PATENT DOCUMENT

Publication Number: US-11240585-B2
Application Number: US-202017023237-A
Country: US
Kind Code: B2

Title: Identification of cushioning members in personal audio devices

Abstract:
A personal audio device (e.g., headphones, earphones) can have an earpiece (e.g., an ear cup or earbud) with a removable cushioning member (e.g., headphone cushions or ear tips for earbuds). The cushioning member can include an identification tag that encodes identification data for the cushioning member. When the cushioning member is attached to the earpiece, the identification tag is brought into proximity with a tag sensor in the earpiece and the earpiece can read the identification tag to determine identification data for the cushioning member. The identification data can be used to modify a behavior of the earpiece and/or of a host device communicably coupled to the earpiece.

Claims:
What is claimed is: 
     
       1. A cushioning member for an earpiece of a personal audio device, the cushioning member comprising:
 a body having a first surface to be placed in contact with a user&#39;s ear area and a second surface, at least the first surface being made of a compliant material; 
 an attachment structure disposed on the second surface and configured to attach the cushioning member to an earpiece of a personal audio device; and 
 an identification tag disposed at or near the second surface such that when the cushioning member is attached to the earpiece, the identification tag is in proximity to a tag sensor disposed in the earpiece, 
 wherein the identification tag encodes identification data for the cushioning member. 
 
     
     
       2. The cushioning member of  claim 1  wherein the body is shaped as an ear cushion for a headphone. 
     
     
       3. The cushioning member of  claim 1  wherein the body is shaped as an ear tip for an earphone. 
     
     
       4. The cushioning member of  claim 1  wherein the identification data includes data indicating one or more of:
 a size of the cushioning member; 
 a color of the cushioning member; 
 a device class of the cushioning member; 
 a manufacturer of the cushioning member; 
 a model identifier of the cushioning member; 
 a unique identifier of the cushioning member; or 
 an active capability supported by the cushioning member. 
 
     
     
       5. The cushioning member of  claim 1  wherein the identification tag includes an arrangement of one or more magnets that encodes the identification data. 
     
     
       6. The cushioning member of  claim 1  wherein the identification tag includes a magnetic shunt having a shape that encodes the identification data. 
     
     
       7. The cushioning member of  claim 1  wherein the identification tag includes an inductive coil tuned to a resonant frequency, wherein the resonant frequency maps to the identification data. 
     
     
       8. The cushioning member of  claim 1  wherein the identification tag includes a surface optically encoded with the identification data. 
     
     
       9. The cushioning member of  claim 1  wherein the identification tag includes a passive near-field communication (NFC) or radio-frequency identification (RFID) tag encoded with the identification data. 
     
     
       10. The cushioning member of  claim 1  wherein the identification tag includes a pattern of metal or non-metal regions where presence or absence of metal in each region encodes the identification data. 
     
     
       11. The cushioning member of  claim 1  wherein the identification tag includes a feature affecting an acoustic property of the cushioning member. 
     
     
       12. The cushioning member of  claim 1  wherein the identification tag includes one or more electrical contacts. 
     
     
       13. The cushioning member of  claim 1  wherein the identification tag is disposed within or on the attachment structure. 
     
     
       14. An earpiece for a personal audio device, the earpiece comprising:
 a housing having a proximal surface; 
 a speaker disposed in the housing; 
 an attachment structure disposed on the proximal surface and configured to attach to a cushioning member; 
 a tag sensor disposed at or near the proximal surface and configured to generate a signal responsive to an identification tag of the cushioning member; 
 identification logic coupled to the tag sensor and configured to determine identification data for the cushioning member based on the signal from the tag sensor; and 
 a controller coupled to the identification logic and configured to receive the identification data from the identification logic. 
 
     
     
       15. The earpiece of  claim 14  wherein the controller is further configured to modify a device behavior of the earpiece in response to the identification data. 
     
     
       16. The earpiece of  claim 14  further comprising a communication interface, wherein the controller is further configured to communicate the identification data to a host device. 
     
     
       17. The earpiece of  claim 14  wherein the housing is shaped as an ear cup. 
     
     
       18. The earpiece of  claim 14  wherein the housing is shaped as an earbud. 
     
     
       19. The earpiece of  claim 14  wherein the identification data includes data indicating one or more of:
 a size of the cushioning member; 
 a color of the cushioning member; 
 a device class of the cushioning member; 
 a manufacturer of the cushioning member; 
 a model identifier of the cushioning member; 
 a unique identifier of the cushioning member; or 
 an active capability supported by the cushioning member. 
 
     
     
       20. The earpiece of  claim 14  wherein the tag sensor includes a magnetic sensor configured to determine a magnetic orientation for each of one or more magnets of the identification tag. 
     
     
       21. The earpiece of  claim 14  wherein the attachment structure includes one or more magnets and the tag sensor includes a magnetic sensor configured to determine a geometric characteristic of a shunt element attached to the one or more magnets. 
     
     
       22. The earpiece of  claim 14  wherein the tag sensor includes a tuner circuit and the identification logic is configured to operate the tuner circuit to determine a resonant frequency of a resonant circuit of the identification tag. 
     
     
       23. The earpiece of  claim 14  wherein the tag sensor includes a light source and light detector configured to read an optically encoded surface of the identification tag. 
     
     
       24. The earpiece of  claim 14  wherein the tag sensor includes an active near-field reader circuit configured to read a passive near-field tag of the identification tag. 
     
     
       25. The earpiece of  claim 14  wherein the tag sensor includes one or more electrical contacts. 
     
     
       26. The earpiece of  claim 14  wherein the tag sensor includes an array of resonant coils and the identification logic is configured to detect an effect of the identification tag on each of the resonant coils. 
     
     
       27. The earpiece of  claim 14  wherein the tag sensor includes a microphone and the identification logic is configured to drive the speaker to produce a sound and to analyze an acoustic response from the microphone, wherein the acoustic response is affected by the identification tag. 
     
     
       28. The earpiece of  claim 14  wherein the tag sensor is disposed within or on the attachment structure. 
     
     
       29. A method comprising:
 detecting, by an earpiece of a personal audio device, presence of a cushioning member; 
 operating, by the earpiece of the personal audio device, reader circuitry to read identification data from an identification tag located on the cushioning member; and 
 modifying a device behavior based at least in part on the identification data. 
 
     
     
       30. The method of  claim 29  wherein the earpiece of the personal audio device transmits the identification data to a host device. 
     
     
       31. The method of  claim 29  wherein modifying the device behavior includes modifying an equalizer setting for the personal audio device. 
     
     
       32. The method of  claim 29  wherein modifying the device behavior includes modifying a behavior of a host device that interoperates with the personal audio device. 
     
     
       33. The method of  claim 32  wherein the host device provides a graphical user interface and modifying the device behavior includes modifying an image of the personal audio device in the graphical user interface based at least in part on the identification data. 
     
     
       34. The method of  claim 29  wherein modifying the device behavior includes one or more of:
 modifying an equalizer setting for the personal audio device; 
 modifying an active noise cancellation profile for the personal audio device; 
 applying a sound filtering algorithm for the personal audio device; 
 modifying a volume limit for the personal audio device; or 
 applying a saved user preference associated with the identification data. 
 
     
     
       35. The method of  claim 29  wherein the identification data includes data indicating whether the cushioning member supports an advanced capability and wherein modifying the device behavior includes enabling or disabling the advanced capability based on the identification data. 
     
