Wearable Audio Device Placement Detection

Abstract

An earphone, comprising: an electroacoustic transducer for generating sound; a proximity sensor configured to detect when the earphone is close to the user's skin; an orientation sensor configured to detect the orientation of the earphone; and a processor configured to estimate whether the earphone is inserted into the user's external auditory canal based on the proximity sensor and the orientation sensor.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application is a continuation - in - part of, and claims priority to, International Patent Application No. PCT / US2021 / 034049, filed May 25, 2021, which in turn claims priority to U.S. Patent Application No. 16 / 882,673, filed May 25, 2020, and is now issued as U.S. Patent No. 11,202,137, issued December 14, 2021. The entire disclosures of both prior applications are hereby incorporated by reference in their entirety for all purposes.

Background Art

[0002] The present disclosure relates to wearable audio devices.

[0003] Wearable audio devices are designed to function best when they are in an appropriate use position on the body and when the user stops operating the device.

Summary of the Invention

[0004] All examples and features mentioned below can be combined in any technically possible way.

[0005] In one aspect, a wearable audio device includes an electroacoustic transducer for generating sound, a proximity sensor configured to detect when the wearable audio device is in proximity to a user, an orientation sensor configured to detect the orientation of the wearable audio device, an internal microphone positioned within the housing of the wearable audio device and configured to detect sound within a cavity at least partially formed by a portion of the housing, and a processor configured to (i) determine whether the wearable audio device is in place on the user's body based on the proximity sensor and the orientation sensor, and (ii) estimate whether the user has completed an operation of the wearable audio device based on the internal microphone.

[0006] Some embodiments include one or any combination of the above and / or the following features. In one embodiment, the proximity sensor includes an infrared sensor. In one embodiment, the orientation sensor includes an inertial measurement unit (IMU). In one embodiment, the IMU includes an accelerometer used to detect the orientation of the wearable audio device. In one embodiment, the proximity sensor has an output, and the processor's estimation of whether the wearable audio device is in place on the user's body is based in part on the level of the proximity sensor output. In one embodiment, after the processor estimates whether the wearable audio device is in place on the user's body, the processor is configured to enable a predetermined wearable audio device function. In one embodiment, the predetermined wearable audio device function includes at least one of a telephone answering capability, a Bluetooth connection, beamforming of a microphone carried by the wearable audio device, playback of audio received from an external audio source, enabling of a user interface function, and tuning of an active noise reduction system.

[0007] Some embodiments include one or any combination of the above and / or the following features. In some embodiments, the wearable audio device further comprises an external microphone configured to sense sound outside the housing, and the processor's estimation of whether the wearable audio device is in place on the user's body is further based on the transfer function between the external microphone and the internal microphone. In one embodiment, the processor is further configured to cause the electroacoustic transducer to generate sound based on the transfer function. In one embodiment, the transfer function is determined at a frequency of up to 1,000 Hz. In one embodiment, the processor is further configured to cause the electroacoustic transducer to generate sound at two different frequencies, the first frequency being at least 1,500 Hz, and the processor is configured to determine whether the wearable audio device nozzle is blocked based at least in part on the first frequency, the second frequency being 1,000 Hz or less, and the processor is configured to determine whether the wearable audio device is in place on the user's body based at least in part on the second frequency.

[0008] Some embodiments include one or any combination of the above and / or the following features. In one embodiment, the generated sound is part of a wearable audio device startup tone sequence. In one embodiment, the processor's estimation of whether the wearable audio device is in place on the user's body includes a first series of steps based on at least a proximity sensor, an orientation sensor, and an internal microphone, and a second series of steps based on at least an internal microphone and an external microphone. In some embodiments, the processor is configured to initiate a first group of wearable audio device functions based on the first series of steps and a second group of wearable audio device functions based on the second series of steps, and the functions of the second group are different from the functions of the first group. In one embodiment, the functions of the first and second groups include at least one of call answering capabilities, Bluetooth connection, microphone beamforming carried by the wearable audio device, playback of audio received from an external audio source, activation of user interface functions, and tuning of an active noise reduction system. In one embodiment, at least during the first series of steps, the internal microphone is monitored at frequencies in the range of 0 to 20 Hz.

[0009] In another aspect, a method for detecting when a wearable audio device is in place on a user's body, the wearable audio device comprising an electroacoustic transducer for generating sound, a proximity sensor configured to detect when the wearable audio device is in proximity to the user, an orientation sensor configured to detect the orientation of the wearable audio device, an internal microphone positioned within the housing of the wearable audio device and configured to detect sound within a cavity at least partially formed by a portion of the housing, and an external microphone configured to sense sound outside the housing, the method comprising estimating whether the wearable audio device is in place on the user's body based on the proximity sensor, the orientation sensor, and the internal microphone, and estimating whether the user has completed an operation of the wearable audio device based on the internal microphone.

[0010] Some embodiments include one or any combination of the above and / or the following features. In one embodiment, the processor is further configured to cause the electroacoustic transducer to generate sound after the processor estimates that the wearable audio device is in place on the user's body, and the processor is further configured to calculate a transfer function between the external microphone and the internal microphone over a specified frequency or frequency range of the generated sound. In one embodiment, the processor's estimation of whether the wearable audio device is in place on the user's body includes two series of steps: a first step based on at least the proximity sensor, the orientation sensor, and the internal microphone, and a second step based on at least the internal microphone and the external microphone, and the processor is configured to initiate a first group of wearable audio device functions based on the first step and a second group of wearable audio device functions based on the second step, and the functions of the second group are different from the functions of the first group.

[0011] In another aspect, a wearable audio device (e.g., headphones) includes an electroacoustic transducer for generating sound, a proximity sensor configured to detect when the wearable audio device is in proximity to a user, an internal microphone positioned within a housing of the wearable audio device (e.g., within an earcup of the headphones) and configured to detect sound within a cavity at least partially formed by a portion of the housing, and a processor configured to estimate whether the wearable audio device is in place on the user's body based at least on the proximity sensor and to estimate whether the user has completed an operation of the wearable audio device based on the internal microphone.

