening device when the portable listening device is accommodated in the cavity, and the circuit system can turn on the radio frequency in the portable listening device by sending an instruction to the portable listening device via the first contact. Earbud with acoustic insert : Some embodiments of the present invention relate to an earplug, which includes: a housing having an open-ear portion; a directional sound port disposed in the open-ear portion; a driver assembly positioned within the housing, the housing having a front volume disposed in front of the driver assembly and a rear volume disposed behind the driver assembly; and an acoustic insert positioned within the housing behind the driver assembly and attached to the inner surface of the housing such that the acoustic insert and the housing form a bass channel routing from the rear volume to a porous port vent within the housing. The acoustic insert may include a notch defined by a raised weld zone acoustically bonded to the inner surface of the housing. In some cases, the notch within the acoustic insert forms three walls of the bass channel, and the housing forms the fourth wall of the bass channel. The acoustic insert may further include pores coupling the front volume to the porous port vent, and the bass channel and the pores may be coupled to a porous cavity vented via the porous port vent. In some examples, the acoustic insert is formed of carbon-doped plastic that absorbs laser energy. In some embodiments, a method of forming an earplug is provided. The method may include: forming a housing having an inner surface and an outer surface; forming an acoustic insert such that it has a notch defined by a raised weld zone; inserting the acoustic insert into the housing such that the raised weld zone is positioned against the inner surface of the housing; and directing a laser through the housing such that it irradiates the raised weld zone of the acoustic insert and welds the raised weld zone to the inner surface of the housing. The housing may be formed of plastic substantially transparent to a certain wavelength of laser, and the acoustic insert may be formed of plastic that absorbs laser energy. Wireless pairing of earplug and case : In some embodiments, a case for a portable listening device that includes a radio frequency may include: a housing having a storage area for the portable listening device; a lid attached to the housing and operable between a closed position in which the lid hides the portable listening device within the case and an open position that allows a user to remove the portable listening device from the storage area; an electrical connector positioned within the storage area, the electrical connector having one or more case electrical contacts that are electrically connected to one or more device electrical contacts of the portable listening device when the portable listening device is stored in the storage area; an input device configured to generate a signal in response to an action by the user; and a processor coupled to the input device and the electrical connector. The processor may be configured to receive the signal from the input device and, in response, send an instruction to the portable listening device via the electrical connector to initiate wireless pairing of the portable listening device with a host electronic device. In some cases, the processor may be further configured to send an instruction to the portable listening device via the electrical connector to turn on its radio frequency in response to receiving the signal from the input device before sending an instruction to the portable listening device to initiate wireless pairing of the portable listening device with the host electronic device. In some embodiments, a method for wirelessly pairing a first electronic device with a second electronic device is provided. The method may include: receiving an input from a user at a third electronic device different from the first device and the second device. In response to receiving the input, the third electronic device may communicate the user input signal to the first electronic device via a wired connection between the third electronic device and the first electronic device. In response to the first electronic device receiving the user input signal, the first electronic device may broadcast a wireless pairing request, and in response to receiving the wireless pairing request, the second electronic device may wirelessly pair with the first device. In some cases, the first electronic device may be a set of wireless earphones, the second electronic device may be a mobile electronic device, and the third electronic device may be a case for a portable listening device. Also, in some embodiments where the third electronic device is a case for a portable listening device, the input from the user may be to open the lid of the case. Earbud case having a socket connector for an earbud : In some embodiments, a case for a pair of earbuds is provided, where each earbud has an ear portion and a stem portion, and the stem portion has an electrical connector disposed at a distal end of the stem portion. The case may include: a housing; an insert positioned within the housing, the insert having a first cavity and a second cavity sized and shaped to receive a first earbud and a second earbud, respectively, each of the first cavity and the second cavity having a receiving opening for receiving the earbud into the cavity and a contact opening opposite the receiving opening; and a contact assembly attached to the insert, the contact assembly including a first pair of electrical contacts extending into the first cavity and a second pair of electrical contacts extending into the second cavity, the first pair of electrical contacts and the second pair of electrical contacts being configured to make electrical contact with the electrical connectors disposed at the distal ends of the first earbud and the second earbud, respectively, via the contact openings. Wireless Earbuds with Electrical Contacts : In some embodiments, a wireless earbud is provided, which includes: a housing having a stem portion aligned with a longitudinal axis, the stem portion including a first end and a second end; a speaker assembly having a driver unit and a directional sound port proximate the first end and offset from the longitudinal axis, wherein the driver unit is aligned to emit sound from the directional sound port and includes a magnet, a voice coil, and a diaphragm; a rechargeable battery disposed within the housing; and a first external contact and a second external contact exposed at an outer surface at the second end of the stem portion and electrically coupled to provide power to the rechargeable battery. The first external contact and the second external contact may each have a partially annular shape and may be spaced apart in a relationship that is opposed and symmetric. In some cases, the perimeters of the first external contact and the second external contact are flush with the outer surface of the stem portion. In some embodiments, a wireless earbud includes: a housing; a rechargeable battery disposed within the housing; a speaker assembly including a driver unit and a directional sound port, wherein the driver unit is aligned to emit sound from the directional sound port and includes a magnet, a voice coil, and a diaphragm; and a plurality of contacts exposed at an outer surface of the housing, each of the plurality of contacts including a conductive substrate having a binary metal alloy plating layer at an outer surface of each contact, the binary metal alloy plating layer including rhodium and ruthenium. In some cases, the weight percentage of rhodium is at least 85%, with the balance being ruthenium. Magnetic Retention of Earbuds within a Cavity : Some embodiments of the present invention relate to a case for earbuds having one or more earbud magnetic components. The case may include: a storage cavity sized and shaped to receive the earbuds; one or more housing magnetic components disposed within the case and positioned and configured to magnetically attract the earbuds and magnetically secure the earbuds within the storage cavity and magnetically attract a second earbud and magnetically secure the second earbud within a second storage cavity; and a lid operable between an open position where the storage cavity is exposed and a closed position where the lid covers the storage cavity. The case may be configured to store a pair of earbuds, and the storage cavity includes a first storage cavity sized and shaped to receive a first earbud of the pair of earbuds and a second storage cavity sized and shaped to receive a second earbud of the pair of earbuds. In some embodiments, the one or more housing magnetic components may include: a first plurality of magnetic components disposed around the first storage cavity and configured to magnetically attract the first earbud and magnetically retain the first earbud within the first storage cavity; and a second plurality of magnetic components disposed around the second storage cavity and configured to magnetically attract the second earbud and magnetically retain the second earbud within the second storage cavity. In some embodiments, an earbud includes: a housing formed to at least partially fit within a user's ear; a directional sound port formed within the housing; a speaker assembly disposed within the housing and including a driver unit including a first magnet, the driver unit aligned to emit sound from the directional sound port; and a magnetic retention component separate from the speaker assembly and positioned within the housing. The housing may have an ear portion and a stem portion, and the magnetic retention component may be disposed within the ear portion. The driver unit may include a diaphragm and a voice coil, and the first magnet may be operatively coupled to the voice coil to move the diaphragm in response to an electrical signal, and the magnetic retention component is not operatively coupled to the voice coil. In some embodiments, a wireless listening system is provided that includes the above-described case and a pair of earbuds. Case having an inductive charging transmitter for charging a portable device : In some embodiments, a case for a portable listening device includes: a housing having one or more cavities configured to receive the portable listening device and an external charging surface; a lid attached to the housing and operable between a closed position where the lid is aligned over the one or more cavities and an open position where the lid is displaced from the one or more cavities; a battery; a first charging system configured to charge the portable listening device when positioned in the one or more cavities; and a second charging system including a transmission coil positioned within the housing adjacent to the external charging surface, the transmission coil configured to wirelessly transmit power to a power receiving coil of an electronic device positioned outside the housing adjacent to the external charging surface. In some embodiments, the portable listening device can be a case for a pair of earbuds; the housing can include a first cavity and a second cavity configured to receive the first earbud and the second earbud, respectively; and the first charging system can be configured to charge the earbuds when the first earbud and the second earbud are positioned within the first cavity and the second cavity. Waterproof socket connector : In some embodiments, a power socket connector is disclosed that includes: a housing composed of an electrically insulating polymer extending between a receiving surface and a back surface, the housing defining a cavity communicating with an opening in the receiving surface to receive a plug portion of a mating plug connector; a contact spacer positioned adjacent to the back surface; a gasket disposed between the back surface of the housing and a contact assembly; a plurality of contacts, each of the plurality of contacts having a tip positioned within the cavity, an anchoring portion that anchors each contact to the contact spacer, and a crossbar portion that connects the tip to the anchoring portion; and a metal bracket disposed around an outer surface of the housing. Earbud with capacitive touch sensor : Some embodiments relate to an earbud that includes: a housing defining a cavity that houses one or more electrical components of the earbud, the housing having a touch-sensitive region at an outer surface of the housing and an inner surface within the cavity that faces the outer surface; a capacitive sensor insert having a first surface and positioned within the housing such that the first surface is adjacent to the inner surface of the housing, the first surface having a metallized circuitry formed thereon; an earbud processor disposed within the housing; and at least one conductor that electrically couples the capacitive sensor insert to the earbud processor. The capacitive sensor insert can be formed to closely match the shape of the housing. In some cases, the metallized circuitry forms at least one self-capacitance sensor, where a self-capacitance circuitry that can be detected when touched by a user is loaded. In other cases, the metallized circuitry includes column electrodes and row electrodes that form at least one mutual-capacitance sensor, where a mutual coupling between the column electrodes and the row electrodes is changed and detected when touched by a user. The capacitive sensor insert is formed of a plastic including metal particles. Case with a torsion spring over-center mechanism : In some embodiments, a case for a listening device includes: a housing having a cavity for receiving the listening device; a lid attached to the housing by a pivot joint to allow the lid to rotate between a closed position where the lid is aligned with the cavity and an open position where the lid is angularly displaced to allow removal of the listening device from the cavity; and a over-center mechanism for the lid, the over-center mechanism including an extension attached to the lid and disposed on a side of the pivot joint opposite to the lid, wherein the extension contacts an arm that blocks the lid from rotating from the open position to the closed position when the lid is then driven to the closed position until the lid moves past the over-center position. To better understand the nature and advantages of the present invention, reference should be made to the following description and drawings. However, it should be understood that each of the figures is provided for illustrative purposes only and is not intended to define a limitation on the scope of the present invention. Also, generally, and unless clearly contrary to the description (where elements in different figures are denoted by the same reference numerals), elements are generally the same or at least similar in function or purpose. Some embodiments of the present invention relate to portable listening devices and cases for containing and / or charging such devices, the cases having improved features that can enhance the user experience associated with using the case and / or the portable listening device. Although the present invention can be used with a wide variety of portable listening devices, some embodiments of the present invention are particularly applicable to wireless earbuds and cases for wireless earbuds, as described in more detail below. For example, in some embodiments, a pair of wireless earbuds are sized and shaped to fit within a case that may also include a rechargeable battery and a charging circuitry. The pair of earbuds can be charged when an earbud detector within the case detects that the earbuds are placed within the case. Additionally, the case can include sensors to detect whether the lid is open so that the radio frequency within each earbud can be activated and thus it can be ready for use by the user. Similarly, when the lid is closed, the radio frequency can be turned off, thus preserving the charge in the earbud battery. In another example, the case can have a pairing button thereon that can be operated to place the earbuds in a pairing mode. In another example, the case can also have one or more charging indicator lights to inform the user of the amount of charge in the case battery as well as the amount of charge in each earbud. In another example, the case can have a lid that has an over-center configuration such that when the lid is in the closed position it is in a first stable position and when in the open position it is in a second stable position, but is in an unstable position when between the closed and open positions. In some embodiments, the over-center configuration can be achieved by using two pairs of magnets, and in other embodiments, it can be achieved by a torsion spring. In other examples, the case can have one or more magnets therein to attract the earbuds into cavities formed within the case and hold the earbuds until the user removes them. In another example, the case can be liquid-tight to prevent liquid from damaging the internal circuitry. The electrical connectors for both earbud recharging and case recharging can resist the penetration of liquid. In another example, the earbuds can have acoustic inserts that form one or more acoustic ports that enable the internal speaker to provide audio performance within the limited space within the earbud housing, such as a bass port vent and a rear vent. In another example, the earbud case can be used to initiate Bluetooth® pairing between the earbuds and a host device. In one embodiment, a lid position sensor detects when the lid is open and initiates pairing of the earbuds. To better understand the features and aspects of the portable listening device and its case according to the present invention, in the following sections, further context of the present invention is provided by discussing several specific implementations of earbuds and cases for earbuds according to embodiments of the present invention. The specific embodiments discussed are for illustrative purposes only, and other embodiments can be used for other portable listening devices and cases for other portable listening devices as well as other devices. As used herein, the term "portable listening device" includes any portable device designed to play sounds audible to a user. Headphones are one type of portable listening device, and portable speakers are another type of portable listening device.The term "headphone" refers to a pair of small portable listening devices designed to be worn on or around a user's head. It converts an electrical signal into a corresponding sound that can be heard by the user. Headphones include traditional headphones worn on the user's head and comprising a left listening device and a right listening device connected to each other by a headband, headset (a combination of headphones and a microphone), and earbuds (very small headphones designed to fit directly into the user's ear). Traditional headphones include on-ear headphones (sometimes called earcup or full-size headphones) with ear pads that completely enclose the user's ear, and supra-aural headphones (sometimes called circum-aural headphones) with ear pads that press against the user's ear rather than enclosing the ear. As used herein, the term "earbud", which may also be referred to as an earpiece or in-ear headphone, includes both small headphones that fit into the user's outer ear facing the ear canal without being inserted into the ear canal; and in-ear headphones that are inserted into the ear canal itself, sometimes called canal earphones. FIG. 1 depicts a simplified plan view of a case 100 for a pair of wireless earbuds according to some embodiments of the present invention. As shown in FIG. 1, the case 100 includes a housing 105, also referred to as a main body, which has one or more cavities 110a, 110b configured to house a pair of earbuds 115a, 115b. In some embodiments, the cavities 110a, 110b may be located on opposite sides of a central plane of the case 100 adjacent to each other. Each cavity 110a, 110b may be sized and shaped to match the size and shape of its respective earbud 115a, 115b. Each cavity may include a stem section 116a, 116b and a plug section 117a, 117b. Each stem section 116a, 116b may be an elongated generally cylindrical cavity extending from its respective plug section 117a, 117b towards the bottom 106 of the case 100. Each plug section 117a, 117b may be offset from its respective stem section 116a, 116b and open at the upper surface 108 of the housing 105. Embodiments of the present invention are not limited to any particular shape, configuration, or number of cavities 110a, 110b, and in other embodiments, the cavities 110a, 110b may have different shapes to accommodate different types of earbuds, may have different configurations and / or may be a single cavity or more than two cavities. The case 100 further includes a lid 120 attached to the housing 105. The lid 120 may be operable between two positions: a closed position where the lid 120 is aligned over one or more cavities 110a, 110b to completely enclose a pair of earbuds 115a, 115b within the housing, and an open position where the lid is displaced from the housing and the cavities 110a, 110b such that a user can remove the earbuds from the cavities or replace the earbuds within the cavities. The lid 120 may be pivotally attached to the housing 105 and may include a magnetic or mechanical system (not shown in FIG. 1) that provides bistable operation to the lid 120, as described more fully below. In some embodiments, the case 100 may also include: a charging system 125 configured to charge a pair of earbuds 115a, 115b; one or more magnets 130 configured to orient and retain the pair of earbuds within one or more cavities 110a, 110b; and other features described further below. FIG. 2 is a simplified block diagram of a system 200 according to an embodiment of the present invention. The system 200 may include a pair of earbuds 202a, 202b; a case 204 for the pair of earbuds; and a power source 205 for charging the case. The earbuds 202a, 202b may be located within the case 204 where they can be conveniently stored and charged (e.g., within an internal space or cavity of the case defined by a housing or an insert within the housing). The case 204 may represent the case 100 discussed above with respect to FIG. 1, and the earbuds 202a, 202b may represent the earbuds 115a, 115b. Each earbud 202a, 202b may each have one or more input components 255, internal components 260, and one or more output components 265.In some embodiments, one or more input components 255 can be a microphone input component and one or more buttons or sensors that temporarily store user touches. In various embodiments, an accelerometer or a capacitive sensor can be used as the input component 255 and can be activated (e.g., by a user) to answer a call or command the earbuds 202a, 202b to enter a pairing mode that can be indicated by lights on either or both earbuds. In various embodiments, one or more internal components 260 can include speakers, microphones, rechargeable batteries, processors, and / or other circuitry and components. In various embodiments, one or more output components 265 can be audio from a speaker, a light, or other indicators. In some embodiments, an indicator light can indicate an incoming call, battery level, pairing mode, or other functions. In some embodiments, each of the earbuds 202a, 202b can include a radio frequency that can be both an input 255 device and an output 265 device. The radio frequency can enable the earbuds to receive an audio signal from an audio player (such as a smartphone). In some embodiments, one or more of the earbuds 202a, 202b include a radio frequency that can also transmit an audio signal (such as a microphone signal) from one or more of the earbuds. In still other embodiments, one or more of the earbuds 202a, 202b can include a radio frequency that can transmit communication signals that can command a receiving device (e.g., a host device such as a smartphone) to perform one or more functions, such as (but not limited to) connecting a phone call, disconnecting a phone call, pausing audio playback, fast-forwarding or rewinding audio playback, or muting a microphone signal. The radio frequency can use any short-range low-power communication protocol, such as Bluetooth®, Low Energy Bluetooth®, or ZigBee among the protocols. The case 204 can include a case processor 210, an earbud detector 215, a radio frequency 217, a lid sensor 220, a case charging circuitry 225, a battery 227, and an earbud charging circuitry 230. The case 204 can also include: an earbud interface 245 that enables the circuitry within the case 204 to communicate with and / or charge the earbuds 202a, 202b; and a power interface 250 that couples the case to a wired or wireless power source 205, such as an AC or DC power source or an inductive charging pad. In some embodiments, the case charging circuitry 225, the battery 227, the earbud charging circuitry 230, and the interfaces 245 and 250 are all representative components of the charging system 125 shown in FIG. 1. The power interface 250 can be part of a socket connector for a micro USB connector, a Lightning connector, or other connector that can provide power to the earbud case 204. Alternatively or in addition to the socket connector, the power interface 250 can include a wireless power receiver that can receive inductive power from the power source 205, such as one or more wireless power receiving coils. The earbud interface 245 can transfer power and / or data between the case 204 and the earbuds via a case transfer interface 270 within each earbud.The earbud interface 245 may include: an electrical connector, such as one of the connectors described herein with respect to FIGS. 4A - 8C; different types of electrical connectors; or a wireless power transmitter, such as a wireless power transfer coil that can transfer inductive power to an inductive power receiver within the earbud. The case processor 210 may be configured to control various functions of the case 204, as described in more detail below. In some embodiments, the earbud detector 215 includes one or more sensors that detect when one or both of the earbuds 202a, 202b are placed within the case 204. In one embodiment, the earbud detector 215 may be a circuit that periodically "pings" the earbud contacts within the case 204 to determine the presence of the earbuds 202a, 202b. In other embodiments, the earbud detector 215 may be any type of mechanical or electrical sensor, such as (but not limited to) a magnetic sensor, an optical sensor, a switch, a Hall effect sensor, a flux sensor, a capacitive sensor, a photodetector, a proximity detector, a momentary switch, or any other type of sensor. In an embodiment where the earbud detector 215 is a flux sensor, the flux sensor may be beneficial for minimizing the power consumption of the case 204. As an example, the flux sensor may be formed in the case 204 by a coil and one or more magnets within the earbuds 202a, 202b for each earbud. Each flux sensor may be configured to generate a current in the coil when the earbud is inserted into or removed from the case 204, and the magnet within the earbud passes through the coil. In another example, the flux sensor may act as a completely passive sensor that does not require power to operate and generates its own energy to notify the processor 210 of the removal or replacement of the earbuds 202a, 202b within the case 204. In some embodiments, a Hall effect sensor may also be beneficial for minimizing power consumption. In various embodiments, one or more sensors may be beneficial such that no bias (e.g., a ping) needs to be applied to the earbud connector, thus reducing contact corrosion and / or oxidation in a wet environment. In one example, the case 204 may include separate earbud storage cavities within the case, such as the cavities 110a, 110b described above, and the earbud detector 215 may include a first earbud detector and a second earbud detector, one detector for each cavity. The first earbud detector may be operatively coupled to detect when an earbud (e.g., the left earbud) is inserted into the first of the cavities, and the second earbud detector may be operatively coupled to detect when an earbud (e.g., the right earbud) is inserted into the other cavity. In other embodiments, a single detector may detect when the earbuds 202a, 202b are placed within the case 204. In response to detecting an earbud inserted into the case, the earbud detector 215 may generate a detection signal that may be sent to and processed by other circuitry within the case 204 to initiate charging of the earbud.When the earbud detectors 215 include a first detector and a second detector that can respectively detect the insertion of the left and right earbuds (or a first earbud and a second earbud that can be interchanged between the left and right ears), each earbud detector can generate a separate detection signal that can initiate charging only for the detected earbud. Similar to initiating charging, the earbud detectors 215 can also be used to stop charging. For example, the earbud detectors 215 can detect when either or both of the earbuds are removed from the case and generate a removal signal to stop charging the removed earbud(s). In some embodiments, the earbud detectors 215 can initiate the charging process for each earbud 202a, 202b when the earbud detectors detect the formation of an electrical contact between the earbuds and the corresponding charging contacts within the housing (e.g., within each cavity 110, 110b). More specifically, in various embodiments, the earbud detectors 215 can "connection test" the charging contacts periodically to see if either or both of the earbuds 202a, 202b are present within each cavity 110a, 110b. Even if either or both of the earbuds 202a, 202b have zero battery charge, they can still have a characteristic impedance or other electrical characteristics that enable the earbud detectors 215 to detect their connection to the charging contacts and initiate charging with the earbud charging circuitry 230. The charging contacts and electrical connections between the earbuds 202a, 202b and the case 204 will be discussed in detail below. In some embodiments, the earbud detectors 215 are part of the processor 210 and the processor performs the sensing. In other embodiments, the earbud detectors 215 are separate active / passive components. In various embodiments, the case 204 does not include a case processor 210, and instead, a circuitry including various active and / or passive components is configured to perform the functions described herein and attributed to the processor. In some embodiments, the case processor 210 can communicate with a pair of earbuds 202a, 202b by sending and receiving data via the earbud interface 245 (and via the case interface of either or both of the earbuds), and can communicate with the power source 205 by sending and receiving data via the power interface 250. That is, in various embodiments, the earbud interface 245 and the power interface 250 can be capable of carrying both power and data signals for one-way or two-way communication. In some embodiments, separate power and data contacts can be used, and in various embodiments, one set of contacts is used for both power and data. For example, in some embodiments, the power source 205 can be a computing device that communicates with the power interface 250 via an interface (not shown) such as a USB interconnect or a Lightning (Lightning-type) interconnect developed by Apple Inc. The interconnect can provide DC current to the case battery 227 for charging and can provide two-way communication between the case processor 210 and the computing device.In another example, the power source 205 can transmit a firmware update to both the cartridge processor 210 and a pair of earbuds 202a, 202b via the same contacts used to charge the device. Data communication between the earbud interface 245 and the pair of earbuds 202a, 202b can use a similar communication protocol as discussed above or any other protocol (such as, serial communication). In some embodiments, in addition to or instead of relying on data exchange via interfaces 245 and 250, the cartridge 204 can also include a radio frequency 217 that enables the cartridge to transmit and receive data communication with the earbuds 202a, 202b and a host device (such as, a smartphone, a tablet computer, a laptop computer, or the like). For example, the radio frequency 217 can be used to initiate a pairing sequence between the earbuds 202a, 202b and the host device. In another example, the radio frequency 217 can be used to receive music downloaded from the host device for storage in the cartridge 204. The lid sensor 220 can detect when the lid of the cartridge (such as, the lid 120 shown in FIG. 1) is in the open position and when the lid is in the closed position. In some embodiments, the cartridge processor 210 is coupled to the lid sensor 220 and receives signals from the lid sensor indicating when the lid is open and closed. More specifically, in some embodiments, the lid sensor 220 can generate an "open" signal and send it to the processor 210 immediately after detecting that the lid is open, and the lid sensor 220 can generate a "closed" signal and send it to the processor 210 immediately after detecting the closing of the lid. The processor 210 can be configured to communicate with the pair of earbuds 202a, 202b to turn on their radio frequencies when the lid is in the open position (such as, in response to receiving the "open" signal), so that they are ready for use by the user, and to turn off their radio frequencies to conserve their power when the lid is in the closed position (such as, in response to receiving the "closed" signal). In various embodiments, the lid sensor 220 can also trigger the cartridge processor 210 to enter the pairing mode when the cartridge lid is open, as explained in more detail below. In some embodiments, the cartridge processor 210 can communicate with the pair of earbuds 202a, 202b via the earbud interface 245 and the cartridge interface 270 using a wired connection as discussed above, while in other embodiments, in addition to or instead of using a wired connection, the cartridge processor 210 can also communicate with the earbuds 202a, 202b wirelessly via interfaces 245 and 270. In some embodiments, the lid sensor 220 can be any type of mechanical or electrical switch, including (but not limited to) momentary switches, capacitive sensors, magnetic sensors (such as, Hall effect), or optical sensors. The cartridge battery 227 provides power for the circuitry associated with the cartridge 204 and can be a rechargeable battery that can be charged via the power interface 250 by the power source 205 and the housing charging circuitry 225. The cartridge battery 227 is also coupled to the earbud interface 245 and can charge the pair of earbuds 202a, 202b in conjunction with the earbud charging circuitry 230.In some embodiments, the earbud charging circuit system 230 can charge a pair of earbuds 202a, 202b at any time when they are properly stored within the cavities 110a, 110b, even if the case 204 is not coupled to a power source 205. Thus, the case 204 may be able to charge a pair of earbuds 202a, 202b when the case is, for example, in a user's pocket, as long as the case battery 227 has sufficient charge. In various embodiments, the case battery 227 may be sealed within the case 204, and in some embodiments, the case battery may be removable for servicing and / or replaceable by another rechargeable battery. The case processor 210 may additionally be coupled to the case charging circuit system 225, which may control the charging of the case battery 227 (e.g., control the voltage and current supplied to the battery to optimize the charging speed and