     
       36. The method of  claim 29  wherein the identification data includes data indicating a size of the cushioning member and wherein modifying the device behavior includes using the size of the cushioning member in a cushioning-member fitting process.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to the following provisional applications: U.S. Application No. 62/902,239, filed Sep. 18, 2019; U.S. Application No. 62/906,624, filed Sep. 26, 2019; and U.S. Application No. 62/925,952, filed Oct. 25, 2019. The disclosures of these provisional applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     This disclosure relates generally to personal audio devices such as earbuds and headphones and in particular to identification of removable cushioning members such as ear tips and cushions by a personal audio device that can support adaptive behavior based on the presence of a particular cushioning member. 
     A “personal audio device” refers to a device that produces sound to be heard by an individual user while limiting the audibility of that sound in an environment around the user. Examples of personal audio devices include headphones and earphones. Headphones generally include one or two audio-producing earpieces (also referred to as “ear cups”) that are designed to be worn over the ear or on the ear. The ear cups are typically connected to a headband, which can help to hold the ear cups in place and can also provide an electrical connection between the ear cups. The ear cups are designed to be worn such that an audio-generating speaker contained in each ear cup directs sound toward an ear of the wearer. A cushion made of compliant material is typically provided around a peripheral portion of the ear cup in order to provide spacing between the speaker and the user&#39;s ear and to provide user comfort while wearing the headphones. The cushion may also provide sound insulation, preventing sound generated by the ear cups from leaking into the environment and/or preventing external sound from reaching the user&#39;s ears. Earphones generally include one or two audio-producing earpieces (also referred to as “earbuds”) that are designed to be inserted into the user&#39;s ears (either into the ear canal or resting against the concha cavum) such that an audio-generating speaker contained in the earpiece (or earbud) is oriented toward the ear canal. An ear tip (also sometimes referred to herein as a “tip”) made of soft material may be provided to cover at least the portion of the earbud that rests against the user&#39;s skin. Similarly to cushions of ear cups, an ear tip of an earbud may increase user comfort and provide at least some degree of sound insulation. 
     SUMMARY 
     Disclosed herein are various embodiments of one or more inventions related to personal audio devices (e.g., headphones, earphones) having an earpiece (e.g., an ear cup or earbud) with a removable cushioning member (e.g., headphone cushions or earphone tips). The cushioning member can include an identification tag that encodes identification data indicative of one or more properties or characteristics of the cushioning member (e.g., size, material, color, manufacturer, etc.). When the cushioning member is attached to the earpiece, the earpiece can read the identification data from the identification tag. For example, the earpiece can include a tag sensor that generates a signal responsive to an electrical, magnetic, electromagnetic, optical, geometrical, or mechanical characteristic of the identification tag and an identification (ID) logic circuit that decodes the signal from the tag sensor to extract the identification data. In some embodiments, based on the identification data, a controller of the personal audio device can modify the behavior of the earpiece. In some embodiments, the earpiece can communicate the identification data to a host device with which the personal audio device is communicably coupled (e.g., a phone, computer, media player, gaming device, or other device that can provide audio output to the personal audio device), and the host device can modify its behavior and/or a behavior of the earpiece based on the identification data. 
     According to some embodiments, a cushioning member for an earpiece of a personal audio device can include a body having a first surface to be placed in contact with a user&#39;s ear area and a second surface, at least the first surface being made of a compliant material; an attachment structure disposed on the second surface and configured to attach the cushioning member to an earpiece of a personal audio device; and an identification tag disposed at or near the second surface such that when the cushioning member is attached to the earpiece, the identification tag is in proximity to a tag sensor disposed in the earpiece. The identification tag can encode identification data for the cushioning member. The body can be shaped, e.g., as an ear cushion for a headphone or as an ear tip for an earphone. 
     Identification tags can be implemented using a number of different structures and techniques. For example, in some embodiments the identification tag can include any or all of: an arrangement of one or more magnets that encodes the identification data; a magnetic shunt having a shape that encodes the identification data; an inductive coil tuned to a resonant frequency, wherein the resonant frequency maps to the identification data; a surface optically encoded with the identification data; a passive near-field communication (NFC) or radio-frequency identification (RFID) tag encoded with the identification data; a pattern of metal and/or non-metal regions where presence or absence of metal in each region encodes the identification data; a feature affecting an acoustic property of the cushioning member; one or more electrical contacts coupled to an identification circuit element (e.g., a resistor or a coupling or absence of coupling to ground). In some embodiments, an identification tag is disposed within or on the attachment structure of the cushioning member. 
     According to some embodiments, an earpiece for a personal audio device can include: a housing having a proximal surface; a speaker disposed in the housing; an attachment structure disposed on the proximal surface and configured to attach to a cushioning member; a tag sensor disposed at or near the proximal surface and configured to generate a signal responsive to an identification tag of the cushioning member; identification logic coupled to the tag sensor and configured to determine identification data for the cushioning member based on the signal from the tag sensor; and a controller coupled to the identification logic and configured to modify a device behavior of the earpiece in response to the identification data. In some embodiments, the earpiece can also include a communication interface configured to communicate the identification data to a host device. The housing can be shaped, e.g., as an ear cup or earbud or the like. In some embodiments, the tag sensor can be disposed within or on the attachment structure. 
     A tag sensor can be implemented using a number of different sensors and technique. For instance, in some embodiments, a tag sensor can include a magnetic sensor configured to determine a magnetic orientation for each of one or more magnets of the identification tag. In some embodiments, the attachment structure can include one or more magnets and the tag sensor can include a magnetic sensor (e.g., a Hall sensor) configured to determine a geometric characteristic of a shunt element attached to the one or more magnets, where the geometric characteristic of the shunt element can encode identification information and thus serve as an identification tag. In some embodiments, the tag sensor can include a tuner circuit and the ID logic can be configured to operate the tuner circuit to determine a resonant frequency of a resonant circuit of the identification tag. In some embodiments, the tag sensor can include a light source and light detector configured to read an optically encoded surface of the identification tag. In some embodiments, the tag sensor can include an active near-field reader circuit configured to read a passive near-field tag of the identification tag. In some embodiments, the tag sensor can include one or more electrical contacts coupled to a circuit that can measure electrical parameters (e.g., resistance and/or grounded vs. ungrounded state) associated with corresponding contacts of the identification tag. In some embodiments, the tag sensor can include an array of resonant coils and the identification logic is configured to detect an effect of the identification tag on each of the resonant coils. In some embodiments, the tag sensor can include a NFC or RFID reader circuit configured to read an identification tag implemented as an NFC or RFID tag circuit. In some embodiments, the tag sensor can include a microphone and the identification logic can be configured to drive the speaker to produce a sound and to analyze an acoustic response from the microphone, wherein the acoustic response is affected by the identification tag. 
     Various types of identification data can be encoded in an identification tag in a cushioning member and read by a tag sensor and identification logic in an earpiece. For instance, identification data can indicate one or more of: a size of the cushioning member; a color of the cushioning member; a device class of the cushioning member; a manufacturer of the cushioning member; a model identifier of the cushioning member; a unique identifier of the cushioning member; and/or an active capability supported by the cushioning member. In some embodiments, the identification data can be a parameter value that can be mapped to indicia of one or more attributes of the cushioning member (e.g., size, color, device class, manufacturer, model, unique identifier, etc.). 
     According to some embodiments, a method of identifying a cushioning member for a personal audio device can include detecting, by an earpiece of a personal audio device, presence of a cushioning member; operating, by the earpiece of the personal audio device, reader circuitry to read identification data from an identification tag located on the cushioning member; and modifying a device behavior based at least in part on the identification data. In some embodiments, the earpiece of the personal device can modify its own behavior in response to the identification data. Additionally or instead, the earpiece of the personal device can transmit the identification data to a host device with which the personal audio device interoperates, and the host device can modify its own behavior and/or the behavior of the personal audio device in response to the identification data. 
     Various types of behavior modification can be implemented in response to identification data. For example, modifying the device behavior can include modifying an audio characteristic including any or all of: modifying an equalizer setting for the personal audio device; modifying an active noise cancellation profile of the personal audio device; applying a sound filtering algorithm for the personal audio device; modifying a volume limit for the personal audio device; and/or applying a saved user preference associated with the identification data. In some embodiments where the personal audio device interoperates with a host device, the host device can modify an image of the personal audio device in a graphical user interface of the host device based at least in part on the identification data. In some embodiments where the identification data includes data indicating whether the cushioning member supports an advanced capability, modifying the device behavior includes enabling or disabling the advanced capability based on the identification data. In some embodiments where the identification data includes data indicating a size of the cushioning member, modifying the device behavior includes using the size of the cushioning member in a cushioning-member fitting process. 
     The following detailed description, together with the accompanying drawings, will provide a better understanding of the nature and advantages of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a first example of a personal audio device according to some embodiments. 
         FIG. 2  shows a second example of a personal audio device according to some embodiments. 
         FIG. 3  shows a simplified block diagram of an earpiece system according to some embodiments. 
         FIGS. 4A-4C  show simplified cross-section views of an earpiece and an ear tip according to some embodiments. 
         FIG. 5  shows a simplified cross-section view through an earpiece and cushion according to some embodiments. 
         FIGS. 6A and 6B  show simplified cross-section views through an earpiece and cushion according to some embodiments. 
         FIG. 7A  shows a partial exploded view of an earpiece system according to some embodiments. 
         FIG. 7B  shows a partially transparent view of a portion of an earpiece according to some embodiments. 
         FIGS. 8A and 8B  are simplified perspective views showing an example of magnetic cushion identification according to some embodiments. 
         FIGS. 9A and 9B  are simplified perspective views showing another example of magnetic cushion identification according to some embodiments. 
         FIG. 10  shows a simplified cross-section view of an ear cup and cushion incorporating magnetic cushion identification according to some embodiments. 
         FIG. 11  shows a simplified view of an ear cup and cushion incorporating NFC circuits according to some embodiments. 
         FIGS. 12A and 12B  show a simplified cross-section view of an earbud and ear tip incorporating NFC circuits according to various embodiments. 
         FIG. 13A  shows a simplified view of an earcup incorporating a sensor coil array according to some embodiments, and  FIG. 13B  shows a more detailed view of a layout of the sensor coil array. 
         FIG. 13C  shows a schematic circuit diagram of a sensor coil array and ID logic circuit according to some embodiments. 
         FIG. 14  shows a simplified view of a cushion incorporating a tag element readable using a sensor coil array according to some embodiments. 
         FIG. 15  shows a more detailed view of a tag element overlying a sensor coil array according to some embodiments. 
         FIG. 16  shows a simplified view of an ear cup and cushion incorporating resonant-circuit-based identification according to some embodiments. 
         FIGS. 17A and 17B  show examples of resonant circuits and reader circuits that can be used according to some embodiments. 
         FIGS. 18A and 18B  illustrate an arrangement for an optical sensor in an ear cup according to some embodiments. 
         FIGS. 19A and 19B  show examples of optical encoding of identification data in a cushion according to various embodiments. 
         FIG. 20  shows an example of an earbud and ear tip according to some embodiments. 
         FIG. 21  shows a flow diagram of a process for acoustic identification according to some embodiments. 
         FIG. 22  shows a simplified view of an ear cup and cushion implementing resistance-based identification data according to some embodiments. 
         FIG. 23  shows a simplified view of an ear cup and cushion implementing contact-based identification data according to some embodiments. 
         FIG. 24  shows a flow diagram of a cushion-identification process that can be performed in an earpiece system according to some embodiments. 
         FIG. 25  shows a table with examples of mapping an ID value to characteristics of a cushioning component according to some embodiments. 