[0012] Some embodiments include one or any combination of the above and / or the following features. In one embodiment, the wearable audio device further includes at least one earcup configured to be positioned over or covering the ear of the wearer when the wearable audio device is placed on the head, and both the proximity sensor and the internal microphone are positioned within the earcup. In some embodiments, the proximity sensor comprises a capacitance proximity sensor. In one embodiment, the capacitance proximity sensor comprises a conductive member within the earcup of the wearable audio device. In one embodiment, the conductive member has a curved outer periphery that mimics the curvature of the human earlobe. In one embodiment, the wearable audio device further includes two earcups configured to be positioned over or covering the ear of the wearer when the wearable audio device is placed on the head, with an internal microphone positioned within each earcup, and the estimation of whether the user has completed an operation of the wearable audio device is based on the internal microphones positioned within each earcup.

[0013] Some embodiments include one or any combination of the above and / or the following features. In some embodiments, the processor is configured to initiate a first group of wearable audio device functions based on an estimation of whether the wearable audio device is in place on the user's body. In one embodiment, the processor is configured to initiate a second group of wearable audio device functions based on an estimation of whether the user has completed an operation of the wearable audio device, and the functions of the second group are different from those of the first group. In one embodiment, the functions of the first and second groups include at least one of call answering ability, Bluetooth connection, microphone beamforming carried by the wearable audio device, playback of audio received from an external audio source, activation of user interface functions, and tuning of an active noise reduction system.

[0014] Some embodiments include one or any combination of the above and / or the following features. In one embodiment, during at least an estimation of whether a user has completed an operation of a wearable audio device, an internal microphone is monitored at frequencies in the range of 0 to 20 Hz. In one embodiment, a proximity sensor has an output, and an estimation by a processor of whether the wearable audio device is in place on the user's body is partially based on the level of the proximity sensor output. In some embodiments, after the processor estimates whether the wearable audio device is in place on the user's body, the processor is configured to enable a predetermined wearable audio device function. In one embodiment, the predetermined wearable audio device function includes at least one of a telephone answering capability, a Bluetooth connection, beamforming of a microphone carried by the wearable audio device, playback of audio received from an external audio source, enabling of a user interface function, and tuning of an active noise reduction system. In one embodiment, the processor is further configured to initiate an active noise reduction (ANR) filter determination procedure after an estimation that the user has completed an operation of the wearable audio device.

[0015] Some embodiments include one or any combination of the above and / or the following features. In some embodiments, the wearable audio device further includes an orientation sensor configured to detect the orientation of the wearable audio device. In one embodiment, the processor is further configured to estimate whether the user has removed the wearable audio device from the user's body, based at least on the orientation sensor. In one embodiment, the processor is configured to reduce power consumption based on an estimate of whether the user has removed the wearable audio device from the user's body. In one embodiment, the estimate of whether the user has removed the wearable audio device from the user's body is further based on a proximity sensor. In one embodiment, the processor's estimate of whether the wearable audio device is in place on the user's body is based on the proximity sensor and the orientation sensor. In one embodiment, the orientation sensor comprises an accelerometer.

Brief Description of the Drawings

[0016]

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Mode for Carrying Out the Invention

[0017] The present disclosure relates to wearable audio devices. Some non-limiting examples of the present disclosure describe wearable audio devices of the type known as earphones. Earphones generally include an electroacoustic transducer for generating sound and are configured to deliver sound directly into the user's ear canal. Earphones can be wireless or wired. In the examples described herein, the earphones are wireless and thus carry a power source (generally a rechargeable battery), a wireless communication system (in one example, a Bluetooth-based communication system), and any necessary processing. Other aspects of earphones not included in the present disclosure are not illustrated or described.

[0018] Also, in some examples of the present disclosure, wearable audio devices of the type known as open audio devices are described. Open audio devices have one or more electroacoustic transducers (i.e., audio drivers) located away from the ear canal opening. In some examples, the open audio devices also include one or more microphones, which can be used to pick up the user's voice and / or for noise cancellation. Open audio devices are further described in U.S. Patent No. 10,397,681, the entire disclosure of which is incorporated herein by reference for all purposes.

[0019] Headphones generally refer to a device that is worn around the ear, over the ear, or in the ear, and radiates acoustic energy directly or indirectly into the ear canal. Headphones are sometimes referred to as earphones, earpieces, headsets, in-ear headphones, or sports headphones, and can be either wired or wireless. Headphones include an electroacoustic transducer (driver) that converts an audio signal into acoustic energy. The acoustic driver may or may not be housed in an earcup or housing configured to be located on the head or ear or inserted directly into the user's ear canal. Headphones may be one for each ear, a single standalone unit, or one of a pair of headphones (each including at least one acoustic driver). One headphone can be mechanically connected to the other headphone, for example, by a headband and / or by a lead wire that transmits the audio signal to the acoustic driver within the headphone. Headphones may include components for receiving an audio signal wirelessly. Headphones may include components of an active noise reduction (ANR) system that may include an internal microphone within the headphone housing. Headphones can also include other functions, such as an additional microphone for the ANR system or one or more microphones used to pick up the user's voice.

[0020] In around-ear headphones or on-ear headphones or off-ear headphones, the headphones may include a headband or other support structure and / or at least one housing or other structure that houses the transducer and is arranged to rest on or above or proximate to the user's ear. The headband can be foldable or folding and can be made of multiple parts. Some headbands include a slider that can be located inside the headband and provides any desired translation of the housing. Some headphones include a yoke pivotally attached to the headband, and the housing is pivotally attached to the yoke to provide any desired rotation of the housing.

[0021] An open audio device includes, but is not limited to, an off-ear headphone, i.e., a device having one or more electroacoustic transducers that are coupled (typically by a support structure) to the head or ear but do not occlude the external auditory meatus. In some embodiments, the open audio device is an off-ear headphone with audio glasses, but this is not intended to limit the present disclosure. This is because in an open audio device, the device is typically configured to deliver sound to one or both ears of the wearer without ear cups or ear buds. Wearable audio systems contemplated herein may include a variety of devices, including over-ear hooks such as wireless headsets, hearing aids, glasses, protective helmets, and other open ear audio devices.

[0022] One or more of the devices, systems, and methods described herein may be used in various embodiments and combinations in a wide variety of wearable audio devices or systems, including wearable audio devices of various form factors. Unless otherwise specified, the term active portion of a wearable audio system as used in this document includes headphones and various other types of wearable audio devices such as acoustic devices worn on the head, shoulders, or body (e.g., audio glasses or other head-mounted audio devices), which include another electroacoustic transducer for receiving and / or generating sound in contact with or without contact with the user's ear.

