Power adaptive active noise reduction (ANR) headset

Abstract

Aspects include active noise reduction (ANR) headphones and methods of controlling such headphones. In some implementations, a headphone comprises: at least one electro-acoustic transducer; the power supply is used for supplying power to the at least one electroacoustic transducer; and a control circuit configured to: apply active noise reduction (ANR) to ambient sound using the at least one electro-acoustic transducer; sampling the voltage drop at the two ends of the power supply; and adjusting a compressor threshold for the ANR based on the sampled voltage drop across the power supply.

Description

[0001] CLAIM OF PRIORITY

[0002] This application claims priority to U.S. Patent Application No. 18 / 122,855, filed March 17, 2023, which is incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates generally to wearable audio devices, such as headphones. More specifically, the present disclosure relates to power adaptive active noise reduction (ANR) headphones and related methods of controlling such headphones. BACKGROUND

[0004] Headphones that deploy active noise reduction (ANR) systems can significantly enhance user comfort and improve communication relative to headphones that only provide passive noise reduction (or occlusion), e.g., audio headphones. However, ANR systems and associated acoustic components can consume a significant portion of the power used to operate such headphones. SUMMARY

[0005] All examples and features mentioned below can be combined in any technically possible manner.

[0006] Various implementations of the present disclosure include active noise reduction (ANR) headphones and methods of controlling such headphones.

[0007] In some particular aspects, a headphone includes at least one electro-acoustic transducer configured to provide audio output, a power source to power the at least one electro-acoustic transducer, and control circuitry configured to apply active noise reduction (ANR) to ambient (e.g., occlusion residual) sound using the at least one electro-acoustic transducer, sample a voltage drop across the power source, and adjust a compressor threshold for the ANR based on the sampled voltage drop across the power source.

[0008] In additional particular aspects, a method of controlling an active noise reduction (ANR) headphone includes applying ANR to ambient (e.g., occlusion residual) sound using the headphone, sampling a voltage drop across a power source of the headphone, and adjusting a compressor threshold for the ANR based on the sampled voltage drop across the power source.

[0009] Implementations can include one of the following features, or any combination thereof.

[0010] In certain aspects, the power source includes one or more batteries.

[0011] In particular cases, the one or more batteries are selected from a group of different batteries having different chemical compositions. In some examples, the batteries have different chemical compositions, such as alkaline chemical composition, lithium chemical composition, and / or nickel-cadmium (NiCad) chemical composition.

[0012] In some implementations, a voltage drop across a first one of the batteries is different than a voltage drop across a second one of the batteries. In some examples, the difference in voltage drop between the two different batteries is due at least in part to a difference in battery chemical composition between the two different batteries.

[0013] In certain cases, the power source includes an external power source.

[0014] In particular implementations, the external power source includes a hardwired connection to an aircraft power source.

[0015] In some cases, adjusting the compressor threshold enhances ANR performance of the headset.

[0016] In certain implementations, the enhanced ANR performance is characterized by at least one of a greater reduction in noise in the audio output or an increase in gain in the audio output.

[0017] In particular aspects, adjusting the compressor threshold increases battery life of the headset. In some examples, adjusting the compressor threshold helps to extend battery life in the event of mechanical disturbances. In particular examples, mechanical disturbances can include head movement by a user (e.g., a pilot) and / or a significant change in ambient noise (e.g., in an aircraft).

[0018] In some cases, adjusting the compressor threshold is performed automatically in response to the sampled voltage drop deviating from a voltage drop threshold.

[0019] In certain aspects, the compressor threshold is adjusted without a user input command.

[0020] In particular implementations, the control circuit is configured to sample the voltage drop on a recurring basis and to dynamically adjust the compressor threshold in response to the sampled voltage drop deviating from the voltage drop threshold.

[0021] In some aspects, the recurring basis includes at least one of continuous sampling or periodic sampling. In some examples, continuous sampling is performed at defined intervals and / or dynamic intervals.

[0022] In certain implementations, adjusting the compressor threshold includes reducing the compressor threshold to reduce power consumption of the headphones. In certain examples, reducing the compressor threshold reduces power consumption of one or more components in the headphones, including the transducer, compressor circuit, and / or ANR circuit.

[0023] In particular cases, sampling the voltage drop includes determining at least one of the following characteristics of the power source: power source impedance, charge or discharge state, battery mass, battery chemical composition, connection quality, or voltage level as a function of time.

[0024] In certain aspects, the headphones further include an interface that enables a user to input at least one characteristic of the power source, where the control circuit is configured to adjust the compressor threshold based on the at least one characteristic of the power source. In some examples, the interface enables the user to input at least one of a battery type, a battery serial number, a battery brand, or a battery size. In further examples, the interface enables the user to scan a quick response (QR) code associated with the battery and / or provide a photograph of the battery.

[0025] In some implementations, the headphones further include a feed-forward microphone input and a feedback microphone input, where the control circuit includes an ANR engine and a compressor, and the compressor is configured to compress feedback loop gain from the feedback microphone input according to the compressor threshold prior to input at the ANR engine.

[0026] In particular aspects, the compressor threshold is determined with a compressor threshold control loop that takes as input a voltage drop across the power source and outputs as output a compressor threshold adjustment.

[0027] In certain cases, the control circuit is further configured to adjust a power source monitoring system based on the sampled voltage drop. In some examples, the power source monitoring system updates a battery charge, a remaining battery life indicator, or a remaining battery time indicator based on the sampled voltage drop.

[0028] In some aspects, sampling the voltage drop across the power source includes transmitting a set of test signals to the power source and measuring a voltage response of each test signal in the set of test signals.

[0029] In certain implementations, the aviation audio device includes the headphones.