lifespan of the battery). In some embodiments, the case charging circuit system 225 may include a DC / DC converter, an AC / DC converter, battery voltage level monitoring circuitry, and / or safety features to properly charge the case battery 227. Similarly, in some embodiments, the case processor 210 may be coupled to the earbud charging circuit system 230, which may control the charging of the batteries within a pair of earbuds 202a, 202b via the earbud interface 245 (e.g., control the voltage and current supplied to the batteries to optimize the charging speed and lifespan of the batteries). In various embodiments, the earbud charging circuit system 230 may include a DC / DC converter, battery voltage level monitoring circuitry, and / or safety features to properly charge the earbud batteries. In various embodiments, the case 204 may include one or more charging indicators 235 that can indicate the charge level of the case battery 227 and / or the pair of earbud batteries such that a user can view the indicators on the outer surface of the case 100 (see FIG. 1). In some embodiments, the charging indicator 235 may include three LEDs, one to indicate the status of the case battery 227 and one for each of the batteries in a pair of earbuds 202a, 202b. In various embodiments, the charging indicator 235 may be a first color (e.g., green) when the respective battery is almost fully charged, a second color (e.g., amber) when the respective battery is less than 75% charged, and a third color (e.g., red) when uncharged or limitedly charged. In some embodiments, the charging indicator 235 may include multiple LEDs for each of the battery 227, earbud 115a, and earbud 115b, where the number of lit LEDs indicates the strength of the battery for each component. For example, in one particular case, three sets of three LEDs may be included on the case 204. In some embodiments, the case 204 may also include one or more user input devices 240.Each included input device 240 can be a button or other types of input components that respond to input from the user or otherwise receive an input activation and generate a signal that can be communicated to the processor 210 or other circuitry within the case 204. The processor 210 or other circuitry can then act on the signal. For example, in various embodiments, the radio frequency for a pair of earbuds 202a, 202b can be Bluetooth® or other radio frequency systems that require a pairing sequence to establish communication between the pair of earbuds and the wireless transmitter in the electronic device. In such embodiments, if the input device 240 is a wireless pairing button, the processor 210 can send a signal to the earbuds via the earbud interface 245 to place the wireless radio frequency within a pair of earbuds 202a, 202b in pairing mode. More specifically, in some embodiments, the user can press the pairing button located on the case 204, and the pairing button notifies the case processor 210 to instruct a pair of earbuds 202a, 202b to enter pairing mode via the interface 245. In some embodiments, a pair of earbuds 202a, 202b may need to be within the case (e.g., within the cavities 110a, 110b as shown in FIG. 1) when entering pairing mode, while in other embodiments, the earbuds may not need to be within the case 204 but only need to be within the wireless communication range of the case. Other details regarding wireless pairing will be discussed later in this application. Referring now to FIG. 3, a simplified cross-sectional perspective view of the case 100 is illustrated. As shown in FIG. 3, the case 100 includes a housing 105 having cavities 110a, 110b for holding a pair of earbuds 115a, 115b and various electronic circuitry. The case 100 further includes a lid 120 that is attached to the housing 105 and can be operated between two positions: a closed position where the lid 120 is aligned over one or more of the cavities 110a, 110b to completely enclose a pair of earbuds 115a, 115b within the housing, and an open position where the cavities 110a, 110b are exposed so that the user can remove or replace the earbuds within the cavities. As discussed above, the lid 120 can be pivotally attached to the housing 105 by a joint 305 such that the lid can be operated between the closed position and the open position. In some embodiments, the lid 120 can have bistable positions where it is stable in the closed position and the open position but is unstable between those positions such that it tends to be attracted to the closed position or the open position. In various embodiments, the bistable operation can be achieved by using a first pair of magnetic elements 310a, 310b and a second pair of magnetic elements 315a, 315b, which will be discussed in more detail below. In some embodiments, a lid sensor 220 can be disposed in the housing 105 and configured to detect when the lid 120 is in the closed position (e.g., can detect when the medium 320 is adjacent to the lid sensor) and when the lid is in the open position (e.g., can detect when the medium is not adjacent to the lid sensor). In some embodiments, the detectable medium can be a magnetic material.A pair of earbuds 115a, 115b are adapted to fit within cavities 110a, 110b, each of which cavities is sized and shaped to receive one of the earbuds. In some embodiments, when each earbud is fully inserted into its respective cavity 110a, 110b, a portion of each earbud extends out of the cavity such that the user can easily grasp and remove the earbud from the case. The lid 120 may include a cavity (or a pair of cavities 360a, 360b, as shown in FIG. 3), and the portion of each earbud that extends out of its respective cavity 110a, 110b extends into this cavity. Although not shown in FIG. 3, each cavity 360a, 360b may be sized and shaped to match the size and shape of the portion of each earbud that is surrounded by the cavity to more securely store the earbuds within the case 100. Each earbud may include a speaker assembly (not shown in FIG. 3) disposed within the outer shell of the earbud. The speaker assembly may include a driver unit aligned to emit sound from a self-orienting sound port. The driver unit may include an electromagnetic voice coil, a speaker diaphragm, and a driver magnet (shown as magnet 325 in FIG. 3) operatively coupled to the voice coil to move the diaphragm in response to an electrical signal and produce sound. In addition to the driver magnet, the earbuds according to some embodiments of the present invention may include an additional magnetic plate 330 that is not operatively coupled to the voice coil. Either or both of the magnet 325 and the magnetic plate 330 may be attracted to at least one outer shell magnetic assembly 130 disposed within the case 100. The attractive force may be strong enough to magnetically secure the first earbud 115a within the first cavity 110a and the second earbud 115b within the second cavity 110b, as discussed in more detail below. In some embodiments, the magnetic plate 330 may be made of a magnetic material, and in various embodiments, it may be made by a metal injection molding process. In some embodiments, the magnetic plate 330 is magnetized, while in other embodiments, it is not magnetized but is magnetically attractive. To increase the magnetic attraction between the magnetic assembly 130 and the magnetic plate 330, the magnetic plate 330 in each earbud may be positioned adjacent to the outer shell of the earbud. Additionally, the magnetic plate is contoured to match the curvature of the outer shell, thereby ensuring a minimum distance between the magnetic plate and the outer shell across the surface of the magnetic plate. Similarly, at least some of the outer shell magnetic assemblies 130 may be positioned as close as possible to the surface of the receiving cavity at a location directly spaced from where the magnetic plate 330 will be when the earbud is housed within the cavity. In some embodiments, the outer shell assembly 130 may be contoured to match the curvature of the receiving area (which matches the curvature of its respective earbud), thereby minimizing the distance between the outer shell magnetic assembly 130 and the magnetic plate 330. In some embodiments, the outer shell 105 and the lid 120 may be made of the same material, while in various embodiments, they may be made of different materials. In some embodiments, both the outer shell 105 and / or the lid 120 may be made of a plastic material, stainless steel, aluminum, or any other material.The charging system 125 may include a circuit board 335 or other circuitous structure, a rechargeable case battery 227, electrical interconnects 340 to a pair of earbuds 115a, 115b, one or more electronic components (such as, a case processor 210), and an electrical connector 345 for connecting to a power source 205 (see FIG. 2). In some embodiments, the connector 345 may be a non-exclusive interface such as a USB connector or may be an exclusive interface such as a Lightning connector developed by Apple Inc. In various embodiments, the connector 345 may be liquid-tight, as discussed in more detail below. One or more charging indicators 235 may be visible on the outer surface 350 of the case 100. In some embodiments, each of the pair of earbuds 115a, 115b may be electrically coupled to the charging system 125 by a connector 347 disposed at the end of the stem portion of each earbud 115a, 115b, as described in more detail below. Figures 4A through 8C illustrate several examples of electrical connectors (similar to connector 347 in FIG. 3) that can be used between each of a pair of earbuds 115a, 115b and a case 100 (see FIG. 3). Although each of FIGS. 4A through 8C illustrates an earbud connector for the first earbud 115a, it should be understood that the second earbud 115b can be configured identically to the first earbud 115a and thus includes a similar electrical connector. Additionally, although the embodiments illustrated in FIGS. 4A through 8C include external contacts disposed at the end of the stem of the earbud, in other embodiments, the contacts can be at different locations. FIGS. 4A and 4B are simplified cross-sectional views of an electrical connector 400 that can be incorporated into an earbud case 100 and an electrical connector 405 at the end of the stem portion of earbud 115a, according to an embodiment of the present invention. According to some embodiments of the present invention, the electrical connector 405 can be used to conduct power and / or data. The connector 405 can be part of the earbud interface and can include a first earbud contact 410 and a second earbud contact 415, respectively. A bottom view of the electrical connector 405 is illustrated in FIG. 4B. In some embodiments, the earbud contacts 410, 415 can be annular and separated by an insulator 420. The socket connector 400 can be used in a case (such as case 100 described above) and can have a first earbud case contact 425 and a second earbud case contact 430. The first annular contact 410 can interface with the first earbud contact 425, and the second annular contact 415 can interface with the second earbud contact 430. The first annular contact 410 and the second annular contact 415 can be any type of conductive material including gold, silver, or palladium-coated copper. In some embodiments, the first earbud contact 410 and the second earbud contact 415 are a power contact and a ground contact, respectively. That is, either the first earbud contact 410 or the second earbud contact 415 can be used for power, and the other can be used for ground. As an example, in some embodiments, the first contact 410 is used for power and the second contact 415 is grounded, while in other embodiments, the first contact 410 is used for ground and the second contact 415 is used for power. In various embodiments, other connector configurations with more than two contacts can be used. The first earbud case contact 425 and the second earbud case contact 430 can be coupled to a charging system 125 (see FIG. 3) via electrical interconnects 340 in the case 100 to facilitate charging and communication of each earbud 115a, 115b. In various embodiments, a circular microphone aperture 435 can be located at the center of the second annular contact 415 of each earbud 115a, 115b to facilitate two-way telephone communication and / or noise cancellation. The microphone aperture 435 can be covered by an aesthetic acoustic mesh to protect the microphone from breakage and damage. FIGS. 5A and 5B illustrate another example socket connector 500 that can be incorporated into an earbud case 100 and an electrical connector 505 at the end of the stem portion of earbud 115a, according to an embodiment of the present invention.However, the connector 500 has an annular contact and a center contact, as described in more detail below. The connector 505 can be part of the earbud interface and can include a first earbud contact 510 and a second earbud contact 515, respectively. A bottom view of the electrical connector 505 is illustrated in FIG. 5B. In some embodiments, the annular contact 510 can be annular and the circular contact 515 can be circular, where the contacts are separated by an insulator 520 (e.g., the insulator 520 can be an air gap). The annular contact 510 can be interfaced with the first earbud contact 525, and the circular contact 515 can be interfaced with the second earbud contact 530. In various embodiments, a circular microphone aperture 535 can be located between the annular contact 510 and the circular contact 515, such that one or more of a pair of earbuds 115a, 115b can be used for two-way telephone communication. FIGS. 6A and 6B illustrate another example socket connector 600 that can be incorporated into the earbud case 100 and an electrical earbud connector 605 disposed at the end of the stem portion of the earbud 115a according to an embodiment of the present invention. The socket connector 600 can be in electrical contact with the electrical earbud connector 605, as described in more detail below. The earbud connector 605 can be part of the earbud interface and can include a first earbud contact 610 and a second earbud contact 615, respectively. A bottom view of the electrical earbud connector 605 is illustrated in FIG. 6B. As shown in FIG. 6B, the contacts 610, 615 can be spaced apart in a relationship that is opposed and symmetric to each other. In some embodiments, each of the earbud contacts 610 and 615 can have a partially annular shape (i.e., partially circular), where the open portion of each contact faces the other. For example, the contact 610 can include ends 610a, 610b and the contact 615 can include ends 615a, 615b, where the end 610a is spaced apart from the end 615a and the end 610b is spaced apart from the end 615b. Although FIG. 6B illustrates each of the contacts 610, 615 as semi-circular, in other embodiments, the contacts can include shorter length arcs and / or have completely different opposed shapes. The earbud contacts 610, 615 can be separated from each other by an insulator 620 (e.g., the insulator 620 can be a dielectric material, as discussed in more detail below). The earbud contact 610 can be interfaced with a first earbud case contact 625, and the earbud contact 615 can be interfaced with a second earbud case contact 630. In various embodiments, a circular microphone aperture 635 can be located between the earbud contacts 610 and 615, such that a pair of earbuds 115a, 115b can be used for two-way telephone communication. The socket connector 600 can include a contact carrier 640 that holds the earbud case contacts 625, 630, as described in more detail below. In some embodiments, the contact carrier 640 can make the earbud socket cavity 645 liquid-tight. In some embodiments, each of the first earbud contact 610 and the second earbud contact 615 can respectively include a contact portion that extends into the earbud receiving cavity of the earbud case when the earbud is positioned within the cavity.The socket connector 600 may include a pair of earbud case contacts 625, 630 positioned on opposite sides of the earbud storage cavity and extending into the earbud storage cavity. The earbud case contacts 625, 630 may be held within the storage grooves 628, 633 of the contact carrier 640, as further discussed below. The contact portions of each earbud contact 610, 615 may have arcuate cross-sections that contact the arcuate contact portions 626, 631 of the contacts 625, 630, respectively, during a mating event when the earbud is inserted into the earbud storage cavity. The combination of the arcuate surfaces on the earbud contacts and the earbud case contacts achieves a wiping motion of the contacts each time the earbud is inserted into and withdrawn from the socket connector, thereby establishing a reliable interconnection. In FIG. 6A, the contacts 625, 630 are illustrated in a deflected state that illustrates the approximate position of the contacts when the earbud 115a is fully inserted into its storage cavity such that the earbud contact engages the earbud case connector. The same contacts 625, 630 are also illustrated in non-deflected states 627, 632 in FIG. 6A, which show the contacts extending into the earbud storage cavity prior to mating with the earbud contacts of the earbud 115a. During the mating event, as the earbud 115a is inserted deeper into the earbud storage cavity, the earbud case contacts 625, 630 begin to contact the earbud contacts and deflect outwardly. The outer contact surfaces of the earbud contacts and the earbud case contacts rub against each other during the mating event and during the demating event when the earbud 115a is removed from the earbud storage cavity. In various embodiments, the deflected arcuate portions 626, 631 of the contacts 625, 630 are deflected by the arcuate portions of the first earbud contact 610 and the second earbud contact 615, respectively, during the insertion and removal of the first and second earbuds. Since the arcuate portions are in direct contact and the contacts 625, 630 are deflected (e.g., spring-loaded), a pair of earbuds 115a, 115b has a vertical (e.g., ejection) force applied thereto when fully mated with the case. In some embodiments, as discussed in more detail herein, one or more magnets may be used to overcome the vertical force and hold the earbuds in their respective cavities. In some embodiments, one of the contacts 625, 630 may be configured to contact the earbud contacts 610, 615 by preloading one of the contacts 625, 630 at a different height than the other (e.g., sequential contacts). This may be used in some embodiments to first form a ground connection to the earbud and then form an active electrical connection to the earbud. Wiping contacts and sequential contacts may be used in any of the connector embodiments disclosed herein. In various embodiments, the contact carrier 640 may include a debris notch 609 disposed below the contact interface region. The debris notch 609 may have a cup-shaped shape defined by sidewalls 609a and may be used to provide a location for debris to fall into either earbud cavity.The debris notch 609 can be disposed between the earbud case contact receiving grooves 628, 633 and spaced apart from the contact area, so that debris does not interfere with the earbuds and thus form an electrical contact with the socket connector 600. The debris notch 609 can further open into the earbud receiving cavity so that debris can be periodically removed as needed. In some embodiments, a separate debris notch 609 is disposed below each earbud contact area, while in other embodiments, a single debris notch can be wide enough to capture debris from two contact areas. The debris notch 609 or a similar debris capture structure can be included in any of the connector embodiments disclosed herein. In one embodiment, the depth of the debris notch 609 below the arcuate portions 626, 631 of the contacts 625, 630 is 50% or greater than 50% of the diameter of the debris notch 609. In another embodiment, the depth of the debris notch 609 is 75% or greater than 75% of the diameter of the debris notch 609, and in another embodiment, its depth is 100% of the diameter (e.g., the ratio of depth to diameter is 1:1) or greater than 100%. In some embodiments, the contact 625 can be made of a copper, nickel, and silver alloy, while in other embodiments, it can be made of a phosphor and bronze alloy, and in other embodiments, different alloys can be used. Referring now to FIG. 6C, an exploded view of the socket connector 600 is shown. As shown in FIG. 6C, the connector 600 includes a first housing 650 and a second housing 655, which define a receiving cavity for a pair of earbuds to hold and guide the stem portion of each earbud into the case 100 (see FIG. 1). Although not shown in FIG. 6C, the receiving cavity in each housing can include an elongate tube portion that opens into a larger earbud receiving opening. The elongate tube portion can be sized and shaped to accommodate the stem section of the earbud, and the larger earbud receiving opening can be sized and shaped to partially or fully accommodate the ear interface portion (i.e., the portion of the earbud that fits within the user's ear). In some embodiments, the housings 650, 655 can be separate components joined together by a contact carrier, while in other embodiments, the housings 650, 655 can be a single component that can be formed (e.g., in a molding process, a 3D printing process, or by a milling process). The contact carrier 640 holds the first earbud contacts 625, 630 that can interface with the first earbud, and also holds the third earbud contact 660 and the fourth earbud contact 665 that can interface with the second earbud, respectively. A collar 670 can be coupled to the top surface 675 of the contact carrier 640. In some embodiments, the collar 670 can have a removable rod (not shown in FIG. 6C) that holds the three pieces of the collar together during assembly and can be removed after assembly so that the rod is not included in the finished earbud case.The distal ends 680, 685 of the first housing 650 and the second housing 655 can be narrower than the elongate tube portions of the housings 650, 655 respectively, and each distal end 680, 685 can be adapted to fit within and coupled to the collar 670 to form the complete housing and socket connector assembly 690 illustrated in FIG. 6D. In the complete assembly, each earbud case contact 625, 630 is adapted to fit within a respective contact opening of the housing 650 and each earbud case contact 625, 630 is adapted to fit within a respective contact opening (e.g., the opening 687 visible in FIG. 6C) of the housing 655. Each contact opening (e.g., the opening 687) enables its respective contact to extend into the earbud receiving cavity within its respective housing 650, 655 during a mating event to make electrical contact with the earbud contacts. When assembled, the housing and contact assembly 690 can establish a liquid-tight seal as defined herein. The housing and contact assembly 690 can then be assembled into a case (such as the case 100 illustrated in FIG. 1). In some embodiments, the first housing 650 and the second housing 655 can be a single housing having two cavities (one cavity for each earbud). As defined herein, a liquid-tight seal shall mean a seal that meets one or more of the following ratings as defined by the International Protection Rating and International Electrotechnical Commission (IEC) 60529 (which may also be referred to as the I.P. 68 rating). In some embodiments, the liquid-tight seal will protect the connector assembly against the ingress of harmful water and have a “liquid ingress” rating between 1 (dripping water) and 8 (immersion over 1 meter). In various embodiments, the liquid-tight seal shall be rated between 1 (dripping water) and 4 (splash water), and in some embodiments, the liquid-tight seal shall be rated between 2 (dripping water when the device is tilted 15 degrees) and 5 (water jets). In various embodiments, the liquid-tight seal shall be rated between 3 (spray water) and 6 (powerful water jets), and in some embodiments, the liquid-tight seal shall be rated between 4 (splash water) and 7 (immersion up to 1 meter). In various embodiments, the liquid-tight seal shall be rated between 5 (water jets) and 8 (immersion over 1 meter), and in some embodiments, liquid-tight shall mean the seal will protect the electronic device from liquid ingress for up to 30 minutes at a depth of up to 100 feet. Turning now to FIGS. 7A and 7B, another example of a socket connector 700 similar to the connector 600 illustrated in FIGS. 6A and 6B is illustrated. However, the socket connector 700 has a different configuration for the contacts and contact carrier, as described in more detail below. This embodiment can use the same earbud connector shown in FIGS. 6A and 6B where the earbud contacts are semi-circular and separated by an insulator. The contact carrier 740 holds respectively the first earbud contacts 725, 730 that can interface with a first earbud and also holds respectively the third earbud contact 760 and the fourth earbud contact 765 that can interface with a second earbud. The cover 770 can be coupled to the bottom surface 775 of the contact carrier 740 by an adhesive layer 773.As illustrated in FIG. 7B, the distal ends of the first housing 750 and the second housing 755 can be respectively adapted within the contact carrier 740 and coupled to the contact carrier to form a complete housing and socket connector assembly 790. The housing and contact assembly 790 can be liquid-tight, thereby meeting one or more of the ranges defined herein. The housing and contact assembly 790 can then be assembled into a case (such as the case 100 illustrated in FIG. 1). Similar to the contact carrier 640, the first earbud contact and the second earbud contact can have an arcuate cross-section and can contact the arcuate portions of the socket connector contacts 725, 730. The combination of the arcuate surfaces can achieve a wiping motion each time the earbud is inserted into and removed from the socket connector, thereby establishing a reliable interconnection. Additionally, in some embodiments, one contact can be configured to contact the earbud first. In one example, the contacts can be pre-loaded at different heights. This can be used in some embodiments to first ground the earbud and then make an active electrical connection with it. Now referring to FIGS. 8A and 8B, another example of a socket connector 800 similar to the connector 400 illustrated in FIGS. 4A and 4B is shown. However, the socket connector 800 has a different configuration for the inner and outer contacts, as described in more detail below. In some embodiments, the earbud contacts 810, 815 can be annular and separated by an electrical insulator 820. The first annular contact 810 can interface with the first earbud contact 825, and the second annular contact 815 can interface with the second earbud contact 830. The first annular contact 810 and the second annular contact 815 can be formed of any type of conductive material including copper and copper alloys, and can be plated with any metal. In various embodiments, a circular microphone aperture 835 can be located at the center of the second annular contact 815, such that one or more of a pair of earbuds 115a, 115b (see FIG. 1) can be used for two-way telephone communication. The microphone aperture 835 can be covered by an aesthetic acoustic mesh to protect the microphone from breakage and damage. Similar to the contact carrier 640, the first earbud contact and the second earbud contact can have an arcuate cross-section and can respectively contact the arcuate portions of the contacts 825, 830 in the socket connector 800. The combination of the arcuate surfaces can achieve a wiping motion each time the earbud is inserted into and removed from the socket connector, thereby establishing a reliable interconnection. Additionally, as shown in FIG. 8A, in some embodiments, the outer surface 821 of the earbud stem can be flush with the outer side surface of the earbud contact. Additionally, in some embodiments, one contact can be configured to contact the earbud first. In one example, the contacts can be pre-loaded at different heights. This can be used in some embodiments to first ground the earbud and then make an active electrical connection with it. Now referring to FIG. 8C, an exploded view of the socket connector 800 is shown, which illustrates how the socket connector can be coupled to the first housing 850 and the second housing 855 that hold and guide the stem portions of each earbud to the case 100 (see FIG. 1).The contact carrier 840 holds the first earbud contact 825 and the second earbud contact 830 for use with the first earbud, respectively, and also holds the third earbud contact and the fourth earbud contact for use with the second earbud. The contact carrier 840 can be coupled to the distal end 880 of the first housing 850 and the distal end 885 of the second housing 855, respectively, to form a complete housing and socket connector assembly. The housing and contact assembly can establish a liquid-tight seal as defined herein. The housing and contact assembly 690 can then be assembled into a case (such as, the case 100 illustrated in FIG. 1). In some embodiments, the first housing 850 and the second housing 855 can be a single housing having two cavities (one cavity for each earbud). In some embodiments, the electrical connectors (e.g., the connector 405 in FIG. 4) on a pair of earbuds 115a, 115b may not be a ring-shaped (e.g., circular) external contact type connector and can be any other type of electrical connector, such as (but not limited to) pins and sockets, pins and contact pads, or wiping arms and contact pads. In various embodiments, one or more contact pads can be located on the vertical portion of the stem portion of the pair of earbuds, and the wiping arms can interface therewith. In another example, the interface connector can be disposed on the ear portion of the earbud housing. The mating connector can be disposed within the case and can interface with the connector when the earbud is placed in its respective cavity. In some embodiments, this connector can be gold-plated to minimize corrosion that can occur due to prolonged contact with the user's ear. In still other examples, radio inductive charging of the earbuds can be used.. Magnetic Retention of Earbuds Figures 9A and 9B illustrate a front perspective view and a rear perspective view, respectively, of one of the wireless earbuds 115a, 115b. As shown in Figures 9A and 9B, the earbuds 115a, 115b include an outer shell having an ear interface portion 903 and a stem portion 910. The ear interface portion 903 can be formed to at least partially fit within the user's ear and can be non-closed, as discussed in more detail below. An aesthetic acoustic mesh 915 can be disposed on the ear interface portion 903 and allows sound to travel from the internal speaker to the user's ear. Some embodiments can have one or more user input components 955 that can be used to answer a call, pause or mute playback, or perform other functions. The outer shells for a pair of earbuds 115a, 115b can be made of a plastic material including, but not limited to, ABS or polycarbonate. Referring now to Figure 10, a top view of the outer shell 105 (see Figure 1) of the case 100 for a pair of earbuds 115a, 115b is illustrated. As shown in Figure 10, the outer shell 105 can include a plurality of retaining magnets 905a to 905h for the earbuds and one or more sensors. The earbuds 115a, 115b can be inserted into cavities 110a, 110b and retained in the cavities by the retaining magnets 905a to 905h. Each cavity 110a, 110b can include a stem section 116a, 116b and a plug section 117a, 117b. The earbud retaining magnets 905a to 905d are used to retain the first earbud 115a, and the retaining magnets 905e to 905h are used to retain the second earbud 115b. However, in other embodiments, fewer or additional retaining magnets 905a to 905h can be used, and the geometry, size, and placement of the magnets can be different from those described. A lid sensor 220 can be used to detect whether the lid 120 (see Figure 1) is closed or open. In the embodiment illustrated in Figure 10, the lid sensor 220 is disposed between the cavities 110a, 110b, but in other embodiments, the lid sensor can be located elsewhere. Lid magnets 910a, 910b can be used to operate the lid (not shown in Figure 10), as discussed in more detail below, and in some situations, the strength of the retaining magnets 905a to 905h can be increased, also as discussed in more detail below. A cross-sectional view A-A is shown in Figure 11 and illustrates a side view of how the earbud 115a can be oriented relative to the magnets discussed above. Figure 11 illustrates a cross-sectional view of the earbud 115a in the case 100. As shown in Figure 11, the earbud 115a is secured within the cavity 110a in the outer shell 105. In some embodiments, the earbud 115a can have a speaker magnet 325 and / or a magnetic plate 330 positioned to align with the earbud retaining magnets 905f and 905h. The speaker magnet 325 and / or the magnetic plate 330 can be attracted to one or more of the earbud retaining magnets 905f and 905h, and one or both can include a magnetic material.As defined herein, a magnetic material is any material that can be attracted by a magnet or that can acquire the properties of a magnet to attract magnetic materials. Such magnetic materials include ferromagnets (i.e., magnets that include iron) and non-ferromagnets. Some example magnetic materials are (but are not limited to): neodymium, steel, nickel, cobalt, and alnico (aluminum nickel cobalt alloy), some alloys of rare earth metals, and some naturally occurring ores (such as lodestone). In contrast, a magnet is a magnetic material that has been magnetized so that it attracts magnetic materials. In one embodiment, the magnetic plate 330 may include a magnetic material, and the magnets 905f and 905h may be oriented and positioned within a certain distance to attract the magnetic plate by a force sufficient to hold the earbud 115a in the housing 105 even when the housing is inverted or shaken. However, the strength of the holding magnets 905f, 905h may be selected to allow the user to grasp the earbud 115a with their fingers and remove the earbud from the housing 105 by applying a force greater than the magnetic holding force. In other embodiments, one or more of the holding magnets 905f, 905h may be positioned and oriented to attract the speaker magnet 325, which may assist in attracting the earbud 115a into the housing 105 and holding the earbud. In other embodiments, an earbud ejection mechanism may be included in the case. For example, when the lid is open (or when an ejection button is pressed), a mechanical ejector pushes the earbud out. In some embodiments, additional magnets (such as those described in FIG. 10) may be used to enhance the attractive and holding forces applied to the magnetic plate 330 and / or the speaker magnet 325. More specifically, the lid magnet 910b may be used to attract the lid 120 (or the magnetic material 1105 disposed within the lid), and may also be used as part of a Halbach array to enhance the magnetic field of the earbud holding magnet 905, thereby attracting the earbud 115a at a greater distance and holding the earbud more securely. A Halbach array is a special configuration of permanent magnets that enhances the magnetic field on one side of the magnetic array while canceling the magnetic field to near zero on the other side. The holding magnets 905e, 905f, and 905g (see FIG. 10) may also be used as part of a Halbach array. Referring now to FIG. 12, a cross-sectional view B-B of the housing 105 from FIG. 10 is shown. As shown in FIG. 12, three earbud holding magnets 905e, 905f, and 905g are disposed within the housing 105 to hold the earbud 115a tightly within its cavity. In some embodiments, the magnets 