         FIG. 26  shows a flow diagram of a fitting process for an ear tip according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein are various embodiments of one or more inventions related to personal audio devices (e.g., headphones, earphones) having an earpiece (e.g., an ear cup or earbud) with a removable cushioning member (e.g., headphone cushions or earphone tips). The cushioning member can include an identification tag that encodes identification data indicative of one or more properties or characteristics of the cushioning member (e.g., size, material, color, manufacturer, etc.). When the cushioning member is attached to the earpiece, the earpiece can read the identification data from the identification tag. For example, the earpiece can include a tag sensor that generates a signal responsive to an electrical, magnetic, electromagnetic, optical, geometrical, or mechanical characteristic of the identification tag and an identification (ID) logic circuit that decodes the signal from the tag sensor to extract the identification data. In some embodiments, based on the identification data, a controller of the personal audio device can modify the behavior of the earpiece. In some embodiments, the earpiece can communicate the identification data to a host device with which the personal audio device is communicably coupled (e.g., a phone, computer, media player, gaming device, or other device that can provide audio output to the personal audio device), and the host device can modify its behavior and/or a behavior of the earpiece based on the identification data. 
     In various embodiments, the identification tag in a cushioning member can be a “passive” tag that does not require a power source in order to be read by an earpiece. For example, the identification tag can be implemented using a piece of magnetic material or a magnetic shunt whose presence and/or geometry can be detected using a magnetic sensor (e.g., Hall effect sensor) located in the earpiece. As another example, the identification tag can be implemented using an optical pattern (e.g., alternating regions of high and low reflectivity) that can be scanned using a tag sensor that includes a light source and light detector located in the earpiece. As yet another example, the identification tag can be implemented as a passive NFC or RFID tag, and the tag sensor in the earpiece can include a compatible NFC or RFID reader. As still another example, the identification tag can be implemented as an inductive coil or other circuit having a particular resonant frequency, and the tag sensor in the earpiece can include a tuner that can be operated to determine the resonant frequency of the coil. As a further example, identification data can be encoded in the acoustic characteristics of a particular cushioning member, and a tag sensor can measure the acoustic characteristics or other characteristics related to the acoustic characteristics such as load impedance of an amplifier. The foregoing are examples of “contactless” identification techniques that do not require an electrically conductive connection between the earpiece and the cushioning member. In other embodiments, a passive identification tag can be implemented using one or more electrical contacts. For instance, an identification tag can include a set of contacts, each of which may or may not be connected to a ground contact, and the reader circuitry in the earpiece can connect to the contacts and read the identification data by detecting the connection pattern of contacts in the identification tag. As another example, an identification tag can be implemented using a resistor having a specific resistance value coupled between two electrical contacts, and the reader circuitry in the earpiece can read the identification data by measuring the resistance value. In still other embodiments, the identification tag can be active, and the tag can draw enough power from the earpiece to communicate identification data to the reader circuitry via a wired or wireless communication channel. 
     In various embodiments, the identification data obtained from an identification tag can include or represent any information that distinguishes one cushioning member from another. For example, the identification data can represent any or all of: a manufacturer identifier; a model identifier; a size identifier; a color identifier; a device-class identifier (e.g., indicating presence or absence of various capabilities or characteristics); a unique serial number; and/or other information as desired. In some embodiments, an identification tag can encode a numerical value that can be mapped by ID logic in the earpiece (or in a connected host device) to a particular set of characteristics of the cushioning member. 
     In various embodiments, the earpiece and/or a host device can change different aspects of their behavior based on the identification data. For example, an equalizer setting can be selected or modified based on the identification data. Hearing-protection settings can be modified, including, e.g., limiting the speaker volume of the earpiece, modifying an active noise cancellation profile for the earpiece, and so on. User interface behavior can also be modified. For instance, if a host device has a display that shows an image of the personal audio device, the displayed image can be modified to match the currently-attached cushioning member. 
     In various embodiments, the earpiece and/or a host device can use the identification data in connection with monitoring the condition of the cushioning member. For example, a host device can track the age or total lifetime usage of a particular cushioning member and suggest replacement at an appropriate interval. 
     In various embodiments, the earpiece and/or a host device can use the identification data to assist with sizing of a cushioning member. For example, ear tips, which fit into a user&#39;s ear, may come in several sizes to accommodate variations in the size of human ears. During fitting of ear tips, an audio leakage test can be performed to assess the fit of a particular tip. Based on the results of the leakage test and identification data indicating a size of the tested tip, the earpiece (or a host device) can suggest a specific tip size to try next. 
     In various embodiments, the earpiece and/or a host device can use the identification data to activate or deactivate advanced capabilities that may be supported by certain cushioning members. For example, it is contemplated that an advanced cushion or ear tip (or other cushioning member) may include one or more biometric monitoring devices such as a pulse sensor, temperature sensor, or moisture (e.g., perspiration) sensor that can provide sensor data to the earpiece, which in turn can communicate the sensor data to a host device or use the data internally (e.g., to generate an audible indication related to the sensor data). Based on whether the identification data indicates that the cushioning member supports a particular monitoring capability, the earpiece can automatically enable or disable its receiver(s) for the monitoring data. 
     1. Personal Audio Devices with Removable Cushioning Members 
       FIG. 1  shows a first example of a personal audio device according to some embodiments, in the form of headphones  100 . Headphones  100  include a pair of earpieces  102  and a band  104  that mechanically connects earpieces  102 . In some embodiments, band  104  may also provide electrical connections between earpieces  102 . Earpieces  102  (also referred to as ear cups) can be made of rigid materials such as rigid plastic and/or metal. Earpieces  102  can be designed and shaped to fit on top of or around the pinnae of the user&#39;s ears, covering the concha cavum. Earpieces  102  can incorporate one or more speakers to produce sound directed toward the user&#39;s ears, control electronics to operate the speakers, a signal interface to receive audio signals in digital or analog format, one or more user input controls (e.g., one or more touch sensitive areas on a surface of one or both of earpieces  102 ), and other components that can be of generally conventional design. 
     To provide user comfort, cushions  106  can be detachably attached to earpieces  102 . For example, cushions  106  can have one or more protruding attachment structures (e.g., on the side facing earpieces  102 ) that snap into complementary slots, holes, clips, or other attachment structures in earpieces  102 , or earpieces  102  can have one or more protruding attachment structures that snap into complementary slots, holes, or other attachment structures in cushions  106 . In some embodiments, magnetic attachment structures can be provided in addition to or instead of mechanical attachment structures. For example, earpieces  102  can have magnets disposed at various locations on an interface surface that faces cushions  106 . Such magnets can be disposed, e.g., near the periphery of earpieces  102 . Cushions  106  can include metal shunts, magnets, or the like at corresponding locations on the interface surface; any structure that is attracted to the magnets in earpieces  102  can be used. These examples are illustrative, and a particular attachment structure or combination of attachment structures is not critical to understanding the present disclosure. 
     Cushions  106  can be formed with a core of foam or other compressible material surrounded by a compliant structural layer that helps to define a shape of a periphery of cushions  106  without imparting rigidity. One or more additional textile layers can be applied if desired, e.g., for user comfort, durability, and/or esthetic appearance. In some embodiments, cushions  106  can incorporate rigid structural elements in areas that do not contact the user&#39;s skin during use. For example, cushions  106  can include a rigid frame that can be made of plastic or the like, and a rigid frame can facilitate attachment and replacement of cushions  106 . For example, a frame can incorporate mechanical and/or magnetic attachment structures. 
     For purposes of the present disclosure, it is assumed that multiple types of cushions  106  that are compatible with the same headphones  102  exist. In various embodiments, different types of cushions  106  may be distinct from each other in terms of size, color, materials, audio performance (e.g., how effectively a particular cushion blocks ambient sound), and/or other characteristics. It is also assumed that different types of cushions  106  are user-interchangeable; that is, a user may attach cushions  106  of different types to the same earpieces  102  at different times. To facilitate identification of which cushions  106  are currently attached to earpieces  102 , each cushion  106  can include an identification tag  108  that encodes identification data indicating the type of cushion. Identification tag  108  can be read by earpiece  102 , allowing the behavior of headphones  100  to automatically adapt based on the particular type of cushion  106  that is attached at any given time. Specific examples are described below. 
     In some embodiments, headphones  100  can operate as an accessory to a host device  120 . Host device  120  can be, for example, a smart phone, a tablet computer, a laptop computer, a desktop computer, a wearable device (e.g., a smart watch), a game console or portable gaming device, or any other electronic device that provides audio output. Headphones  100  can connect to host device  120  via a wired or wireless communication channel that supports transfer of audio data (in digital and/or analog formats) from the host device to the personal audio device. In some embodiments, the communication channel can be bidirectional, allowing headphones  100  to communicate information to host device  120 . For example, headphones  100  can communicate cushion identification data read from identification tag  108  to host device  120 , and host device  120  can modify its behavior based on the cushion identification data received from headphones  100 . Specific examples are described below. It should be understood that information other than audio signals and cushion identification data can also be communicated between headphones  100  and host device  120 . For example, headphones  100  can provide a user input interface that includes, e.g., tactile controls (buttons, touch-sensitive surfaces, or the like) and/or a microphone for voice input, and headphones  100  can communicate user input to host device  120 . Such interaction is not relevant to understanding the present disclosure. 
       FIG. 2  shows a second example of a personal audio device according to some embodiments, in the form of earphones  200 . Earphones  200  include a pair of earpieces  202 . Earpieces  202  (also referred to as earbuds) can be made of a rigid material such as plastic and/or metal and can incorporate one or more speakers to produce sound, control electronics to operate the speakers, one or more user input controls (e.g., one or more touch sensitive areas on a surface of one or both of earpieces  202 ), and so on. In this example, earpieces  202  each have an end portion  204  designed to rest within an outer portion of a user&#39;s ear canal, and in some embodiments, the speaker(s) can be located in or adjacent to end portion  204 . 
     To provide user comfort, ear tips (also referred to herein as “tips”)  206  can be detachably attached to end portion  204 . For example, tips  206  can include a base portion that can slide over and tightly fit to end portion  204 . As with earcups  102  and cushions  106  of FIG.  1 , a variety of mechanical and/or magnetic attachment structures may be used, and a particular attachment mechanism is not critical to understanding the present disclosure. 
     In some embodiments, ear tips  206  can be formed from silicone rubber or other compressible elastic material. The body of ear tips  206  can be shaped according to the general dimensions of an ear canal or other portion of an ear, and the body can include an attachment portion that is compatible with the form factor of end portion  204  so that ear tips  206  can be attached to (and removed from) earbuds  202  at end portion  204 . The body of ear tips  206  can also include a compliant outer lobe or cup that extends outward from the attachment portion, providing a pliable surface to contact the user&#39;s ear canal. 
     For purposes of the present disclosure, it is assumed that multiple types of ear tips  206  that are compatible with the same earpieces  202  exist. In various embodiments, different types of ear tips  206  may be distinct from each other in terms of size, color, materials, audio performance (e.g., how effectively a particular ear tip blocks external sound), and/or other characteristics. It is also assumed that different types of ear tips  206  are user-interchangeable; that is, a user may attach ear tips  206  of different types to the same earpiece  202  at different times. To facilitate identification of which ear tips  206  are currently attached to earpieces  202 , each ear tip  206  can include an identification tag  208  that encodes information data indicating the type of ear tip. Identification tag  208  can be read by earpiece  202 , allowing the behavior of earphones  200  to automatically adapt based on the particular type of ear tip  206  that is attached at any given time. Specific examples are described below. 