[0030] In particular aspects, adjusting the compressor threshold helps to comply with aviation-specific communication protocols. In some examples, adjusting the compressor threshold helps to comply with protocols related to communication dropouts or disconnections, Bluetooth (BT) resets, garbled communications, and / or total harmonic distortion (THD) standards. In particular cases, adjusting the compressor threshold helps to comply with aviation-specific communication protocols that require ten percent or less THD (e.g., Federal Aviation Administration protocols).

[0031] Two or more features described in this disclosure, including those described in the SUMMARY, can be combined to form specific implementations not specifically described herein.

[0032] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a schematic diagram of an audio device according to various implementations.

[0034] Figure 2 is a schematic diagram of another audio device according to various implementations.

[0035] Figure 3 is a schematic diagram of another audio device according to various implementations.

[0036] Figure 4 is a schematic diagram of electronics included in an audio device according to various implementations.

[0037] Figure 5 is a schematic diagram of an active noise reduction (ANR) circuit in an audio device according to various implementations.

[0038] Figure 6 is a flowchart illustrating a process of adjusting ANR in an audio device according to various implementations.

[0039] It is noted that the figures of the various implementations are not necessarily drawn to scale. The figures are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents similar elements between the figures. DETAILED DESCRIPTION

[0040] As noted herein, various aspects of the present disclosure generally relate to active noise reduction (ANR) headphones with power adaptation capabilities. In particular cases, a headphone (e.g., an audio headphone) is configured to adjust an ANR configuration based on a detected characteristic of a headphone power source. In more particular cases, an audio headphone is configured to adjust a compressor threshold for ANR based on a sampled voltage drop across the headphone power source.

[0041] For the purposes of illustration, components generally labeled as the same in the figures are considered to be essentially identical components and redundant discussion of those components is omitted for the sake of clarity.

[0042] As noted herein, ANR systems and associated acoustic components can consume a significant portion of a headphone’s power resources. In certain conventional cases, a low state of charge, battery chemistry, and / or a low quality power source can result in an increased internal power source impedance, leading to an increased voltage drop across the power source caused by the load current. This can degrade the ANR performance of a headphone that relies on such a power source. In additional conventional cases, ANR systems are designed for worst-case power source scenarios, e.g., high power source impedance and / or low state of charge. These conventional ANR systems do not adapt to different power source characteristics and thus can not fully utilize the performance capabilities of the headphone (e.g., when a higher quality power source is available).

[0043] In contrast to these conventional systems, various implementations include a headphone with a control circuit configured to: apply ANR to ambient sound (or earcup residual sound); sample a voltage drop across a power source (of the headphone); and adjust a compressor threshold for the ANR based on the sampled voltage drop across the power source. In particular cases, the power source includes one or more batteries, and the headphone is configured to detect different voltage drops across different batteries and adjust a compressor threshold for ANR based on those different voltage drops.

[0044] Aspects and implementations disclosed herein can be applicable to a wide variety of wearable audio devices. In some cases, wearable audio devices can take a variety of form factors, such as earphones (whether ear-enclosing or not), headphones, watches, eyewear, audio accessories or apparel (e.g., audio hats, audio gaiters, audio jewelry), headgear (e.g., for military, industrial, or motorcycling applications), neck-worn speakers, shoulder-worn speakers, body-worn speakers, etc. Some aspects disclosed can be particularly applicable to personal (wearable) audio devices, such as over-ear headphones, on-ear headphones, in-ear headphones (also known as earbuds), audio eyewear, or other head-worn audio devices. Wearable audio devices are primarily described herein in the context of headphones (e.g., over-ear or in-ear), but the present disclosure is not intended to be limited by this unless explicitly stated otherwise.

[0045] Wearable audio devices described in accordance with various implementations can include features present in one or more other wearable electronic devices, such as smart eyewear, smart watches, etc. These wearable audio devices can include additional hardware components, such as one or more cameras, location tracking devices, microphones, etc., and be capable of voice recognition, visual recognition, and other smart device functionality. The descriptions of wearable audio devices included herein are not intended to exclude these additional functionalities in such devices.

[0046] Wearable audio devices described herein can be used in a variety of different applications, such as for aviation, aerospace, military (e.g., in vehicles and / or for dismounted applications), broadcasting, coaching (e.g., for sports / athletic events, such as football games), gaming, industrial (e.g., manufacturing, warehouse), construction, conferencing, vehicle-based transportation services (e.g., truck or van delivery), racing, motorcycles or motorbikes, professional audio (e.g., studio production, audio mixing, live performance), and general lifestyle applications (e.g., consumer electronics wearable audio devices, such as earphones or earbuds), among other applications that can be appreciated based on the present disclosure. Moreover, a single wearable audio device (e.g., a single headphone) can be used for multiple different applications, as the control platform of the audio device enables customization of the audio device to optimize adaptability for different applications. In some implementations, customization of the audio device control platform occurs automatically based on one or more accessories connected to the audio device. Other triggering events can alternatively or additionally be used to customize the audio device, such as based on user input using a connected control module (e.g., using an embedded control module and / or a mobile device application), environmental conditions (e.g., ambient noise level), sensor input (e.g., atmospheric pressure), or other triggering events that will be apparent in light of the present disclosure.