905g and 905e may have angled upper surfaces to partially conform to the circular shape of the ear interface portion 805 of the earbud 115a. Any configuration or arrangement of magnets may be used to attract the speaker magnet 325 and / or the magnetic plate 330. In some embodiments, the carrier 920 may be formed to hold and position one or more of the magnets 905a to 905h.Also, as described above with respect to FIG. 3, the magnetic plates 330 in each earbud may be positioned adjacent to the earbud housing and contoured to match the curvature of the housing (as shown in FIGS. 11 and 12) to ensure a minimum distance between the magnetic plate and the housing across the surface of the magnetic plate and to increase the magnetic attraction between the housing magnetic assembly and the magnetic plate 330 using the least amount of magnetic material. Similarly, some or all of the housing magnetic assemblies 905a through 905h may be positioned as close as possible to the appropriate surface of the earbud case and contoured to match that surface. Box actuated magneticallyFigures 13 through 21 illustrate a box 1300 having a lid with a magnetically actuated over-center position and several example magnet geometries. As shown in FIG. 13, box 1300 may be similar to box 100 described in FIG. 1 and used to hold a pair of earbuds. However, box 1300 may be used for a variety of other purposes, such as (but not limited to) a container for storing medications, a container for storing cigars, or a recharge container for a micro portable media player. Referring now to FIGS. 13 and 14 simultaneously, in some embodiments, box 1300 may include a housing 1305 having a storage opening 1301 and a bottom surface 1302 disposed opposite the storage opening. Similar to the boxes discussed above, box 1300 may have a closed position as illustrated in FIG. 13, where housing 1305 is covered by a lid 1310 pivotally coupled to the housing. Box 1300 may also have an open position as illustrated in FIG. 14, where lid 1310 is pivotally displaced from housing 1305 by an angle θ. Box 1300 may further include an upper wall 1303 opposite a lower wall 1304 and a first side wall 1306 opposite a second side wall 1307, where the walls extend between storage opening 1301 and bottom surface 1302 to define a cavity 1308 in communication with storage opening 1301. Storage opening 1301 may be further defined by four wall ends 1309a, 1309b, 1309c, and 1309d including the ends of upper wall 1303, lower wall 1304, first side wall 1306, and second side wall 1307, respectively. A first pair of magnetic elements 1315a, 1315b may be oriented so that they repel each other and are disposed near a pivot joint 1317, where a first magnetic element 1315a of the first pair is disposed within housing 1305 and a second magnetic element 1315b of the first pair is disposed within lid 1310. In some embodiments, both of the first pair of magnetic elements 1315a, 1315b may be magnets. A second pair of magnetic elements 1320a, 1320b are oriented so that they attract each other and are disposed near wall end 1309a opposite pivot joint 1317, where a first magnetic element 1320a of the second pair is disposed within housing 1305 and a second magnetic element 1320b of the second pair is disposed within lid 1310. In some embodiments, both of magnetic elements 1320a, 1320b may be magnets, while in another embodiment, one of the magnetic elements may be a magnet and the other element is a magnetic material. In some embodiments, box 1300 may be configured to establish an over-center configuration for lid 1310, where it is in a first stable position when the lid is in the closed position (illustrated in FIG. 13) and in a second stable position when in the open position (illustrated in FIG. 14), but in an unstable position when between the closed and open positions.In some embodiments, this can be achieved by the attractive force between the second pair of magnetic elements 1320a, 1320b overwhelming the repulsive force of the first pair of magnetic elements 1315a, 1315b when the lid 1310 transitions from the open position to the closed position. This condition can be graphically explained as illustrated in FIG. 15. In some embodiments, any of the magnetic configurations disclosed herein can be configured in a multi-pole configuration to concentrate the magnetic fields within and between the magnets. In some embodiments, multi-poles can be used for magnetic elements 1320a and 1320b, where 1320a has a north pole adjacent to the south end, and 1320b has a south pole attracted to the north pole of 1320a and a north pole attracted to the south pole of 1320a. In other embodiments, any other configuration can be used. The multi-pole configuration can be beneficial for attenuating the magnetic field outside the cartridge range so that it does not interact unfavorably with other magnetic objects (such as a card with a magnetic stripe on it). FIG. 15 illustrates a graph of the magnetic force on the lid 1310. As shown in FIG. 13, the lid 1310 has an over-center position due to the forces applied to it from the two pairs of magnetic elements. As discussed above, the first pair of magnetic elements 1315a, 1315b (see FIGS. 13 and 14) are oriented to have a repulsive force shown as a line marked with F. Repulsion The repulsive force of the marked line. Similarly, the second pair of magnetic elements 1320a, 1320b are oriented to have an attractive force shown as a line marked with F Attraction in the graph. As can be seen from an examination of FIG. 14, when the lid 1310 is closed, the angle θ = 0°, and when the lid is fully open (e.g., the lid is pivotally displaced from the housing 1305 to its maximum extent), the angle θ = 180°. At a certain angle marked as X°, there is an over-center position of the lid 1310, at which the lid is unstable and it will "automatically" (i.e., via magnetic attraction) move towards the closed position or the open position. Continuing to refer to FIG. 15, at the angle 0°, the lid 1310 is closed and the attractive force (F Attraction ) of the second pair of magnetic elements 1320a, 1320b is greater than the repulsive force (F Repulsion), so the lid is fastened in the closed position. In some embodiments, even if the first pair of magnetic elements 1315a, 1315b and the second pair of magnetic elements 1320a, 1320b have the same strength, the over-center design will still work because the force exerted by the first pair of magnetic elements on the pivot joint is less than the force exerted by the second pair of magnetic elements on the pivot joint. More specifically, since the first pair of magnetic elements 1315a, 1315b are closer to the pivot joint, they will apply a smaller moment to the lid 1310 compared to the second pair of magnetic elements 1320a, 1320b. However, as the lid 1310 transitions to a larger angle θ (i.e., when transitioning to the open position), the second pair of magnetic elements 1320a, 1320b move apart from each other faster than the first pair of magnetic elements 1315a, 1315b. Since the magnetic force varies exponentially with distance, compared to F Repulsion , F Attraction decreases faster, so at a certain angle X°, F Repulsion overcomes F AttractionAnd the lid will be attracted to the open position. When transitioning from the open position to the closed position, the opposite occurs, and after passing the center point, the lid will be attracted to the closed position. In some embodiments, the first pair of magnetic elements 1315a, 1315b can be configured to prevent the lid 1310 from fully opening (i.e., in the fully open condition, θ is 180°). In some embodiments, the first pair of magnets 1315a, 1315b can be configured to be repulsive, so in such embodiments, the magnetic elements can be extended such that when the lid 1310 rotates towards the 180° open position, the first pair of magnetic elements 1315a, 1315b repel each other such that the weight of the lid is supported by their repulsive force and the lid is essentially suspended in the semi-open position. Some shapes of the magnets (such as an "L") can be used to enhance the force to support the lid 1310 in the semi-open position. In various embodiments, the force vectors of the first pair of magnetic elements 1315a, 1315b can be adjusted to increase or decrease this effect, as discussed in more detail below. In some embodiments, the cartridge 1300 can be designed to give the user a specific feel. For example, in one embodiment, the cartridge 1300 can be designed such that the user can hold the cartridge 1300 in the closed position in their hand, and by buckling their wrist, the lid 1310 will snap open and remain in the open position without leaning on 1305. In other embodiments, the lid 1310 can be in the open position, and the user can buckle their wrist and cause the lid to close. In other embodiments, the user can use their hand to attempt to open the lid 1310, and once the lid has moved a certain distance, the lid will snap open or spring open. In other embodiments, the user can grasp the lid 1310 and move it towards the closed position, and at a certain distance, the lid will snap closed or spring closed. Now referring to FIG. 16, another embodiment of a cartridge 1600 having a magnetically actuated lid 1604 is illustrated. As shown in FIG. 16, the cartridge 1600 has: a pair of magnetic elements having misaligned magnetic poles (i.e., force vectors); and another pair of magnetic elements having a high permeability material for increasing the magnetic force. Similar to the previous embodiment, the lid 1604 is pivotally attached to the housing 1603. However, in this case, the first pair of magnetic elements 1605a, 1605b are oriented such that the force vectors are directly aligned as illustrated by the arrows. In this scenario, the lid 1604 can still have a center-of-the-center position, however, the F from the first pair of magnetic elements 1605a, 1605b Repulsionwill be less than the situation described in FIG. 13. However, this misalignment feature of the force vector can be used to prevent the cover 1604 from transitioning to the fully open 180° position. More specifically, the magnetic force from the first pair of magnetic elements 1605a, 1605b can prevent the cover 1604 from traveling to the closed position, but can also prevent the cover from traveling to the 180° open position. Other variations of the misaligned magnetic force vector can be used and are within the scope of the present invention. Continuing to refer to FIG. 16, the second pair of magnetic elements 1610a, 1610b can have high permeability materials 1615a, 1615b that at least partially surround them to increase the attraction between the second pair of magnetic elements. The high permeability materials discussed herein can be any material having a relatively high magnetic permeability. The magnetic permeability of a material is a measure of the material's ability to support the formation of a magnetic field within itself. More specifically, it is the degree of magnetization that the material acquires in response to an applied magnetic field. Thus, the more "magnetic conductive" or less resistant a material is to a magnetic field, the higher its magnetic permeability. Following this behavior, the high permeability materials 1615a, 1615b discussed herein can essentially redirect the magnetic field from the second pair of magnetic elements 1610a, 1610b such that the attraction is increased. High permeability materials can also be used for repulsive magnets, cover magnets, or magnets for attracting earbuds and securing them within a case. FIG. 17 illustrates another embodiment of the case 1700. As shown in FIG. 17, the case 1700 has springs attached to the first pair of magnetic elements and the second pair of magnetic elements to modify the over-center behavior of the cover. The case 1700 can have a first pair of magnetic elements 1705a, 1705b configured to repel and a second pair of magnetic elements 1710a, 1710b configured to attract. However, in this embodiment, springs 1707a, 1707b can be attached to the first pair of magnetic elements 1705a, 1705b, and springs 1717a, 1717b can be attached to the second pair of magnetic elements 1710a, 1710b. The springs 1707a, 1707b, 1717a, 1717b can be used to modify the over-center position and behavior of the cover 1704. For example, when in the closed position, the first magnetic elements 1705a and the second magnetic elements 1705b can repel each other and compress the springs 1707a, 1707b, thereby reducing some of the repulsive force. Conversely, when in the closed position, the second pair of magnetic elements 1710a, 1710b can be attracted closer together, thereby generating a higher attraction because the springs 1717a, 1717b allow the magnetic elements to move closer together. Other configurations of springs can be used with the magnetic elements without departing from the present invention. Now referring to FIGS. 18 through 21, various magnet geometries can be used in the cases discussed above. These are merely examples, and other geometries can be used without departing from the present invention. FIG. 18 shows a square bar 1800, while FIG. 19 shows a rectangular bar 1900. FIG. 20 shows an "L" shaped bar 2000, and FIG. 21 shows a cylindrical bar 2100.Spring-Actuated CaseReferring to FIGS. 22A through 22D, a case and a spring-actuated hinge are described. As shown in FIG. 22A, case 2200 has a lid 2210 with a spring-actuated over-center mechanism 2220. Case 2200 can be similar to case 100 described in FIG. 1 and case 1300 described in FIG. 13, and in some embodiments, can be used to store and charge a pair of earbuds or other types of portable listening devices. However, in other embodiments, case 2200 can be used to store a variety of other objects different from portable listening devices. Similar to the cases discussed above, case 2200 can have a closed position as shown in FIG. 22A, where outer shell 2205 is covered by lid 2210 pivotally coupled to the outer shell. Case 2200 can also have an open position as shown in FIG. 22D, where lid 2210 is pivotally displaced from outer shell 2205. The spring-actuated over-center mechanism 2220 is shown in more detail in an exploded view in FIG. 22A. Lid 2210 includes an extension 2225 attached to the lid and disposed on the side of the lid opposite the pivot joint 2230. That is, when lid 2210 rotates about pivot joint 2230, extension 2225 also rotates about the pivot joint. Extension 2225 has a rounded distal end 2226 that contacts spring-loaded arm 2235 such that when the lid is then driven to the closed position (shown in FIG. 22D), the lid resists rotation from the open position to the closed position until the lid moves past the over-center position (shown in FIG. 22C). Spring-loaded arm 2235 is attached at a first end to a second pivot joint 2240 and extends to a distal tip 2245. Spring-loaded arm 2235 can have a rounded distal tip 2245 and first and second surfaces 2246 and 2247 respectively configured to face each other and extend between the distal tip and the first end. In the illustration of FIG. 22A, spring-loaded arm 2235 has a clockwise torque applied from a torsion spring. As lid 2210 moves toward the open position, extension 2225 rotates in a clockwise direction about pivot joint 2230, slides along a first portion 2248 of first surface 2246, and forces arm 2235 to rotate in a counterclockwise direction to increase the clockwise torque on the arm. Thus, spring-loaded mechanism 2220 blocks lid 2210 from transitioning from the closed position (shown in FIG. 22A) toward the open position (shown in FIG. 22D). FIG. 22B illustrates an isometric view of spring-loaded mechanism 2220. As shown in FIG. 22B, spring-loaded mechanism 2220 includes spring-loaded arm 2235, extension 2225, torsion spring 2250, and spring stop 2255. Torsion spring 2250 is formed around the pin of second pivot joint 2240. However, in other embodiments, different configurations for the mechanism can be used, including (but not limited to) cantilever springs and helical springs. FIG. 22C illustrates case 2200 with lid 2210 partially open.As shown in FIG. 22C, the lid 2210 is shown in an over-center position, where it is in a first stable position when the lid is in the closed position (illustrated in FIG. 22A) and in a second stable position when in the open position (illustrated in FIG. 22D), but in an unstable position when between the closed and open positions. In some embodiments, the over-center effect of the lid 2210 can be achieved by the extension 2225, which has a rounded distal end 2226 that contacts the arm 2235, and the arm has a clockwise torque applied thereto. In various embodiments, when in the unstable position between the closed and open positions, the extension 2225 is oriented perpendicular to the first surface 2246. In some embodiments, the arm 2235 and / or the distal end 2226 may have a lubricant and / or one or more lubricant channels thereon to maintain a low coefficient of friction between the parts and provide smooth actuation. FIG. 22D illustrates the case 2200 with the lid 2210 fully open. As shown in FIG. 22D, the lid 2210 is past the over-center position and in a stable open position. In some embodiments, the stable position can be achieved by the extension 2225 passing over the over-center location on the arm 2235, where the extension 2225 slides along a second portion 2249 of the first surface 2246, and the arm holds the lid open due to the clockwise moment applied to the arm by the torsion spring 2250 (see FIG. 22B). Earbud Case with Wireless Charging Transmitter Referring now to FIG. 23, which illustrates an earbud case 2300 including a wireless power transmission component 2330 that enables the case to wirelessly charge an accessory electronic device outside rather than inside the case. For example, as shown in FIG. 23, the case 2300 is depicted as wirelessly charging a watch 2301 placed above and aligned with the wireless power transmission component 2330. Although FIG. 23 illustrates the watch as the charged accessory device, embodiments of the present invention can equally be used to wirelessly charge other suitable devices. In some cases, embodiments of the present invention are particularly suitable for use with portable electronic media devices (because of their potentially smaller form factor). As used herein, an electronic media device includes any device having at least one electronic component that can be used to present human-perceivable media. Such devices can include, for example, portable music players (e.g., MP3 devices and the iPod from Apple Inc. TMdevices), portable video players (e.g., portable DVD players), cellular phones (e.g., smart phones such as the iPhone device of Apple Inc.), video cameras, digital still cameras, projection systems (e.g., holographic projection systems), gaming systems, PDAs, and tablet computers (e.g., the iPad device of Apple Inc.), laptop computers, or other mobile computers. Some of these devices may be configured to provide audio, video, or other data or sensory output. In the embodiment illustrated in FIG. 23, the case 2300 may include all or some of the features of the case 204 discussed above with respect to FIG. 2 along with a second charging system, where the wireless power transfer component 2330 is positioned within the housing 2335 adjacent to the external charging surface 2340. In some embodiments, the external charging surface 2340 may be any external surface of the case 2300. The wireless power transfer component 2330 may be configured to wirelessly transfer power across the housing 2335 to a power receiving coil (not shown in FIG. 23) of the watch 2301 when the watch 2301 is positioned outside the housing 2335 adjacent to the external charging surface 2340, as discussed in more detail below. As further shown in FIG. 23, the watch 2301 includes a housing 2302 that houses a display 2304 and various input devices (including a dial 2306 and buttons 2308). The watch 2301 may be worn on a user's wrist and fastened thereto by a strap 2310. The housing 2302 also houses electronic circuitry (not shown in FIG. 23), including a processor and communication circuitry. A battery (not shown in FIG. 23) inside the housing 2302 powers the watch 2301. The battery may be recharged by the wireless power transmission system, and the watch 2301 may include circuitry configured to operate as a receiver in the wireless power transmission system, while the wireless power transmitter component 2330 is the transmitter in the system. One example of a wireless power transmission system is an inductive power transmission system. In an inductive power transmission system, the power receiving electronic device includes or otherwise incorporates an inductive power receiving element configured to wirelessly receive power and / or charge one or more internal batteries. Similarly, the charging device (i.e., the power transfer component) includes or otherwise incorporates an inductive power transfer element configured to wirelessly transfer power to the power receiving electronic device. FIG. 24 is a block diagram of an inductive power receiving system 2400 according to an embodiment of the present invention. As shown in FIG. 24, the system 2400 is an inductive power receiving system that may be located within the housing 2302 of the watch 2301 (see FIG. 23) or within different types of electronic accessories that may be charged by the wireless power transfer component 2330. When the power receiving system 2400 is operatively coupled to a suitable inductive power transfer component (such as the wireless power transfer component 2330), the battery 2402 within the device may be wirelessly charged.The battery 2402 is operably connected to the receiving coil 2404 via a power conditioning circuitry 2406. The receiving coil 2404 can be inductively coupled to the transmission coil of the charging device to wirelessly receive power from the charging device and transfer the received power to the battery 2402 within the electronic device via the power conditioning circuitry 2406. The power conditioning circuitry 2406 can be configured to convert the alternating current received by the receiving coil 2404 into direct current power for use by other components of the device. The processing unit 2410 can direct power via one or more routing circuits and under the execution of appropriate programs resident in the memory 2412 to perform or coordinate one or more functions of the electronic device that are typically powered by the battery 2402. Referring now to FIG. 25, a case 2300 is illustrated, which has a pair of earbuds 115a, 115b stored within the outer shell 2505 of the case and covered by a lid 2520. The case 2300 can charge the earbuds 115a, 115b in the same manner as the case 100 discussed above (i.e., by a wired connection or by a wireless power transfer system). However, the case 2300 can also include an inductive charging system 2525 that is positioned and configured to charge different portable electronic devices located outside rather than inside the case 2300. The inductive charging system 2525 can include a wireless power transmission component to wirelessly charge auxiliary devices such as a watch 2301 (see FIG. 23). In some embodiments, the case 2500 can be different from the case 100 (see FIG. 1) and can have any other configuration with one or more cavities and a lid covering the one or more cavities. In one example, the lid 2520 can be separable from the case. The inductive charging system 2525 can include a wireless charging circuitry within the outer shell 2505 that enables the case 2300 to recharge a battery (e.g., the battery 2402 of the watch 2301 (see FIG. 24)) wirelessly. FIG. 26 is a block diagram of a wireless charging system 2600 according to an embodiment of the present invention. As shown in FIG. 26, the wireless charging system 2600 includes an inductive power transfer component 2602. The inductive power transfer component 2602 includes a power source 2604 operably coupled to a transmission coil 2606 to transfer power to a wearable device via electromagnetic induction or magnetic resonance, which can be a case battery 227 (see FIG. 2). The transmission coil 2606 can be an electromagnetic coil (e.g., the coil 2404 in FIG. 24) that generates a time-varying electromagnetic flux to induce a current in an electromagnetic coil within the electronic device. The transmission coil 2606 can transfer power at a selected frequency or frequency band. In one example, the transmission frequency is substantially fixed, but this is not required. In another example, the transmission frequency can be adjusted to improve the power transfer efficiency for specific operating conditions. More specifically, if the accessory requires more power, a high transmission frequency can be selected, and if the accessory requires less power, a low transmission frequency can be selected.In other examples, the transmission coil 2606 can generate a static electromagnetic field and can physically move, shift, or otherwise change its position to generate a spatially varying electromagnetic flux that induces a current in the receiving coil. When the watch 2301 (see FIG. 23) is operatively coupled to the case 2300 (e.g., placed on or adjacent to the case), the wearable electronic device can receive charge to replenish the charge of its rechargeable battery or provide power to operating components associated with the electronic device. To facilitate the transfer of electromagnetic energy, the transmission coil 2606 can be positioned within the housing of the case 2300 (see FIG. 23) such that it is aligned with the receiving coil 2404 (see FIG. 24) in the watch 2301 along a common axis. If misaligned, the power transfer efficiency between the transmission coil 2606 and the receiving coil 2404 (see FIG. 24) can decrease as the misalignment increases. In some embodiments, one or more alignment features can be used to assist in alignment along the common axis, including mechanical alignment features (e.g., notches, lugs, stops) and magnetic features (e.g., alignment magnet 2630), as discussed in more detail below. As an example, the alignment magnet 2630 can be included in the case 2300 and magnetically mates with an alignment magnet (not shown) in the watch 2301 to facilitate proper alignment of the case and the wearable electronic device. More specifically, the alignment magnet 2630 attracts the mating alignment magnet in the watch 2301 such that the wearable device is laterally moved into a specific location and held firmly against the outer surface of the case. Additionally, the top and bottom surfaces of the case 2300 and the watch 2301 can cooperate to further facilitate alignment. For example, in one embodiment, the bottom surface of the watch 2301 is convex and the top surface of the case 2300 is concave to follow the same curvature as the bottom surface of the wearable device. In some embodiments, the case 2300 (see FIG. 23) can also include one or more sensors to determine whether the watch 2301 is present and ready to receive the transmitted power from the charger. For example, the watch 2301 can include an optical sensor such as an infrared proximity sensor. When the watch 2301 is attached to the case 2300, the infrared proximity sensor can generate a signal to determine the presence of the wearable device. Other methods or structures for verifying the presence of the watch 2301 can include mass sensors, mechanical interlocks, switches, buttons or the like, Hall effect sensors, or other electronic sensors. Some embodiments can include a priority charging algorithm to preferentially use the stored charge in the case battery 227 (see FIG. 2) depending on which rechargeable devices are coupled to the case 2300. For example, the charging system 2525 (see FIG. 25) can be programmed to first recharge the earbuds 115a, 115b and then the watch 2301. In another example, the user can be able to program the charging priority order, and in another example, the case 2300 can simply charge any device coupled to it.In other examples, the case 2300 can be coupled to a power source via a connector 345 (see FIG. 3), and can charge one device, preferentially charge multiple devices, or charge multiple devices simultaneously. Some embodiments can have a wired interface for charging the battery 2402 (see FIG. 24) of the case 2300 and / or for exchanging data with the watch 2301. The wired interface can be in addition to or in place of the wireless interface. For example, in one embodiment, the case 2300 can include contacts sized and positioned to physically and electrically couple to one or more contacts on the watch 2301. The contacts can include one or more power contacts and one or more data contacts, such as a pair of differential data contacts. In another embodiment, the connector 345 (see FIG. 3) of the case can be used to charge the watch 2301. Box Charged in a Wireless Manner Referring now to FIG. 27, a simplified perspective view of the box 2700 on the charging station 2705 is illustrated. As shown in FIG. 27, the box 2700 may be similar to other boxes in the present invention (such as the box 100 in FIG. 1) and may be charged inductively by the charging station 2705. The box 2700 may have a rechargeable battery that can be recharged inductively by a wireless charging system similar to the wireless charging system described and depicted above with reference to FIGS. 23 to 26. More specifically, all of the features described above with respect to the watch 2301 charged inductively may be used in the box 2700 charged inductively. The wireless charging station 2705 may include a wireless charging circuitry within the housing 2710 that enables the box 2700 to recharge its internal battery in a wireless manner. The wireless charging station 2705 may include an inductive power transfer coil 2715 similar to the wireless power transfer component 2602 described above in FIG. 26. The inductive power transfer coil 2715 is capable of transferring power to the box 2700 via electromagnetic induction or magnetic resonance. When the box 2700 is operatively coupled to the charging station 2705 (e.g., placed on or adjacent to the charging station), the box may receive a charge to replenish the charge of its rechargeable battery or provide power to the operating components associated with the box. To facilitate the transmission of electromagnetic energy, the transfer coil 2715 may be positioned within the housing of the charging station 2705 such that it is aligned with one or more receiving coils 2720 in the box 2700 along a common axis. If misaligned, the power transfer efficiency between the transfer coil 2715 and the receiving coil 2720 may decrease as the misalignment increases. In some embodiments, one or more alignment features may be used to assist in the alignment along the common axis, including mechanical alignment features (e.g., notches, lugs, stops) and magnetic features (e.g., alignment magnets), as discussed herein. In other embodiments, the box 2700 may include more than one receiving coil and may detect which receiving coil is better aligned and selectively receive charge only from that particular coil. In various embodiments, the box 2700 may use one or more planar receiving coils 2720; however, in other embodiments, other receiving coil designs may be used. Figures 28 and 29 of the waterproof socket connector illustrate the liquid-tight electrical connector 2800. As shown in Figure 28, the electrical connector 2800 may have mounting flanges and sealing features to resist or be impervious to liquid penetration. Similar to the connector 345 in Figure 3, the electrical connector 2800 can be used to couple power and data to a box. In some embodiments, the connector 2800 can be, for example, any non-proprietary interface such as a USB connector or can be any proprietary interface such as the Lightning connector used by Apple Inc. (Cupertino, CA). In various embodiments, the connector 2800 can be liquid-tight, as discussed in more detail below. A metal bracket 2805 is formed around the outer portion of the connector 2800 and has one or more mounting holes 2810 for securing the connector to a circuit board or base. The connector 2800 has a receiving surface 2815 that has a front opening (not shown in Figure 28 but shown in Figure 3 for connector 345) for receiving the plug portion of a mating connector. The interconnect surface 2820 contains a plurality of metal pins 2825 each connected to an internal electrical contact, as described in more detail below. One or more ground pins 2826 may also extend from the interconnect surface 2820. The metal pins 2825 and the ground pins 2826 can be sealed by a overmolded portion 2830, so that these pins are liquid-tight. The metal bracket 2805 can be two pieces and welded together, as described below. The metal bracket 2805 may also have one or more deformable fingers 2835 that can be used to secure the components of the connector 2800 together. As shown in Figure 29, the connector 2800 includes a contact plate 2980 coupled to a housing 2905 by a gasket to make the connector liquid-tight. The housing 2905 is made of an electrically insulating polymer that extends between the receiving surface 2815 and the back surface 2910. The housing 2905 defines a cavity 2915 that communicates with the front opening in the receiving surface 2815 to receive the plug portion of a mating plug connector. The spacer 2920 is formed of a plastic material and has a plurality of retaining features 2925 each configured to receive an electrical contact from a set of electrical contacts 2930 that can be press-fit thereto. Each electrical contact in the set of electrical contacts 2930 can include an elongated cross-bar portion 2935 that extends between a contact tip 2940 and an anchoring portion 2945. Each contact tip 2940 is positioned within the cavity 2915 such that it can be electrically coupled to a corresponding plug connector contact during a mating event. The cross-bar portion 2935 allows the tip 2940 of each contact to deflect slightly downward during a mating event and biases the tip to maintain physical and electrical contact with a contact in the plug connector that is aligned with a particular socket contact. The anchoring portion 2945 can be a generally flat plate that has one or more cutouts adapted to fit within a slot 2950 in the housing 2905 to secure or anchor the contact in place.The set of electrical contacts 2930 may further include electrical conductors 2955 that extend out of the interconnect surface 2820 of the connector assembly 2800 (see FIG. 28), and these electrical conductors may couple the receptacle connector to a printed circuit board or a similar substrate. Each contact in the set of contacts 2930 may also have an alignment portion 2960 adjacent to the anchoring portion 2945 to align the contact structure within the slot 2950 of the housing 2905. In some specific embodiments, the set of electrical contacts 2930 includes eight contacts spaced apart from each other along a single row. The ground latch 2965 may be formed of conductive metal and inserted through the ground slot 2970 in the spacer 2920. The ground latch may include a first spring arm and a second spring arm that extend along opposite sides of the set of contacts 2930. The first spring arm and the second spring arm may latch to the retention features of the corresponding plug connector to assist in retaining the plug connector within the receptacle connector 2800 after a mating event. In other embodiments, the ground latch 2965 may be insert-molded within the spacer 2920. The spacer 2920 together with the set of contacts 2930 and the ground latch 2965 may then be overmolded by the dielectric overmolding portion 2975. The overmolding portion 2975 covers a portion of the spacer 2920 and the anchoring portion of each contact in the set of contacts 2930, thereby forming a liquid-tight seal for the conductors 2955 and the ground latch 2965 and establishing an integrated contact board 2980. The gasket 2985 may be positioned