     Similarly to headphones  100 , earbud set  200  can operate as an accessory to a host device  220 . Host device  220  can be, for example, a smart phone, a tablet computer, a laptop computer, a desktop computer, a wearable device (e.g., a smart watch), a game console or portable gaming device, or any other electronic device that provides audio output. Earbuds  202  can connect to host device  220  via a wired or wireless communication channel that supports transfer of audio data (in digital and/or analog formats) from the host device to the personal audio device. In some embodiments, the communication channel can be bidirectional, allowing earbuds  202  to communicate information to host device  220 . For example, earbuds  202  can communicate tip identification data read from identification tag  208  to host device  220 , and host device  220  can modify its behavior based on the tip identification data received from earbuds  202 . Specific examples are described below. It should be understood that information other than audio signals and tip identification data can also be communicated between earbuds  202  and host device  220 . For example, earbuds  202  can provide a user input interface that includes, e.g., tactile controls (buttons, touch-sensitive surfaces, or the like) and/or a microphone for voice input, and earbuds  200  can communicate user input to host device  120 . Such interaction is not relevant to understanding the present disclosure. 
     It is to be understood that headphones  100  and earbud set  200  are illustrative of personal audio devices having earpieces and cushioning member suitable for use in embodiments of the claimed invention. Identification tags as described herein can be incorporated into any cushion, ear tip, or other replaceable user-contacting component (referred to as a “cushioning member”) of a personal audio device and can be read by any compatible earpiece to which the cushioning member is attached. Earpieces and compatible cushioning members can have a variety of form factors and attachment structures. 
     In some embodiments, cushion-member identification data can be used locally within the personal audio device to modify one or more of its behaviors. Additionally or instead, the personal audio device can transmit cushion-member identification data to a host device with which the personal audio device is communicably coupled, and the host device can modify one or more of its behaviors in response to the cushion-member identification data. 
     2. Identification of Cushioning Members 
     According to various embodiments, identification of cushioning members can be based on an identification tag disposed in or on the cushioning member that can be read using reader circuitry (or a tag sensor) in the earpiece. Examples will now be described. In the following description, some examples are described with reference to ear cups and cushions (e.g., ear cups  102  and cushions  106  of headphones  100  of  FIG. 1 ), and some examples are described with reference to earbuds and ear tips (e.g., earbuds  202  and ear tips  206  of  FIG. 2 ). It will be appreciated that examples described with reference to ear cups and cushions can be applied to earbuds and ear tips and vice versa. 
     2.1. Earpiece Systems with ID Tag and Tag Sensor 
       FIG. 3  is a simplified block diagram of an earpiece system  300  according to some embodiments. Earpiece system  300  includes an earpiece  302  and a removable cushioning member  306 . Earpiece  302  (which can be, e.g., ear cup  102  of  FIG. 1  or earbud  202  of  FIG. 2 ) can include a controller  310 , a speaker  312 , a tag sensor  314 , and a communication interface  316 . Controller  310  can be implemented, e.g., using one or more microprocessors, microcontrollers, field-programmable gate arrays (FPGAs), or other logic circuits of generally conventional design. In some embodiments, controller  310  can be housed entirely within earpiece  302  (e.g., within ear cup  102  of  FIG. 1  or earbud  202  of  FIG. 2 ). 
     Removable cushioning member  306  (which can be, e.g., cushion  106  of  FIG. 1  or ear tip  206  of  FIG. 2 ) can include an identification (ID) tag  308 . ID tag  308  can include any storage medium or structure capable of encoding cushion-member identification data in a physical form that can affect a signal generated by tag sensor  314  of earpiece  302 . ID tag  308  can be passive or active and can operate with or without an electrical connection. Example implementations of ID tag  308  and corresponding tag sensors  314  are described below. 
     Speaker  312  can be an audio speaker of generally conventional design located within earpiece  302  and can include, e.g., an amplifier and a transducer to convert electrical signals to motion of a vibrational element (e.g., a diaphragm). Tag sensor  314  can be disposed within earpiece  302  and configured to generate a signal responsive to identification data encoded in identification tag  308  of cushioning member  306 ; examples are described below. Communication interface  316  can include hardware and/or firmware components to enable communication with a host device  350  (e.g., host device  120  of  FIG. 1  or host device  220  of  FIG. 2 ). For example, communication interface  316  can implement standard wireless communication protocols such as Bluetooth, Wi-Fi, or the like. In addition or instead, a wired communication interface supporting a standard or custom communication protocol or other communication interface can be supported. 
     Controller  310  can incorporate a number of logic modules implemented using any appropriate combination of hardware and/or software components. For example, audio input module  322  can receive audio data (in digital or analog format) from an audio source. The audio source can be, for example, an internet connection, a radio receiver, a microphone positioned to detect ambient sounds in the environment, an analog audio input jack, host device  350  communicating with earpiece  302  via communication interface  316 , or any other audio source. Signal processing module  324  can perform signal-processing operations on the audio data, including decoding, digital-to-analog conversion, equalization (e.g., selectively adjusting amplitudes associated with different frequency bands), volume control (e.g., adjusting analog signal amplitude), generating audio data associated with an active noise-cancellation operation, mixing of audio data from multiple audio sources (e.g., mixing noise-cancellation audio with audio input such as music or voice data), and/or any other type of audio signal processing that may be desired. Audio driver  326  can drive speaker  312  based on an audio signal output from signal processing module  324 . User input module  328  can support user interaction. For example, user input module  328  can be configured to receive and interpret voice commands from the user and/or to detect operation of a user control located on the personal audio device or elsewhere. Based on received user input, user input module  328  can provide instructions to other modules of controller  310 , e.g., to select an audio source, control volume, or adjust other settings, or send instructions or data to a host device via communication interface  316 . In some embodiments, controller  310  can also include a user output module  330  to provide information or prompts to the user, e.g., using audible, visual, or tactile indicators. Configuration module  332  can store configuration settings (e.g., one or more equalizer profiles, volume limits, noise-cancellation profiles, etc.). In some embodiments, some or all of the configuration settings can be associated with identification data for a particular type of cushioning member  306  or with characteristics of cushioning member  306  that can determined from the identification data. Accordingly, configuration module  332  can modify the behavior of signal processing module  324  and/or other components of controller  310  based on identification data obtained from ID tag  308  of cushioning member  306 . ID logic module  334  can obtain signals from tag sensor  314  responsive to ID tag  308  and can interpret the signals to “read” the identification data encoded in ID tag  308 . ID logic module  304  can provide the identification data read from ID tag  308  to configuration module  332 , to other modules or components of controller  310 , and/or to host device  350  via communication interface  316 . 
     It will be appreciated that earpiece system  300  is illustrative and that variations and modifications are possible. An earpiece system may include other components not shown in  FIG. 3 , such as microphones or touch-sensors to receive user input. Where a host device is present, some or all of the signal processing, user input, user output, and configuration operations described above as being performed by controller  310  can instead be performed by appropriate components (including one or more suitably programmed processors) of the host device. It should also be understood that, although a single earpiece system  300  is shown, a personal audio device can include a pair of earpiece systems  300  (e.g., as shown in  FIGS. 1 and 2 ). In some embodiments, one instance of earpiece system  300  may act as a primary earpiece that communicates with the host device and relays signals and/or other information to and from the other (secondary) earpiece; in other embodiments, each instance of earpiece system  300  can communicate directly with the host device, and the pair of earpiece systems might or might not also communicate directly with each other. 
     Further, while earpiece system  300  is described with reference to particular blocks, it is to be understood that these blocks are defined for convenience of description and are not intended to imply a particular physical arrangement of component parts. Further, the blocks need not correspond to physically distinct components. Blocks can be configured to perform various operations, e.g., by programming a processor or providing appropriate control circuitry, and various blocks might or might not be reconfigurable depending on how the initial configuration is obtained. Embodiments of the claimed invention can be realized in a variety of apparatus including electronic devices implemented using different combinations of circuitry and software. 
     According to various embodiments, earpiece  302  can read ID tag  308  when tag sensor  314  is brought into proximity with ID tag  308 . The term “reading” of an identification tag is used herein to refer to the process of obtaining signals from tag sensor  302  responsive to physical characteristics of a particular ID tag  308  and interpreting the signals (e.g., using ID logic  334 ) to extract identification data. The extracted identification data can be, e.g., a numerical value (or bit string) that represents identifying information such as a cushion size, color, material composition, manufacturer, and/or other characteristic(s). To enable reading of ID tag  308  by earpiece  302 , ID tag  308  and tag sensor  314  can be disposed on or within cushioning member  306  and earpiece  302  in respective locations such that attaching cushioning member  304  to earpiece  302  results in bringing ID tag  308  and tag sensor  314  into proximity to tag sensor  314  such that signals generated by tag sensor  314  are affected by specific properties of ID tag  308  that are different for different cushion types. 
     By way of example,  FIGS. 4A and 4B  show simplified cross-section views of an earpiece  402  and an ear tip  406  according to some embodiments. Earpiece  402  and ear tip  406  can correspond to earbud  202  and ear tip  206  of  FIG. 2  and can implement earpiece system  300  of  FIG. 3 . In  FIG. 4A , ear tip  406  is shown attached to earpiece  402 , and in  FIG. 4B , ear tip  406  is shown detached from earpiece  402 . 
     Earpiece  402  can have a proximal surface  403  oriented toward ear tip  406 . A central portion of proximal surface  403  can project forward to form an end portion  404 , which can be shaped as a circular or elliptical cylinder extending from proximal surface  430 . (In some embodiments, end portion  404  can be tapered along its length; other shapes may also be used.) In some embodiments, end portion  404  (or other portions of proximal surface  403 ) can include mechanical retention features (not shown) to hold ear tip  406  in place when ear tip  406  is attached to end portion  404 ; examples include an elastic ring or spring, a lip, a protrusion or notch, or the like. In some embodiments, a magnetic retention feature can be provided. In some embodiments, ear tip  406  can be made of an elastic material, and the elasticity of ear tip  406  can hold ear tip  406  in place over end portion  404 . End portion  404  can include a tag sensor  414  disposed near a sidewall surface of end portion  404 . Tag sensor  414  can include various electrical, magnetic, electromagnetic, optical, mechanical, acoustic, or other components; examples are descried below. Depending on implementation, tag sensor  414  can extend around part or all of the circumference of end portion  404 . Tag sensor  414  can be coupled to an ID logic circuit  434 , which need not be in proximity to the surface of end portion  404  and can be disposed anywhere within earpiece  402 . ID logic circuit  434  can be configured to interpret signals from tag sensor  414  and to output cushion-member identification data. 
     Ear tip  406  can include a sidewall  416 , which can define a central opening  407  complementary to end portion  404  of earbud  402 . For instance, the inner surface of sidewall  416  can be shaped as a circular or elliptic cylinder. A flexible lobe or cap  420  can extend outward from a front end of sidewall  416 . Flexible lobe  420  can be designed to fit into a user&#39;s ear canal and to be pliant to conform to the shape of the ear canal. Sidewall  416  can be more rigid than flexible lobe  420  and can include retention features such as an elastic ring or spring, a lip, a protrusion or notch, a magnetic retention feature, or the like, and the retention features of sidewall  416  can be complementary to corresponding retention features of end portion  404  of ear tip  406 . In some embodiments, the elasticity and static friction of sidewall  416  may serve as retention features. 
     Sidewall  416  can include ID tag  408 , which can be embedded within sidewall  416  or disposed on the inner surface of sidewall  416 . ID tag  408  can be or include one or more physical features that are distinct for different cushion types. These physical features can encode identification information specific to a particular type of ear tip  406 ; examples are described below. Depending on implementation, ID tag  408  can have a cylindrical or curved shape that extends around part or all of the circumference of sidewall  416 . This can facilitate reading of ID tag  408  in cases where sidewall  416  is circularly symmetric or does not have a preferred attachment orientation. 