[0047] Some example implementations relate to audio devices including aviation headsets. Pilots of both general aviation and commercial aviation use aviation headsets. Such headsets can connect to an aircraft communication system, for example, to communicate with air traffic control (ATC) or with other pilots. Headsets can also be used as a public address system, for example, for a pilot to speak to passengers on an aircraft. Aircraft communication systems often include analog communication systems, such as intercoms. In some cases, such intercom systems can be configured to communicate on the very high frequency (VHF) band (e.g., 18 MHz to 136.975 MHz), where each channel is separated from adjacent channels by a pre-designated width of the band (e.g., 8.33 kHz in Europe and 25 kHz elsewhere). Analog modulation techniques such as amplitude modulation (AM) can be used for communication, and conversations can be performed in a simplex fashion. In some cases, for example, for transoceanic flights, other bands, such as the high frequency (HF) band, can be used for satellite communication. For example, aviation headsets can be used by, for example, pilots and air traffic controllers to communicate with each other. Even within the context of aviation use cases, headsets can be optimized based on the class or specific aircraft being used. For example, classes can include, for example, propeller aircraft, jet aircraft, or helicopters, while specific aircraft can include, for example, a Boeing 737, a Boeing 777, an Airbus A320, or a McDonnell Douglas DC-9.

[0048] Figure 1 An example of a wearable audio device 10 including an aviation headset 100 is shown in FIG. 1. In particular cases, the headset 100 includes a frame with at least one earpiece (e.g., ear cup) 105 on each side that fits over, around, or on the ear of a user. In some cases, the frame is optional such that the earpieces 105 are tethered or wirelessly connected to other components in the wearable audio device 10. Each of the ear cups 105 houses a sound transducer or speaker. The headset 100 also includes a headband (e.g., over-the-ear bridge) 110 for connecting the two earpieces (e.g., ear cups) 105. In various implementations, the headset 100 is configured to position the at least one, and in some cases, both earpieces 105 in proximity to the ear of a user. For example, the headset 100 (and other headset forms of the audio device 10 described herein) can be configured to position the earpieces 105 in proximity to the ear of a user when worn by the user. In certain cases, this proximity includes positioning the earpieces 105 on or over the ear (e.g., using ear cups), in the ear (e.g., using earbuds), resting on the ear (e.g., using ear hooks), etc. In some cases, the proximity positioning results in full, partial, or no occlusion of the ear of the user.

[0049] In some implementations, an electronic component (e.g., a microphone, such as a boom microphone) 115 can be physically connected to one of the ear cups 105. The headset 100 can be connected to an aircraft intercom system using a connection cable 120, which can also include a control module 125 that includes one or more controls for the headset 100. In some cases, analog signals to or from the aircraft intercom system are sent through a wired connection provided by the connection cable 120. In other cases, or in additional cases, the headset 100 can include electronics 70, such as a control chip and / or circuitry, an electro-acoustic transducer, a microphone and associated modules, power components such as a battery and / or connectors, interface components such as capacitive touch interface components, and the like. In particular cases, the electronics 70 include a controller coupled with the electro-acoustic transducer, where the controller is also configured to connect with the electronic component (e.g., when in a locked position with the audio device 10). In various implementations, the controller includes one or more processors and is configured to communicate with on-board memory and / or one or more remote storage devices.

[0050] It will also be appreciated that the electronics 70 can include other components not specifically depicted in the figures, such as communication components (e.g., wireless transceivers (WT)) configured to communicate with one or more other electronic devices connected via one or more wireless networks (e.g., a local WiFi network, a Bluetooth connection, or a radio frequency (RF) connection), as well as amplification and signal processing components. The electronics 70 can also include motion and / or position tracking components, such as optical tracking systems, inertial measurement units (IMUs), microelectromechanical systems (MEMS) devices such as combined multi-axis accelerometers, gyroscopes, and / or magnetometers, and the like.

[0051] While Figure 1The example of FIG. 1 illustrates an aviation headset that includes over- the-ear earcups, but aviation headsets of other form factors, including those with in-ear or on-ear earphones, are also compatible with the technology described herein. In examples involving in-ear earphones, the over-the-head bridge can be omitted, and the boom microphone can be attached to the user through the headset or through a separate structure. Also, as used in this document, the term headset includes various types of acoustic devices that can be used for aviation purposes, including, for example, earphones and earbuds. Additional headset features are disclosed, for example, in U.S. Patent Application No. 15 / 238,259, filed August 16, 2016, “Communications Using Aviation Headsets,” and U.S. Patent Application No. 16 / 953,272, filed November 19, 2020, “Wearable Audio Device with Control Platform,” each of which is incorporated herein by reference in its entirety.

[0052] It should also be understood that any of the components described as being connected or coupled to another component in the audio device 10 or other systems disclosed in accordance with particular implementations can communicate using any conventional hardwired connection and / or additional communication protocols. In some cases, the communication protocols can include a Wi-Fi protocol using a wireless local area network (LAN), a communication protocol such as IEEE 802.11b / g, a cellular network-based protocol (e.g., one of a third, fourth, or fifth generation (3G, 4G, 5G cellular network) or a number of Internet of Things (IoT) protocols, such as: Bluetooth, BLE Bluetooth, ZigBee (mesh LAN), Z-Wave (sub-GHz mesh network), 6L0WPAN (Lightweight IP protocol), LTE protocol, RFID, ultrasonic audio protocol, etc. In various particular implementations, separately housed components in the audio device 10 are configured to communicate using one or more conventional wireless transceivers.

[0053] It should be understood that the wearable audio device 10 according to various implementations can take additional form factors. For example, Figure 2A wearable audio device 10 in the form of a personal communication headset 10 (e.g., an aviation headset) is shown. Reference numerals followed by“A” or“B” indicate features that correspond to the right or left side, respectively, of the audio device 10. The audio device 10 includes a headband having an arcuate section 130, a right end, and a left end. Right and left housings 132A and 132B are located at the right and left ends, respectively, of the headband. The arcuate section 130 serves as an over-the-head bridge between the right and left housings 132. A spring band 134 (e.g., spring steel) extends from the right housing 132A through the arcuate section 130 to the left housing 132B. The spring band 134 provides a clamping force to move the housings 132 toward each other (approximately along a horizontal plane through the wearer’s head) while the headband is worn by a user. The right and left housings 132 can move a distance upward and toward the arcuate section 130 or can move a distance downward and away from the arcuate section to accommodate smaller or larger heads, respectively.