against the back surface 2910 of the housing 2905, and the contact board 2980 may then be pressed against the gasket to form a liquid-tight assembly. The metal bracket 2805 may include a top bracket 2990a that is laser welded to the bottom bracket 2990b. The bracket fingers 2835 may be formed to hold the contact board 2980 against the housing 2905 such that the connector 2800 is liquid-tight. That is, if liquid is to enter the receiving opening of the connector (see connector 345 in FIG. 3), the liquid will not be able to pass through the connector and enter the box 100.. Wireless Earbuds Referring now to FIGS. 30 to 46, a description and explanation of the open-back earbuds 3000a, 3000b and a method of manufacturing the same will be provided. As shown in FIGS. 30 and 31, the earbuds 3000a, 3000b may be similar to the earbuds 115a, 115b described in FIG. 1. However, the earbuds 3000a, 3000b may include various other features included in ear sensing and acoustic characteristics, which will be described in more detail below. FIGS. 30 and 31 respectively show a front perspective view and a rear perspective view of the open-back left earbud 3000a (FIG. 30) and the open-back right earbud 3000b (FIG. 31). Generally, open-back earbuds are designed not to form an airtight seal between the ear (or ear canal) and the outer surface of the earbud. In contrast, closed-back earbuds are generally designed to fit inside the user's ear canal and form a substantially airtight seal. Each earbud 3000a, 3000b may include an outer housing 3005 having an ear portion 3010 coupled to a stem portion 3015. The housing 3005 may have an asymmetrical shape that aids in retention in the ear but does not form an airtight seal with the user's ear or ear canal. The absence of an airtight seal may benefit from the volumes within the earbud, which are specifically adjusted (e.g., by specifically shaping the volumes and / or adding materials to the volumes) to achieve a desired frequency response. The ear portion 3010 may include a directional sound port 3020 that is offset relative to the central axis of the earbud. The directional sound port 3020 may be designed to direct sound waves from an internal driver (e.g., a part of the earbud speaker, which is not shown in FIGS. 30 and 31) directly into the user's ear canal. Additionally, secondary pores in the earbud may be used in the housing 3005 to achieve a desired sound performance. For example, one or more secondary pores may act as controlled leakage orifices to expose the acoustic pressure within the earbud to the external surrounding environment. In this aspect, the secondary pores may be calibrated to modify the acoustic response of the earbud. In this embodiment, each of the earbuds 3000a, 3000b includes a front leakage orifice 3025 and a multi-orifice 3030 formed in the ear portion 3010. The multi-orifice 3030 may include both a rear vent 3035 and a bass port 3040, which will be described in more detail below. Furthermore, the earbuds according to embodiments of the present invention may be constructed to have a seamless decorative surface layer, even if two or more than two parts are joined together to form parts of the earbud. The ear portion 3010 of the earbuds 3000a, 3000b may also include one or more "in-ear" sensors to assist each of the earbuds 3000a, 3000b in determining whether the earbud is in the user's ear. In one embodiment, an optical tragus sensor 3045 is configured to sense the presence or absence of the user's tragus, and an optical concha sensor 3050 is configured to sense the presence or absence of the user's concha.The tragus sensor 3045 and the concha sensor 3050 can each use any type of optical sensor, including (but not limited to) an LED or a vertical cavity surface emitting laser (VCSEL) device. Other embodiments can include one or more capacitive sensors and / or accelerometers to detect the presence and / or orientation of the user's ear, as described in more detail below. This ear detection can be used for features such as (but not limited to) determining which earbud 3000a, 3000b to use as a microphone when the user needs to receive a call and when the user stops using one earbud and starts using the other. The distal end 3055 of the stem portion 3015 of each earbud 3000a, 3000b can include an electrical connector 3060 that is formed to contact a corresponding connector (e.g., a socket connector) of a charging station and / or an earbud charging case, such as one of the connector structures described in FIGS. 4A through 8C. In one particular embodiment, each connector 3060 can include a first contact and a second contact spaced apart in an opposed and symmetric relationship, such as the partial annular earbud contacts 610 and 615 shown in FIG. 6B. Each of the first contact and the second contact can include an outer peripheral edge flush with the outer surface of the stem portion and include an arcuate or other curved surface that creates a strong wiping motion during a contact mating event. The electrical connector 3060 can be used to recharge an internal battery within each earbud 3000a, 3000b and, in some situations, can also be used to transfer data to and from each earbud. The distal end 3055 can also include a bottom microphone port 3065 (e.g., the microphone aperture 635 illustrated in FIG. 6B), which works in conjunction with a top microphone port 3070 to receive user voice and / or perform noise cancellation. FIGS. 32 and 33 illustrate partial cross-sections of the earbuds 3000a, 3000b. As shown in FIG. 32, the earbuds 3000a, 3000b include a driver 3205, an acoustic insert 3220, a flexible circuit 3225, an antenna 3330, a rechargeable battery 3335, and an electrical connector 3060. The driver 3205 is located within the ear portion 3010 and defines a front acoustic volume 3210 in front of the driver and a rear acoustic volume 3215 behind the driver. The driver 3205 can include an electromagnetic voice coil, a driver magnet, and a speaker diaphragm (not shown in FIG. 32). The acoustic insert 3220 is positioned behind the driver 3205 and bonded to the outer shell 3005, as described in more detail below. The ear portion 3010 further includes a stacked portion of the flexible circuit 3225 that can contain one or more sensors, controllers, and various other circuits for operating the earbuds 3000a, 3000b. The flexible circuit 3225 can include a flexible portion and a non-flexible portion, such as a multi-layer epoxy and glass composite circuit board, and can further couple together the various electronic systems of the earbuds 3000a, 3000b, as described in more detail below.The stem portion 3015 of the earbuds 3000a, 3000b may include an antenna 3330, a rechargeable battery 3335, and an electrical connector 3060. A portion of the flexible circuit 3225 may extend downward and be electrically connected to the electrical connector 3060. As shown in FIG. 33, the earbuds 3000a, 3000b include a number of internal sensors. In FIG. 33, some of the internal components of the earbuds 3000a, 3000b have been removed for clarity purposes. The ear portion 3010 may contain a tragus sensor 3045, an antihelix optical sensor 3050, and an accelerometer 3315 that may work together to determine whether the earbuds 3000a, 3000b are in the user's ear. The flexible circuit 3225 (see FIG. 32) may be used to electrically couple all of these devices together. FIGS. 34 and 35 are simplified views of the flexible circuit 3225 showing a foldable flexible circuit diagram. As shown in FIG. 34, the flexible circuit 3225 is shown in a planar pattern. FIG. 35 shows the flexible circuit 3225 when it is folded up when installed in the earbuds 3000a, 3000b, as shown in FIG. 32. Referring now to FIGS. 34 and 35 simultaneously, various parts of the flexible circuit 3225 are described. The concha portion 3405 can be used to attach to and communicate with the optical concha sensor 3050 (see FIG. 33). For this purpose, the concha portion 3405 can include one or more electrical terminals that can be coupled to the contacts of the optical concha sensor 3050. The processor portion 3410 can include one or more central processing units, controllers, and passive components. The processor portion 3410 can be a rigid portion of the flexible circuit 3225 and can include multiple stacked routing layers. In one embodiment, the processor portion can have 4, 6, 8, or 10 routing layers. The accelerometer portion 3415 can include one or more accelerometers to assist in detecting the position and / or orientation of the earbud, assist in acting as a microphone that can be used to reduce wind noise, and act as a user input device for recognizing touch or touch sequences on the earbud housing. The top microphone portion 3420 can be used to attach to and communicate with the top microphone via one or more electrical terminals. The tragus sensor portion 3430 can be used to attach to and communicate with the optical tragus sensor 3045 (see FIG. 33) via one or more terminals formed within the portion 3430, and the bottom microphone portion 3435 can be used to attach to and communicate with the bottom microphone via one or more terminals formed within the portion 3435. Each of the flexible portions 3440 can be flexible enough to fold up the flexible circuit 3225, as illustrated in FIG. 35. Additionally, each of the flexible portions 3440 can include one or more electrical traces that carry electrical signals between different components of the flexible circuit 3225. For example, the flexible portion 3440 between the concha portion 3405 and the processor portion 3410 can include one or more electrical traces that run between the concha portion terminals and the processor. Similarly, the flexible portion 3440 between the bottom microphone portion 3435 and the processor portion 3410 can include one or more electrical traces that run between the bottom microphone terminals and the processor. Figures 36 to 41 of the earbud connector illustrate several embodiments of an earbud connector (such as connector 3060 in Figure 30) that can be used in the distal end of the stem portion of each earbud. As shown in Figure 36, connector 3600 can be attached to the distal ends 3055 of earbuds 3000a, 3000b and is used to couple charging and data signals to the earbuds. Connector 3600 can be mated with a socket connector (such as the socket connectors disclosed in Figures 4A to 8C) that can be placed in a case or docking station. Connector 3600 is illustrated in a partially assembled state before it is attached to the distal ends 3055 of the stem portions 3015 of earbuds 3000a, 3000b. In this embodiment, connector 3600 includes an inner circular metal contact 3610 and an outer circular metal contact 3615, with a dielectric ring 3620 separating the two contacts. In various embodiments, the inner circular contact 3610 can have a hole 3613 therein that can be used for both the socket connector contact surface and the hole for the microphone. In some embodiments, the inner circular contact 3610 and the outer circular contact 3615 can be separately manufactured components and can be made of a metal or alloy that can have one or more plating layers, as described in more detail below. In various embodiments, the inner circular contact 3610 and the outer circular contact 3615 can be made of copper or a copper-based alloy such as (but not limited to) C5212 phosphor bronze. In some embodiments, the inner circular contact 3610 and the outer circular contact 3615 can be individually machined, cast, or metal injection molded. In other embodiments, it can be made of conductive plastic or insulating plastic plated with one or more metals or alloys. As shown in Figure 37, connector 3600 includes an inner circular contact 3610 and an outer circular contact 3615 that can be separately manufactured as individual components. In one example, the inner circular contact 3610 and the outer circular contact 3615 include one or more ridges 3625 to achieve increased holding force for the dielectric ring 3620. To electrically couple the inner circular contact 3610 and the outer circular contact 3615 to earbuds 3000a, 3000b, the contacts can each include coupling tabs. More specifically, the inner circular contact 3610 can have a first coupling tab 3630 for attaching to a portion of the flexible circuit 3225 (see Figures 34 to 36). In some embodiments, the first coupling tab 3630 is welded to a metallized pad 3635 (see Figure 36) on the flexible circuit 3225. However, in other embodiments, it can be attached by conductive epoxy resin or other methods. The outer circular contact 3615 can have a second coupling tab 3640 for attaching to a portion of the flexible circuit 3225 (similar to the foregoing procedure). As described above, the outer circular contact 3615 can have an arcuate cross-section to facilitate the wiping of the mating contacts, thereby providing a reliable interconnection with the socket connector. The inner circular contact 3610 can also have an arcuate or inclined cross-section to facilitate the wiping of the contacts with the socket connector.In some embodiments, the inner circular contact 3610 and the outer circular contact 3615 may be plated with one or more metals that can prevent oxidation of the contact surfaces to reduce the interconnect resistance, and in other embodiments, the plating may be used to provide an aesthetically appealing appearance, as described in more detail below. In various embodiments, the inner circular contact 3610 and the outer circular contact 3615 may first be plated with a nickel layer, followed by a final gold layer. In some embodiments, the inner circular contact 3610 and the outer circular contact 3615 may be plated with a first copper layer having a thickness between 3 microns and 5 microns, followed by a gold layer having a thickness between 0.5 microns and 0.7 microns, followed by a gold layer having a thickness between 0.1 microns and 0.2 microns, followed by a palladium layer having a thickness between 0.5 microns and 0.8 microns, followed by a gold layer having a thickness between 0.1 microns and 0.2 microns, followed by a binary alloy layer including a first element and a second element having a thickness between 0.7 microns and 1.0 microns. In some embodiments, the inner circular contact 3610 and the outer circular contact 3615 may be plated with a first copper layer having a thickness between 3 microns and 4.5 microns, followed by a gold layer having a thickness between 0.5 microns and 0.9 microns, followed by a palladium layer having a thickness between 0.5 microns and 0.8 microns, followed by a gold layer having a thickness between 0.1 microns and 0.2 microns, followed by a binary alloy layer including a first element and a second element having a thickness between 0.65 microns and 1.0 microns. In these and other embodiments of the present invention, the first element of the binary alloy layer may be an element in a first group consisting of platinum, palladium, iridium, osmium, and rhodium. In these and other embodiments of the present invention, the first element may be rhodium. In these and other embodiments of the present invention, the second element of the binary alloy layer may be an element in a second group consisting of platinum, palladium, iridium, osmium, and ruthenium. In these and other embodiments of the present invention, the second element may be ruthenium. In these and other embodiments of the present invention, the first element may comprise approximately 85 weight percent of the binary alloy, while the second element may comprise approximately 15 weight percent of the binary alloy. In these and other embodiments of the present invention, the first element may comprise approximately 90 weight percent of the binary alloy, while the second element may comprise approximately 10 weight percent of the binary alloy. In these and other embodiments of the present invention, the first element may comprise approximately 95 weight percent of the binary alloy, while the second element may comprise approximately 5 weight percent of the binary alloy. In these and other embodiments of the present invention, the first element may comprise more than or approximately 99 weight percent of the binary alloy, while the second element may comprise less than or approximately 1 weight percent of the binary alloy. In these and other embodiments of the present invention, the first element may comprise more than or approximately 99.5 weight percent of the binary alloy, while the second element may comprise less than or approximately 0.5 weight percent of the binary alloy.In some embodiments, a combination of rhodium and ruthenium for a binary alloy can be used to prevent oxidation of the contact surface while providing an aesthetically appealing gray or silver appearance. Other combinations and compositions for plating are within the scope of the present invention. In still other embodiments, the first coupling tab 3630 and the second coupling tab 3640 can be masked prior to the final layer of the binary alloy, leaving a gold surface for improved weldability. After the inner circular contact 3610 and the outer circular contact 3615 are plated, they can be insert molded to form the connector 3600 as shown in FIG. 38. The dielectric ring 3620 can be molded between and around portions of the inner circular contact 3610 and the outer circular contact 3615 and can be used to form auxiliary connectors 3600 attached to one or more attachment tabs 3655 of the earbuds 3000a, 3000b as illustrated in FIG. 36. Turning now to FIGS. 39 and 40, a perspective view of the connector 3900 is illustrated. As shown in FIGS. 39 and 40, the connector 3900 is similar to the connector 3600 illustrated in FIG. 36; however, the connector 3900 includes two semi-circular contacts instead of circular inner and outer contacts. The end view of the connector 3900 is similar to the end view of the connector 605 illustrated in FIG. 6B. The connector 3900 includes a first semi-circular contact 3910 and a second semi-circular contact 3915, with a dielectric layer 3920 separating the two contacts. The first semi-circular contact 3910 and the second semi-circular contact 3915 can be spaced apart in a relationship that is opposed and symmetric to each other. In various embodiments, the first semi-circular contact 3910 and the second semi-circular contact 3915 can respectively form a void 3913 therebetween that can be used for both the socket connector contact surface and the void for the microphone. The first semi-circular contact 3910 and the second semi-circular contact 3915 can be manufactured and plated respectively using the same procedures described above with respect to the connector 3600. To electrically couple the first semi-circular contact 3910 and the second semi-circular contact 3915 to the earbuds 3000a, 3000b respectively, they can each include coupling tabs similar to those of the connector 3600. More specifically, the first semi-circular contact 3910 can have a first coupling tab 3930 for attachment to a portion of the flexible circuit 3225 (see FIGS. 34 to 36). The second semi-circular contact 3915 can have a second coupling tab 3940 for attachment to a portion of the flexible circuit 3225 (similar to the foregoing procedure). After the first semi-circular contact 3910 and the second semi-circular contact 3915 are plated respectively, they can be insert molded to form the connector 3900 as shown in FIG. 40. The dielectric layer 3920 can be molded between and around portions of the first semi-circular contact 3910 and the second semi-circular contact 3915 and can be used to form auxiliary connectors 3900 attached to one or more attachment tabs 3955 of the earbuds 3000a, 3000b as illustrated in FIG. 36. FIG. 41 illustrates a simplified perspective view of the capacitive sensor insert of the earbud 4100. As shown in FIG. 41, the earbud 4100 includes a housing 4105 and a capacitive sensor insert 4110 that can sense user touches on the outer surface 4115 of the housing. The capacitive sensor insert 4110 has a sensor circuitry 4120 that can establish one or more capacitive sensors, which will be explained in more detail below. For example, the sensor circuitry 4120 can establish a first capacitive sensor in region 4125 on the outer surface 4115 of the housing 4105 that can be used to detect touches of the user's ear for ear sensing, and can establish a second capacitive sensor in region 4130 that can be used to detect touches of the user's finger to answer a call or perform any other function. FIG. 42 illustrates a simplified cross-section of the earbud housing 4105. As shown in FIG. 42, the housing 4105 includes a capacitive sensor insert 4110 positioned within a cavity 4205 defined by the housing. The cavity can also house one or more other components of the earbuds 3000a, 3000b. The earbud housing 4105 has at least one touch-sensitive region 4125, 4130 formed by the capacitive sensor insert 4110 at the outer surface 4115 of the housing. The housing 4105 has an inner surface 4210 within the cavity 4205 that is opposite the outer surface 4115. The capacitive sensor insert 4110 has a first surface 4215 positioned adjacent to the inner surface 4210 of the housing 4105, and the first surface has a metallized sensor circuitry 4120 (see FIG. 41). The capacitive sensor insert 4110 has a second surface 4220 that is opposite the first surface 4215. FIGS. 43 and 44 respectively illustrate simplified plan views of the capacitive sensor inserts 4300, 4400. As shown in FIGS. 43 and 44, different types of circuitry can be used to form the capacitive sensors. For example, in FIG. 43, a self-capacitance circuitry can be used, and in FIG. 44, a mutual-capacitance sensor circuitry can be used. Now referring to FIG. 43, a plan view of the sensor insert 4300 is illustrated. As shown in FIG. 43, the sensor insert 4300 has a self-capacitance sensor circuitry 4305 that senses touches of the user (e.g., the user's ear and / or finger) on the outer surface 4115 (see FIG. 42) of the housing 4105. The user touch loads the self-capacitance circuitry and / or increases the ground parasitic capacitance that is interpreted and communicated by the sensor insert 4300 to the earbud processor. The sensor circuitry 4305 can have one or more interconnect regions 4310 that allow it to be coupled to the earbud processor by one or more conductors, such as solder pads or plated-through vias. In one embodiment, the sensor insert 4300 is formed of a plastic that includes metal particles. A laser can then be used to laser-activate regions 4315 on the first surface 4320 of the sensor insert 4300 that correspond to the desired locations of the sensor circuitry 4305.The laser activation area can then be metallized in a plating bath. In one example, a metal circuitry can be plated onto the activation area to form a sensor circuitry 4305. This process can be referred to as laser direct structuring in the art. Other methods can be used to form the sensor insert 4300 without departing from the present invention. For example, in another embodiment, a flexible circuit can be adhered to the first surface 4320 of the sensor insert and used as the sensor circuitry. In another example, the first surface 4320 can be fully plated, and photoimageable ink can be used for etching. In other embodiments, the sensor insert 4300 can have one or more acoustic pores 4325 that allow sound to pass through and can be aligned with the sound port of the earbud. In some embodiments, the insert 4300 can be formed in a hemispherical or other shape to closely match the shape of the external earbud housing. Additionally, in some embodiments, the sensor circuitry 4305 can fully surround or partially surround the acoustic pores. Referring now to FIG. 44, a plan view of a sensor insert 4400 is illustrated. As shown in FIG. 44, the sensor insert 4400 has a mutual capacitance sensor circuitry 4405 that senses the touch of a user (e.g., the user's ear and / or finger) on the outer surface 4115 (see FIG. 42) of the housing 4105. The touch of the user changes the mutual coupling between the column electrodes and the row electrodes 4410 that are sequentially scanned and communicated to the earbud processor. The sensor circuitry 4405 is formed on the first surface 4407 of the sensor insert 4400 and can have one or more interconnect areas 4415, such as solder pads or plated vias, that allow it to be coupled to the earbud processor by one or more conductors. As described above with respect to the sensor insert 4300 in FIG. 43, the sensor insert 4400 can be manufactured in the same manner and can have similar features and functions. Additionally, in some embodiments, the sensor insert 4400 can include one or more acoustic pores 4425 that allow sound to pass through the sensor circuitry 4305, and at least some of the sensor circuitry 4405 can fully surround or partially surround the acoustic pores. Additionally, in some embodiments, the sensor insert 4400 can be formed in a hemispherical or other shape to closely match the shape of the external earbud housing.. Figure 45A shows a simplified rear perspective view of the earplug 3000a with the acoustic insert. As shown in Figure 45A, the earplug 3000a includes an acoustic insert 4505 (shown in dashed lines within the housing 3005 and in solid lines outside the housing) that can be used to provide ventilation for the driver (e.g., speaker) within the earplug 3000a. More specifically, the acoustic insert 4505 can be used to assist in forming a combined porous port 3030 including a bass port 3040 and a rear vent 3035. In some embodiments, certain features of the acoustic insert 4505 can be used to form acoustic ventilation holes in a relatively small and restricted area such as the earplug housing. The earplug 3000a can have multiple acoustic pores, some of which are shown in Figure 30. In addition to the bass port 3040, the rear vent 3035, and the porous port 3030, each earplug can also have a directional sound port 3020 and a front leak hole 3025. These pores can provide ventilation for the driver, provide sound for the user, and can help to adjust the frequency response of the earplug 3000a. More specifically, each pore is not just a random opening, but can be intentionally formed for a specific purpose, i.e., to help adjust the frequency response and / or to change the frequency response of the earplug 3000a in a way that helps to provide consistent bass response both on the same user and across users. The acoustic pores can each also include various meshes (e.g., directional sound port mesh, front leak mesh, rear vent mesh, bass port mesh, and porous port mesh) covering or adapted to the corresponding acoustic pores of the earplug 3000a. Figure 45B shows a simplified side view of the earplug 3000a with the acoustic insert 4505. As shown in Figure 45B, the acoustic insert 4505 and the driver 4570 are disposed within the housing 3005 (illustrated in dashed lines). Now referring to both Figure 45A and Figure 45B, the function of the acoustic insert 4505 will be described in more detail. The driver 4570 can be positioned within the cavity 4510 of the housing 3005 to form a front volume 4515 in front of the driver and a rear volume 4520 behind the driver. The driver 4570 can be positioned such that the front volume 4515 and the rear volume 4520 are acoustically isolated. The front volume 4515 and the rear volume 4520 can be at least partially formed within the cavity 4510 by the housing 3005 and sized and shaped to achieve the desired frequency response of the earplug. In some embodiments, a portion of the acoustic insert 4505 is formed to closely match the contour of the inner surface 4525 of the housing 3005. More specifically, the raised region 4530 of the acoustic insert 4505 can be formed to fit tightly against the inner surface 4525 such that it can be joined to the inner surface 4525 to form an acoustically sealed bass port channel 4527 and a porous port chamber 4507. That is, the bass port channel 4527 can be formed by the first wall 4535, the second wall 4540, and the third wall 4545 of the bass port notch 4550 and the fourth wall formed by the inner surface 4525 of the housing 3005.Similarly, the raised region 4530 can seal against the inner surface 4525 to form a porous oral cavity 4507 with an acoustic seal. The bass port channel 4527 can have an inlet aperture 4555 that communicates with the rear volume 4520. The bass port channel 4527 can be routed from the inlet aperture 4555 to an outlet aperture 4560 formed within the porous oral cavity 4507 that can vent to the surroundings. The rear vent hole 3035 can also be routed to the porous oral cavity 4507 to provide a vent from the rear volume 4520 through the rear vent aperture 4565 in the acoustic insert 4505 to the porous oral cavity 4507. The size and shape of the bass port channel 4527 and the rear vent aperture 4565 can be formed for a particular purpose, namely, to help adjust the frequency response and / or vary the frequency response of the earbud 3000a in a way that provides consistent bass response across the same user and across users. The outer shell 3005 can serve as an enclosure for the remaining components of the earbud assembly and can be formed in any suitable manner and made of any suitable material. For example, in one embodiment, the outer shell 3005 is made of molded plastic. Similarly, the acoustic insert 4505 can be made of any suitable material including molded plastic. A variety of methods can be used to couple the raised region 4530 of the acoustic insert to the inner surface 4525 of the outer shell 3005. In one embodiment, the outer shell 3005 can be made of an ABS plastic that is substantially transparent or at least translucent to a laser of a certain wavelength (Figure 46, step 4605). The acoustic insert 4505 can be made of a plastic that is opaque or at least mostly opaque to the same laser (Figure 46, step 4610). The acoustic insert 4505 can be placed within the cavity 4510 of the outer shell 3005 such that the raised region 4530 bears firmly against the inner surface 4525 (Figure 46, step 4615). A laser beam from the laser can then be directed through the outer shell 3005 such that it irradiates the raised region 4530, thereby melting at least a portion of the raised region and bonding it to the inner surface 4525 of the outer shell 3005 (Figure 46, step 4620). In some embodiments, to enable the laser to be directed through the outer shell 3005, the outer shell 3005 can use a relatively low amount of pigment, a pigment that is transparent to the laser, or other features that allow the laser to transmit through the outer shell with sufficient energy to melt at least a portion of the raised region 4530. The acoustic insert 4505 can be made of a plastic that contains an absorptive dopant such as carbon, so it absorbs the laser energy. In one embodiment, a laser system similar to a direct laser structuring laser can be used to perform the laser bonding operation. In other embodiments, the raised region 4530 can be coupled to the inner surface 4525 by other methods such as (but not limited to) pressure sensitive adhesives, thermally activated films, or laser activated adhesives.. Wireless pairing Figures 47 to 49 illustrate a wireless pairing system 4700, which includes a pair of wireless earphones 4710 (e.g., a pair of wireless earbuds) that can be wirelessly paired with a host device 4715 (e.g., a computer, smartphone, tablet, smartwatch, or the like), where the pairing is initiated by an intermediate device 4705 (e.g., a case for the earphones). The intermediate device 4705 can, in response to a user input, instruct the wireless earphones 4710 to enter a pairing sequence with the host device 4715. The user input can be a user-initiated event, such as opening the earbud case lid 4720 or pressing an input button 4725. In some embodiments, the earphones 4710 can receive a pairing instruction via a wired connection between the intermediate device 4705 and the wireless earphones 4710 (e.g., via mating electrical contacts in a case for a pair of wireless earbuds and the earbuds as described above). In other embodiments, the intermediate device 4705 can include a radio frequency that conveys the instruction to a radio frequency within the wireless earphones 4710. After receiving the pairing instruction, the earphones 4710 can immediately initiate a pairing sequence to the host device 4715 via a wireless communication protocol that supports two-way data transfer (e.g., via Bluetooth®). In some situations, the earphones 4710 are a pair of wireless earbuds, and only one earbud in the pair (i.e., the primary earbud) is paired with the accompanying host device 4715. In such situations, the primary earbud is communicatively coupled to the other earbud (secondary earbud) so that audio data received by the primary wireless earbud from the host device 4715 can be shared with the communicatively coupled secondary wireless earbud. In some embodiments, the earphones 4710 do not include a user input mechanism, such as a button that can be pressed for the user to initiate pairing between the earphones and the host device 4715, and the wireless pairing between the intermediate device 4705 and the host device 4715 can be initiated only via the intermediate device 4705 (e.g., in response to a user input generated by opening the case lid or pressing an input button on the case or other suitable means) or by the host device 4715. Figure 48 illustrates a wireless pairing system 4800 according to an embodiment of the present invention, which includes the intermediate device 4705, earphones 4710, and host device 4715 shown in Figure 47. Although Figure 48 illustrates a simplified block diagram of each of the intermediate device 4705, wireless earphones 4710, and host device 4715, it should be understood that each of the illustrated devices can include functions and features in addition to those functions and features illustrated in Figure 48. For example, although not shown in Figure 48, each of the intermediate device 4705, wireless earphones 4710, and host device 4715 can include a battery that provides power to various components of each device, such as a rechargeable battery. In some embodiments, the host device 4715 can be an electronic device or a portable media player, such as an iPod manufactured and sold by Apple Inc. (the assignee of the present application) TM Media player. Generally, a media player can be any device capable of storing and playing media assets including (but not limited to) audio, video, and / or still images. Alternatively, the host device 4715 can be a mobile phone (e.g., using conventional cellular communication technology), a personal digital assistant (PDA), or a multi-functional device combining media player, mobile phone, and / or PDA functions, such as the iPhone manufactured and sold by Apple Inc. TM Mobile device. The host device 4715 can also be a general-purpose computer, such as a handheld computer, a laptop computer, a desktop computer, or the like. The host device 4715 includes a processor 4820, a memory 4825, a user interface 4830, a first wireless transceiver 4835 (e.g., a Bluetooth transceiver), a second wireless transceiver 4840 (e.g., a cellular transceiver), and a wired input / output component 4845. The processor 4820, which can be implemented as one or more integrated circuits, can control the operation of the host device 4715. For example, in response to a user input signal provided by the user via the user interface 4830, the processor 4820 can initiate a program to search for, list, or play media assets stored in the memory 4825. When communicating with the cellular transceiver 4840, the processor 4820 can control the dialing and receiving of phone calls. The second transceiver 4840 can also be used for data communication with a network including a network storage 4815. The first transceiver 4835 can be used to support short-range wireless communication (e.g., Bluetooth communication) between the host device 4715 and various accessory devices including the earphone 