     As shown in  FIG. 4A , when ear tip  406  is attached to earpiece  402 , tag sensor  414  is in close enough proximity to ID tag  408  of ear tip  406  to allow tag sensor  414  to generate a signal responsive to the distinctive physical features of identification tag  408 ; in other words, tag sensor  414  can generate different signals in response to ID tags  408  that have different physical features. The arrangement of identification tag  408  and tag sensor  414  is also implementation-dependent. For instance, if ear tip  406  has a preferred rotational orientation, identification tag  408  can be positioned such that it is in proximity to tag sensor  414  when ear tip  406  is in the preferred rotational orientation. (In such cases, failure to read the identification data can trigger a notification to the user that ear tip  406  may be incorrectly oriented.) In embodiments where ear tip  406  does not have a preferred rotational orientation, identification tag  408  and tag sensor  414  can be arranged to allow tag sensor  414  to read identification tag  408  regardless of rotational orientation. For instance, identification tag  408  can extend around the circumference of sidewall  416 , or multiple copies of identification tag  408  can be disposed around the circumference of sidewall  416  such that one copy can be within proximity for reading by tag sensor  414  regardless of rotational orientation. As another example, tag sensor  414  can extend around the periphery of end portion  404 , or multiple copies of tag sensor  414  can be disposed around the periphery of end portion  404  such that one copy can be within proximity of ID tag  408  regardless of rotational orientation. Other arrangements that provide proximity between ID tag  408  and tag sensor  414  can also be used. For example, as shown in  FIG. 4C , tag sensor  414  can be disposed at or near a peripheral portion of proximal surface  403 , and identification tag  408  can be disposed at or near a corresponding location on the rear surface of sidewall  416 . 
     In various embodiments, proximity-based identification tags can be implemented in cushioning members having other form factors. For example,  FIG. 5  shows a simplified cross-section view through an earpiece  502  and cushion  506  according to some embodiments. Earpiece  502  and cushion  506  can correspond to ear cup  102  and cushion  106  of  FIG. 1 . In this example, earpiece  502  includes magnets  510  disposed at various locations around the periphery of earpiece  502 , close to interface surface  503 . Magnets  510  can be, e.g., rare earth magnets such as NdFeB magnets and can be polarized in a desired orientation. Tag sensor  514  can be disposed in a region between magnets  510 , near or on interface surface  507 . Tag sensor  514  can be coupled to an ID logic circuit  534 , which need not be in proximity to interface surface  503  and can be disposed anywhere within earpiece  502 . ID logic circuit  534  can be configured to interpret signals from tag sensor  514  and to output cushion-member identification data. 
     Cushion  506  can include attachment structures  512  that align with magnets  510 . Attachment structures  512  can be magnets polarized to be attracted to magnets  510 , or attachment structures  512  can be shunts made of a material that is attracted to magnets  510 . ID tag  508  can be disposed in a region between attachment structures  512 , near or on interface surface  507 , in a location such that when attachment structures  512  become magnetically attached to magnets  510 , ID tag  508  is in proximity to tag sensor  514 , allowing tag sensor  514  to read ID tag  508 . In various embodiments, ID tag  508  and tag sensor  514  can be any distance from attachment structures  512  and magnets  510 . Further, in some embodiments, the shape of attachment structures  512  can be used to represent cushion identification data, and a physically distinct ID tag  508  is not required. (An example of encoding identification data in a magnetic attachment structure is described below.) 
     In some embodiments, mechanical attachment structures may be used to attach an ear cup to a cushion, in addition to or instead of magnetic structures.  FIGS. 6A and 6B  show simplified cross-section views through an earpiece  602  and cushion  606  according to some embodiments. Earpiece  602  and cushion  606  can correspond to ear cup  102  and cushion  106  of  FIG. 1 . In  FIG. 6A , cushion  606  is shown detached from earpiece  602 , and in  FIG. 6B , cushion  606  is shown attached to earpiece  602 . Earpiece  602  has a proximal surface  603  oriented toward cushion  606 . Proximal surface  603  can include a recess  605 , and a tag sensor  614  can be disposed adjacent to (or on a surface of) recess  605 . Cushion  606  has a protruding structure  616  that extends outward from a rear surface  617  of cushion  606 . An ID tag  608  can be positioned within or on a surface of protruding structure  616 . In some embodiments, protruding structure  616  and/or recess  605  can include additional mechanical retention features (not shown) to hold cushion  606  in place when cushion  606  is attached to earpiece  602 . 
     As shown in  FIG. 6B , when cushion  606  is attached to earpiece  602 , tag sensor  614  is in proximity to ID tag  608 . (The arrangement is complementary to that shown in  FIGS. 4A and 4B , in that in  FIGS. 4A and 4B , the protruding part is on the earpiece and holds the tag sensor while the recess is in the cushioning member and holds the ID tag.) It should be understood that a reverse arrangement can also be provided, in which a recess is formed in cushion  606  and a peg or other protruding part extends from proximal surface  603  of earpiece  602  into the recess. 
     It should be understood that these examples of positioning of ID tags and corresponding tag sensors are illustrative and that many variations are possible. Interface surfaces can be curved or flat as desired. Mechanical or magnetic retention features for attaching a cushioning member to an earpiece can be located in various positions on the earpiece or cushioning member, and the ID tag and tag sensor can be located within or adjacent to or spaced apart from retention features as desired. Depending on the particular identification technology, the ID tag and/or tag sensor can be visible on the interface surface, or they can be covered by surface material. 
     An identification tag (or ID tag) can be or include any physical structure that encodes identification data. In other words, an ID tag can be or include any physical structure that can be constructed or formed in multiple versions such that the version of the structure present in each type of cushioning member that is to be distinguished differs from the version present in other types in a way that can be detected by a sensor (i.e., that results in the sensor generating a distinctive signals for each version of the structure). Sections 2.2-2.9 describe examples of physical structures that can be used to encode identification data and corresponding tag sensors and ID logic that can read the identification data. 
     2.2. Magnetic Identification 
     As described above with reference to  FIG. 5 , a cushion can attach to an earpiece magnetically. In some embodiments, magnetic-attachment components in a cushion can be leveraged to provide an identification tag. An example will now be described. 
       FIG. 7A  shows a partial exploded view of an earpiece system  700  according to some embodiments. Earpiece system  700  incorporates an earpiece  702  (e.g., an implementation of ear cup  102  of  FIG. 1 ) and a cushioning member  706  (e.g., an implementation of cushion  106  of  FIG. 1 ). Earpiece  702  has a housing  710  and a cover  712  that attaches to housing  710 . Cover  712  can have a peripheral annular shelf  716  and sidewall  718  surrounding a central recessed surface  713 . Cover  712  can be made of plastic and/or other rigid materials. Cushioning member  706  includes an annular cushion element  720  and an annular frame  722  attached to cushion  720 . Frame  722  can have a peripheral annular shelf  726  and a sidewall  727  shaped and sized such that frame  722  can nest in cover  712  with sidewall  727  of frame  722  abutting sidewall  718  of cover  712  and the underside of annular shelf  726  of frame  722  abutting the upper surface of annular shelf  716  of cover  712 . 
     One or more attachment structures can be used to detachably couple (e.g., magnetically couple) cover  712  and frame  722  when the frame  722  is nested within cover  712 . For example, when frame  722  has been positioned in cover  712 , the securing mechanisms can prevent frame  722  from being removed until a certain force threshold has been reached. In various embodiments, the attachment structures can be or include multiple components that engage with one another to attach frame  722  to cover  712 . For example, a “shunt” element  708 , such as metallic plate, may be positioned in one or more corner regions of frame  722 , and a magnet array  728  may be positioned in each corresponding region of cover  712 . Shunt element  708  can be or include a magnet and/or a metallic plate that can be made of steel, iron, nickel, cobalt, stainless steel, aluminum, gold, and/or any other material that can magnetically couple with magnet array  728 . Magnet array  728  can include one or more magnets, which can be permanent magnets made of ferromagnetic materials such as rare earth magnets (e.g., NdFeB magnets or the like). The magnets of magnet array  728  can have magnetic polarities oriented in specific directions. For example, the magnets can be arranged in a Halbach array (e.g., a rotating pattern of magnetic orientations), an alternating array (e.g., adjacent magnets have opposite magnetic orientations), and/or a single pole orientation (e.g., all magnets have the same magnetic orientation). Magnet array  728  can generate magnetic flux that can act on shunt element  708  to hold frame  722  in place when frame  722  is nested in cover  712 . In some embodiments, a magnet array  728  can be positioned at each of four (rounded) corner regions of annular shelf  716 . In some embodiments, magnet arrays  728  and/or shunt elements  708  can be arranged such that magnet arrays  728  exert sufficient force to hold frame  722  in place only when cushion  706  is inserted in a “correct” orientation. In embodiments where cushion  706  should be attached in a particular orientation, such an arrangement can aid the user in properly orienting the cushion. 
       FIG. 7B  shows a partially transparent view of a portion of earpiece system  700  with frame  722  nested in cover  712 , illustrating operation of the attachment mechanism. Shunt element  708  on annular shelf  726  of cushion  706  is proximate to magnet array  728  on annular shelf  716  of earpiece  702 . In some embodiments, an additional metal shunt  730  can be positioned on cover  712  (e.g., between magnet array  728  and electronic components positioned within earpiece housing  710 ). Metal shunt  730  can prevent or reduce magnetic flux from magnet array  728  from interfering with electronic components contained in earpiece  702 . 
     In some embodiments, magnet array  728  and shunt element  708  can be used to provide identification data for cushion  706 .  FIGS. 8A and 8B  are simplified perspective views showing an example of magnetic cushion identification according to some embodiments. An identification system  800  includes magnet array  728  disposed on a portion of annular shelf  716  of cover  712  (as shown in  FIG. 7A ). A tag sensor  834  is disposed on annular shelf  716  adjacent to magnet array  728 . Tag sensor  834  can be, for example, a Hall effect sensor or other sensor capable of detecting magnetic flux from magnet array  728 . 
     An identification tag to distinguish different types of cushions  704  can be provided by varying the size and/or shape of shunt element  708 .  FIG. 8A  shows a first shunt element  808   a  that can be used to indicate a first cushion type, and  FIG. 8B  shows a second shunt element  808   b  that can be used to indicate a second cushion type. As shown in  FIG. 8A , when a cushion having first shunt element  808   a  becomes attached to magnet array  728 , magnetic flux (indicated by looping arrows  805   a ) is shunted away from tag sensor  834 . As shown in  FIG. 8B , when a cushion having second shunt element  808   b  becomes attached to magnet array  728 , magnetic flux (indicated by looping arrows  805   b ) is shunted through tag sensor  834 . Accordingly, tag sensor  834  can produce a different signal depending on whether first shunt element  808   a  or second shunt element  808   b  is present. Thus, shunt elements  808   a ,  808   b  can provide an identification data encoding scheme that distinguishes two cushion types. 
       FIGS. 9A and 9B  are simplified perspective views showing another example of magnetic cushion identification according to some embodiments. An identification system  900  includes magnet array  728  disposed on a portion of annular shelf  716  of cover  712  (as shown in  FIG. 7 ). A tag sensor  934  is disposed on annular shelf  716  between magnets of magnet array  728 . Tag sensor  934  can be, for example, a Hall effect sensor or other sensor capable of detecting magnetic flux from magnet array  728 . 
     An identification tag for a particular cushion  704  can be provided by varying the size and/or shape of a shunt element.  FIG. 9A  shows a first shunt element  908   a  that can be used to indicate a first cushion type, and  FIG. 9B  shows a second shunt element  908   b  that can be used to indicate a second cushion type. As shown in  FIG. 9A , when a cushion having first shunt element  908   a  becomes attached to magnet array  728 , magnetic flux (indicated by looping arrows  905   a ) is shunted around tag sensor  934 . As shown in  FIG. 9B , when a cushion having second shunt element  908   b  (which is split at a location  910  along its length) becomes attached to magnet array  728 , magnetic flux (indicated by looping arrows  905   b ) is shunted through tag sensor  934 . Accordingly, tag sensor  934  can produce a different signal depending on whether first shunt element  908   a  or second shunt element  908   b  is present. Thus, shunt elements  908   a ,  908   b  can also provide an identification data encoding scheme that distinguishes two cushion types. 
     In the examples of  FIGS. 8A-8B and 9A-9B , two types of cushions can be distinguished based on whether magnetic flux is shunted away from or through tag sensor  834  or tag sensor  934 . In some embodiments, it may be desirable to increase the number of cushion types that can be distinguished. To increase the number of cushion types that can be distinguished, some embodiments can include multiple instances of magnet array  728  (e.g. one instance at each corner of earpiece  702 ), with each instance of magnet array  728  having an associated tag sensor (e.g., tag sensor  834  or tag sensor  934 ). Each tag sensor can provide one bit of information, depending on whether the corresponding shunt element shunts the magnetic flux through or away from that sensor. The shapes of the various instances of shunt element  708  can be varied independently of each other. Accordingly, if there are N instances of magnet array  728  and N instances of shunt element  708 , then N bits of identification data can be provided, allowing 2 N  cushion types to be distinguished. In another approach, each instance of magnet array  728  can include multiple tag sensors disposed between adjacent magnets, and shunt element  708  can be split or not split (as shown in  FIGS. 9A-9B ) at various locations, so that a single shunt element can encode multiple bits of information. These two approaches can be combined, with multiple magnet arrays each having multiple tag sensors, to further increase the number of cushion types that can be distinguished. 
     In some embodiments, a magnet array may be included in a cushion in addition to or instead of in an earpiece.  FIG. 10  shows an example of a cushion  1006  according to some embodiments that includes a magnet array  1008 . Magnet array  1008  includes a number of individual permanent magnets  1010  (or regions of ferromagnetic material), each having a specific magnetic orientation (indicated by arrows). Ear cup  1002  can have a tag sensor  1014  that includes an array of Hall effect sensors  1016 . Hall effect sensors  1016  can be positioned such that they are adjacent to magnet array  1008  when cushion  1006  is attached to ear cup  1002 . The pattern of magnetic orientations of magnet array  1008  can encode cushion identification data. Hall effect sensors  1016  can respond to the magnetic orientations, enabling ID logic  1018  to extract identification data from the pattern of magnetic orientations. In some embodiments, each magnet  1010  can encode one bit of identification data. Thus, an identification tag for a cushion can include a magnet array, and the corresponding tag sensor can include sensors to detect a pattern of magnetic orientation for the magnet array. 