[0054] A pad (right pad 136A or left pad 136B, collectively 136) is attached to each housing 132 and serves to comfortably secure the headset 10 to the head. As used herein,“pad” means a compliant member that can compress and / or deform under an applied pressure and is configured for contact with the user’s head in a manner that supports the headband. In some cases, each pad 136 extends from its front end above the ear to its rear end lower on the head and behind the ear when the audio device (headset) 10 is on the head. In certain cases, the pads 136 each have a contoured surface 138 for contacting the user’s head. A boom 140 extends from a rotatable base 142 near the bottom of one of the housings (e.g., the right housing 132A as illustrated) and serves to position and support a microphone 144 attached at the other end. The boom 140 can be partially adjusted by rotating about its base 142 to place the microphone 144 in an appropriate position relative to the user’s mouth. The boom 140 can be permanently affixed to the housing 132A or can be removable so that the audio device 10 can be used for both aviation and non-aviation purposes (e.g., music playback). A connector 146 for a communications cable extends from the bottom of the right housing 132A. An earpiece (e.g., earbud) connector cable 148 extends from one end of each housing 132 and connects with an earpiece 150 such as an earbud or other type of in-ear earphone. Additional features of the audio device 10 in U.S. Patent No. 10,187,718, which is incorporated by reference herein in its entirety, are described therein. Figure 2

[0055] Figure 3 ​Another audio device 10 is depicted, which includes over-ear headphones 310. The headphones 310 can include a pair of earpieces (e.g., earcups) 320 configured to fit over or on a user’s ears. A headband 330 spans between the pair of earpieces 320 and is configured to rest on a user’s head (e.g., across the top of the head or around the head). In some implementations, the headband 330 can include a head cushion 340. Depending on the particular implementation, electronics 70 and other components for controlling the headphones 310 are stored within one or both of the earpieces 320. The electronics 70 can include portions of or connectors for one or more electronic components, as described with respect to the audio devices 10 herein. It will be appreciated that the various wearable audio devices described herein can utilize features of various implementations, and reference is made to Figures 1 to 3 The wearable audio devices 10 shown and described are merely illustrative. In addition to the electronics 70, various implementations of the audio devices (or headphones) 10 can include one or more accessory ports for accommodating (e.g., interfacing with or connecting to) accessories, such as a boom microphone, a battery module, a power connector, a sensor module, a communication module (e.g., a wireless module, such as for enabling Bluetooth or Wi-Fi, and / or a wired module), a self-powered communication module (e.g., a self-powered Bluetooth module), and / or a microphone module. In particular cases, the accessories can be coupled with one or more portions of the headphones 10, such as via the earpieces or earcups. Other connection configurations are also possible in various implementations. Additional details for exemplary accessory connections for the earpieces 400 are included in U.S. Patent Application No. 16 / 930,579, “Wearable Audio Device with Modular Component Attachment,” filed July 16, 2020, which is incorporated by reference in its entirety.

[0056] Figure 4 is a schematic diagram of example electronics 70 in a headphone 10 according to various implementations. As described herein, in certain implementations, one or more components in the electronics 70 can be located in a separate device (e.g., a smart device such as a smartphone, tablet, control module, electronic flight bag, etc.). Additionally, one or more functions performed by components in the electronics 70 can be performed at a device separate from the wearable audio device 10, or duplicated at the separate device. In various particular implementations, each earpiece in the headphone includes a separate electronics 70.

[0057] In any case, returning to Figure 4The electronics 70 can include at least one transducer 500 for providing audio output. The electronics 70 can also include one or more sensors 510, such as a location-based sensor (e.g., a geo-location sensor), a motion-based sensor (e.g., an inertial measurement unit or IMU), an optical sensor, one or more microphones (e.g., a microphone array), and the like. The electronics 70 can also include one or more communication devices 520, such as one or more transmitters and / or receivers (e.g., wireless and / or hardwired transmitters / receivers). In various implementations, the communication devices 520 are configured for multiple communication protocols, e.g., Bluetooth, BLE, Zigbee, and the like, as well as radio communication and intercom communication. The electronics 70 can also include an accessory port connector 530 for detecting connection (e.g., electrical and / or communication connection) with an accessory (e.g., the accessory 420). At least one power source 540 (e.g., one or more batteries, charging devices, and / or hardwired power sources) and an interface 550 (e.g., a user interface such as a touchscreen, a capacitive touch interface, a gesture detection interface, a voice command interface, and the like) are shown.

[0058] The transducer 500, the sensors 510, the communication devices 520, the connector 530, the power source 540, and / or the interface 550 can be connected with a control circuit (or controller) 560, which in some cases includes one or more processors (PUs) for performing the functions described herein. In various implementations, the processor is coupled with a memory. In some cases, the functions of different processors are performed in different controllers 560 (not depicted). However, in other cases, the controller 560 can include one or more processors for performing the functions specified by, for example, execution of instructions stored in a memory. In particular implementations, the controller 560 can include an ANR circuit 570 for controlling active noise reduction (ANR) functions in the headphones 10. As described herein, the ANR circuit 570 can be configured to adjust audio output at the transducer 500 based on a detected voltage drop across the power source 540.