[0023] Specific implementations of wearable audio devices that primarily serve the purpose of acoustically outputting audio are presented in some detail, but it should be noted that the presentation of such specific implementations is intended to facilitate understanding through the provision of examples and should not be construed as limiting either the scope of the disclosure or the scope covered by the claims.

[0024] In some embodiments, the wearable audio device includes a proximity sensor configured to detect when the earphone is proximate to the user. In one embodiment, the proximity sensor detects the user's skin. In one embodiment, the proximity sensor is an infrared (IR) sensor capable of detecting when the wearable audio device is close to or in contact with the skin of the ear. In one embodiment, the IR sensor output is within a predetermined range or at least a predetermined threshold level for the usage position determination to be made. In some embodiments, the wearable audio device also includes an orientation sensor configured to detect the orientation of the wearable audio device. In one embodiment, the orientation is determined along three mutually orthogonal axes in space. Since the wearable audio device is designed to be worn in a specific orientation, knowing the orientation via the orientation sensor can indicate whether the device is in place. For example, when the earphone is held inside the ear of an upright head, the internal orientation sensor has a known orientation in three-dimensional space. The resultant value of the orientation sensor can be within a nominal predetermined range for the usage position determination to be made. The wearable audio device further includes a processor configured to estimate whether the wearable audio device is in place on the user's body based on the proximity sensor and the orientation sensor. In some embodiments where the wearable audio device is an earphone, the proper place is within the user's external auditory canal.

[0025] In some embodiments, the wearable audio device also includes an internal microphone. In one embodiment, the internal microphone is positioned within the housing of the wearable audio device. In one embodiment, the microphone is positioned to detect sound within a cavity that is at least partially formed by a portion of the housing. When the internal microphone is used within the wearable audio device, the processor can also be configured to estimate whether the user has completed an operation of the wearable audio device. In some embodiments, the operation includes placing the wearable audio device in place on the body or removing it from the body. In some embodiments, the wearable audio device also includes an external microphone. In one embodiment, the external microphone is positioned to detect sound external to the wearable audio device housing. When the external microphone is used within the wearable audio device, the processor can also be configured to calculate an audio transfer function between the internal microphone and the external microphone and, based on the transfer function, estimate whether the wearable audio device is in its proper use position (e.g., in the ear).

[0026] FIG. 1 is a perspective view of a wireless in-ear earphone 10. The earphone is a non-limiting example of a wearable audio device. The earphone 10 includes a body or housing 12 that houses the active components of the earphone. Portion 14 is coupled to the body 12 and is flexible so that it can be inserted into the entrance of the ear canal. Sound is delivered through the opening 15. The retention loop 16 is configured and arranged to be positioned within the outer ear, e.g., within the antihelix, to help hold the earphone in the ear. Earphones are well known in the art (e.g., disclosed in U.S. Patent No. 9,854,345, the disclosure of which is hereby incorporated by reference in its entirety for all purposes), and thus specific details of the earphone are not described further herein.

[0027] FIG. 2 is a partial cross-sectional view of only certain elements of the earphone 20 useful for a better understanding of the present disclosure. The earphone 20 includes a housing 21 that surrounds an electroacoustic transducer (audio driver) 30. The housing 21 includes a front housing portion 50 and rear housing portions 60 and 62. The transducer 30 has a diaphragm 32 that is driven to create sound pressure within the front cavity 52. The sound pressure is directed out from the front housing portion 50 through the sound outlet 54. The internal microphone 80 is located inside the housing 21. An exemplary microphone 80 is within the sound outlet 54 as shown in FIG. 2. The external microphone 81 is configured to sense sound outside the housing 21. In one embodiment, the internal microphone 80 is used as a feedback microphone for active noise reduction, and the external microphone 81 is used as a feedforward microphone for active noise reduction. Earphones such as those shown by the earphone 10 in FIG. 1 typically include a flexible tip (not shown) that engages with the neck 51 of the housing portion 50 to help direct sound into the ear canal. The earphone housing 21 further includes a rear enclosure made from the rear housing portions 60 and 62 and a grill 64. It should be noted that the details of the earphone 20 are exemplary aspects of the earphone and do not limit the scope of the present disclosure. This is because the present in-ear detection can be used in various types and designs of earbuds and earphones as well as other wearable audio devices.

[0028] The transducer 30 further includes a magnetic structure 34. The magnetic structure 34 includes a transducer magnet 38 and a magnetic material that functions to confine and guide the magnetic field from the magnet 38. As a result, as is well known in the field of electroacoustic transducers, the magnetic field interacts appropriately with the coil 33 to drive the diaphragm 32. The magnetic material includes a cup 36 and a front plate 35, and as is also known in the art, both of these are preferably made of materials having a relatively high magnetic susceptibility. The transducer printed circuit board (PCB) 40 carries electrical and electronic components (not shown) involved in driving the transducer. Pads 41 and 42 are locations where wires (not shown) can be coupled to the PCB 40.

[0029] In one embodiment, an inertial measurement unit (IMU) 72 is used to detect the orientation of the earphone in three-dimensional space. The IMU can include a three-axis accelerometer that can be used to determine the orientation. Using an accelerometer to determine the orientation of a device that includes or carries the accelerometer is known in the art and thus will not be described further herein. The IMU can also include one gyroscope, or three gyroscopes configured to determine the rotational velocity about three mutually orthogonal axes. The gyroscope can be used additionally or alternatively to determine the orientation of the earphone. Using a gyroscope to determine the orientation of a device that includes or carries the gyroscope is known in the art and thus will not be described further herein. In one embodiment, the IMU 72 is mounted on the PCB 70, but the IMU can be located elsewhere within or on the earphone.

[0030] In some embodiments, the proximity sensor 76 is used to detect that the earphone 20 is in proximity to the user's skin. In one embodiment, the proximity sensor 76 can be an infrared (IR) sensor or a capacitance sensor. The IR sensor can be used to detect proximity to the skin, while the capacitance sensor can detect that the device is in contact with the skin. The IR sensor can be used to detect that the earphone is in proximity to the skin. Since the earphone needs to be in the ear when in the proper use position, the components of the earphone are either in contact with the skin or near the skin. Thus, by positioning the IR sensor on a part of the earphone that contacts or is near the skin, it becomes possible to use the IR sensor as a proximity sensor. In one embodiment, the IR sensor is positioned to detect the tragus. In another example, a distance sensor such as a time-of-flight sensor can be used to detect the distance between the wearable audio device and a desired location on the body (e.g., inside the ear). When the wearable audio device is in place, the device is properly positioned at a known location on the body (e.g., inside the ear, above the ear, or other locations on the head), so the distance from the device to the proper location should be 0 or close to 0.