     It will be appreciated that the foregoing examples of magnetic-based identification of a cushioning member are illustrative and that variations and modifications are possible. Magnetic-based identification can be implemented in any earpiece system where the cushioning member is magnetically attached to the earpiece, including cushions attached to ear cups and ear tips attached to earbuds. Further, magnetic features similar to those described above can be provided for purposes of identifying the cushioning member, regardless of whether magnetic attachment structures are used. 
     2.3. RF-Based Identification 
     Another proximity-based identification technique that can be leveraged according to some embodiments is near-field communication or radio-frequency identification. In some embodiments, an identification tag in a cushioning member can include a passive near-field communication (NFC) or radio-frequency identification (RFID) tag encoded with the identification data. A corresponding tag sensor can incorporate a compatible NFC or RFID coil coupled to circuitry implementing an NFC or RFID tag reader. As used herein, the terms “NFC” and “RFID” refer generally to communication protocols that use a “reader” circuit to generate a time-varying electromagnetic field in a first antenna (e.g., a first coil) and to sense fluctuations in the field due to a passive “tag” circuit coupled to a second antenna (e.g., a second coil) that is placed in near-field range of the first coil. Various protocols for NFC and RFID have been defined and may be used, or a custom protocol can be devised by persons skilled in the art. 
       FIG. 11  shows a simplified view of an ear cup  1102  and cushion  1106  according to some embodiments, incorporating an NFC reader. Ear cup  1102  can include magnet arrays  1128  disposed around the periphery. Cushion  1106  can include shunt elements  1108  disposed at locations corresponding to magnet arrays  1128  to enable cushion  1106  to be securely attached to earcup  1102 . Magnet arrays  1128  and shunt elements  1108  can be similar to examples described above; however, magnet arrays  1128  and shunt elements  1106  need not support cushion identification. In other embodiments, mechanical or other attachment features can be used in addition to or instead of magnet arrays  1128  and shunt elements  1108 . 
     Cushion  1106  can also include an NFC coil  1112  coupled to NFC tag circuit  1114  to provide a passive identification tag. Ear cup  1102  can include an NFC coil  1116  (a tag sensor) coupled to ID logic circuit  1118 , which can include an NFC reader circuit. In some embodiments, the NFC coils and circuits can conform to existing NFC standards and can be of conventional design. When cushion  1106  is attached to ear cup  1102 , NFC coil  1112  is brought into proximity with NFC coil  1116 . ID logic circuit  1118  can be triggered to supply current to NFC coil  1116 , thereby stimulating NFC coil  1112  and tag circuit  1114  and enabling ID logic circuit  1118  to read data stored in tag circuit  1114 . Any NFC or RFID protocol can be used to store and communicate data from tag circuit  1114  to ID logic circuit  1118 . 
     NFC identification (or other RFID-based identification) can also be implemented in an earbud and ear tip.  FIG. 12A  shows a simplified cross-section view of an earbud  1202  and ear tip  1206  according to some embodiments. Earbud  1202  and ear tip  1206  can be similar to earbud  402  and ear tip  1206  of  FIG. 4C , with the identification tag and tag sensor implemented using NFC technologies. Earbud  1202  can include an NFC coil  1216  (a tag sensor) disposed adjacent to proximal surface  1203  surrounding end portion  1204 . NFC coil  1216  can be coupled to an ID logic circuit  1218  that incorporates NFC reader circuitry. Ear tip  1206  can include an NFC coil  1212  disposed within annular sidewall  1215  surrounding central opening  1207 . NFC coil  1212  can be coupled to an NFC tag circuit  1214  disposed within sidewall  1215 . NFC tag circuit  1214  can encode identification data for ear tip  1206 . In some embodiments, the NFC coils and circuits can conform to existing NFC standards and can be of conventional design. When ear tip  1206  is attached to earbud  1202 , NFC coil  1212  is brought into proximity with NFC coil  1216 . ID logic circuit  1218  can be triggered to supply current to NFC coil  1216 , thereby stimulating NFC coil  1212  and tag circuit  1214  and enabling ID logic circuit  1218  to read data stored in tag circuit  1214 . Any NFC or RFID protocol, including conventional protocols, can be used to store and communicate data from tag circuit  1214  to ID logic circuit  1218 .  FIG. 12B  shows an alternative arrangement for NFC coils in which NFC coil  1216  in earbud  1202  and NFC coil  1212  in ear tip  1206  are arranged concentrically. Other arrangements are also possible, provided that when ear tip  1206  is positioned around front portion  1204  of earbud  1202 , the NFC coils are brought into sufficient proximity to enable reading of the data stored in NFC tag  1214 . 
     It will be appreciated that the NFC-based identification tags and reader circuitry are illustrative and that variations and modifications are possible. The particular arrangement and geometry of the coils can be modified. Depending on the particular construction and communication protocol, an NFC or RFID tag circuit (e.g., tag circuit  1114  or tag circuit  1214 ) can store multiple bytes or even kilobytes of information, which can support a very large number of unique identifiers of cushion types. In some embodiments, an ID tag can encode a unique identifier for an individual cushion (or pair of cushions). 
     2.4. Identification Using Resonant Circuits 
     Some NFC or RFID protocols allow a tag circuit to encode large amounts of data. In some embodiments, it may be desirable to distinguish a smaller number of cushion types, and a simplified NFC or RFID protocol can be used. For example, a reader circuit may include a small number of resonant coils that can each be stimulated to detect presence or absence of a nearby metal element; an ID tag can encode identification data in a pattern of metal elements. 
       FIG. 13A  shows a simplified view of an earcup  1302  incorporating an RFID sensor according to some embodiments. Earcup  1302  can be similar to other earcups described above and can include attachment elements  1328  for attaching a cushion. A coil array  1308  (implementing a tag sensor) can be disposed within ear cup  1302 , adjacent to the surface to which the cushion is to be attached. Coil array  1308  can include an array of sensor coils coupled to ID logic circuit  1310 .  FIG. 13B  shows a more detailed view of a layout of coil array  1308  according to some embodiments. Coil array  1308  can include a number of separate coils  1312   a - 1312   d . While four coils arranged in a 2×2 array are shown, it will be appreciated that any number and arrangement of coils can be used. It should be understood that the resonance properties of each of coils  1312   a - 1312   d  can be affected by placing a conductive object or non-conductive object adjacent to that coil  1312   a - 1312   d.    
       FIG. 13C  shows a simplified schematic circuit diagram of coil array  1308  and ID logic circuit  1310  according to some embodiments. Each coil  1312   a - 1312   d  is represented as an equivalent circuit having an inductor and a capacitor. Coils  1312   a - 1312   d  are coupled to a resonant circuit driver  1314  and an inductive sensing core  1316 . Resonant circuit driver  1314  can be operated to drive each coil  1312   a - 1312   d  at various frequencies, and inductive sensing core  1316  can sense the response. Based on signals produced by inductive sensing core  1316 , a logic module  1318  can determine whether a conductive object is present or absent adjacent to each coil, and a digital encoding module  1320  can generate a four-bit digital output based on the output of logic module  1318 . The four-bit output can include, for example, a bit corresponding to each of coils  1312   a - 1312   d , with value “1” indicating that a conductive object is present and value “0” indicating that a conductive object is absent. A communication interface  1322  (e.g., implementing I 2 C or other standard communication protocols) can receive control signals to control operation of ID logic circuit  1310 . 
     Cushions designed for identification by coil array  1308  can include an arrangement of conductive areas encoding a four-bit identifier. For example,  FIG. 14  shows a simplified view of a cushion  1406  according to some embodiments. Cushion  1406  can include attachment elements  1408  that enable attachment to attachment elements  1328  of ear cup  1302  of  FIG. 13A . Tag element  1410  can be positioned on or beneath the surface of cushion  1406  that abuts ear cup  1302 . Tag element  1410  can include four demarcated areas  1412   a - 1412   d , and identification data for the cushion can be represented by an appropriate pattern of conductive plates across the four areas. In the example shown in  FIG. 14 , areas  1412   a  and  1412   d  have conductive plates while areas  1412   a  and  1412   d  do not have conductive plates. Different patterns can be used to distinguish different cushion types. 
       FIG. 15  shows tag element  1410  overlying coil array  1308  according to some embodiments. Coils  1312   a  and  1312   d  align with areas  1412   a  and  1412   d  of tag element  1410 , which have overlying conductive plates, while coils  1312   b  and  1312   c  align with areas  1412   b  and  1412   c , which do not have overlying conductive plates. Accordingly, ID logic circuit  1310  can generate an identification pattern, e.g., “1001.” A different arrangement of conductive plates can produce a different identification pattern, allowing different cushion types to be distinguished. 
     The resonant coil arrangement of  FIG. 15  is illustrative and variations and modifications are possible. Resonant coil arrays can be implemented in a variety of form factors and arrangements. Further, while a resonant coil array is illustrated in the context of an ear cup and cushion, it should be understood that a similar principle can be applied to earbuds and ear tips, although space constraints may limit the number of coils. In some embodiments, a tag sensor using an array of N resonant coils can support identifiers for 2N types of cushions. 
     In the preceding example, each resonant circuit provides one bit of identification data. In other embodiments, a single resonant circuit can provide larger amounts of identification data.  FIG. 16  shows a simplified view of an ear cup  1602  and cushion  1606  according to some embodiments, incorporating a resonant circuit for tag identification. Ear cup  1602  can include magnet arrays  1628  disposed around the periphery. Cushion  1606  can include shunt elements  1608  disposed at locations corresponding to magnet arrays  1628  to enable cushion  1606  to be securely attached to earcup  1602 . Magnet arrays  1628  and shunt elements  1608  can be similar to examples described above; however, magnet arrays  1628  and shunt elements  1606  need not support cushion identification. In other embodiments, mechanical or other attachment features can be used in addition to or instead of magnet arrays  1628  and shunt elements  1608 . 
     Cushion  1606  can have a “tag” circuit  1612  disposed at a particular location. Ear cup  1602  can have a tag sensor  1616  disposed at a location that is proximate to tag circuit  1612  when cushion  1606  is attached to ear cup  1602 . Tag sensor  1616  can be coupled to ID logic circuit  1618 , which can be disposed elsewhere within ear cup  1602 . 
     Tag circuit  1612  can be a resonant circuit (“RC”), and ID logic circuit  1618  can incorporate tuner circuitry. In operation, ID logic circuit  1618  can drive tag sensor  1616  at various frequencies and detect the resonant frequency of tag circuit  1612 . By way of example,  FIG. 17A  shows a resonant circuit  1712  and reader circuit  1716  according to some embodiments. Resonant circuit  1712  can implement tag circuit  1612 . In this example, resonant circuit  1712  includes a capacitor  1720  and an inductor  1722  connected in a ring. Reader circuit  1716  can implement tag sensor  1616  and ID logic circuit  1618 . In this example, reader circuit  1716  includes an inductor  1732  coupled to a tuner  1734 . Resonant circuit  1712  and reader circuit  1716  can be arranged such that inductor  1722  is in proximity (at a fixed distance) to inductor  1732  when a cushion in which resonant circuit  1712  is present is attached to an ear cup in which reader circuit  1716  is present. Tuner  1734  can determine a resonant frequency, which depends on the inductance of inductor  1732 , as well as the particular inductance of inductor  1722  and the particular capacitance of capacitor  1720 . Accordingly, identification data for a cushion can be encoded in resonant circuit  1712  by configuring resonant circuit  1712  to have a resonant frequency assigned to a particular cushion type. In some embodiments, capacitor  1720  has the same (within manufacturing tolerance) capacitance for all cushion types, and cushion type information can be encoded by selecting the inductance of inductor  1722 . In other embodiments, inductor  1722  can have the same inductance (again, within manufacturing tolerance) for all cushion types, and cushion type information can be encoded by selecting the capacitance of capacitor  1720 . The number of cushion types that can be distinguished in this manner depends on the frequency range of tuner  1732  and the precision with which tuner  1732  can measure a particular resonant frequency. In some embodiments, a low-complexity tuner circuit can distinguish, e.g., up to about 10 different frequencies, each of which can be mapped to a particular value of a cushion identification parameter. 
     Other resonant circuit configurations can also be implemented.  FIG. 17B  shows another example of a tag circuit  1752  and tag sensor  1756  according to some embodiments. In this example, tag circuit  1752  includes a resistor  1760  and inductor  1762 . Similarly to resonant circuit  1712  of  FIG. 17A , identification data can be encoded in resonant circuit  1752  by configuring resonant circuit  1752  to have a resonant frequency assigned to a particular cushion type. In some embodiments, such configuration can be accomplished by varying either resistor  1760  or inductor  1762  while holding the other constant. Those skilled in the art will appreciate that numerous other resonant circuit configurations can be used. 