[0059] Figure 5A schematic of ANR circuit 570 is shown, in accordance with various implementations. ANR circuit 570 includes an ANR engine (or ANR subsystem) 580 configured to control audio output to transducer 500 (e.g., adjust gain on an amplifier 590 such as a differential amplifier) based on input from feedback microphone 600 (illustrated as feedback loop 610) and input from feed-forward microphone 620 (after passing through feedback filter 624) (illustrated as feed-forward loop 630). A compressor threshold loop 640 is shown, which illustrates an ANR compressor (also referred to as an ANR feedback attenuator) 650 configured to compress feedback input to ANR engine 580 according to a compressor threshold 660.

[0060] Compression of feedback loop 610 input is performed prior to feedback loop input 610 entering ANR engine 580 (or outside of ANR engine 580) because uncompressed (e.g., noise- overloaded) feedback signals can overload electronics in ANR engine 580. For example, uncompressed feedback signals can have a wide dynamic range (e.g., caused by noise and / or buffeting) and have values higher than a maximum input value for electronics of circuitry in ANR engine 580.

[0061] In various implementations, ANR compressor 650 is configured to compensate for noise overload to ANR circuit 570, for example, due to sudden changes in environmental noise conditions and / or environmental noise exceeding a threshold. In operation, ANR compressor 650 is configured to reduce gain from ANR feedback loop 610 in response to detecting a noise overload event, detecting a potential noise overload event, and / or in response to predicting a noise overload event.

[0062] As Figure 5 As illustrated, ANR circuit 570 includes a compressor threshold loop 640 that enables adjustment of compressor threshold 660 based on sampled voltage drops across power supply 540. Compressor threshold 660 can control an amount of attenuation of input signals from feedback loop 610 prior to input at ANR engine 580. Compressor threshold loop 640 is configured to sample voltage drops across power supply 540 (e.g., periodically, regularly, and / or on a recurring basis), and adjust compressor threshold 660 based on those sampled voltage drops (e.g., in response to changes in voltage drops and / or deviations of voltage drops from a threshold). As Figure 6In various implementations, the ANR circuit 570 is configured to perform processes including (P1) applying active noise reduction (ANR) to the ambient sound (or earmuff residual sound) to provide an audio output at the transducer 500, and (P2) sampling a voltage drop across the power supply 540. In decision (D3), the ANR circuit 570 compares the sampled voltage drop to a voltage drop threshold (or thresholds), and if the voltage drop deviates from the threshold (D3 is “Yes”), in process (P4) the ANR circuit 570 adjusts a compressor threshold 660 of the ANR (e.g., the ANR engine 580). If D3 is No (the voltage drop does not deviate from the threshold), the ANR circuit 570 continues to sample the voltage drop across the power supply 540 on a periodic and / or continuous basis (resumes to process (P2)).

[0063] With continued reference to the example ANR circuit 570 in Figure 5 In certain instances, in addition to or as an alternative to using the voltage detector 670, sampling the voltage drop across the power supply 540 includes determining at least one of the following characteristics of the power supply 540: power supply impedance, charge or discharge state, battery mass, battery chemistry, connection quality, or voltage level over time.

[0064] In various implementations, the voltage drop can be measured by determining the voltage difference between the positive and negative terminals of the power supply 540 (e.g., a battery) under different loads. The correlation between the measured power supply current and voltage enables determination of the power supply 540 (e.g., a battery) impedance and its state of charge. This charge determination can also be achieved by momentarily loading the power supply 540 with a pre-determined load (resistor) and measuring the voltage across the terminals of the power supply 540. The power supply (e.g., battery) voltage drop, the known resistor value, and the measured power supply current can enable determination of the power supply 540 impedance and state of charge. Further, an increase in the power supply 540 (e.g., a battery) impedance can indicate a change in the state of charge of the power supply 540.

[0065] As used herein, power supply mass (within the same chemistry, such as battery chemistry) can vary according to the power supply manufacturer and is generally related to cost. Proprietary chemistries and manufacturing enhancements (in addition to the base chemistry) from some manufacturers can enable greater battery capacity and lower power supply impedance than others. Higher power supply mass can enable greater current delivery capability and longer battery life.

[0066] In some aspects, sampling the voltage drop across power supply 540 includes transmitting a set of test signals to power supply 540 and measuring the voltage response of each test signal in the set of test signals. In particular cases, as Figure 5 As exemplified (as optional), sampling circuit 672 can be used to sample the voltage drop across power supply 540. Sampling circuit 672 can include fixed resistor 674 and control switch 676 for sampling the voltage drop across the power supply. In particular cases, fixed resistor 674 and control switch 676 can be used to create a predetermined load current from power supply 540. Analyzing the voltage at power supply 540 and the voltage drop across resistor 674 enables determination of the power supply impedance. In certain cases, control switch 676 can be controlled, for example, by controller 560 via hardware and / or software functionality, which can include one or more microcontrollers.

[0067] As exemplified in the example circuit in Figure 5 Voltage drop amplifier (or power supply sense amplifier) 680 amplifies the voltage drop signal detected by voltage detector 670, and the amplified signal passes through low pass filter (LPF) 690. The output of LPF 690 is summed with the output from a different portion 640A of compressor threshold loop 640. This portion 640A of compressor threshold loop 640 includes: amplifier 692 to amplify a driver resistance signal that compares the output from voltage regulator 694 and the output of differential amplifier 590; low pass filter 696 to filter the amplified signal; and envelope detector 700 to output a demodulated envelope of the signal from low pass filter 696. The output of envelope detector 700 and low pass filter 690 from another portion 640 of compressor threshold loop 640 are used to define compressor threshold 660. In certain cases, the output of envelope detector 700 and low pass filter 690 are summed to define an adjustment to compressor threshold 660.