[0031] The earphone 20 also includes a processor 74. In some embodiments, the processor 74 is configured to process the outputs of the IMU 72, proximity sensor 76, internal microphone 80, and external microphone 81. As will be apparent to those skilled in the art, the processor will of course also be involved in other processing required for earphone functionality, such as processing digital sound files played by the earphone. In one embodiment, the processor is configured to estimate whether the wearable audio device is in place on the user's body based on both the proximity sensor and the orientation sensor. In some examples, the processor's estimation of whether the wearable audio device is in place on the user's body is further based on the transfer function between the external microphone and the internal microphone. In one embodiment, the processor is configured to estimate whether the user has completed an operation of the wearable audio device based on the internal microphone. In some embodiments, the proximity sensor has an output, and the processor's estimation of whether the wearable audio device is in place on the user's body is partially based on the level of the proximity sensor output. In one embodiment, the processor's estimation of whether the wearable audio device is in place on the user's body is partially based on whether the proximity sensor output has reached a threshold level. For example, as the wearable audio device approaches the skin, the IR sensor output increases. For any given IR sensor, an output reaching a predetermined level can be considered equivalent to the sensor being within a predetermined distance of the skin.

[0032] In some embodiments, the processor's estimation of whether a wearable audio device is in place on the user's body includes a plurality of series of steps. In one embodiment, the first step is based on a proximity sensor and an orientation sensor, the second step is based on an internal microphone, and the third step is based on internal and external microphones. In one embodiment, the processor is configured to initiate a first group of wearable audio device functions based on the first and second steps, and a second group of wearable audio device functions based on the third step. In one embodiment, the functions of the second group are different from the functions of the first group. In some embodiments, the functions of the first and second groups include at least one of call answering ability, Bluetooth connection, beamforming of the microphone carried by the wearable audio device, playback of audio received from an external audio source, activation of user interface functions, and tuning of an active noise reduction system.

[0033] In some embodiments, the processor is configured to cause an electroacoustic transducer to generate sounds that are used in a high-confidence determination of whether the wearable audio device is in place. In one embodiment, this high-confidence determination is made only after the processor has made a first-level low-confidence determination that the wearable audio device is in place on the user's body and the user has stopped operating the device. In one embodiment, the processor is configured to calculate a transfer function between an external microphone and an internal microphone over a specified frequency range. In one embodiment, the generated sound is part of a wearable audio device startup tone sequence.

[0034] In one embodiment, the processor is configured to cause the electroacoustic transducer to generate sound at two (or more) different frequencies for determining a proper location / improper location. In one embodiment, the first frequency is at least 1,500 Hz (e.g., 1,500 - 3,000 Hz), and the processor is configured to determine whether the wearable audio device nozzle is blocked, at least in part, based on that frequency. In one embodiment, the second frequency is less than 1,000 Hz, and the processor is configured to determine whether the wearable audio device is in place on the user's body, at least in part, based on that frequency. It should be understood that when a frequency or frequency range is described herein, the frequency or range is often approximate. When a specific frequency is specified, it should be understood that the actual frequency can be approximately or nearly the specified frequency. One reason is that even if the actual frequency is different from the stated frequency, the results may not differ dramatically.

[0035] Internal and external microphones can be used to detect sounds analyzed for different methods and different purposes. There can be multiple functions for which the microphone is used. One is to determine that the user is adjusting the wearable audio device. The internal microphone can be monitored for this function. In one embodiment, the monitoring can be done at a frequency of up to 20 Hz, and the monitoring is passive, i.e., the microphone is used to monitor the sound inside the wearable audio device without using a driver to play sound. If the wearable audio device is an earphone, the internal microphone can be a feedback microphone located within the earphone nozzle. When the earphone is being operated (i.e., when it is inserted into the ear or removed from the ear), the operation produces sounds in the range of up to 20 Hz. Therefore, detecting sounds in this range can be considered equivalent to detecting the operation of the earphone. Also, when the earphone is inserted into the ear, the cavity bounded by the driver, the earphone nozzle, the ear canal, and the eardrum is sealed, causing a DC pressure spike. The DC pressure spike occurs at 0 Hz but spreads slightly within the frequency range. Therefore, monitoring the internal microphone in the range of 0 to 20 Hz is useful for estimating one or both of when the earphone is inserted into the ear and when the earphone is no longer being operated.

[0036] A second function for which the microphone can be used is to make a more reliable determination that the wearable audio device is in place on the user's body. The internal and external microphones can be used for this function. In one embodiment, the audio transfer function between the external microphone and the internal microphone is determined. This determination can be made at frequencies or frequency ranges where there is a separation in the magnitude of the transfer function values between a proper location and an improper location (e.g., inside and outside the ear of an earphone). In the case of an earphone, in the frequency range of 0 to 1,000 Hz, the magnitude of the transfer function is different between the in-ear state and the out-of-ear state. Thus, by determining the transfer function in this frequency range, it can be reliably indicated whether the earphone is in the ear or not. The same principle can be used for other types of earphones, headphones, and other types of wearable audio devices. The particular frequency or frequency range where there is a separation in the magnitude of the transfer function values between a proper location and an improper location is unique for any given product. The determination of the "proper location" can then be made at frequencies or frequency ranges where there is a good amplitude value separation.

[0037] Another function that the microphone can be used for is to determine whether the nozzle of the earphone is blocked. The earphone nozzle may be blocked by a finger when the earphone is being operated (for example, when the earphone is placed in place in the ear or when it is removed from the ear). Therefore, the determination that the nozzle is blocked can be used as an indicator of lower reliability that the earphone is being operated and thus not in its proper use position. In one embodiment, in one frequency range, the audio transfer function between the external microphone and the internal microphone has a certain value when the nozzle is blocked by a finger and a different value when the wearable audio device is in free air or in its proper use position. For example, in the range of 1,500 to 3,000 Hz, there is a different response when the earphone nozzle is blocked by the thumb compared to when the earphone is in or out of the ear (having a similar response). As another example, the transfer function of the earphone in the frequency range of 0 to 1,000 Hz can be low when the earphone is in free air and high when the nozzle is blocked (either by a finger or by the earphone being sealed within the ear canal). Therefore, the transfer function can be an indicator that the earphone is being operated and can also be an indicator that the earphone is in the ear. This determination can be used together with the other determinations described herein to make a final determination as to whether the wearable audio device is in its proper use position.