4710. The memory 4825 can store any information including Bluetooth pairing information, as described in more detail below. The wired input / output component 4845 can be any wired connection, such as a USB protocol or a proprietary protocol, such as Apple Lightning TMProtocols used by the connector. The wireless earphone 4710 can be a traditional earphone worn on the user's head, a headset (a combination of an earphone and a microphone), an earplug (a very small earphone designed to fit directly into the user's ear), or any other portable listening device. In some embodiments, the wireless earphone 4710 includes a processor 4850, a wired input / output component 4855, a memory 4860, and a wireless transceiver 4865 (e.g., a Bluetooth transceiver). The processor 4850, which can be implemented as one or more integrated circuits, can control the operation of the earphone 4710. The wired input / output component 4855 can be any wired connection between the intermediate device 4705 and the wireless earphone 4710, including a proprietary interconnect. In one example, the wired input / output component 4855 is an electrical connector that provides a direct electrical connection between the earphone and the intermediate device when the wireless earphone 4710 is docked (e.g., stored in a case) with the intermediate device 4705, such as connector 347 (see FIG. 3) or any of the connectors illustrated in FIGS. 4A to 8C. The wired input / output component 4855 can be used to charge the wireless earphone 4710 and / or communicate data with the intermediate device 4705. In one example, the wired input / output component 4855 of the earphone 4710 can be used to receive a signal from the wired input / output component 4875 of the intermediate device 4705, thereby initiating the pairing sequence of the earphone, as described in more detail below. The wireless transceiver 4865 can be used to support short-range wireless communication (e.g., Bluetooth communication) between the earphone 4710 and various host devices, including the host device 4715. In one embodiment, the intermediate device 4705 can also be equipped with a wireless transceiver (not shown; e.g., a Bluetooth transceiver) that can communicate wirelessly with the wireless transceiver 4865. The wireless transceiver 4865 enables the earphone 4710 to communicate wirelessly with the host device after a channel for wireless communication has been established between it and the host device 4715. For example, the earphone 4710 and the host device 4715 can each be equipped with Bluetooth® technology, including appropriate short-range transceiver units. In some embodiments, it is possible to establish a Bluetooth ® pairing between the host device 4715 and the earphone 4710 using conventional techniques, such as manually entering the password (or PIN code) associated with the earphone 4710 into the host device 4715. In other embodiments, Bluetooth ®Pairing. Memory 4860 can store the firmware for operating the earphones 4710 and data for coupling with other wireless earbuds and for pairing the earphones 4710 with an accompanying host device. For example, memory 4860 can store the connection history of the accompanying host device (such as host device 4715) that has been previously paired with the earphones 4710. This connection history can include data for automatically pairing the earphones 4710 with the accompanying host device without having to configure the connection between the earphones and the accompanying host device (e.g., entering a password, exchanging shared secrets, etc.). For example, the connection history can include one or more link keys (such as Bluetooth link keys) for connecting to a wireless network. Memory 4860 can also store the MAC address that uniquely identifies the earphones 4710 and the paired matching MAC address of another earphone that has been previously coupled with the wireless earbud 115. For example, in one embodiment, the earphones 4710 are wireless earbuds and memory 4860 can store the paired matching MAC address of the earbuds. In another example, once the earphones 4710 are paired with the host device 4715, the host device can save the relevant pairing information from the earphones 4710 to a network storage system 4815 (such as cloud storage). In one embodiment, the relevant pairing information stored in the network storage 4815 can then be used by other host devices to pre-pair with the wireless earphones 4710. As an illustrative example, in one embodiment, the wireless earphones are initially paired with an iPhone. The iPhone communicates the pairing information to the user's iTunes or iCloud account saved on a remote network separate from the host device 4715 (e.g., in iCloud). The wireless earphones will then be listed on the user's iTunes or iCloud account as an authorized wireless device for that account. For example, the user's iCloud account can include a first list of host devices (one or more smartphones, one or more tablets, and one or more laptops), including the host device 4715, which are automatically authorized to pair with one or more wireless earphones (including the wireless earphones 4710) added to the account, based on the device's previous authorization and / or authentication relative to the iCloud account. The user can then go to their iPad, and the iPad can automatically pair with the earphones based on the list of approved pairings in the user's iCloud account without having to initiate a separate pairing sequence between the earphones 4710 and the iPad. Multiple host devices can be pre-authorized and use this feature to automatically pair. In some embodiments, the intermediate device 4705 can be a case, docking station, or another type of accessory or electronic device for the earphones 4710. In some embodiments, the intermediate device 4705 includes a processor 4870, a wired input / output 4875, a user input device 4880, and a memory 4885.The processor 4870, which can be implemented as one or more integrated circuits, can control the operation of the intermediate device 4705 by executing computer instructions stored in a computer-readable memory or medium, such as memory 4885. For example, the instructions stored in memory 4885 can cause the processor 4870 to send instructions to the earphones 4710 (e.g., via the wired I / O interface 4875 or via a wireless channel between the intermediate device 4705 and the wireless earphones 4710) in response to a user input signal provided by the user input device 4880 to enter a pairing sequence with the host device. The wired input / output piece 4875 can be any wired connection between the intermediate device 4705 and the wireless earphones 4710, including a proprietary interconnect. In one example, the wired input / output piece 4855 is part of the electrical connector 347 between a pair of earbuds 115a, 115b and the case 100 (see FIG. 3), and can be any of the connectors illustrated in FIGS. 4A through 8C. The wired input / output piece 4855 can be used for charging and / or data. In various embodiments, the wired input / output piece 4855 can be used to transmit a signal to the earphones 4710 to initiate a pairing sequence, as described in more detail below. The user input device 4880 can be any device that can be operated by the user. In one embodiment, the user input device 4880 is a lid sensor that detects the opening or closing of the lid of the intermediate device 4705, such as the lid sensor 220 (see FIG. 2). In one example, an open event is detected, and the processor 4870 sends a signal to the processor 4850 of the earphones 4710 via the wired input / output piece 4875 of the intermediate device to the wired input / output piece 4855 of the earphones to initiate a pairing sequence and / or turn on the Bluetooth transceiver 4865. In another example, the wireless earphones 4710 have never been paired before and the earphones 4710 enter a pairing sequence. In another example, the earphones 4710 have been paired previously, and the earphones 4710 turn on the Bluetooth transceiver 4865 but do not initiate a pairing sequence. In one embodiment, the intermediate device 4705 can include one or more indicator lights to inform the user that it has sent a pairing signal to the earphones 4710. FIG. 49 depicts a method 4900, where an intermediate device (e.g., intermediate device 4705) initiates a wireless pairing between a host device (e.g., host device 4715) and a pair of wireless earphones (e.g., wireless earphones 4710). The method illustrated in FIG. 49 can be performed by, for example, a processor within the intermediate device executing computer instructions stored in a computer-readable memory (e.g., processor 4870 executing instructions stored in computer-readable memory 4885). In step 4905, the intermediate device receives a user input. In some embodiments, the intermediate device is a case for a pair of earphones or a pair of earbuds. In various embodiments, the user input can be to open the lid of the case; press a button on the case; or any operation on the case that the case transient stores as a user input indicating a need to initiate a pairing sequence.In a particular example, when the user opens the lid of the case, the lid sensor sends a signal to the processor 4870 to notify the processor that the lid has been opened. In step 4910, in response to receiving user input, the intermediate device determines whether the earphones are connected to the intermediate device. For example, in some embodiments, the intermediate device is an earbud case, and the pair of wireless earphones is a pair of wireless earbuds adapted to be stored in the earbud receiving cavity of the case. The earbud case may include one or more earbud detectors as described above, which may generate a signal indicating whether the earbuds are stored in the case as described above and may determine whether the earbuds are stored in the case, and send a signal indicating whether the earbuds are stored in the case to the processor. As a particular example, the earbud case may determine whether the earbuds are stored in the case based on whether one or more electrical contacts on the earbuds are electrically connected to one or more electrical contacts in the case. In another embodiment, the intermediate device is a docking station coupled to the earphones by a mating connector. In some embodiments, if the earphones are not connected to the intermediate device, the intermediate device takes no action (step 4912), and if the earphones are connected to the intermediate device, the method proceeds to step 4915. In other embodiments, step 4910 is optional, and the intermediate device proceeds to step 4915 regardless. However, in such embodiments, if the earphones are not communicatively coupled to the intermediate device, the earphones will not receive the instructions generated in step 4915, and thus the final result of method 4900 will be "no action" in such cases (step 4912). In step 4915, in response to the intermediate device determining that the earphones are connected to the intermediate device, the intermediate device transmits a "start pairing" instruction or signal to the earphones. In one embodiment, the intermediate device transmits "start pairing" via the charging connection between the earphones and the intermediate device. In another embodiment, the intermediate device may wirelessly send a signal to the earphones. In an example, different user inputs cause the intermediate device to transmit different "start pairing" signals to the earphones that can be recognized by the earphones. As an example where the intermediate device is a case for a pair of earbuds, the case may transmit an instruction to the earbuds to automatically pair with a known and previously paired host when the case is opened. If the input button is pressed, before or after the lid is opened, the case may transmit an instruction to the earbuds to enter an exploration mode instead of the automatic pairing mode. The exploration mode then enables the earbuds to be selectively paired with different host devices by the user using a standard pairing sequence. In some embodiments, as described above, step 4910 is optional, and the intermediate device transmits a "start pairing" request signal to the earphones without attempting to determine whether the earphones are connected, but if the earphones are not connected, the signal will not be received. In step 4920, the earphones receive the "start pairing" signal from the intermediate device via the electrical connector or via a wireless connection. In step 4925, in response to receiving the "start pairing" signal, the earphones determine whether to initiate the pairing sequence.In one embodiment, the earphone checks the pairing memory in the earphone and determines whether this pairing is the first pairing of the earphone or a subsequent pairing. If it is the first pairing, the earphone processor can determine what type of user input is received to determine whether the pairing should be initiated. For example, for the first pairing (e.g., the pairing memory of the earphone is empty), if the user opens the lid, the pairing can be initiated, but if the user presses the button, the pairing is not initiated. However, if this is a subsequent pairing (e.g., the pairing memory of the earphone has at least one temporary entry), then if the user opens the lid, the pairing is not initiated, but if the user presses the button, the pairing is initiated. These are only examples, and other logical sequences are within the scope of the present invention. In another example, the earphone will only pair with a host device within a predetermined proximity of the earphone. In one example, the earphone will only pair with a host electronic device within 10 meters, while in another embodiment, the host electronic device must be within 5 meters, and in another embodiment, within 3 meters, and in yet another embodiment, within 1 meter. The maximum proximity pairing distance between the earphone and the host device can be set at the earphone or the host device. In some embodiments, the distance can be controlled by the earphone based on the strength of the wireless signal sent from the earphone to the host device. For example, the earphone can broadcast a pairing signal at a reduced predetermined power level to ensure that the electronic device is within the desired proximity. In one embodiment, the earphone can broadcast a pairing signal having 80% or less than 80% of its normal broadcast power (i.e., its normal signal strength). In another embodiment, the pairing signal can be 50% or less than 50% of the normal signal strength, and in another embodiment, it can be 25% or less than 25% of the normal signal strength. In some embodiments, the distance can be controlled by the host electronic device based on the strength of the signal received from the earphone. For example, in some embodiments, if the strength of the wireless signal transmitting the pairing request is higher than a predetermined threshold value, the host electronic device will only accept the wireless pairing request from the first device, and the predetermined threshold value is higher than the minimum signal strength required for normal wireless communication between the first device and the second device. In one embodiment, the predetermined threshold value is 200% higher than the normal minimum signal strength required for wireless communication between the earphone and the host device. In another embodiment, the predetermined threshold value is 150% higher than the normal minimum signal strength, and in other additional embodiments, it can be 100% or 50% higher than the normal minimum signal strength. Regardless of the method adopted, if the host electronic device is not close enough to the earphone, the earphone will not accept (or will not receive) the pairing request and will not take further action to complete the pairing (step 4927). However, if the required conditions are met, the method continues to step 4930. In step 4930, in response to the earphone determining that the pairing sequence should be initiated (or should continue), the earphone transmits a wireless pairing signal using the common wireless protocol between the earphone and the host device.In some embodiments, this signal may be a standardized recurring Bluetooth signal that can stop after a predetermined time period in the absence of a response. In other embodiments, other known wireless protocols may be used. In step 4935, in response to receiving a pairing signal, the host device authenticates and pairs with the earphones. In one example, the host device provides a prompt to the user asking whether pairing should be performed before pairing with the earphones. If the user accepts, the host device sends data to the earphones and performs authentication of the earphones. In some cases, before initiating a wireless pairing sequence between a pair of wireless earphones and a host device, a case for a pair of wireless earbuds according to the present invention can automatically turn on the wireless radio frequency of the earbuds when the user opens the lid that encloses the earbuds within the case. FIG. 50 illustrates a method 5000 according to some embodiments of the present invention, where the earbud case (e.g., intermediate device 4705) turns on the wireless radio frequency of a pair of earbuds (e.g., wireless earphones 4710) stored within the case. As shown in FIG. 50, method 5000 may begin when intermediate device 4705 detects that lid 4720 has moved from a closed position to an open position (step 5005). If the earbuds are not in the case, no action is taken (step 5020). If wireless earphones 4710 are within the case (step 5010), the case can generate an instruction and send it to the pair of earbuds, the instruction causing the earbuds to turn on their wireless radio frequency. In some embodiments, the instruction may be sent via one or more electrical contacts located within the storage cavity as described above. Once the earbuds turn on their wireless radio frequency, the earbuds can be further instructed to initiate a pairing sequence with the host device. In some embodiments, a single interaction with the case by a user (e.g., opening lid 4720 or pressing button 4725) can generate instructions that are sent to the earbuds to both turn on the earbud wireless radio frequency and initiate the pairing sequence (as described with respect to FIG. 49). In some embodiments, a single instruction from intermediate device 4705 can initiate two actions, and in other embodiments, the case can send multiple instructions in response to a single event. In other embodiments, the closing of lid 4720 can automatically turn off the wireless radio frequency in the earbuds, as described with respect to FIG. 51 illustrating a method 5100 according to some embodiments of the present invention. As shown in FIG. 51, method 5100 may begin when intermediate device 4705 detects that lid 4720 has moved from an open position to a closed position (step 5105). If the earbuds are not in the case, no action is taken (step 5120). If wireless earphones 4710 are within the case (step 5110), the case can generate an instruction and send it to the pair of earbuds, the instruction causing the earbuds to turn off their wireless radio frequency, thus saving the charge of the battery within the earbuds. Although the various embodiments and examples described above mainly focus on earbuds and cases for storing such earbuds, embodiments of the present invention are not limited thereto, and the techniques of the present invention described above are equally applicable to earphones and other listening devices and cases therefor.For example, in one embodiment, the case 100 depicted in FIG. 1 can be a case for a pair of headphones rather than a pair of earbuds. In this embodiment, the cavities 110a, 110b can be sized and shaped to hold the left and right ear pads of the headphones along with a portion of the band connecting the two ear pads. In other embodiments, a single cavity can be included in the case to hold some or all of the ear pads and the headband connector. Similarly, in other embodiments, the case 100 can be sized and shaped to hold a portable speaker or other types of listening devices. For simplicity, various internal components, such as circuitry, buses, memories, storage devices, and other components of a pair of earbuds 115a, 115b, the case 100 (see FIG. 1), and the wearable electronic device 2301 (see FIG. 23) are sometimes not shown in the figures. Also, it should be noted that some embodiments have been described as procedures depicted as flowcharts or block diagrams. Although each figure may describe the procedure as a series of sequential operations, many of the operations can be performed in parallel or simultaneously. In addition, the order of the operations can be reconfigured. The procedure can have additional steps not included in the figures. In the foregoing description, embodiments of the present invention have been described with reference to numerous specific details that can vary according to different embodiments. Accordingly, the specification and the drawings are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indication of the scope of the present invention and what the applicant intends as the scope of the present invention is: the literal scope and the equivalent scope of the set of such patent claims issued from this application in the specific form in which the patent claims are issued, including any subsequent corrections. The specific details of particular embodiments can be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present invention. Additionally, spatial relative terms such as "bottom" or "top" and the like can be used to describe the relationship of one element and / or feature to another (other) element and / or feature, as (for example) illustrated in the figures. It should be understood that, in addition to the orientation depicted in the figures, the spatial relative terms are intended to also encompass different orientations of the device during use and / or operation. For example, if the device in the figures is flipped over, an element described as the "bottom" surface can then be oriented "above" other elements or features. The device can be oriented in other ways (e.g., rotated 90 degrees or in other orientations) and the spatial relative descriptors used herein are interpreted accordingly. The following list of embodiments and examples is set forth to provide additional support and detail indicative of the scope and breadth of the various embodiments of the present invention. For convenience and ease of reference, the embodiments and examples are listed under different headings. It should be understood that the various features listed under a particular heading can be included in or used by the embodiments listed under different headings.. In some embodiments, an earbud case having a charging system provides a case for transporting a portable listening device including a rechargeable battery and electrical contacts and charging the portable listening device. The portable listening device case may include: a housing configured to receive the listening device; a lid attached to the housing and operable between a closed position in which the lid hides the listening device within the case and an open position in which the lid is displaced from the housing such that a user can remove the listening device from the case; a detector configured to generate a detection signal when the listening device is placed in the housing; and a charging circuitry configured to initiate charging of the rechargeable battery in response to receiving the detection signal. In some embodiments, a case for a pair of earbuds includes: a housing having one or more cavities configured to receive one or more of the pair of earbuds; a lid attached to the housing and operable between a closed position in which the lid is aligned over the one or more cavities and an open position in which the lid is displaced from the one or more cavities; and a charging system. The charging system may include: a case battery; an earbud detector configured to detect when an earbud is placed in one or more of the cavities; and a charging circuitry configured to initiate charging of the earbud when the earbud detector detects that the earbud is inserted into one or more of the cavities. The one or more cavities may include: a first cavity configured to receive a first earbud of the pair of earbuds; and a second cavity sized and shaped to receive a second earbud of the pair of earbuds. The earbud detector may include: a first earbud sensor configured to detect when the first earbud is placed in the first cavity; and a second earbud sensor configured to detect when the second earbud is placed in the second cavity. In some cases, each of the first earbud sensor and the second earbud sensor may detect the insertion of its respective earbud by detecting a magnetic field generated by the earbud, and the charging circuitry may be configured to initiate charging of the first earbud when the first earbud sensor detects the first earbud in the first cavity and initiate charging of the second earbud when the second earbud sensor detects the second earbud in the second cavity. In some embodiments, the housing may include a first cavity configured to receive a first earbud of the pair of earbuds and a second cavity sized and shaped to receive a second earbud of the pair of earbuds, and the case may further include a first charging contact positioned within the first cavity to deliver power to the first earbud and a second charging contact positioned within the second cavity to deliver power to the second earbud, and the earbud detector may include a detection circuitry operatively coupled to the first charging contact and the second charging contact, the detection circuitry detecting one or more electrical characteristics of the first earbud and the second earbud when the first earbud and the second earbud are placed in their respective cavities. In some cases, the earbud detector periodically applies a voltage to the first charging contact to detect the first earbud and periodically applies a voltage to the second charging contact to detect the second earbud. In some embodiments, the charging circuitry initiates charging of the earbud by turning on the earbud charging circuitry.Also, the case may include a first plurality of battery level indicators that visually indicate the level of the case battery disposed within the case and a second plurality of battery level indicators that visually indicate the level of one or more rechargeable batteries within the pair of earbuds. The case further includes: a pairing input mechanism disposed on the case and operatively coupled to the circuitry within the case, the pairing input mechanism sending a signal to at least one of the pair of earbuds to place the earbud in a pairing mode; and / or a connector configured to interface with a power source that supplies power to the case to charge the case battery. The connector may also be configured to provide a communication path between the power source and a case processor within the case such that data can be transmitted from the power source to the case processor. In some embodiments, there is provided a case for a pair of earbuds, each earbud having an ear interface portion, a stem, an earbud battery, and a radio frequency. The case may include: a housing having a first cavity configured to receive a first earbud of the pair of earbuds and a second cavity configured to receive a second earbud of the pair of earbuds; a lid attached to the housing and operable between a closed position in which the lid hides the earbuds within the case and an open position that allows a user to remove the earbuds from the case; and a charging system. The charging system may include: a case battery; a first connector configured to interface with a power source for charging the case battery; a second connector configured to couple to each of the first earbud and the second earbud, the second connector having at least one contact positioned within the first cavity and at least one contact positioned within the second cavity; an earbud detector configured to detect when an earbud is placed in either the first cavity or the second cavity; and a charging circuitry configured to initiate charging of the earbud battery when the earbud detector detects an earbud inserted into the first cavity or the second cavity and configured to stop charging the earbud when the earbud detector detects the earbud removed from the cavity. Each of the first earbud and the second earbud may include a connector at a distal end of the stem, the connector having a power contact and a ground contact. The second connector may couple the power connection and the ground connection of the charging circuitry to each earbud when the first earbud and the second earbud are respectively placed within the first cavity and the second cavity. The charging system may include a first charging contact positioned within the first cavity and a second charging contact positioned within the second cavity, and the earbud detector may detect the insertion of the first earbud into the first cavity by detecting the electrical characteristics of the first earbud via the first charging contact and detect the insertion of the second earbud into the second cavity by detecting the electrical characteristics of the second earbud via the second charging contact. The case may further include a user input device disposed on an outer surface of the case, the user input device operable by a user to place the radio frequency of one of the earbuds in a pairing mode.. Box with a Magnetic Over - center Mechanism Some embodiments of the present invention relate to a box that can be used to store a portable listening device or another type of electronic device. The box may include: a housing having a cavity for receiving the electronic device and a receiving opening, the cavity being in communication with the receiving opening; a lid fastened to the housing by a pivotable joint, the lid being operable between an open position where the receiving opening is exposed and a closed position where the lid covers the receiving opening; and a plurality of magnetic elements disposed within the housing and the lid, the plurality of magnetic elements being configured to establish an over - center position for the lid such that when the lid is then attracted to the closed position, the lid resists rotation from the open position to the closed position until the lid moves past the over - center position. The housing may include: opposing first and second side walls and opposing third and fourth side walls extending between the first and second side walls; a bottom wall extending between the first, second, third, and fourth side walls; and an insert positioned within the internal space defined by the side walls and the bottom wall, wherein the insert defines the shape of the cavity; and a receiving opening opposed to the bottom wall, the receiving opening being in communication with the receiving cavity. The receiving cavity may be configured to receive one or more listening devices. The plurality of magnetic elements may be configured to establish an over - center configuration for the lid, wherein the lid is in a first stable position when in the closed position and in a second stable position when in the open position, but is in an unstable position between the closed and open positions. When the lid is in the closed position, the attractive force between the second pair of magnetic elements may overcome the repulsive force of the first pair of magnetic elements; when the lid is in the open position, the repulsive force between the first pair of magnetic elements may overcome the attractive force of the second pair of magnetic elements. In some cases, one or more of the plurality of magnetic elements may be partially surrounded by a high magnetic permeability material. In some cases, one or more of the plurality of magnetic elements are oriented such that when the lid is in the closed position, its magnetic poles are not aligned with its mating magnetic elements, and in some cases, one or more of the plurality of magnetic elements may be fastened to a spring that allows unilateral movement. In some embodiments, a box for a portable listening device is provided. The box may include: a housing having a cavity for receiving the listening device; a lid attached to the housing by a pivotable joint to allow the lid to rotate between a closed position where the lid is aligned over the cavity and an open position where the lid is angularly displaced to allow the listening device to be removed from the cavity; and a plurality of magnetic elements disposed within the housing and the lid, the plurality of magnetic elements being configured to fasten the lid in the closed position and prevent the lid from moving from the open position to the closed position. The plurality of magnetic elements may include a first pair of magnetic elements configured to repel each other and a second pair of magnetic elements configured to attract each other. The first pair of magnetic elements may include a first magnet positioned in the lid adjacent to the pivotable joint and a second magnet positioned in the housing adjacent to the pivotable joint and oriented to repel the first magnet.The second pair of magnetic elements may include a first magnetic element positioned in the cover opposite the pivot joint and a second magnetic element positioned in the housing wall opposite the pivot joint and oriented to attract the first magnetic element. In some cases, both of the magnetic elements in the second pair of magnetic elements are magnets. In some cases, one of the magnetic elements in the second pair of magnetic elements is a magnet and the other magnetic element is a magnetic material. The over-center position may be established by a combination of the repulsive force between the first magnetic element and the second magnetic element, the attractive force between the third magnetic element and the fourth magnetic element, and the distances of the first magnetic element, the second magnetic element, the third magnetic element, and the fourth magnetic element from the pivot joint. In some embodiments, a case for a portable listening device includes: a housing having a cavity for receiving the listening device and a receiving opening in communication with the cavity; a cover fastened to the housing by a pivot joint, the cover being operable between an open position where the receiving opening is exposed and a closed position where the cover covers the receiving opening; a first magnetic element located in the cover near the pivot joint and oriented to repel a second magnetic element located in the housing near the pivot joint; and a third magnetic element located in the cover at the distal end of the cover opposite the pivot joint and oriented to attract a fourth magnetic element located in the housing at the distal end of the housing opposite the pivot joint; wherein the first magnetic element, the second magnetic element, the third magnetic element, and the fourth magnetic element cooperate to define an over-center position for the cover disposed between the open position and the closed position such that when the cover is driven to the closed position, the cover resists rotation from the open position to the closed position until the cover moves past the over-center position. In some examples, the plurality of magnetic elements may include a first pair of magnetic elements oriented such that they repel each other and are positioned near the pivot joint connecting the housing to the cover, wherein the first magnetic element of the first pair is disposed within the case and the second magnetic element of the first pair is disposed within the cover. In some examples, the plurality of magnetic elements may include a second pair of