[0068] As noted herein, variations in power source characteristics can affect headset performance, and in some cases, result in degraded performance, overuse of power resources, and / or underuse of performance capabilities. The ANR circuit 570 shown and described herein is configured to improve headset performance, increase battery life, etc. by dynamically adjusting the compressor threshold 660 based on the characteristics of the power source 540. In certain implementations, the power source 540 includes one or more batteries. For example, the power source 540 can include one or more replaceable, rechargeable, and / or disposable batteries. In particular cases, the one or more batteries are selected from a set of different batteries having different chemical compositions. In some examples, the batteries have different chemical compositions, such as alkaline, lithium, and / or nickel-cadmium (NiCad) chemical compositions. In some implementations, a voltage drop across a first one of the batteries is different than a voltage drop across a second one of the batteries. In some examples, the difference in voltage drop between the two different batteries is due at least in part to a difference in battery chemical composition between the two different batteries.

[0069] In additional implementations, the power source 540 includes an external power source. Example external power sources can include hardwired connections, such as hardwired connections to an aircraft power source or a military vehicle power source. In some cases, differences in external power source type and / or connection quality can be detectable by the ANR circuit 570, for example, by associated voltage drops that differ across those power sources 540.

[0070] As noted herein, in certain specific embodiments, adjusting the compressor threshold 660 enhances the ANR performance of the headset 10. For example, the enhanced ANR performance can be characterized by a greater reduction in noise at the audio output to transducer 500 and / or an increase in gain at the audio output to transducer 500. In other specific embodiments, adjusting the compressor threshold 660 increases the battery life of the headset 10 (e.g., the battery-powered power supply 540). In some examples, adjusting the compressor threshold 660 helps extend battery life in the event of mechanical disturbances. In certain examples, mechanical disturbances may include head movement of the user (e.g., a pilot) and / or significant changes in ambient noise (e.g., in an aircraft). For example, when the headset 10 is used as an aviation and / or military headset, the user (e.g., a pilot) may frequently and / or suddenly change head orientation (or viewing direction), which may affect the masking seal of the headset on the user's ear or ear area. Furthermore, significant changes in ambient noise are common in aviation and / or military applications. In conventional headphones, changes in occlusion and / or significant fluctuations in ambient noise can lead to overload events (e.g., clicking, garbled speech in communications, etc.) and overburden the power supply. Compared to conventional headphones, headphones 10 are configured to respond effectively to changes in occlusion and significant changes in ambient noise, for example, by conserving power resources when not beneficial and / or enhancing noise cancellation performance when beneficial.

[0071] In some cases, such as regarding Figure 6 As indicated in the flowchart, adjusting the compressor threshold 660 is performed automatically in response to a sampled voltage drop deviating from a voltage drop threshold. For example, the voltage drop threshold may be equal to approximately 3%, 5%, 10%, 15%, 20%, or a value such as X volts. In various embodiments, the ANR circuit 570 samples the voltage drop across the power supply 540 and automatically adjusts the compressor threshold 660 if the voltage drop deviates from the threshold (e.g., greater than Z% or less than Y volts). That is, the ANR circuit 570 is configured to adjust the compressor threshold 660 without user input commands. In various embodiments, the automatic adjustment of the compressor threshold 660 is based on one or more sampled voltage drops deviating from the voltage drop threshold (or multiple thresholds). In some embodiments, the voltage drop threshold comprises a series of values ​​or percentages. In other cases, the threshold is adjusted over time, for example, based on a recent history of sampled voltage values.

[0072] In certain cases, the ANR circuit 570 is configured to sample the voltage drop on a recurring basis and dynamically adjust the compressor threshold 660 in response to the sampled voltage drop deviating from a voltage drop threshold. In some aspects, the recurring basis includes continuous sampling and / or periodic sampling. In some examples, the continuous sampling is performed at a defined interval and / or a dynamic interval. In certain additional cases, the ANR circuit 570 samples the voltage drop in response to a triggering event. Various non-limiting triggering events can include detecting a change in attachment connection of the audio device 10, detecting a change in power source 540 (e.g., between a battery or between a battery and a hardwired power source), detecting a change in power state of the audio device 10 (e.g., power cycle, power on, sleep mode), detecting a change in environmental acoustic conditions (e.g., a significant change in ambient noise level), or a user interface command to initiate or change an operating mode of the audio device 10.

[0073] In certain implementations, adjusting the compressor threshold 660 includes reducing the compressor threshold 660 to reduce power consumption of the headphone 10. In certain examples, reducing the compressor threshold 660 reduces power consumption of one or more components in the headphone, including the transducer 500, the compressor circuit 660, and / or the ANR circuit 570. In various implementations, reducing the compressor threshold 660 can extend the life of the power source 540.

[0074] As noted herein, the sampled voltage drop across the power source 540 can be sampled by determining at least one of the following characteristics of the power source 540: power source impedance, charge or discharge state, battery mass, battery chemical composition, connection quality, or voltage level as a function of time. In certain aspects, the interface 550 enables a user to input at least one characteristic of the power source 540, where the control circuit 560 is configured to adjust the compressor threshold based on the characteristic of the power source 540. In some examples, the interface 550 enables a user to input at least one of a battery type, a battery serial number, a battery brand, or a battery size. In further examples, the interface 550 enables a user to scan a quick response (QR) code associated with the battery and / or provide a photograph of the battery.

[0075] In additional implementations, the controller 560 Figure 4) includes a power monitoring system (MS) 710 configured to monitor aspects of the power source 540, such as the quality of the power connection, the remaining available power of the power source 540 (e.g., in the case of a battery), and the like. The power monitoring system 710 can provide real-time or near real-time information about the power source, e.g., via one or more interfaces 550 at the headset 10, such as via a visual display and / or audio output of the transducer 500. In particular cases, the power monitoring system 710 updates a battery power level, a remaining battery life indicator, or a remaining battery time indicator based on a sampled voltage drop across the power source 540.