     It will be appreciated that the resonant circuit implementations shown herein are illustrative and not limiting. Further, while examples are shown in the context of identifying a cushion attached to an ear cup, similar techniques can be adapted for identifying an ear tip attached to an earbud or other types of cushioning members attached to an earpiece. As noted above, the number of distinct cushion types that can be identified using resonant circuits as ID tags depends on the ability of the sensor circuit to distinguish different resonant frequencies. To increase the number of distinct cushion types that can be identified, multiple resonant tag circuits and corresponding sensor circuits can be disposed at various locations around the cushion and ear cup, and different combinations of resonant frequencies of the tag circuits can be used to encode different cushion identifiers. For instance, if each reader circuit can distinguish a number M of different frequencies, and N tag/reader circuit combinations are present, then M*N cushion types can be distinguished. 
     2.5. Optical Identification 
     In some embodiments, an identification tag can include a region of material (e.g., plastic, metal, textile) disposed on the surface of a cushioning member that optically encodes identification data, and the tag sensor in the earpiece can include an active optical sensor that directs light (e.g., infrared light) onto the optical identification tag and senses reflected light from the optical identification tag. The amount of identification data encoded can vary depending on the particular sensor and encoding scheme. In the simplest case, cushions made of two different textiles having different reflectivity can be distinguished using a binary optical sensor to provide one bit of identification data. In other embodiments, an optical sensor can distinguish multiple reflectivity levels, increasing the amount of identification data. In still other embodiments, an optical sensor may include an imaging sensor (or an array of sensors) that can detect a pattern of reflectivity across an area, and an arrangement of regions of high and low reflectivity on the surface of the cushioning member can be used to encode two or more bits of identification data. 
     In some embodiments, an optical tag sensor can be provided by leveraging an optical sensor used to detect whether an earpiece is being worn.  FIGS. 18A and 18B  illustrate an arrangement for an optical sensor in an ear cup according to some embodiments.  FIG. 18A  shows a cross-section view of the front cover of an ear cup and an attached cushion, and  FIG. 18B  shows a perspective view of the front cover of the earcup and the cushion in a detached state. In the illustrated embodiment, an optical sensor is configured to detect whether an ear cup is on a user&#39;s ear. 
     Referring first to  FIG. 18A , ear cup  1802  can include a housing  1801  (shown in part) and a cover  1804  attached to housing  1801 . Cover  1804  can include multiple perforated holes to enable sound from a speaker positioned within housing  1801  to be directed out of housing  1801  toward a user&#39;s ear. An earpiece cushion assembly  1806  can be detachably attached to housing  1801  and cover  1802 , e.g., using magnetic attachment as described above and/or mechanical attachment. 
     An optical sensor  1820  can be attached to housing  1801  (or to cover  1804 ) and oriented to detect a portion of a user (e.g., an ear of a user) positioned in a region  1805  within the inner periphery of ear cup  1802  and cushion assembly  1806 . For example, sensor  1820  can have a field of view (FOV)  1822  (the area in which light is emitted from the sensor and the area in which the sensor can detect reflected light) that is a relatively wide cone to encompass a large region within region  1805  yet is confined to the inner periphery of the ear cup assembly. Sensor  1820  can be an electro-optical device that includes one or more emitters (e.g., one or more vertical cavity surface emitting lasers, VCSELs) and an optical receiver (e.g., an array of photo sensors). In some embodiments, sensor  1820  includes a single nanosecond-pulse VCSEL laser in the infrared wavelength range and a beam steering device that can direct the laser pulses at different individual fields of view within the larger FOV  1822  of sensor  1820 . 
     In some embodiments, sensor  1820  further includes an array of single photon avalanche diodes (SPADs) as the receiver that can detect the reflected beams from within FOV  1822 . When ear cup  1802  with attached cushion  1806  is placed on a user&#39;s head, sensor  1820  emits collimated beams of pulsed radiation at different locations within FOV  1822 . The pulsed laser beams can reflect off of the user (e.g., off the user&#39;s ear or portion of the user&#39;s skull surrounding the ear) and be detected by the SPAD array optical receiver of sensor  1820 . A processor or similar control circuit (not shown) within ear cup  1802  can be coupled to sensor  1820  to control the timing of the laser pulses and receive detection signals generated by the optical receiver. The processor can utilize the known timing of the laser pulses and other known information to determine the distance to the user&#39;s ear (or other reflected object) using time of flight calculation techniques. For example, the time of flight can be determined by emitting a beam of light at an object and measuring the time it takes a receiver to detect the light reflected off the object. In some embodiments, sensor  1820  can detect objects between approximately zero and at least approximately 300 mm away from sensor  1820 . For example, sensor  1820  can detect objects positioned approximately 1 mm to approximately 100 mm away from sensor  1820 . 
     Sensor  1820  can be electrically coupled to a processor for processing of the data detected by the SPAD array. The processor can determine if the intensity of the reflected light meets a certain threshold and if the distance of the object indicates it is within the region  1805 . SPADs are highly sensitive devices that can detect radiation as small as a single photon in some instances. Because of the sensitivity of the SPAD optical receiver array and the ability of sensor  1820  to both detect an intensity of reflected radiation and determine a distance from the sensor to the object that the pulsed beams are reflected from, either or both of intensity or distance can be used to determine whether the ear cup assembly is on a user&#39;s head. 
     As shown in inset in  FIG. 18A , sensor  1820  can be positioned behind an aperture  1808  formed in a sidewall portion  1810  of housing  1801  and cover  1804  to enable sensor  1820  to both project radiation into region  1805  and receive radiation reflected from one or more surfaces within region  1805  back to the optical sensor. 
     In various embodiments, sensor  1820  can be positioned on a carrier  1821  that can couple with sidewall portion  1810  and span the width of aperture  1808 . Carrier  1821  can provide a mounting angle to direct sensor  1820  such that FOV  1822  spans a desired area and avoids an undesired area (such as the surfaces of cushion  1806 ). Antireflective coatings and optically transparent windows can be used to further optimize performance of sensor  1820 . In some embodiments, a second optical sensor  1820   a  can be positioned opposite sensor  1820 . 
       FIG. 18B  shows a perspective view of cover  1804  and cushion assembly  1806 . Cover  1804  can include apertures  1808  as described above to allow passage of light from sensors  1820 ,  1820   a . Cushion  1806  can include regions  1830  corresponding to the positions of apertures  1808  (one such region is visible in  FIG. 18B ; while the other is not shown, its location can be inferred). In some embodiments, one of opposing regions  2530  can be an aperture to facilitate detection of whether the ear cup is on the user&#39;s head using one of sensors  1820 ,  1820   a , while the other of regions  1830  can be an opaque region that encodes identification data. Opaque region  1830  can be read by sensor  1820  or  1820   a  (depending on the orientation of cushion  1806  relative to earpiece  1804 ) to determine cushion-identifying information. 
       FIGS. 19A-19C  show examples of encoding identification data into region  1830  of cushion  1806  according to various embodiments. As shown in  FIG. 19A , detachable cushion  1806  can include a sidewall  1906  that extends over aperture  1808  such that a region of sidewall  1906  is exposed to optical sensor  1820   a . Sidewall  1906  can have a target pattern  1908  printed on its surface within the exposed region such that target pattern  1908  can be detected by optical sensor  1820   a . For example, to distinguish two cushion types, target pattern  1908  can be an area of high reflectivity for a first cushion type or an area of low reflectivity for a second cushion type, and sensor  1820   a  can use a threshold test to determine the cushion type. To distinguish a larger number of cushion types, multiple levels of reflectivity can be defined, with the upper limit based on the ability of sensor  1820   a  to reliably distinguish the levels. Alternatively, an imaging approach can be used where the printed pattern includes a fixed number of areas (or pixels), each of which has either high or low reflectivity, and sensor  1820   a  can interrogate each area (e.g., using an array of photosensors and/or beam steering techniques) to separately determine the reflectivity of each pixel. The number of pixels can be chosen based on the number of cushion types to be distinguished. 
       FIG. 19B  shows another example of detachable cushion  1806  including a sidewall  1906  that extends over aperture  1808  such that a region of sidewall  1906  is exposed to optical sensor  1820   a . In this example, a target pattern  1928  is injected into sidewall  1906 , e.g., using a second-shot molding process with a material having the desired reflectivity. Similarly to the embodiment of  FIG. 19A , two or more cushion types can be distinguished based on reflectivity levels and/or a pattern of high and low reflectivity areas within target pattern  1928 . 
     It will be appreciated that the optical-sensor embodiments described herein are illustrative and that variations and modifications are possible. For example, multiple optical sensors can be disposed at various aperture locations around the sidewall of an ear cup, and identification data can be encoded using any or all of: presence or absence of cushion material over each aperture; reflectivity of the cushion material over each aperture; and/or a pattern of regions of different reflectivity at each aperture. The amount of identification data that can be encoded depends on the number of distinct regions and/or reflectivity levels that can be independently sensed by the optical sensor(s) in the ear cup. In some embodiments, particularly where the number of cushion types to be distinguished is small, the material of sidewall  1906  can itself encode the cushion-identifying information without affixing or injecting any other pattern. It should also be understood that similar techniques can be applied to an ear tip and earbud. 
     2.6. Acoustic Identification 
     In some embodiments, different cushion types may have different acoustic characteristics. Where this is the case, the cushion itself can encode identifying information, and acoustic techniques such as electromechanical impedance spectroscopy can be used to read the cushion identification data. 
       FIG. 20  shows an example of an earbud  2002  and ear tip  2006  according to some embodiments. Earbud  2002  defines an acoustic chamber  2008  and has an acoustic driver  2010 . For example, driver  2010  can include a diaphragm  2014  that can be induced to oscillate by a transducer (not shown) coupled to an amplifier  2016 . As diaphragm  2014  oscillates, as indicated by dashed line  2010   a , air in acoustic chamber  2008  can be excited, producing sound waves that exit through an acoustic port  2018  (e.g., an opening) in front portion  2004 . In some embodiments, a microphone  2020  can be placed within acoustic port  2018  to receive sound. 
     Similarly to embodiments described above, front portion  2004  can receive and attach to ear tip  2006 . Ear tip  2006  has a sidewall  2022  that surrounds front portion  2004 . As described above, various mechanical, magnetic or friction-based attachment structures can be used to detachably attach ear tip  2006  to earbud  2002 . Ear tip  2006  can also have a compliant lobe or cap  2024  that can conform to a user&#39;s ear canal as described above. Ear tip  2006  can also include a tag element  2028  that can be disposed, e.g., within sidewall  2022 . Tag element  2028  can incorporate passive circuitry, such as a metal band, a coil, a plate, or the like, that can provide resistance, capacitance, and/or inductance, depending on the particular configuration. 
     Earbud  2002  can also include ID logic  2030 . ID logic  2030  can communicate with amplifier  2016  and microphone  2020  to perform acoustic identification of ear tip  2006 .  FIG. 21  shows a flow diagram of a process  2100  for acoustic identification that can be implemented in ID logic  2030  according to some embodiments. At block  2102 , ID logic  2030  can drive an acoustic transducer at a target frequency. For example, ID logic  2030  can operate amplifier  2016  to drive diaphragm  2014 . At block  2104 , ID logic  2030  can measure an output parameter. For example, ID logic  2030  can receive a detected (acoustic) response from microphone  2020  and determine a load impedance on amplifier  2016 . Alternatively, ID logic  2030  can incorporate a meter connected to amplifier  2016  to measure load impedance without relying on microphone  2020 . At block  2106 , ID logic  2030  can compare the measured output parameter to parameter values associated with specific cushion types, and at block  2108 , ID logic  2030  can determine identification data for ear tip  2006  based on the comparison. 
     In some embodiments, multiple measurements can be used to determine the identification data. For example, ID logic  2030  can drive amplifier  2016  at a target frequency in each of a current-driven (“HOR”) mode and a voltage-driven (“ZOR”) mode. The acoustic response from microphone  2020  varies with load impedance in HOR mode but not in ZOR mode. Accordingly, the difference between acoustic responses from microphone  2020  in HOR and ZOR modes can provide a measurement of load impedance. The measurement can be repeated across a number of target frequencies to create a load impedance profile. The load impedance profile can be affected by the particular characteristics of tag element  2028 , making it possible to distinguish ear tips of different types. 
     In some embodiments, a small amount of ear tip identifying information can be encoded in this manner. For example, it may be possible to detect whether an ear tip is present or absent based on the load impedance profile, which can be useful information, e.g., for earbuds that are designed to be used either with or without an ear tip. As another example, two or three configurations of tag element  2028  may be distinguishable based on load impedance profiles, and the configurations can be used to encode an ear tip size (e.g., small, medium, large or just small and large). 
     Depending on the frequencies used, ear tip identification using electromechanical impedance spectroscopy techniques may be audible to the user, which may not be desirable. To avoid or minimize audible sounds, some embodiments use ultrasonic frequencies (above the range of normal human hearing). Some embodiments can use frequencies within the range of human hearing, at amplitudes that are close to the noise threshold, with modulation or keying schemes to improve the signal quality. 