magnetic elements oriented such that they attract each other and are positioned opposite the pivot joint, wherein the first magnetic element is disposed within the case and the second magnetic element is disposed within the cover. In some embodiments, the over-center position is established by a combination of the repulsive force between the first pair of magnetic elements, the attractive force between the second pair of magnetic elements, the distance of the first pair of magnetic elements from the pivot joint, and the distance of the second pair of magnetic elements from the pivot joint.. Earbud Case with Wireless RF Shutdown Feature In some embodiments, a case for a portable listening device with wireless radio frequency is provided. The case includes: a housing having a cavity configured to receive the portable listening device; a lid attached to the housing and operable between a closed position in which the lid hides the portable listening device within the case and an open position in which the lid is displaced from the housing such that a user can remove the portable listening device from the case; a lid sensor for detecting whether the lid is in the closed position or the open position; and a circuit system configured to turn on the wireless radio frequency when the lid sensor detects that the lid has moved from the closed position to the open position. The lid sensor can generate an open signal when the lid moves from the closed position to the open position, and the circuit system can be configured to turn on the wireless radio frequency in response to the open signal. In some cases, the case may further include an electrical connector having a first contact positioned within the cavity to electrically connect to a second contact on the portable listening device when the portable listening device is received within the cavity, and the circuit system can turn on the wireless radio frequency in the portable listening device by sending an instruction to the portable listening device via the first contact. A device detector can be configured to detect when the portable listening device is received within the cavity, and the circuit system can be configured not to send an instruction to the portable listening device unless the device detector detects that the portable listening device is received within the cavity. In various cases, the lid sensor can be a Hall effect sensor, the electrical connector can also provide an electrical connection that enables the case to charge a rechargeable battery within the listening device, and / or the portable listening device can be a pair of earbuds. In some embodiments, a case for a portable listening device with wireless radio frequency includes: a housing having a cavity configured to receive the portable listening device; a lid attached to the housing and operable between a closed position in which the lid hides the portable listening device within the case and an open position in which the lid is displaced from the housing such that a user can remove the portable listening device from the case; a device detector configured to detect when the portable listening device is placed in the cavity; a lid sensor for detecting whether the lid is in the closed position or the open position; and a circuit system configured to turn off the wireless radio frequency when the lid sensor detects that the lid has moved from the open position to the closed position. The lid sensor can generate a closed signal when the lid moves from the open position to the closed position, and the circuit system can be configured to turn off the wireless radio frequency in response to the closed signal. In some cases, the case may further include an electrical connector having a first contact positioned within the cavity to electrically connect to a second contact on the portable listening device when the portable listening device is received within the cavity, and the circuit system can turn off the wireless radio frequency in the portable listening device by sending an instruction to the portable listening device via the first contact.In some embodiments, a case for a pair of earbuds may include: a housing having a first cavity configured to receive a first earbud of the pair of earbuds and a second cavity configured to receive a second earbud of the pair of earbuds; a lid attached to the housing and operable between a closed position in which the lid hides the earbuds within the case and an open position that allows a user to remove the earbuds from the case; a lid sensor for detecting whether the lid is in the closed position or the open position; a case battery; a circuitry configured to charge an earbud battery within each earbud; and a circuitry configured to turn on a radio frequency in the earbuds when the lid sensor detects that the lid has moved from the closed position to the open position and turn off the radio frequency in the earbuds when the lid sensor detects that the lid has moved from the open position to the closed position. In some embodiments, the lid sensor may generate an open signal when the lid moves from the closed position to the open position and a closed signal when the lid moves from the open position to the closed position, and the circuitry included within the case may be configured to turn on the radio frequency in response to the open signal and turn off the radio frequency in response to the closed signal. In various embodiments, the case may further include a device detector for detecting when a portable listening device is received within the cavity, and the circuitry within the case may be configured to send an instruction to the portable listening device to turn on or off the radio frequency only when the device detector detects that the portable listening device is received within the cavity. In various examples, the lid sensor may be a Hall effect sensor. The case may also include one or more earbud detectors configured to detect when an earbud is placed in either the first cavity or the second cavity, and the circuitry may be configured to turn on the radio frequency in the first earbud when one or more earbud detectors detect that the first earbud is received in the first cavity and the lid sensor detects that the lid is in the closed position, and configured to turn off the radio frequency in the second earbud when one or more earbud detectors detect that the second earbud is received in the second cavity and the lid sensor detects that the lid is in the closed position. Earbud with Acoustic Insert Some embodiments of the present invention relate to an earbud that includes: a housing having an open-ear portion; a directional sound port disposed in the open-ear portion; a driver assembly positioned within the housing, the housing having a front volume disposed in front of the driver assembly and a rear volume disposed behind the driver assembly; and an acoustic insert positioned within the housing behind the driver assembly and attached to an inner surface of the housing such that the acoustic insert and the housing form a bass channel routing from the rear volume to a porous port vent within the housing, wherein the bass port channel can alter the frequency response of the earbud. The acoustic insert can include a notch defined by a raised weld zone acoustically bonded to the inner surface of the housing. In some cases, the notch within the acoustic insert forms three walls of the bass channel, and the housing forms a fourth wall of the bass channel. The acoustic insert can further include a pore coupling the front volume to the porous port vent, and the bass channel and the pore can be coupled to a porous cavity vented via the porous port vent. In some examples, the acoustic insert is formed from carbon-doped plastic that absorbs laser energy. In some examples, the earbud housing can be made from acrylonitrile butadiene styrene (ABS) with titanium dioxide pigment. The acoustic insert can be attached to the inner surface of the earbud housing by a laser bonding interface or by an adhesive. In some embodiments, a method of forming an earbud is provided. The method can include: forming a housing having an inner surface and an outer surface; forming an acoustic insert such that it has a notch defined by a raised weld zone; inserting the acoustic insert into the housing such that the raised weld zone is positioned against the inner surface of the housing; and directing a laser through the housing such that it irradiates the raised weld zone of the acoustic insert and welds the raised weld zone to the inner surface of the housing. In some cases, the housing can be formed from plastic substantially transparent to a laser of a certain wavelength, and the acoustic insert can be formed from carbon-doped plastic that absorbs laser energy. An earbud according to some embodiments can include: a housing having an ear portion coupled to a stem; a cavity formed within the ear portion; a driver assembly positioned within the cavity and defining a front volume disposed in front of the driver assembly and a rear volume disposed behind the driver assembly; an acoustic insert positioned within the cavity behind the driver assembly and attached to an inner surface of the housing; and a bass channel formed by the acoustic insert and the housing, the bass channel being routed from the rear volume to the external environment via a vent. The acoustic insert can include a notch defined by a raised weld zone bonded to the inner surface of the housing. The acoustic insert can further include a pore coupling the front volume to the external environment. Wireless Pairing of Earbuds and Case In some embodiments, a case for a pair of wireless earbuds having a wireless radio frequency may include: a housing having a first cavity configured to receive a first earbud of the pair and a second cavity configured to receive a second earbud of the pair; a lid attached to the housing and operable between a closed position in which the earbuds are hidden within the case and an open position that allows a user to remove the earbuds from the case; a connector configured to couple to each of the first and second earbuds, the connector having a first contact positioned in the first cavity and a second contact positioned in the second cavity; a lid sensor configured to generate a detection signal when the lid moves from the closed position to the open position; and a circuitry coupled to the first or second contact and configured to send one or more signals to the pair of wireless earbuds in response to the detection signal, thereby turning on the wireless radio frequency and initiating pairing of the pair of wireless earbuds with an electronic device. The circuitry may include a processor operatively coupled to a computer-readable memory storing instructions executable by the processor to send one or more signals. The connector may include a first power contact for the first earbud of the pair and a second power contact for the second earbud of the pair, and each of the first and second power contacts may be configured to transmit both power and data to the first and second earbuds, respectively. In some embodiments, a case for a portable listening device including a wireless radio frequency may include: a housing having a storage area for the portable listening device; a lid attached to the housing and operable between a closed position in which the portable listening device is hidden within the case and an open position that allows a user to remove the portable listening device from the storage area; an electrical connector positioned within the storage area, the electrical connector having one or more case electrical contacts that are electrically connected to one or more device electrical contacts when the portable listening device is stored in the storage area; an input device configured to generate a signal in response to an action by a user; and a processor coupled to the input device and the electrical connector. The processor may be configured to receive a signal from the input device and, in response, send an instruction via the electrical connector to the portable listening device to initiate wireless pairing of the portable listening device with a host electronic device. In some cases, the processor may be further configured to, prior to sending an instruction to the portable listening device to initiate wireless pairing of the portable listening device with a host electronic device, in response to receiving a signal from the input device, send an instruction via the electrical connector to the portable listening device to turn on its wireless radio frequency. In various embodiments, the portable listening device may be a pair of wireless earbuds (the pair including a first earbud and a second earbud), and the electrical connector may include a first contact for transmitting power to the first wireless earbud and a second contact for transmitting power to the second wireless earbud.A circuit system located within a housing can be configured to transfer data signals between the case and a first wireless earbud and a second wireless earbud via a first contact and a second contact, respectively, also used to charge the earbuds. The input device can include one or both of a lid sensor activated by the user moving the lid from a closed position to an open position and a pressable button on the case. In some cases including two or more different input devices (such as a lid sensor and a pressable button), the different input devices can generate different signals that can be distinguished by a processor and used by the processor to initiate different pairing procedures. The case can also include a rechargeable battery coupled to one or more case electrical contacts within the case, the one or more case electrical contacts configured to provide charge to the first wireless earbud and the second wireless earbud to recharge the batteries within the earbuds. In some embodiments, a method of wirelessly pairing a first electronic device with a second electronic device is provided. The method can include: receiving an input from a user at a third electronic device different from the first device and the second device. In response to receiving the input, the third electronic device can convey the user input signal to the first electronic device via a wired connection between the third electronic device and the first electronic device. In response to the first electronic device receiving the user input signal, the first electronic device can broadcast a wireless pairing request, and in response to receiving the wireless pairing request, the second electronic device can wirelessly pair with the first device. In some cases, the first electronic device can be a set of wireless earphones, the second electronic device can be a mobile electronic device, and the third electronic device can be a case for a portable listening device. Also, in some embodiments where the third electronic device is a case for a portable listening device, the input from the user can be to open the lid of the case. In the method, the wired connection between the third electronic device and the first electronic device can include a connector for charging the first electronic device. Also, in response to receiving a signal by the first electronic device, the first electronic device can broadcast a wireless pairing request with a predetermined signal strength less than its normal broadcast power, and the second device will only accept the wireless pairing request from the first electronic device if the signal strength of the wireless signal transmitting the request is higher than a predetermined threshold value, the predetermined threshold value being higher than the minimum signal strength required for normal wireless communication between the first electronic device and the second electronic device. In some embodiments, before the first electronic device broadcasts a wireless pairing request, it checks its memory to determine if it has previously wirelessly paired with another device. In some embodiments, if the first electronic device has previously paired with another electronic device, the first electronic device does not broadcast a wireless pairing request. Additionally, in some embodiments, if the lid of the third device is open, the third device can transmit a first user input signal, and if a button on the third device is pressed, a second user input signal different from the first signal is transmitted. Earbud Case with Socket Connector for Earbuds In some embodiments, there is provided a case for a pair of earbuds, where each earbud has an ear portion and a stem portion, and the stem portion has an electrical connector disposed at the distal end of the stem portion. The case may include: a housing; an insert positioned within the housing, the insert having a first cavity and a second cavity sized and shaped to receive a first earbud and a second earbud respectively, each of the first cavity and the second cavity having a storage opening for receiving the earbud into the cavity and a contact opening opposite the storage opening; and a contact assembly attached to the insert, the contact assembly including a first pair of electrical contacts extending into the first cavity and a second pair of electrical contacts extending into the second cavity, the first pair of electrical contacts and the second pair of electrical contacts being configured to make electrical contact with the electrical connectors disposed at the distal ends of the first earbud and the second earbud respectively via the contact openings. The insert may include a first housing and a second housing joined together, the first housing including the first cavity and the second housing including the second cavity. The case may further include a collar bonded to the top of the contact assembly and to the perimeter of the distal ends of each of the first housing and the second housing. The first pair of electrical contacts and the second pair of electrical contacts may each have an arcuate portion positioned by a contact carrier to couple to the electrical connectors disposed at the distal ends of the first earbud and the second earbud. The contact assembly may include a cavity formed below the arcuate portion, where the cavity has a depth extending below the arcuate portion. The depth of the cavity may be greater than half the diameter of the cavity so that the cavity can capture debris such as lint. The arcuate portions of the contacts may deflect outward when the pair of earbuds are received within the first cavity and the second cavity. In some embodiments, the contact assembly is formed of a dielectric material and a liquid-tight seal may be formed between the contact assembly and the insert. In some embodiments, there is provided an electrical connector assembly for an earbud charging system. The electrical connector assembly may be configured to receive an earbud having an ear portion and a stem portion, the stem portion having an earbud connector disposed at the distal end of the stem portion. The electrical connector assembly may include: a housing having a storage opening for receiving the earbud in a stem-first orientation, a distal end opposite the storage opening, and a contact opening adjacent the distal end and open to a pair of storage openings; a contact carrier formed of a dielectric material and coupled to the distal end of the housing, the contact carrier having a cavity sized to receive the distal end of the housing and a pair of contact receiving slots; and a pair of deflectable electrical contacts disposed within the pair of contact receiving slots, each deflectable electrical contact having a contact portion extending through the contact opening of the housing. The distal end of the housing may be disposed within the cavity and bonded to the contact carrier. In some embodiments, the housing may include a pair of gap slots disposed in the distal end such that the contact portions of the pair of deflectable electrical contacts protrude through the slots when the distal end of the housing is disposed within the cavity. The electrical connector assembly may further include a collar bonded to the top of the contact carrier and to the perimeter of the housing, and the contact portions of the deflectable electrical contacts may be positioned to interfere with the earbud connector when the earbud is received by the electrical connector assembly.In some embodiments, the electrical connector assembly may further include a second housing, a second contact carrier, and a second pair of deflectable electrical contacts such that the connector assembly can accommodate a pair of earbuds. In some embodiments, a case for a pair of earbuds is provided, where each earbud has an ear interface portion and a stem portion, and the stem portion has an electrical connector disposed at the distal end of the stem portion. The case may include: an outer shell; an insert positioned within the outer shell, the insert having a first earbud receiving cavity and a second earbud receiving cavity sized and shaped to respectively receive a first earbud and a second earbud, each of the first receiving cavity and the second receiving cavity having a receiving opening for receiving the earbud into the receiving cavity in a stem-first orientation, a contact opening at the opposite end of the receiving opening; a contact carrier formed of a dielectric material and coupled to the insert, the contact carrier having a first pair of contact receiving slots and a second pair of contact receiving slots disposed at a contact interface region, a debris notch configured to capture debris positioned between the first pair of contact receiving slots, and a second debris notch sized and shaped to capture debris disposed below the contact interface region and positioned between the first pair of contact receiving slots; a first pair of deflectable electrical contacts disposed within the first pair of contact receiving slots, each of the first pair of deflectable electrical contacts having a contact portion extending into the first receiving cavity in the contact interface region; and a second pair of deflectable electrical contacts disposed within the second pair of contact receiving slots, each of the second pair of deflectable electrical contacts having a contact portion extending into the second receiving cavity in the contact interface region. In some cases, the debris notch may include a first debris notch positioned between the first pair of contact receiving slots and a second debris notch positioned between the second pair of contact receiving slots. Each of the first earbud receiving cavity and the second earbud receiving cavity may include an elongate tube portion sized and shaped to receive the stem portion of the earbud and a larger earbud receiving opening sized and shaped to at least partially receive the ear interface portion. The contact portion of each of the deflectable electrical contacts may have a curved profile. Wireless Earbuds with Electrical Contacts In some embodiments, a wireless earbud is provided that includes: a housing having a stem portion aligned with a longitudinal axis, the stem portion including a first end and a second end; a speaker assembly having a driver unit and a directional sound port proximate the first end and offset from the longitudinal axis, wherein the driver unit is aligned to emit sound from the directional sound port and includes a magnet, a voice coil, and a diaphragm; a rechargeable battery disposed in the housing; and a first external contact and a second external contact that are exposed at the outer surface at the second end of the stem portion and are electrically coupled to provide power to the rechargeable battery. The second contact may be electrically coupled to ground. In some embodiments, the wireless earbud further includes a data communication circuit system operatively coupled to the first contact and configured to transmit data to and from the wireless earbud via the first contact. The first external contact and the second external contact may each have a partially annular shape and may be spaced apart in an opposed and symmetric relationship, with a dielectric material therebetween. In some cases, the perimeters of the first external contact and the second external contact are flush with the outer surface of the stem portion. In some instances, the first external contact and the second external contact each include an arcuate peripheral contact surface. In some embodiments, the first external contact and the second external contact form a circular shape that has an acoustic aperture at the center for positioning a microphone at the second end of the stem portion of the earbud. In some embodiments, the first electrical contact and the second electrical contact are each circularly shaped, with the second electrical contact concentrically positioned within the first electrical contact. In some cases, the first contact and the second contact are terminated at the outer surface of each contact with a binary metal alloy plating layer that includes rhodium and ruthenium. In some embodiments, a wireless earbud includes: a housing having a stem portion aligned with a longitudinal axis, the stem portion including a first end and a second end; a speaker assembly having a driver unit and a directional sound port proximate the first end and offset from the longitudinal axis, wherein the driver unit is aligned to emit sound from the directional sound port and includes a magnet, a voice coil, and a diaphragm; a rechargeable battery disposed in the housing; a first semi-circular contact disposed at the outer surface at the second end of the stem portion and electrically coupled to the rechargeable battery; and a second semi-circular contact disposed at the outer surface at the second end of the stem portion, with a first partially annular contact and a second partially annular contact spaced apart in an opposed and symmetric relationship. In some embodiments, a wireless earbud includes: a housing; a rechargeable battery disposed in the housing; a speaker assembly including a driver unit and a directional sound port, wherein the driver unit is aligned to emit sound from the directional sound port and includes a magnet, a voice coil, and a diaphragm; and a plurality of contacts exposed at the outer surface of the housing, each of the plurality of contacts including a conductive substrate having a binary metal alloy plating layer at the outer surface of each contact, the binary metal alloy plating layer including rhodium and ruthenium.In some cases, the weight percentage of rhodium is at least 85%, with the remainder being ruthenium. The plurality of contacts can be external contacts disposed at the outer surface of the housing. In some cases, the thickness of the binary metal alloy plating layer is between 0.65 microns and 1.0 microns, and the plurality of contacts can include at least one intermediate layer disposed between the conductive substrate and the binary metal alloy plating layer. Magnetic Retention of Earbuds within a Cavity Some embodiments of the present invention relate to a case for earbuds having one or more earbud magnetic components. The case may include: a storage cavity sized and shaped to receive an earbud; one or more housing magnetic components disposed within the case and positioned and configured to magnetically attract an earbud and magnetically secure the earbud within the storage cavity and magnetically attract a second earbud and magnetically secure the second earbud within a second storage cavity; and a lid operable between an open position where the storage cavity is exposed and a closed position where the lid covers the storage cavity. The case may be configured to store a pair of earbuds, and the storage cavity includes a first storage cavity sized and shaped to receive a first earbud of the pair of earbuds and a second storage cavity sized and shaped to receive a second earbud of the pair of earbuds. In some embodiments, the one or more housing magnetic components may include: a first plurality of magnetic components disposed around the first storage cavity and configured to magnetically attract the first earbud and magnetically retain the first earbud within the first storage cavity; and a second plurality of magnetic components disposed around the second storage cavity and configured to magnetically attract the second earbud and magnetically retain the second earbud within the second storage cavity. In some examples, the first plurality of magnetic components may include a first magnetic component positioned and configured to magnetically attract a speaker magnet within the first earbud, and the second plurality of magnetic components may include a second magnetic component positioned and configured to magnetically attract a speaker magnet within the second earbud. In other examples, the first plurality of magnetic components may include a first magnetic component positioned and configured to magnetically attract a magnetic plate disposed within an ear portion of the first earbud, and the second plurality of magnetic components may include a second magnetic component positioned and configured to magnetically attract a magnetic plate disposed within an ear portion of the second earbud. In some cases, the first plurality of magnetic components may include one or more magnetic components disposed around a portion of an ear interface portion of the first storage cavity that receives the first earbud, and the second plurality of magnetic components may include one or more magnetic components disposed around a portion of an ear interface portion of the second storage cavity that receives the second earbud. In some cases, the first plurality of magnetic components may include a first housing magnetic component configured to attract a speaker magnet within the first earbud and a second housing magnetic component configured to attract a magnetic plate disposed within an ear portion of the first earbud; and the second plurality of magnetic components may include a third housing magnetic component configured to attract a speaker magnet within the second earbud and a fourth housing magnetic component configured to attract a magnetic plate disposed within an ear portion of the second earbud. In some cases, the first plurality of magnetic components includes a first set of magnetic components forming a first Halbach array to increase the attraction to the first earbud, and the second plurality of magnetic components includes a second set of magnetic components forming a second Halbach array to increase the attraction to the second earbud.The first Halbach array and the second Halbach array can be configured to attract the first earbud and the second earbud into respective cavities and magnetically hold them within the cavities until they are removed by the user. In some embodiments, an earbud includes: a housing formed to at least partially fit within a user's ear; a directional sound port formed within the housing; a speaker assembly disposed within the housing and including a driver unit that includes a first magnet, the driver unit being aligned to emit sound from the directional sound port; and a magnetic holding assembly separated from the speaker assembly and positioned within the housing. The housing can have an ear portion and a stem portion, and the magnetic holding assembly can be disposed within the ear portion. The driver unit can include a diaphragm and a voice coil, and the first magnet can be operatively coupled to the voice coil to move the diaphragm in response to an electrical signal, and the magnetic holding assembly is not operatively coupled to the voice coil. In some embodiments, a wireless listening system is provided that includes a pair of wireless earbuds and a storage case for one of the pair of earbuds. Each wireless earbud can include: a housing formed to at least partially fit within a user's ear; a directional sound port formed within the housing; a speaker assembly disposed within the housing and including a driver unit that includes a first magnet, a diaphragm, and a voice coil, and wherein the first magnet is operatively coupled to the voice coil to move the diaphragm in response to an electrical signal, the driver unit being aligned to emit sound from the directional sound port; and a magnetic holding assembly separated from the speaker assembly and positioned within the housing. In some cases, the magnetic holding assembly is positioned within the ear portion of the housing, and in some cases, it includes a magnetic material plate contoured to match the shape of the housing. The storage case can include: a first receiving cavity sized and shaped to receive the first earbud of the pair of earbuds; a second receiving cavity sized and shaped to receive the second earbud of the pair of earbuds; a plurality of housing magnetic components disposed within the case and positioned and configured to magnetically attract the first earbud and magnetically secure the first earbud within the first receiving cavity and magnetically attract the second earbud and magnetically secure the second earbud within the second receiving cavity; and a lid that can operate between an open position where the first receiving cavity and the second receiving cavity are exposed and a closed position where the lid covers the first receiving cavity and the second receiving cavity. The plurality of housing magnetic components can include a first magnetic component positioned and configured to magnetically attract the speaker magnet within the first earbud and a second magnetic component positioned and configured to magnetically attract the speaker magnet within the second earbud. The plurality of housing magnetic components can further include a third magnetic component positioned and configured to magnetically attract the magnetic plate disposed within the ear portion of the first earbud and a fourth magnetic component positioned and configured to magnetically attract the magnetic plate disposed within the ear portion of the second earbud. The plurality of housing magnetic components can include a plurality of magnets configured to form a Halbach array, the Halbach array being positioned to attract and hold each wireless earbud.. A case with an inductive charging transmitter for charging a portable device In some embodiments, a case for a portable listening device includes: a housing having one or more cavities configured to receive the portable listening device and an external charging surface; a lid attached to the housing and operable between a closed position where the lid is aligned over the one or more cavities and an open position where the lid is displaced from the one or more cavities; a battery; a first charging system configured to charge the portable listening device when positioned in the one or more cavities; and a second charging system including a transmission coil positioned within the housing adjacent to the external charging surface, the transmission coil configured to wirelessly transmit power to a power receiving coil of an electronic device positioned outside the housing adjacent to the external charging surface. The case may further include alignment features that align the transmission coil with the receiving coil on a common axis. In various embodiments, the alignment features may be alignment magnets in the case that magnetically engage mating alignment magnets in the wearable electronic device; may be centered within the transmission coil; and / or may be recessed features within the external charging surface that engage raised features formed on the bottom surface of the wearable electronic device. The circuitry within the case may detect whether the portable listening device is within the one or more cavities and whether the electronic device is positioned adjacent to the external charging surface. If the portable listening device is within the one or more cavities and the electronic