[0076] As noted herein, various aspects of the headset 10 can be beneficial in consumer applications, commercial aircraft use, private aircraft use, transportation, military use, and the like. In certain implementations, the headset 10 is part of an aviation audio device required to comply with aviation-specific communication protocols. In some examples, adjusting the compressor threshold 660 facilitates compliance with protocols related to communication dropouts or disconnections, Bluetooth (BT) resets, garbled communications, and / or total harmonic distortion (THD) standards. In particular cases, adjusting the compressor threshold 660 facilitates compliance with aviation-specific communication protocols that require ten percent or less THD (e.g., Federal Aviation Administration protocols).

[0077] As noted herein, various particular implementations enable the headset to adaptively assign a compressor threshold for the ANR system based on characteristics of the headset power source. In particular cases, the headset 10 is configured to operate using various power sources or multiple types of power sources, such as different battery types, e.g., including alkaline, lithium, NiCad, and the like, and to tailor the compressor threshold accordingly. Certain conventional headsets fix the compressor threshold based on assumptions about the power source or predetermined characteristics of the power source (e.g., the power source is an alkaline battery of a particular quality). While voltage discharge across an alkaline battery can generally be linear in nature, voltage discharge across different battery types (e.g., lithium) can follow different patterns. Further, power source impedance, battery quality (high versus low), state of charge, and connection quality can all affect the output of the power source (e.g., battery). As noted herein, conventional headsets fail to account for the above-noted variations in power source characteristics (e.g., battery characteristics) and tailor the compressor threshold accordingly. Various particular implementations can sample the voltage drop across the power source and adjust the compressor threshold accordingly, periodically, continuously, or responsively (e.g., in response to a triggering event). Further, various particular implementations can use information about the power source (e.g., a battery brand or model) to determine the compressor threshold.

[0078] Still further, various implementations of the headset 10 can be configured to assign different compressor thresholds for different ANR modes. For example, as described in U.S. Patent Application No. 16 / 953,272 (previously incorporated by reference), the headset can be configured to apply different ANR modes based on one or more inputs or triggering events. The ANR modes can differ from one another based on a number of acoustic characteristics, including but not limited to maximum noise cancellation level, filter coefficients, equalization, frequency spectrum, etc. The headset 10 can implement switching of ANR modes, for example, using the interface 550. For example, the interface 550 can include a touch interface, buttons, switches, or other physical interface for selecting or switching between ANR configurations. In certain implementations, the interface 550 can include a mechanical switch, such as a two-position switch or a three-position switch, that enables a user to command the controller 560 to switch between modes, ANR configurations, and / or other settings. In some examples, the interface 550 includes a mechanical switch that enables a user to switch between at least two ANR configurations. For example, the mechanical switch enables switching between one use-specific ANR configuration (e.g., an aviation-specific ANR configuration) and another use-specific ANR configuration (e.g., a broadcast-specific ANR configuration or a music playback-specific ANR configuration).

[0079] Additionally, various implementations of the headset 10 can be configured to sample the voltage drop across the power supply 540 in response to connection of an accessory at the headset 10 and / or disconnection of the accessory 420 at the headset 10 Figure 4 ). In some cases, the ANR circuit 570 is further configured to adjust the compressor threshold based on a type of the accessory 420 connected at the headset 10, e.g., where the controller 560 can assign a battery usage mode for the accessory 420. In such cases, the controller 560 can be configured to adjust the compressor threshold 660 based on both the sampled voltage drop across the power supply 540 and the type of the accessory 420 connected to the headset 10. Non-limiting examples of accessories can include a cable (e.g., a connector cable) configured to attach the headset 10 to at least one other device (e.g., an electronic flight bag, an external sensor module, etc.), a microphone or microphone array, one or more image capture devices (such as a camera), one or more light capture devices (such as one or more photodetectors, a lidar sensor, or a light detection device (e.g., for scanning or transmitting / receiving)), a positioning system (such as a global positioning system (GPS), a local positioning system, or an indoor positioning system, etc.). Additional triggering events that can be used to initiate sampling of the voltage drop across the power supply 540, e.g., to adjust the compressor threshold 660, are described in U.S. Patent Application No. 16 / 953,272 (previously incorporated by reference).

[0080] Various implementations include headphones configured to perform active noise reduction (ANR) in accordance with the methods described herein. Other aspects of ANR that can be compatible with the implementations herein are described in U.S. Patent Application No. 16 / 788,365 (“Computational Architecture for Active Noise Reduction,” filed February 12, 2020), which is incorporated by reference in its entirety.

[0081] As noted herein, headphones 10 in accordance with various implementations provide a variety of benefits over conventional audio devices. For example, headphones 10 in accordance with various implementations are capable of implementing customized performance and power management functions based on power source characteristics, and are configured to extend battery life and / or improve performance relative to conventional headphones. Additionally, in some cases, headphones 10 are configured for use in multiple scenarios and / or industries, e.g., from casual use by consumers to professional use by pilots, military personnel, sports coaches, or entertainment professionals. Headphones 10 are configured to apply different ANR compression thresholds based on characteristics of the power source. Headphones 10 shown and described in accordance with various implementations can enhance user experience and improve performance relative to conventional audio devices.