[0038] Figure 3 shows the steps of a method 100 for detecting that a wearable audio device is in place on a user's body. At step 102, a proximity sensor is monitored for proximity detection events. At step 104, an orientation sensor is monitored for proper orientation of the wearable audio device. In one embodiment, both sensors are monitored simultaneously. When the proximity sensor and the orientation sensor reach a threshold indicating the likelihood of an in-ear event, at step 105, an internal microphone is monitored. In one embodiment, the monitoring of the microphone is performed in the range of 0 to 20 Hz to detect that the wearable audio device is being operated by the user and that the earphone is inserted into the ear, as described elsewhere in this specification. Based on the monitoring of the proximity sensor, the orientation sensor, and the internal microphone, at step 106, a low-confidence determination is made as to whether the device is in the proper position (i.e., in place on the user's body). In this non-limiting example, the device is an earphone, and thus the determination is a determination as to whether the device is in place in the ear. If a low-confidence in-ear determination is made, at step 108, a first group of earphone functions is enabled. In some embodiments, the earphone functions that may be enabled based on this low-confidence determination include some or all of automatic power on / off, automatic audio pause / resume, automatic phone answering function, Bluetooth connection / reconnection, beamforming of the microphone carried by the wearable audio device, enabling of user interface functions, and tuning of the active noise reduction system. More specifically, in one embodiment, the functions enabled after the low-confidence determination are background functions such as turning on the processor, sensors, and Bluetooth. As a result, the chip, sensors, and other aspects of the audio device that consume power remain off until a first-level determination is made, thus saving battery power.

[0039] Next, method 100 proceeds to a second level of high-confidence determination that the earphone is in place in the ear. At step 110, the internal and external microphones are monitored. Next, at step 112, the driver is enabled to play one or more tones. The purpose of playing the tones is to receive the tones at the microphones and determine whether there is tone reception as would be expected if the wearable audio device is in the proper position for use and the user has stopped operating the wearable audio device. In an example of an earphone, the microphones used for this purpose include an internal microphone used for feedback-based active noise reduction and an external microphone used for feedforward-based active noise reduction. Both types of microphones are known in the field of active noise reduction for wearable audio devices and are thus not further described herein. The internal microphone is typically positioned to be able to sense sound within the cavity formed by the driver, the earphone nozzle, and the ear canal. An example is microphone 80 in FIG. 2. The external microphone is capable of sensing sound outside the housing of the earphone. An example is microphone 81 in FIG. 2. In method 100, at step 114, the transfer function (G sd ) between the two microphones is determined. G sdThe determination is described in U.S. Patent No. 10,462,551, entitled "Wearable Audio Device with Head On / Off State Detection," issued on October 29, 2019, the entire disclosure of which is incorporated herein by reference for all purposes. The acoustic coupling from the driver to the microphone (exemplified by the transfer function) changes when the earphone is in the ear and when it is outside the ear (at least at one or more frequencies). In one embodiment, a processor of the wearable audio device is configured to cause the electroacoustic transducer to generate sound and calculate the transfer function after the processor makes a first-level estimation that the wearable audio device is in place on the user's body. In one embodiment, the transfer function is calculated over a specified frequency range that can be in the range of 0 to 1,000 Hz. In some embodiments, the reproduced sound is part of a series of tones for a typical type of device startup in an electronic device.

[0040] If the transfer function is as expected, at step 116, a high-confidence in-ear determination is made. In one embodiment, this second-stage high-confidence determination also involves the first-stage determination (proximity to the user, proper orientation, and microphone-based determination that the user has stopped operating the wearable audio device). In other words, the device is considered (with low confidence) to be in the proper usage position of the device both when it is in the correct physical location and when the user is not operating the device (which is expected to occur when the user is satisfied that the device is in place). In one embodiment, as part of the second-stage high-confidence determination, the indicator of the blocked nozzle is G within the range of 0 to 1,000 Hz. sdIt is calculated simultaneously. If the calculation of the blocked nozzle indicates that the nozzle is blocked, the high-reliability determination can be delayed for a short time to ensure that the user has stopped operating the earphone. If the in-ear state remains the same after that time, a high-reliability determination is made. After the second-stage high-reliability determination is made, in step 118, a second group of earphone functions is enabled. In some embodiments, the functions of the second group are different from those of the first group. In one embodiment, the functions of the second group include both functions involved in user interaction (such as switches, capacitive touch sensors, and microphone beamforming) and tuning of the active noise reduction system. In some embodiments, multiple steps can be performed on different subsystems. For example, there may be a sensor subsystem (using a proximity sensor, an orientation sensor, and an internal microphone) used in the first low-reliability stage and a microphone subsystem (using internal and external microphones) used in the second-stage high-reliability determination. This would allow the microphone subsystem to be turned on only when needed to conserve power. This design will require some message exchange between subsystems.

[0041] In some embodiments, the monitoring of the proximity sensor and the orientation sensor continues during the process of making the second stage determination. One reason is that the wearable audio device can determine whether it has been removed from its use location. For example, earphones can be placed in the ear and then quickly removed. Alternatively, perhaps the user may continue to adjust the earphones for a short time after they are placed in the ear. By monitoring the proximity sensor and / or the orientation sensor throughout the startup sequence, the determination that the device is in place and the user has completed operating the device can be made with higher confidence. Also, continuous or periodic monitoring of the microphone and calculation of the transfer function can be used to confirm that the device has been moved from its use location (e.g., removed from the ear). In some embodiments, the processor can activate a timer that can be used as part of the proper location / improper location determination. For example, there may be a higher confidence that the user has stopped adjusting the position of the device if the high-confidence determination remains for at least a short time (perhaps 1 - 2 seconds). Also, a timer can be used to turn off the earphone function only after a short time when the proximity sensor stops sensing proximity (which occurs when the earphone is removed from the ear), which can help prevent false position determinations that may annoy the user. For example, if the driver and the external microphone are disabled when the device is removed from its use location, a false determination may cut off a phone call or music or a podcast contrary to the user's wishes.