device is positioned adjacent to the external charging surface, the circuitry may preferentially charge the portable listening device and then charge the electronic device. In some embodiments, the first charging system and the second charging system may receive power from the case battery and may also receive power from a case connector. The case may further include a plurality of magnetic elements disposed within the housing and the lid, the plurality of magnetic elements configured to secure the lid in the closed position and prevent the lid from moving from the open position to the closed position. The plurality of magnetic elements may include a first pair of magnetic elements configured to repel each other and a second pair of magnetic elements configured to attract each other. In some embodiments, the portable listening device may be a case for a pair of earbuds; the housing may include a first cavity and a second cavity configured to receive the first earbud and the second earbud, respectively; and the first charging system may be configured to charge the earbuds when positioned within the first cavity and the second cavity.In some embodiments, a case for a pair of earbuds includes: a housing having an external charging surface and a first cavity and a second cavity configured to receive a first earbud and a second earbud of the pair of earbuds, respectively; a lid operable between a closed position where the lid is aligned over the first cavity and the second cavity and an open position where the lid is displaced from the first cavity and the second cavity; a battery; a first charging system configured to charge the earbuds when the first earbud and the second earbud are positioned within the first cavity and the second cavity; and a second charging system including a transmission coil positioned within the housing adjacent to the external charging surface, the transmission coil configured to wirelessly transmit power to a power receiving coil of an electronic device positioned external to the housing adjacent to the external charging surface. The case may further include alignment magnets configured to align the transmission coil with the receiving coil. The transmission coil may be an electromagnetic coil that generates a time-varying electromagnetic flux to induce a current in the receiving coil. In various embodiments, the lid is attached to the housing by a hinge, and / or the lid may be separable from the housing. In some embodiments, a case for a pair of earbuds is provided. Each earbud may include an ear interface portion, a stem, an earbud battery, and a radio frequency. The case includes: a housing having a first cavity configured to receive a first earbud of the pair of earbuds and a second cavity configured to receive a second earbud of the pair of earbuds; a lid operable between a closed position where the lid hides the pair of earbuds within the case and an open position where the lid is displaced from the case such that a user can remove the earbuds from the case; and a first charging system and a second charging system. The first charging system may include: a case battery; a wireless power receiving coil positioned within the housing, the wireless power receiving coil configured to wirelessly receive power from a wireless power source; a connector configured to couple to each of the first earbud and the second earbud, the second connector having at least one contact positioned within the first cavity and at least one contact positioned within the second cavity; and a charging circuitry operatively coupled to charge the case battery and provide power from the wireless power received via the wireless power receiving coil to the connector to charge the first earbud and the second earbud. The second charging system may include a transmission coil positioned within the housing and configured to wirelessly transmit power to a power receiving coil of an auxiliary electronic device positioned adjacent to the case. The case may further include an earbud detector configured to detect when an earbud is placed in either the first cavity or the second cavity. The transmission coil may be positioned adjacent to an external charging surface that is part of an outer housing of the case, and the case may further include alignment magnets configured to align the transmission coil with the receiving coil. In some embodiments, the auxiliary electronic device is a wearable electronic device.. Waterproof Socket Connector In some embodiments, a electrical socket connector is disclosed, which includes: a housing composed of an electrically insulating polymer extending between a receiving surface and a back surface, the housing defining a cavity communicating with an opening in the receiving surface to receive a plug portion of a mating plug connector; a contact spacer positioned adjacent to the back surface; a gasket disposed between the back surface of the housing and the contact assembly; a plurality of contacts, each of the plurality of contacts having a tip positioned within the cavity, an anchoring portion anchoring each contact to the contact spacer, and a crossbar portion connecting the tip to the anchoring portion; and a metal bracket disposed around an outer surface of the housing. The cavity includes a groove aligned with each of the plurality of contacts; the metal bracket may include a top bracket attached to a bottom bracket; the gasket may form a liquid-tight seal between the contact assembly and the housing; and each of the plurality of contacts includes an electrically conductive wire extending out of the contact assembly. In some embodiments, the electrical socket connector further includes a dielectric overmolding component formed around a portion of the contact spacer and the anchoring portion of each of the plurality of contacts, the dielectric overmolding component forming a liquid-tight seal for each of the plurality of contacts. In some embodiments, a ground latch is included in the dielectric overmolding and coupled to the dielectric overmolding. The ground latch may include a first spring arm and a second spring arm extending on opposite sides of the plurality of contacts. In some embodiments, the plurality of contacts consists of eight contacts spaced apart from each other along a single row. In some other embodiments, the electrical socket connector includes: a housing composed of an electrically insulating polymer extending between a receiving surface and a back surface, the housing defining a cavity communicating with a front opening in the receiving surface to receive a plug portion of a mating plug connector, and wherein the housing has a plurality of grooves forming a part of the cavity; a contact assembly including: (i) a contact spacer positioned adjacent to the back surface; (ii) a plurality of contacts, each of the plurality of contacts having a tip extending through one of the plurality of grooves into the cavity, an anchoring portion coupled to the contact spacer, and a crossbar portion connecting the tip to the anchoring portion; and (iii) a ground latch having a first spring arm and a second spring arm on opposite sides of the plurality of contacts; a gasket disposed between the back surface of the housing and the contact assembly; and a metal bracket disposed around an outer surface of the housing and formed to secure the contact assembly to the housing. In some embodiments, the electrical socket connector further includes an overmolded dielectric component, and wherein the contact assembly includes a spacer, and the overmolded dielectric component is formed around a portion of the spacer and around the anchoring portion of each contact of the plurality of contacts. The overmolded dielectric component forms a liquid-tight seal for each of the plurality of contacts. In some embodiments, the contact assembly further includes a ground latch having a first retaining feature and a second retaining feature on opposite sides of the plurality of contacts, and the overmolded dielectric component secures the ground latch to the contact assembly.In some cases, the metal bracket includes a top bracket attached to the bottom bracket, and the plurality of contacts include electrical conductors extending out of the contact assembly. In some embodiments, the gasket forms a liquid-tight seal between the contact assembly and the housing. In some embodiments, the electrical socket connector includes: a housing composed of an electrically insulating polymer extending between a receiving surface and a back surface, the housing defining a cavity in communication with a front opening in the receiving surface to receive a plug portion of a mating plug connector, and wherein the housing has a plurality of slots forming part of the cavity; a contact assembly including: (i) a contact spacer positioned adjacent the back surface; (ii) a plurality of contacts, each of the plurality of contacts having a tip extending through one of the plurality of slots into the cavity, an anchoring portion coupled to the contact spacer, and a crossbar portion connecting the tip to the anchoring portion; and (iii) a ground latch having a first spring arm and a second spring arm on opposite sides of the plurality of contacts; a gasket disposed between the back surface of the housing and the contact assembly; and a metal bracket disposed around an outer surface of the housing and formed to secure the contact assembly to the housing. Some embodiments of earbuds with a capacitive touch sensor relate to an earbud that includes: a housing that defines a cavity for receiving one or more electrical components of the earbud, the housing having a touch-sensitive area at an outer surface of the housing and an inner surface within the cavity that faces the outer surface; a capacitive sensor insert having a first surface and positioned within the housing such that the first surface is adjacent to the inner surface of the housing, the first surface having a metallized circuitry formed thereon; an earbud processor disposed within the housing; and at least one conductor that electrically couples the capacitive sensor insert to the earbud processor. The capacitive sensor insert can be formed to closely match the shape of the housing. In some cases, the metallized circuitry forms at least one self-capacitance sensor, where a self-capacitance circuitry that can be detected when touched by a user is loaded. In other cases, the metallized circuitry includes column electrodes and row electrodes that form at least one mutual-capacitance sensor, where the mutual coupling between the column electrodes and the row electrodes is changed and detected when touched by a user. The capacitive sensor insert is formed of a plastic that includes metal particles. In various embodiments, the capacitive sensor insert can include one or more acoustic pores that allow sound to pass through; the metallized circuitry can at least partially surround one or more acoustic pores; and / or the capacitive sensor insert can be configured to detect when the earbud is in a user's ear and / or detect a touch by the user on the outer surface of the earbud housing. In some embodiments, an earbud includes: a housing that defines an enclosed cavity for receiving one or more electrical components of the earbud, the earbud housing having a touch-sensitive area at an outer curved surface of the housing and an inner curved surface within the enclosed cavity that faces the outer curved surface; a directional sound port formed within the housing; a speaker assembly disposed within the enclosed cavity and including a driver unit that includes a magnet, the driver unit being aligned to emit sound from the directional sound port; a capacitive sensor configured to sense a user touch on the touch-sensitive area, the capacitive sensor including a sensor insert positioned within the enclosed cavity and one or more acoustic pores aligned with the directional sound port, the sensor insert having a first surface adjacent to the inner curved surface and contoured to match the inner curved surface, the first surface including a metallized circuitry formed thereon and at least partially surrounding the acoustic pores; and a processor coupled to the capacitive sensor and disposed within the enclosed cavity. In some embodiments, the first surface is contoured to closely match the contour of the housing. In various embodiments, the metallized circuitry can form at least one self-capacitance sensor and / or the metallized circuitry can form at least one mutual-capacitance sensor. In some cases, the metallized circuitry can include a plurality of column and row electrodes, and the capacitive sensor can be configured to sequentially scan the column electrodes and the row electrodes to determine whether the mutual coupling between the column electrodes and the row electrodes has changed.According to some embodiments, an earbud includes: a housing that defines a cavity for housing one or more electrical components of the earbud, the earbud housing having a touch-sensitive area at an outer surface of the housing and an inner surface within the cavity that faces the outer surface; a directional sound port formed within the housing; a speaker assembly disposed within the housing and including a driver unit that includes a magnet, the driver unit being aligned to emit sound from the directional sound port; a capacitive sensor that senses a user touch on the touch-sensitive area, the capacitive sensor including a sensor insert having a first surface and positioned within the housing such that the first surface is adjacent to the inner surface of the housing, the first surface having a metallized circuitry formed thereon; and a processor coupled to the capacitive sensor and disposed within the cavity. In some embodiments, a case having a torsion spring over-center mechanism for a listening device includes: a housing having a cavity for accommodating the listening device; a lid attached to the housing by a pivotable joint to allow the lid to rotate between a closed position where the lid is aligned with the cavity and an open position where the lid is angularly displaced to allow removal of the listening device from the cavity; and an over-center mechanism for the lid, the over-center mechanism including an extension attached to the lid and disposed on a side of the pivotable joint opposite the lid, wherein the extension contacts an arm that blocks the lid from rotating from the open position to the closed position when the lid is then driven to the closed position until the lid moves past the over-center position. The arm may have a force applied to it by a spring that forces it into contact with the extension. The spring may be a torsion spring. The arm may include a first end attached to an arm pivot and a second end opposite the first end. The arm may include a first surface and a second surface configured to face each other and extend between the first end and the second end, wherein the extension is positioned to slidably contact the first surface as the lid transitions between the open position and the closed position. The extension may be further oriented perpendicular to the first surface when the lid is in the over-center position, and the extension may include a rounded contact end that slidably contacts the first surface of the arm as the lid transitions between the open position and the closed position. In some embodiments, a case for an electronic device includes: a housing having a cavity for accommodating the electronic device and an access opening, the cavity being in communication with the access opening; a lid fastened to the housing by a first pivotable joint, the lid being operable between an open position where the access opening is exposed and a closed position where the lid covers the access opening; and a spring-loaded over-center mechanism for the lid. The spring-loaded over-center mechanism may include: an extension coupled to the lid and having a rounded contact portion at a distal end; an arm coupled to the housing by a second pivotable joint, the arm extending between a first end attached to the second pivotable joint and a second end opposite the first end, the arm having a first surface and a second surface extending between the first end and the second end; and a torsion spring formed around the second pivotable joint such that it applies a moment to the arm, thereby forcing the arm against the rounded portion of the extension. The spring-loaded over-center mechanism may block the lid from rotating from the open position to the closed position when the lid is then driven to the closed position until the lid moves past the over-center position. The extension and the arm may be configured such that the extension slidably contacts a first portion of the first surface near the first end as the lid is between the open position and the over-center position; the distal end of the extension is oriented perpendicular to the first surface when the lid is at the over-center position; and the extension slidably contacts a second portion of the first surface near the second end as the lid is between the closed position and the over-center position. The extension may have a rounded portion at a distal end that slidably contacts the arm as the lid transitions between the open position and the closed position. The torsion spring may be pre-loaded against a spring stop attached to the housing.The cavity can be formed to accommodate a pair of earbuds, and the case can further include a charging circuitry configured to charge the pair of earbuds and a sensor configured to detect whether the lid is in an open position or a closed position. In some embodiments, a case for a pair of earbuds includes: a housing having a first receiving cavity sized and shaped to receive a first earbud of the pair of earbuds and a second cavity sized and shaped to receive a second earbud of the pair of earbuds; a lid fastened to the housing by a first pivot joint, the lid being operable between an open position where the first cavity and the second cavity are exposed and a closed position where the lid covers the first cavity and the second cavity; a spring-loaded over-center mechanism coupled to the lid and configured to block the lid from rotating from the open position to the closed position when the lid is then driven to the closed position until the lid moves past the over-center position; and a charging circuitry configured to charge the first earbud when the first earbud is received in the first cavity and to charge the second earbud when the second earbud is received in the second cavity. The spring-loaded over-center mechanism can include: (i) an extension coupled to the lid and having a rounded contact portion at a distal end; (ii) an arm coupled to the housing by a second pivot joint, the arm extending between a first end attached to the second pivot joint and a second end opposite the first end, the arm having a first surface and a second surface extending between the first end and the second end; and (iii) a torsion spring formed around the second pivot joint such that it applies a moment to the arm, thereby forcing the arm against the rounded portion of the extension. The torsion spring can be pre-loaded against a spring stop attached to the housing. The embodiments and examples disclosed herein are selected and described in sequence to best explain the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention in various examples and to utilize the invention with various modifications as are suitable for the particular use contemplated. Accordingly, it will be understood that the invention is intended to cover all modifications and equivalents within the scope of the embodiments and examples listed above and all modifications and equivalents within the scope of the following claims. 100: Box 105: Housing 106: Bottom 108: Upper surface 110a: Cavity 110b: Cavity 115a: Earplug 115b: Earplug 116a: Stem section 116b: Stem section 117a: Plug section 117b: Plug section 120: Lid 125: Charging system 130: Magnet / Housing magnetic assembly 200: System 202a: Earplug 202b: Earplug 204: Box 205: Wired or wireless power source 210: Box processor 215: Earplug detector 217: Radio frequency 220: Lid sensor 225: Box charging circuitry / Casing charging circuitry 227: Box battery 230: Earplug charging circuitry 235: Charging indicator 240: User input device 245: Earplug interface 250: Power interface 255: Input member 260: Internal components 265: Output member 270: Box transmission interface 305: Connector 310a: Magnetic element 310b: Magnetic element 315a: Magnetic element 315b: Magnetic element 320: Detectable medium 325: Speaker magnet 330: Magnetic plate 335: Circuit board 340: Electrical interconnect 345: Electrical connector 347: Electrical connector 350: External surface 360a: Cavity 360b: Cavity 400: Electrical connector 405: Electrical connector 410: First earplug contact / First annular contact 415: Second earplug contact / Second annular contact 420: Insulator 425: First earplug box contact 430: Second earplug box contact 435: Circular microphone aperture 500: Socket connector 505: Electrical connector 510: First earplug contact / Ring contact 515: Second earplug contact / Circular contact 520: Insulator 525: First earplug contact 530: Second earplug contact 535: Circular microphone aperture 600: Socket connector 605: Electrical earplug connector 609: Debris notch 609a: Side wall 610: First earplug contact 610a: End 610b: End 615: Second earplug contact 615a: End 615b: End 620: Insulator 625: First earplug box contact 626: Arcuate contact portion 627: Non-deflected state 628: Storage groove 630: Second earplug box contact 631: Arcuate contact portion 632: Non-deflected state 633: Storage groove 635: Circular microphone aperture 640: Contact carrier 645: Earplug socket cavity 650: First housing 655: Second housing 660: Third earplug contact 665: Fourth earplug contact 670: Collar 675: Top surface 680: Distal end 685: Distal end 687: Opening 690: Housing and socket connector assembly / Housing and contact assembly 700: Socket connector 725: First earplug contact / Socket connector contact730: First earplug contact / socket connector contact 740: Contact carrier 750: First housing 755: Second housing 760: Third earplug contact 765: Fourth earplug contact 770: Cover 773: Adhesive layer 775: Bottom surface 790: Housing and socket connector assembly / housing and contact assembly 800: Socket connector 805: Ear interface portion 810: Earplug contact / first annular contact 815: Earplug contact / second annular contact 820: Electrical insulator 821: Outer surface 825: First earplug contact 830: Second earplug contact 835: Circular microphone aperture 840: Contact carrier 850: First housing 855: Second housing 880: Remote end 885: Remote end 903: Ear interface portion 905a: Earplug retaining magnet 905b: Earplug retaining magnet 905c: Earplug retaining magnet 905d: Earplug retaining magnet 905e: Earplug retaining magnet 905f: Earplug retaining magnet 905g: Earplug retaining magnet 905h: Earplug retaining magnet 910: Rod portion 910a: Cover magnet 910b: Cover magnet 915: Aesthetic acoustic mesh 920: Carrier 955: User input 1105: Magnetic material 1300: Box 1301: Storage opening 1302: Bottom surface 1303: Upper wall 1304: Lower wall 1305: Outer shell 1306: First side wall 1307: Second side wall 1308: Cavity 1309a: Wall end 1309b: Wall end 1309c: Wall end 1309d: Wall end 1310: Cover 1315a: First magnetic element 1315b: Second magnetic element 1317: Pivot joint 1320a: First magnetic element 1320b: Second magnetic element 1600: Box 1603: Outer shell 1604: Cover 1605a: Magnetic element 1605b: Magnetic element 1610a: Magnetic element 1610b: Magnetic element 1615a: High permeability material 1615b: High permeability material 1700: Box 1704: Cover 1705a: First magnetic element 1705b: Second magnetic element 1707a: Spring 1707b: Spring 1710a: Magnetic element 1710b: Magnetic element 1717a: Spring 1717b: Spring 1800: Square rod 1900: Rectangular rod 2000: "L" - shaped rod 2100: Cylindrical rod 2200: Box 2205: Outer shell 2210: Cover 2220: Spring - actuated over - center mechanism / spring - loaded mechanism 2225: Extension 2226: Rounded remote end 2230: Pivot joint 2235: Spring - loaded arm 2240: Second pivot joint 2245: Remote tip 2246: First surface 2247: Second surface 2248: First part 2249: Second part2250: Torsion spring 2255: Spring stop 2300: Earbud case 2301: Watch 2302: Housing 2304: Display 2306: Dial 2308: Button 2310: Belt piece 2330: Wireless power transfer component 2335: Outer shell 2340: External charging surface 2400: Inductive power receiving system 2402: Battery 2404: Receiving coil 2406: Power conditioning circuitry 2410: Processing unit 2412: Memory 2505: Outer shell 2520: Cover 2525: Inductive charging system 2600: Wireless charging system 2602: Inductive power transfer component 2604: Power source 2606: Transmission coil 2630: Alignment magnet 2700: Case 2705: Wireless charging station 2710: Outer shell 2715: Inductive power transfer coil 2720: Receiving coil 2800: Liquid-tight electrical connector / connector assembly / socket electrical connector 2805: Metal bracket 2810: Mounting hole 2815: Storage surface 2820: Interconnect surface 2825: Metal pin 2826: Ground pin 2830: Overmolded portion 2835: Deformable finger / bracket finger 2905: Outer shell 2910: Back 2915: Cavity 2920: Spacer 2925: Retaining feature 2930: Electrical contact 2935: Elongated crossbar portion 2940: Contact tip 2945: Anchoring portion 2950: Groove 2955: Conductive wire 2960: Alignment portion 2965: Ground latch 2970: Ground groove 2975: Dielectric overmolded portion 2980: Integrated contact plate 2985: Washer 2990a: Top bracket 2990b: Bottom bracket 3000a: Non-closed left earbud 3000b: Non-closed right earbud 3005: External outer shell 3010: Ear portion 3015: Stem portion 3020: Directional sound port 3025: Front leakage orifice 3030: Perforated orifice 3035: Rear vent 3040: Bass port 3045: Optical tragus sensor 3050: Optical concha sensor 3055: Remote 3060: Electrical connector 3065: Bottom microphone port 3070: Top microphone port 3205: Driver 3210: Front acoustic volume 3215: Rear acoustic volume 3220: Acoustic insert 3225: Flexible circuit 3315: Accelerometer 3330: Antenna 3335: Rechargeable battery 3405: Concha portion 3410: Processor portion 3415: Accelerometer portion 3420: Top microphone portion 3430: Tragus sensor portion 3435: Bottom microphone portion 3440: Flexible portion 3600: Connector 3610: Inner circular metal contact 3613: Void 3615: Outer circular metal contact 3620: Dielectric ring3625: Ridge 3630: First coupling tab 3635: Metallized pad 3640: Second coupling tab 3655: Attachment tab 3900: Connector 3910: First semi-circular contact 3913: Pore 3915: Second semi-circular contact 3920: Dielectric layer 3930: First coupling tab 3940: Second coupling tab 3955: Attachment tab 4100: Earplug 4104: Earplug housing 4105: Housing 4110: Capacitive sensor insert 4115: External surface 4120: Sensor circuitry 4125: Touch-sensitive area 4130: Touch-sensitive area 4205: Cavity 4210: Internal surface 4215: First surface 4220: Second surface 4300: Capacitive sensor plug-in 4305: Self-capacitive sensor circuitry 4310: Interconnection area 4315: Area 4320: First surface 4325: Acoustic pore 4400: Capacitive sensor insert 4405: Mutual-capacitive sensor circuitry 4407: First surface 4410: Column electrodes and row electrodes 4415: Interconnection area 4425: Acoustic pore 4505: Acoustic insert 4507: Porous oral cavity 4510: Cavity 4515: Front volume 4520: Rear volume 4525: Internal surface 4527: Bass port channel 4530: Raised area 4535: First wall 4540: Second wall 4545: Third wall 4550: Bass port notch 4555: Inlet pore 4560: Outlet pore 4565: Rear ventilation pore 4570: Driver 4700: Wireless pairing system 4705: Intermediate device 4710: Wireless earphone 4715: Host device 4720: Earplug case lid 4725: Input button 4800: Wireless pairing system 4815: Network storage / Network storage system 4820: Processor 4825: Memory 4830: User interface 4835: First wireless transceiver 4840: Second wireless transceiver 4845: Wired input / output component 4850: Processor 4855: Wired input / output component 4860: Memory 4865: Wireless transceiver / Bluetooth transceiver 4870: Processor 4875: Wired input / output component 4880: User input device 4885: Memory 4900: Method 5000: Method 5100: Method FIG. 1 is a side view of a case having a lid and configured to hold a pair of earbuds according to an embodiment of the present invention; FIG. 2 is a system-level diagram of a case having a charging system coupled to a pair of earbuds according to some embodiments of the present invention; FIG. 3 is a simplified cross-sectional view of the case shown in FIG. 1; FIG. 4A is a partial cross-sectional view of an earbud connector according to an embodiment of the present invention; FIG. 4B is a plan view of the earbud connector illustrated in FIG. 4A; FIG. 5A is a partial cross-sectional view of another embodiment of an earbud connector according to the present invention; FIG. 5B is a plan view of the earbud connector illustrated in FIG. 5A; FIG. 6A is a partial cross-sectional view of another embodiment of an earbud connector according to the present invention; FIG. 6B is a plan view of the earbud connector illustrated in FIG. 6A; FIG. 6C is an isometric exploded view of a connector assembly for the earbud connector illustrated in FIG. 6A; FIG. 6D is an isometric view of the assembled earbud connector illustrated in FIG. 6A; FIG. 7A is an isometric exploded view of another embodiment of an earbud connector according to the present invention; FIG. 7B is an isometric view of the assembled earbud connector illustrated in FIG. 7A; FIG. 8A is a partial cross-sectional view of another embodiment of an earbud connector according to the present invention; FIG. 8B is a plan view of the connector on the earbud illustrated in FIG. 8A; FIG. 8C is an isometric exploded view of the earbud connector illustrated in FIG. 8A; FIGS. 9A and 9B are front and rear isometric views, respectively, of one of the earbuds shown in FIG. 1; FIG. 10 is a top view of the case shown in FIG. 1 with the lid removed; FIG. 11 is a partial cross-sectional view of an earbud held in a cavity within the case illustrated in FIG. 10 along section A-A; FIG. 12 is a partial cross-sectional view of an earbud held in a cavity within the case illustrated in FIG. 10 along section B-B; FIG. 13 is an isometric view of a case having an over-center lid according to some embodiments of the present invention; FIG. 14 is an isometric view of the case shown in FIG. 13 with the over-center lid in the open position; FIG. 15 is a graph showing the attractive and repulsive forces associated with an over-center lid according to some embodiments of the present invention; FIG. 16 is a side view of a case according to some embodiments of the present invention, the case including a pair of magnets having misaligned magnetic poles and a pair of magnets surrounded by a high magnetic permeability material; FIG. 17 is a side view of a case including two pairs of magnets attached to springs according to some embodiments of the present invention; FIG. 18 is an isometric view of a magnet that can be used in a case according to some embodiments of the present invention; FIG. 19 is an isometric view of a magnet that can be used in a case according to some embodiments of the present invention; FIG. 20 is an isometric view of a magnet that can be used in a case according to some embodiments of the present invention; FIG. 21 is an isometric view of a magnet that can be used in a case according to some embodiments of the present invention; FIG. 22A is a side view of a case having a torsion spring over-center mechanism according to some embodiments of the present invention, where the lid of the case is closed; FIG. 22B is an isometric view of the torsion spring over-center mechanism illustrated in FIG. 22A;FIG. 22C is a side view of the case illustrated in FIG. 22A, where the lid of the case is partially open; FIG. 22D is a side view of the case illustrated in FIG. 22A, where the lid of the case is further open; FIG. 23 is a simplified perspective view of a wireless charging system according to an embodiment of the present invention; FIG. 24 is a block diagram of an inductive power receiving system that can be part of the charging system illustrated in FIG. 23 according to some embodiments; FIG. 25 is a simplified plan view of the earbud case illustrated in FIG. 23; FIG. 26 is a block diagram of an embodiment of the inductive power transmission system illustrated in FIG. 23; FIG. 27 is a simplified isometric view of an inductive charging case on an inductive charging system according to some embodiments of the present invention; FIG. 28 is an isometric view of an electrical connector that can be included in the case illustrated in FIG. 1 according to some embodiments of the present invention; FIG. 29 is an isometric exploded view of the electrical connector illustrated in FIG. 28; FIG. 30 illustrates an isometric front view and a rear view of a left earbud according to some embodiments of the present invention; FIG. 31 illustrates an isometric front view and a rear view of a right earbud according to some embodiments of the present invention; FIG. 32 is a cross-sectional view of one of the earbuds illustrated in FIGS. 30 and 31; FIG. 33 is a cross-sectional view of one of the earbuds illustrated in FIGS. 30 and 31, where some components are removed; FIG. 34 is a plan view of a flexible circuit board that can be used in an earbud according to some embodiments of the present invention; FIG. 35 is an isometric view of the flexible circuit board illustrated in FIG. 34; FIG. 36 is an isometric view of a connector structure that can be included in the earbuds illustrated in FIGS. 30 and 31; FIG. 37 is an isometric view of the contacts of the connector structure illustrated in FIG. 36 according to some embodiments of the present invention; FIG. 38 is an isometric view of the contact structure illustrated in FIG. 36; FIG. 39 is an isometric view of an earbud connector contact according to an embodiment of the present invention; FIG. 40 is an isometric view of the insert molded connector contact illustrated in FIG. 39; FIG. 41 is an isometric view of an earbud with a capacitive sensor insert according to some embodiments of the present invention; FIG. 42 is a cross-section of the earbud and the capacitive sensor insert illustrated in FIG. 41; FIG. 43 is a plan view of a capacitive sensor insert illustrated according to an embodiment of the present invention; FIG. 44 is a plan view of a capacitive sensor insert illustrated according to an embodiment of the present invention; FIG. 45A is an illustration of an earbud with an acoustic insert according to an embodiment of the present invention; FIG. 45B is an illustration of an earbud with the acoustic insert illustrated in FIG. 45A; FIG. 46 is a flowchart illustrating steps associated with manufacturing an earbud according to some embodiments of the present invention; FIG. 47 illustrates a system 47 according to some embodiments of the present invention; FIG. 48 is a simplified block diagram of a system 4800 according to some embodiments of the present invention; FIG. 49 is a flowchart illustrating steps associated with pairing wireless earphones with a host device according to some embodiments of the present invention; FIG. 50 is a flowchart illustrating steps associated with activating a wireless radio frequency in an earbud according to some embodiments of the present invention;FIG. 51 is a flowchart illustrating steps associated with radio frequency in a cancellation-enabled earbud according to some embodiments of the present invention. 100: Case 105: Housing 106: Bottom 108: Upper surface 110a: Cavity 110b: Cavity 115a: Earbud 115b: Earbud 116a: Stem section 116b: Stem section 117a: Plug section 117b: Plug section 120: Cover 125: Charging system 130: Magnet / housing magnetic assembly