[0082] Although elements of several views of the drawings can be shown and described as discrete elements in a block diagram and can be referred to as “circuitry,” unless otherwise indicated, these elements can be implemented as one or a combination of analog circuitry, digital circuitry, or one or more microprocessors executing software instructions. The software instructions can include digital signal processing (DSP) instructions. Operations can be performed by analog circuitry or by microprocessors executing software that performs mathematical or logical operations equivalent to the analog operations. Unless otherwise indicated, signal lines can be implemented as discrete analog or digital signal lines, a single discrete digital signal line with appropriate signal processing capable of handling separate audio signal streams, or elements of a wireless communication system. Some of the processes can be described in block diagrams. The activities performed in each block can be performed by one element or by a plurality of elements, and can be separated in time. The elements performing the activities of a block can be physically separated. Unless otherwise indicated, audio signals can be encoded and transmitted in digital or analog form; conventional digital-to-analog or analog-to-digital converters can be omitted from the drawings. Some of the drawings can include logical elements, such as decision blocks, comparators, or logic gates. The output of a logical element will be designated as “0” (which corresponds to “No” or “Low” or “Open Circuit”) or “1” (which corresponds to “Yes” or “High” or “Closed Circuit”).

[0083] In various implementations, components described as being “coupled” to one another can be joined along one or more interfaces. In some implementations, these interfaces can include junctions between distinct components, and in other cases, these interfaces can include solid and / or integrally formed interconnections. That is, in some cases, components that are “coupled” to one another can be formed simultaneously to define a single continuous member. However, in other implementations, these coupled components can be formed as separate members and subsequently joined through known processes (e.g., welding, fastening, ultrasonic welding, bonding). In various implementations, accessories (e.g., electronic components) described as being “coupled” can be linked via conventional hardwiring and / or wireless means such that these accessories can communicate data with one another. Additionally, subcomponents within a given component can be considered linked via conventional pathways, which can not necessarily be illustrated.

[0084] Other implementations not specifically described herein are also within the scope of the following claims. The elements of different implementations described herein can be combined to form further implementations not specifically described herein. Some elements of the structures described herein can be removed without adversely affecting their operation. Additionally, various independent elements can be combined into one or more separate elements to perform the functions described herein.

Claims

1. A headset comprising: at least one electro-acoustic transducer configured to provide an audio output; a power source to power the at least one electro-acoustic transducer; and a control circuit configured to: apply active noise reduction (ANR) to ambient sound using the at least one electro-acoustic transducer; sample a voltage drop across the power source; and adjust a compressor threshold for the ANR based on the sampled voltage drop across the power source.

2. The headset of claim 1, wherein the power source comprises one or more batteries.

3. The headset of claim 2, wherein the one or more batteries are selected from a group of different batteries having different chemical compositions.

4. The headset of claim 3, wherein a voltage drop across a first of the batteries is different than a voltage drop across a second of the batteries.

5. The headset of claim 1, wherein the power source comprises an external power source.

6. The headset of claim 5, wherein the external power source comprises a hardwired connection to an aircraft power source.

7. The headset of claim 1, wherein adjusting the compressor threshold enhances ANR performance of the headset.

8. The headset of claim 7, wherein the enhanced ANR performance is characterized by at least one of a greater reduction in noise in the audio output or an increase in gain of the audio output.

9. The headset of claim 1, wherein adjusting the compressor threshold increases battery life of the headset.

10. The headset of claim 1, wherein adjusting the compressor threshold is performed automatically in response to the sampled voltage drop deviating from a voltage drop threshold.

11. The headset of claim 10, wherein the compressor threshold is adjusted without a user input command.

12. The headset of claim 10, wherein the control circuit is configured to sample the voltage drop on a recurring basis and to dynamically adjust the compressor threshold in response to the sampled voltage drop deviating from the voltage drop threshold.

13. The headset of claim 12, wherein the recurring basis comprises at least one of continuous sampling or periodic sampling.

14. The headset of claim 1, wherein adjusting the compressor threshold comprises lowering the compressor threshold to reduce power consumption of the headset.

15. The headset of claim 1, wherein sampling the voltage drop comprises determining at least one of the following characteristics of the power source: power source impedance, charge or discharge state, battery mass, battery chemical composition, connection quality, or voltage level over time. ​ 16. The headphone of claim 1, further comprising an interface that enables a user to input at least one characteristic of the power source, wherein the control circuit is configured to adjust the compressor threshold based on the at least one characteristic of the power source.

17. The headphone of claim 1, further comprising a feed-forward microphone input and a feedback microphone input, wherein the control circuit comprises an ANR engine and a compressor, wherein the compressor is configured to compress a feedback loop gain from the feedback microphone input according to the compressor threshold prior to input at the ANR engine.

18. The headphone of claim 17, wherein the compressor threshold is determined with a compressor threshold control loop that takes as input a voltage drop across the power source and outputs a compressor threshold adjustment.

19. The headphone of claim 1, wherein the control circuit is further configured to adjust a power source monitoring system based on the sampled voltage drop.

20. The headphone of claim 1, wherein sampling the voltage drop across the power source comprises transmitting a set of test signals to the power source and measuring a voltage response of each test signal in the set of test signals.

21. A method of controlling an active noise reduction (ANR) headphone, comprising: applying ANR to ambient sound using the headphone; sampling a voltage drop across a power source of the headphone; and adjusting a compressor threshold for the ANR based on the sampled voltage drop across the power source.

22. The method of claim 21, wherein the power source comprises one or more batteries.

23. The method of claim 22, wherein the one or more batteries are selected from a group of different batteries having different chemical compositions, wherein a voltage drop across a first battery of the batteries is different than a voltage drop across a second battery of the batteries.

24. The method of claim 21, wherein the power source comprises an external power source, wherein the external power source comprises a hard-wired connection to an aircraft power source.

25. The method of claim 21, wherein adjusting the compressor threshold enhances an ANR performance of the headphone when providing an audio output, wherein the enhanced ANR performance is characterized by at least one of a greater reduction in noise in the audio output or an increase in gain in the audio output.

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