[0042] FIG. 4 is a graph 130 showing the transfer function (G sd ) between the external microphone and the internal microphone of the earphone (as described above) over a frequency range up to approximately 10,000 Hz. The solid line 134 shows the transfer function when the earphone is in the ear, and the dotted line 132 shows the transfer function when the earphone is in free space. As can be seen, the magnitude of the transfer function is different at frequencies up to 1,000 Hz. Therefore, determining the transfer function in the range of 0 - 1,000 Hz indicates whether the earphone is in the ear.

[0043] Some embodiments of the present disclosure relate to detecting an around-ear or on-ear headphone arrangement having ear cups configured to be positioned respectively over or on the ears. The arrangement detection can be based on a proximity sensor such as a capacitance proximity sensor, a microphone that senses sound inside the ear cup (as opposed to external ambient sound), and an accelerometer, which may be a function of an IMU but need not be. As will be described below, in some embodiments, these sensors are used to make a first-level determination that the headphones are placed on the head, a second-level determination that the headphones are in place on the head and available for use, and a third-level determination that the headphones have been removed from the head.

[0044] In some embodiments, wearable audio device (e.g., on-ear or over-ear headphones) placement detection relies on three types of sensors: capacitance, microphone, and IMU / accelerometer. The placement detection algorithm can be thought of as having multiple different stages. In the first stage, a capacitance sensor is used to detect whether one or both ear cups are covering or around the user's ear (i.e., the headphones are worn). In some embodiments, there is a single capacitance sensor in / on one of the ear cups. In other embodiments, there is a capacitance sensor in each of the two ear cups. The capacitance sensor (e.g., the electrodes or conductive members of the sensor) is shaped to pick up the most definitive parts of the ear using self-capacitance. The input from the capacitance sensor is monitored to determine whether / when a threshold indicating an on-head event is met. This can be considered a low-confidence determination that the user has placed the headphones on their head. When an on-head event is detected, a first group of one or more headphone functions is enabled. The first group of headphone functions can include one or more of power-on, automatic audio playback, automatic phone answering function, Bluetooth connection, beamforming of an external microphone carried by the headphones, and enabling of user interface (UI) functions. In one embodiment, the functions enabled after the low-confidence determination are background functions such as turning on the processor, sensors, and Bluetooth. As a result, the chip, sensors, and other aspects of the audio device that consume power remain off until the first level of determination is made, thus saving battery power.

[0045] Next, when the input from the capacitance sensor reaches a threshold indicating an on-head event, a second stage is executed, and the input from one or more internal microphones (e.g., feedback microphones used in an active noise reduction or ANR system) is monitored to detect an "end of wear" which is when the user has finished preparing the headphones (i.e., the headphone cups are fully in place, or "worn"). In one embodiment, the microphone monitoring is performed in the range of 0 to 20 Hz to detect that the wearable audio device is being operated by the user. After a determination is made in the second stage that the user has stopped operating the headphones, a second group of earphone functions is enabled. In some embodiments, the functions of the second group are different from those of the first group. In one embodiment, the functions of the second group include both functions involved in interaction with the user (such as switches, capacitance touch sensors, and beamforming of microphones), and tuning of the ANR system. In that regard, measurements for providing customized ANR are delayed until an "end of wear" state is detected. These measurements generally consist of playing a tone and measuring the response with a feedback microphone to measure the unique response of the user's ear canal. Customized ANR in headphones is described in U.S. Patent No. 10,937,410, the entire disclosure of which is incorporated herein by reference for all purposes.

[0046] In some embodiments, an inertial monitoring unit (IMU) or an accelerometer is used to detect when the headphones are placed flat / horizontally and indicate an off-head state (i.e., the headphones are removed or "off the head"). In response, the power of the headphones is turned off. In some embodiments, the input from a capacitance sensor is used in combination with the input from the IMU / accelerometer to make a determination that the headphones are in an off-head state. That is, the input from the capacitance sensor can be monitored to detect that the user has removed the headphones, but the headphones delay powering off until the input from the IMU / accelerometer indicates that the headphones are placed horizontally. This can help prevent false off-head detections. Thus, for example, if the user removes the headphones for a short time to readjust, the headphones may not change any functions until the IMU / accelerometer exceeds some threshold. This helps avoid interruption of headphone functions, such as when the user lifts one or both earcups, which can occur, for example, when the headphones are adjusted after being worn.

[0047] In embodiments of this specification, a wearable audio device includes an electroacoustic transducer for generating sound, a proximity sensor configured to detect when the wearable audio device is in proximity to a user, an internal microphone positioned within a housing of the wearable audio device and configured to detect sound within a cavity at least partially formed by a portion of the housing, and a processor configured to estimate whether the wearable audio device is in place on the user's body based at least on the proximity sensor and to estimate whether the user has completed an operation of the wearable audio device based on the internal microphone.

[0048] In one embodiment, the wearable audio device further includes at least one earcup configured to be positioned over or covering the wearer's ear when the wearable audio device is placed on the head, and both the proximity sensor and the internal microphone are positioned within the earcup. In some embodiments, the proximity sensor comprises a capacitance proximity sensor. In one embodiment, the capacitance proximity sensor comprises a conductive member within the earcup of the wearable audio device. In one embodiment, the conductive member has a curved outer periphery that mimics the curvature of the human auricle. In one embodiment, the wearable audio device further includes two earcups configured to be positioned over or covering the wearer's ear when the wearable audio device is placed on the head, and there is an internal microphone positioned within each earcup, and an estimation of whether the user has completed the operation of the wearable audio device is based on the internal microphones positioned within each earcup.

[0049] In some embodiments, the processor is configured to initiate a first group of wearable audio device functions based on an estimation of whether the wearable audio device is in place on the user's body. In one embodiment, the processor is configured to initiate a second group of wearable audio device functions based on an estimation of whether the user has completed the operation of the wearable audio device, and the functions of the second group are different from the functions of the first group. In one embodiment, the functions of the first and second groups include at least one of telephone answering capability, Bluetooth connection, microphone beamforming carried by the wearable audio device, playback of audio received from an external audio source, activation of user interface functions, and tuning of an active noise reduction system.