Claims

1. A portable listening system comprising: a first housing having a first ear portion sized and shaped to support the first housing on a user's first ear; a second housing separate from the first housing and having a second ear portion sized and shaped to support the second housing on a user's second ear; a first accelerometer positioned within the first housing and configured to generate a first signal in response to detecting contact between a user's finger and the first housing; a second accelerometer positioned within the second housing and configured to generate a second signal in response to detecting contact between the user's finger and the second housing; a first processor positioned within the first housing and configured to output a third signal to a separate electronic device in response to receiving the first signal; and a second processor positioned within the second housing and configured to output a fourth signal to the separate electronic device in response to receiving the second signal.

2. The portable listening system of claim 1, wherein the first accelerometer is configured to sense a sequence of taps by the user’s finger on the first housing.

3. The portable listening system of claim 1, wherein the first accelerometer is further configured to detect one orientation of the first housing.

4. The portable listening system of claim 1 further includes an in-ear sensor attached to the first housing and configured to detect when the first housing is at least partially inserted into one of the user's ears.

5. The portable listening system of claim 4, wherein the in-ear sensor includes a pair of optical sensors to detect a user's tragus and concha.

6. An earplug system comprising: a first housing having a first ear portion sized and shaped to be at least partially inserted into a user's first ear; a first accelerometer positioned within the first housing and configured to generate a first signal when the first accelerometer detects contact between a user's finger and the first housing; a first processor positioned within the first housing and configured to output a second signal to a separate electronic device in response to receiving the first signal; a second housing having a second ear portion sized and shaped to be at least partially inserted into a user's second ear; a second accelerometer positioned within the second housing and configured to generate a third signal when the second accelerometer detects contact between the user's finger and the second housing; and a second processor positioned within the second housing and configured to output a fourth signal to the separate electronic device in response to receiving the third signal.

7. The earphone system of claim 6, wherein the first accelerometer is configured to sense a series of touches by the user’s finger on the first housing.

8. The earphone system of claim 6, wherein the first accelerometer is further configured to detect the orientation of one of the first housings.

9. The earplug system of claim 6 further includes an in-ear sensor attached to the first housing and configured to detect when the first housing is at least partially inserted into one of the user's ears.

10. The earplug system of claim 9, wherein the in-ear sensor includes a pair of optical sensors for detecting a user's tragus and concha.

11. A portable listening system comprising: a first housing having a first ear portion sized and shaped to support the first housing on a user's first ear; a first rechargeable battery located within the first housing; a first processor located within the first housing and coupled to the first rechargeable battery; a first radio frequency unit located within the first housing and coupled to the first rechargeable battery; a first antenna located within the first housing; a first accelerometer located within the first housing and configured to transmit a first signal to the first processor in response to detecting contact between a user's finger and the first housing, wherein in response to receiving the first signal, the first processor transmits a second signal to a separate electronic device; a second housing having a second ear portion sized and shaped to support the second housing on a user's second ear; and a second rechargeable battery located within the second housing. A second processor located within the second housing and coupled to the second rechargeable battery; a second radio frequency unit located within the second housing and coupled to the second rechargeable battery; a second antenna located within the second housing; and a second accelerometer located within the second housing and configured to transmit a third signal to the second processor in response to detecting contact between a user's finger and the second housing, wherein in response to receiving the third signal, the second processor transmits a fourth signal to the separate electronic device.

12. The portable listening system of claim 11, wherein in response to receiving the first signal, the first processor transmits the second signal to the separate electronic device via the first radio frequency and the first antenna.

13. The portable listening system of claim 11, wherein the first accelerometer is further configured to detect one orientation of the first housing.

14. The portable listening system of claim 11 further includes an in-ear sensor attached to the first housing and configured to detect when the first housing is at least partially inserted into the user's first ear.

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