[0050] In one embodiment, during the estimation of whether at least the user has completed the operation of the wearable audio device, the internal microphone is monitored at frequencies in the range of 0 to 20 Hz. In one embodiment, the proximity sensor has an output, and the processor's estimation of whether the wearable audio device is in place on the user's body is partially based on the level of the proximity sensor output. In some embodiments, after the processor estimates whether the wearable audio device is in place on the user's body, the processor is configured to enable a predetermined wearable audio device function. In one embodiment, the predetermined wearable audio device function includes at least one of a telephone answering capability, a Bluetooth connection, beamforming of a microphone carried by the wearable audio device, playback of audio received from an external audio source, enabling of a user interface function, and tuning of an active noise reduction system. In one embodiment, the processor is further configured to initiate an active noise reduction (ANR) filter determination procedure after the estimation that the user has completed the operation of the wearable audio device.

[0051] In some embodiments, the wearable audio device further includes an orientation sensor configured to detect the orientation of the wearable audio device. In one embodiment, the processor is further configured to estimate whether the user has removed the wearable audio device from the user's body based at least on the orientation sensor. In one embodiment, the processor is configured to reduce power consumption based on the estimation of whether the user has removed the wearable audio device from the user's body. In one embodiment, the estimation of whether the user has removed the wearable audio device from the user's body is further based on the proximity sensor. In one embodiment, the processor's estimation of whether the wearable audio device is in place on the user's body is based on the proximity sensor and the orientation sensor. In one embodiment, the orientation sensor comprises an accelerometer.

[0052] FIG. 5 is a schematic cross-sectional view of an over-ear headphone 150 in place on a user's head 152. Only one earcup 160 is shown positioned covering the ear 154, defining an internal cavity 161 between the earcup 160 and the head 152 / ear 154. In most but not all cases, the headphones include two substantially identical earcups, one for each ear, mechanically connected by a headband 162. In the case of on-ear headphones, the earcups are designed to be positioned covering rather than on top of the outer ear or pinna. The headphone 150 includes an electroacoustic transducer 170 and an internal microphone 164, with the transducer 170 positioned to generate sound pressure within the cavity 161 and the microphone 164 positioned to sense the sound pressure within the cavity 161. An external microphone 166 is positioned to sense sound outside the earcup 160. A processor 168 is operably connected to the microphones 164 and 168 and the transducer 170. The headphone 150 also includes a proximity sensor (not shown) configured to detect when the headphone is in proximity to being used. An exemplary proximity sensor is further described below with reference to FIG. 6. Other typical hardware and functions of the headphones are not shown or described.

[0053] FIG. 6 is an internal view of the earcup frame 180 for an over-ear headphone. The frame rim 182 carries a cushion (not shown). Region 184 is where an electroacoustic transducer (not shown) is located. The conductive member 186 is positioned on the inner surface of the frame 180. The conductive member 186 is configured as a capacitance proximity sensor used to detect the proximity of the earcup to the user's skin (e.g., the ear or pinna). When the conductive member 186 approaches the skin, the capacitance changes. In some cases, the capacitance level indicates the proximity of the conductive member 186 to the skin. Thus, the capacitance level can be used as a threshold indicator of the placement of the earcup over or covering the ear. A processor (not shown) is configured to measure this capacitance change via a trace 188 connected to the processor. The conductive member 186 has a position and shape within the earcup such that it is configured to overlap at least a portion of the human outer ear or pinna when the earcup is worn. In this way, the size, position, and shape of the conductive member 186 enhance the likelihood of ear detection. In some embodiments, ear detection is used as a first low-level indication that the user has placed the headphones on their head. As will be described in more detail elsewhere in this specification, in some embodiments, the processor is configured to activate one or more functions of the headphones based at least in part on the proximity sensor. The proximity sensor can be located in one or both of the earcups.

[0054] FIG. 7 shows a method 190 of operation of a headphone attachment / detachment detection method. This method includes a first determination as to whether the headphones are placed on the head, a second determination as to whether the headphones are fully worn (in other words, the headphones are in place over or covering the ears and are usable), and a third determination as to whether the headphones have been removed from the head.

[0055] In step 192, the processor monitors the proximity sensor to detect proximity to the head. In some embodiments, there is a proximity sensor that is part of only one of the two earcups. In other embodiments, there are two proximity sensors that are part of each of the two earcups. When the head is sensed, at step 194, an on-head determination is made, and then, at step 196, a first group of the headphone functions is enabled. Since the on-head determination is based on only a single sensor, it may be regarded as a low-confidence determination. In some embodiments, this first group of the headphone functions includes one or more of power-on, automatic playback of enabled audio, automatic telephone answering enabled, Bluetooth connection, beamforming of the microphone carried by the headphones, and enabling of the UI function. In one embodiment, the functions to be enabled are background functions such as turning on the processor, the sensor, and Bluetooth. As a result, other aspects of the headphones that use the chip, the sensor, and power may remain off until the on-head determination is made. This saves power.

[0056] The determination of the second level that the headphones are fully worn and ready for use is based on monitoring one or more internal microphones of one or both earcups at step 198. The microphone can be the feedback microphone of the headphone ANR system. In one embodiment, at least one microphone in each earcup is monitored to detect when the user stops touching or moving both earcups, which typically occurs briefly while the user adjusts the position of the earcups after the headphones are placed on the head to obtain a more comfortable and better audio result. In one embodiment, the microphone output is monitored in the range of about 0 - 20 Hz. This range is selected in part because sound / vibration in this range is generally not affected by the ANR system, and thus the response is expected to be the same regardless of which ANR is enabled. When a low threshold of the sound monitored in the 0 - 20 Hz range is reached, at step 200, a determination of the end of wearing is made, and at step 202, a second group of headphone functions is enabled. In some embodiments, the functions of the second group are different from those of the first group. In one embodiment, the functions of the second group include both functions involved in user interaction (such as switches, capacitive touch sensors, and beamforming of microphones) and the tuning of the ANR system. In some embodiments, the measurements for providing customized ANR are delayed until the "end of wearing" state is detected. These measurements generally consist of playing a tone and measuring the response with a feedback microphone to measure the unique response of the user's ear canal.

[0057] The third sensed state is when the user has removed or taken off the headphones. In some embodiments, at step 204, one or both of the proximity sensor and the inertial monitoring unit (IMU), or the accelerometer, are monitored, and at step 206, it is detected when the headphones are placed flat / horizontally, and the processor makes a determination of the off-head state (i.e., the headphones are removed or "taken off"). In response to this, at step 208, the processor is activated and one or more headphone functions are deactivated. In some embodiments, the headphones are powered off in response to off-head detection. In embodiments that use an accelerometer to detect orientation, when the headphones are worn on the head in a normal upright position, there is a steady-state acceleration due to gravity in one direction, which can be called the "vertical" direction, and no acceleration in two orthogonal directions. When the headphones are removed and placed approximately flat, the steady-state acceleration is not in the original axis. Thus, the processor can use the accelerometer to determine whether the headphones are placed flat.

[0058] In some embodiments, the input from the proximity sensor (e.g., a capacitance proximity sensor) is used in combination with the input from the IMU / accelerometer to make a determination that the headphones are in the off-head state. In some embodiments, the input from the proximity sensor is monitored to detect when the user has removed the headphones, but the headphones delay powering off until the input from the IMU / accelerometer indicates that the headphones are placed horizontally. This can help prevent false off-head detections. Thus, for example, if the user removes the headphones or earcups for a short time to readjust them, the headphones may not change their function until the proximity sensor exceeds some threshold. This helps avoid interruption of headphone functions, which can occur, for example, when the user lifts one or both earcups, such as when the headphones are adjusted after being worn or when the head is tilted sideways for a short time.

[0059] When a process is represented or suggested by a block diagram, the steps can be performed by one element or a plurality of elements. These steps can be performed together or at different times. The elements performing the activities may be physically the same, or may be in proximity to each other, or may be physically separate. One element may perform the activities of two or more blocks. The audio signal may or may not be encoded and may be transmitted in either digital or analog format. Conventional audio signal processing devices and operations may be omitted from the drawings.

[0060] Examples of the systems and methods described herein include computer components and computer-implemented steps that will be apparent to those of ordinary skill in the art. For example, it should be understood by those of ordinary skill in the art that computer-implemented steps may be stored as computer-executable instructions on a computer-readable medium such as, for example, a floppy disk, hard disk, optical disk, flash ROM, non-volatile ROM, and RAM. Further, it should be understood by those of ordinary skill in the art that computer-executable instructions may be executed on various processors such as, for example, a microprocessor, digital signal processor, gate array, etc. For ease of explanation, not all steps or elements of the systems and methods are described herein as part of a computer system, but those of ordinary skill in the art will recognize that each step or element may have a corresponding computer system or software component. Accordingly, such computer systems and / or software components are enabled by describing their corresponding steps or elements (i.e., their functionality) and are within the scope of the present disclosure.

[0061] Multiple implementations have been described. Nevertheless, additional modifications can be made without departing from the scope of the concepts of the invention described herein, and thus other examples are understood to be within the scope of the following claims.

Claims

1. A wearable audio device, comprising: an electroacoustic transducer for generating sound; a proximity sensor configured to detect when the wearable audio device is in proximity to a user; an internal microphone positioned within a housing of the wearable audio device and configured to detect sound within a cavity at least partially formed by a portion of the housing; a processor configured to estimate whether the wearable audio device is in place on the user's body based at least on the proximity sensor, and to estimate whether the user has completed an operation of the wearable audio device based on the internal microphone; A wearable audio device comprising the above components.

2. The wearable audio device according to claim 1, further comprising at least one earcup configured to be positioned above or covering an ear of a wearer when the wearable audio device is placed on the head, wherein both the proximity sensor and the internal microphone are positioned within the earcup.

3. The wearable audio device according to claim 1, wherein the proximity sensor includes a capacitance proximity sensor.

4. The wearable audio device according to claim 3, wherein the capacitance proximity sensor includes a conductive member inside the earcup of the wearable audio device.

5. The wearable audio device according to claim 4, wherein the conductive member is configured to overlap at least a part of a human auricle.

6. The wearable audio device according to claim 1, further comprising two earcups configured to be positioned above or covering an ear of a wearer when the wearable audio device is placed on the head, each earcup having an internal microphone positioned therein, and wherein the estimation of whether the user has completed an operation of the wearable audio device is based on the internal microphones positioned within each of the earcups.

7. The wearable audio device according to claim 1, wherein the processor is configured to start a first group of wearable audio device functions based on the estimation of whether the wearable audio device is in place on the user's body.

8. The wearable audio device according to claim 7, wherein the processor is configured to start a second group of wearable audio device functions based on the estimation of whether the user has completed an operation of the wearable audio device, and the functions of the second group are different from the functions of the first group.

9. The wearable audio device according to claim 8, wherein the first and second groups of functions include at least one of telephone answering ability, Bluetooth connection, beamforming of a microphone carried by the wearable audio device, playback of audio received from an external audio source, activation of user interface functions, and tuning of an active noise reduction system.

10. The wearable audio device according to claim 1, wherein the internal microphone is monitored at a frequency in the range of 0 to 20 Hz at least during the estimation of whether the user has completed an operation of the wearable audio device.

11. The wearable audio device according to claim 1, wherein the proximity sensor has an output, and the processor's estimation of whether the wearable audio device is in place on the user's body is partially based on the level of the output of the proximity sensor.

12. The wearable audio device according to claim 1, wherein after the processor estimates whether the wearable audio device is in place on the user's body, the processor is configured to activate a predetermined wearable audio device function.

13. The wearable audio device of claim 12, wherein the predetermined wearable audio device function includes at least one of a telephone answering capability, a Bluetooth connection, beamforming of a microphone carried by the wearable audio device, playback of audio received from an external audio source, activation of a user interface function, and tuning of an active noise reduction system.

14. The wearable audio device of claim 1, wherein the processor is further configured to initiate an active noise reduction (ANR) filter determination procedure after an estimation that the user has completed an operation of the wearable audio device.

15. The wearable audio device of claim 1, further comprising an orientation sensor configured to detect an orientation of the wearable audio device.

16. The wearable audio device of claim 15, wherein the processor is further configured to estimate whether the user has removed the wearable audio device from the user's body based at least on the orientation sensor.

17. The wearable audio device of claim 16, wherein the processor is configured to reduce power consumption based on the estimation of whether the user has removed the wearable audio device from the user's body.

18. The wearable audio device of claim 16, wherein the estimation of whether the user has removed the wearable audio device from the user's body is further based on the proximity sensor.

19. The wearable audio device of claim 15, wherein the processor's estimation of whether the wearable audio device is in place on the user's body is based on the proximity sensor and the orientation sensor.

20. The wearable audio device of claim 15, wherein the orientation sensor includes an accelerometer.

21. The wearable audio device of claim 1, further comprising two ear cups configured to be positioned on or over the ears of a wearer when the wearable audio device is placed on the head, and a proximity sensor is disposed within each ear cup.

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