     It will be appreciated that this acoustic identification technique is illustrative and that variations and modifications are possible. A variety of different tag circuit configurations can be implemented, including circuits similar to those shown in  FIGS. 17A and 17B . Acoustic identification techniques can also be applied to identification of cushions attached to ear cups. For example, cushions made of different materials may produce different frequency response profiles (e.g., bass response may be affected by the material composition of a particular cushion), and where this is the case acoustic spectroscopy can be used to distinguish different cushion types. 
     2.7. Capacitive Sensors 
     Another identification technique can be implemented in earpieces that have touch-sensitive interfaces. For example, some existing headphones and earbuds allow the user to touch specific areas on the exterior surface of an earpiece to adjust volume, start or stop music playback, answer or end a phone call, or control other operations. Touch-sensitive interfaces can be implemented using capacitive sensor logic that receives and interprets capacitance measurements from sensor points located in various areas on the surface of the earpiece. 
     In some embodiments, capacitive sensor logic can be leveraged to implement identification of a cushioning member attached to an earpiece. For example, in the embodiment of  FIG. 5 , ear cup  502  can have a touch-sensitive interface with sensor points disposed on external surface  501  (where a user can touch them while wearing ear cup  502 ). Additional sensor points for the touch-sensitive interface can be positioned on interface surface  503 . Interface surface  507  of cushion  506 , which contacts interface surface  503  of ear cup  502 , can be patterned with surface deviations that encode identification data. When cushion  506  becomes attached to ear cup  502 , the capacitive sensor logic in ear cup  502  can read the resulting pattern of signals from the sensor points on interface surface  503  and decode the identification data. 
     It should be understood that capacitive sensing can be used for ear tip identification in an earbud and more generally for cushioning member identification in any earpiece that is instrumented with a touch-sensitive interface. In some embodiments, a touch-sensitive interface can be implemented exclusively for cushioning member identification. 
     2.8. Electrical Contacts for Identification 
     The foregoing embodiments incorporate contactless identification tags, meaning that identification data can be communicated without an electrically conductive path connecting the ID tag and the tag sensor. Contactless D tags can be desirable in some instances, such as where moisture that may corrode electrical contacts may be a concern. In some embodiments, however, electrical contacts can be used to couple a tag sensor to an identification tag. 
       FIG. 22  shows a simplified view of an ear cup  2202  and cushion  2206  according to some embodiments. Cushion  2206  can be removably attached to ear cup  2202  using attachment structures  2208 ,  2228 , which can be similar to other embodiments described above. Cushion  2206  also includes an identification tag  2210 , which can be implemented using a resistor  2212  coupled between two electrical contacts  2214 . Ear cup  2202  includes a tag sensor  2216  which can be implemented using electrical contacts  2218  coupled to an ID logic circuit  2220 . When cushion  2206  is attached to ear cup  2202 , electrical contacts  2214  and  2218  are in contact with each other, allowing current to flow. ID logic circuit  2220  can include circuitry usable to determine the resistance of resistor  2210  (e.g., a conventional voltage divider circuit or the like), and the resistance of resistor  2210  can provide identification data for cushion  2206 . In these embodiments, the number of unique identifiers corresponds to the number of resistance values that can be distinguished. In some embodiments, the number of unique identifiers can be further increased by providing additional contacts and additional resistors, with the particular combination of resistors encoding the identification data. 
     As another example,  FIG. 23  shows a simplified view of an ear cup  2302  and cushion  2306  according to some embodiments. Cushion  2306  can be removably attached to ear cup  2302  using attachment structures  2308 ,  2328 , which can be similar to other embodiments described above. Cushion  2306  also includes an identification tag  2310 , which can be implemented using a set of electrical contacts  2314 . One electrical contact  2314   g  can be a designated ground contact, and some of the electrical contacts  2314  can be connected to ground contact  2314   g  while others are unconnected (floating). Ear cup  2302  includes a tag sensor  2316  which can be implemented using a set of electrical contacts  2318  coupled to an ID logic circuit  2320 . Electrical contact  2318   g  can be grounded as shown. When cushion  2306  is attached to ear cup  2302 , electrical contacts  2314  and  2318  are in contact with each other, allowing current to flow. Ground contact  2314   g  can be in contact with grounded contact  2318   g  so that ground contact  2314   g  is also grounded. ID logic circuit  2320  can include circuitry to determine whether each of electrical contacts  2318  is grounded (as would be the case if the corresponding one of electrical contacts  2314  is coupled to ground contact  2314   g ) or floating (as would be the case if the corresponding one of electrical contacts  2314  is not coupled to ground contact  2314   g ). The state of each contact (grounded or ungrounded) can provide one bit of identification data. If there are N active contacts  2314  (excluding ground contact  2314   g ), then 2N cushion types can be distinguished. 
     It will be appreciated that the foregoing examples of identification techniques using electrical contacts are illustrative and that variations and modifications are possible. Any number and arrangement of contacts can be provided. It should be understood that electrical contacts to enable communication of tag information can also be implemented in an ear tip and earbud or in any other type of cushioning member and earpiece. 
     2.9. Active Identification Tags 
     In the foregoing examples, the identification tag can be a passive element that does not require power or logic circuitry in the cushioning member. In other embodiments, an identification tag in a cushioning member (e.g., identification tag  108  of  FIG. 1  or identification tag  208  of  FIG. 2 ) can include an active element (e.g., a transceiver) that can communicate via a two-way communication channel with reader circuitry located in a corresponding earpiece (e.g., ear cup  102  of  FIG. 1  or earbud  202  of  FIG. 2 ). Depending on implementation, the communication channel can be wired or wireless. Where the identification tag is an active element, the identification tag can be configured to receive operating power from the earpiece, and the earpiece can be configured to supply operating power to the identification tag. For example, power contacts may be provided to transfer power from the earpiece to the identification tag. Alternatively, inductive power transfer can be used to provide power from the earpiece to the identification tag without requiring a wired connection. In some embodiments, an active identification tag may be supported in combination with additional active components within a cushioning member. 
     3. Processes for Identifying Cushioning Members 
     3.1. Identification Process Overview 
     Referring again to  FIG. 3 , regardless of the particular implementation of identification tag  308  and associated tag sensor  314  and identification logic  334 , an earpiece  302  (e.g., ear cup or earbud) can read the identification tag  308  of a cushioning member  306  (e.g., cushion or ear tip) and adapt some aspect of its behavior accordingly. 
       FIG. 24  is a flow diagram of a process  2400  that can be performed in an earpiece system such as earpiece system  300  of  FIG. 3  according to some embodiments. At block  2402 , process  2400  can detect the presence of cushioning member  304 . For example, earpiece  302  may include a proximity or presence sensor that detects when cushioning member  306  is attached by a user. Examples of proximity sensors are known in the art and include, e.g., Hall effect sensors that can respond to a magnetic element disposed within cushioning member  306 , optical sensors that can detect occlusion by cushioning member  306 , mechanical switches that may be deflected into a different position when cushioning member  306  is attached, or the like. As another example, earpiece  302  can periodically poll tag sensor  314  to determine whether a cushioning member is present. A particular presence detection mechanism or process is not required. 
     At block  2404 , process  2400  can obtain identification data (or identification information) from cushioning member  306 , e.g., by operating tag sensor  314  and ID logic  334  to read identification tag  308 . Identification tag  308  can encode identification data using a variety of physical structures, including any of the above-described magnetic, RF-based, resonance-based, optical, acoustic, capacitive, or electrical structures, or any other structure. As used herein, identification data can provide at least some additional information beyond merely indicating presence or absence of a cushioning member. For example, the identification data can represent any or all of: a manufacturer identifier; a model identifier; a size identifier; a color identifier; a device-class identifier (e.g., indicating presence or absence of various capabilities or characteristics); a unique serial number; and so on. Identification data can be encoded in or on identification tag  308  in any manner that enables earpiece  302  to read or receive the identification data while cushioning member  306  is attached, including any or all of the examples described above. 
     In embodiments where earpiece system  300  operates as an accessory to a host device  350 , at block  2406 , process  2400  can communicate the identification data to the host device, e.g., via communication interface  316 . Communication of identification data to a host device is not required, and in some embodiments a host device may not be present. 
     At block  2408 , earpiece system  300  and/or host device  350  can modify a device behavior based on the identification data. In some embodiments, the modification applies to the earpiece. For example, an equalizer setting for earpiece  302  can be selected or modified based (entirely or in part) on the identification data. As another example, settings related to hearing protection can be modified, such as volume limits, active noise cancellation profiles, or the like. In some embodiments where earpiece  302  is used as an accessory for host device  350 , and behavior of host device  350  can be modified. The modified behavior of host device  350  can, but need not, relate to providing audio to earpiece  302 . For instance, the host device may provide a graphical user interface that includes an image of a personal audio device with which the host device is currently interoperating. In some embodiments, the image can be modified based on the identification data, e.g., by changing the color, shape, or other aspects of appearance of the cushioning member in the image to resemble aspects of the particular cushioning member that is currently attached. 
     It will be appreciated that process  2400  is illustrative and that variations and modifications are possible. For instance, in some embodiments, the operations of detecting presence of a cushioning member and obtaining identification data from the cushioning member can be combined. In some embodiments, a personal audio device can include two instances of earpiece system  300  (one for each ear). Where this is the case, each earpiece  302  can read the ID tag  308  of its attached cushioning member  304  and can communicate the identification data to the other earpiece  302  and/or to host device  305 . (If the identification data read by the two earpieces is not consistent, e.g., the cushions are of two different types, various actions can be taken. For example, the user can be alerted to the mismatch. In some embodiments, host device  350  can determine which identification data to use for modifying device behavior.) In some embodiments, an ID tag  308  may be included in only one cushioning member of a pair, in which case only one earpiece  302  would read an ID tag  308 . In some embodiments, identification data can be used for other purposes in addition to (or instead of) modifying device behavior. 
     3.2. Using Identification Data 
     Depending on the particular identification data available in a given embodiment, an earpiece and/or host device can use identification data in a number of ways. By way of example of identification data,  FIG. 25  shows a table  2500  with examples of mapping an ID value (column  2502 ) to characteristics of a cushioning member according to some embodiments. In this example, the cushioning members are ear tips that attach to earbuds. Different ear tips can be distinct in size, color, material, and/or manufacturer. Each ID value in column  2502  maps to a different combination of size, color, material, and manufacturer. ID tag  308  for a given ear tip can encode one of the defined ID values, and ID logic  334  can use tag sensor  314  to determine which ID value is encoded in a particular ID tag  308 . Earpiece  302  or host device  350  can decode the ID value, e.g., by referring to a lookup table implementing table  2500 , to determine the corresponding characteristics of size, color, material and manufacturer. It should be understood that table  2500  is an example. Depending on the amount (e.g., number of bits) of identification data available in a particular tag, more or fewer characteristics can be distinguished and/or a given characteristic can have more or fewer distinct values. 
     3.2.1. Behavior Modification 
     As described above with reference to  FIG. 24 , an earpiece  302  and/or host device  350  can modify its behavior based on identification data for an attached cushioning member  306 . The particular modification of behavior in various embodiments can depend on the type of information available, as well as the capabilities of earpiece  302  and/or host device  350 . Examples will now be described. 
     In some embodiments, an earpiece  302  and/or host device  350  can modify its behavior by changing audio output characteristics based on the cushion type identified by the cushion identification data. For instance, it is known in the art that equalizer settings can be used to improve perceived sound quality of a speaker. The audible frequency spectrum can be subdivided into a number of bands, and the relative responses in different bands can be increased or decreased according to the equalizer settings. Optimal equalizer settings may depend in part on the characteristics of the speaker. In the case of personal audio devices such as earphones and headphones, cushioning members made of different materials and/or having different geometries (size and/or shape) can have different effects on sound waves produced by a speaker; hence, the optimal equalizer settings can be different for cushioning members of different types. 
     Accordingly, in some embodiments, the identification data can include a device class identifier that distinguishes cushion types based on materials and/or geometry. The earpiece or host device can store a lookup table that maps each device class identifier to recommended equalizer settings and can select equalizer settings based at least in part on the device class identifier. In some embodiments, the recommended equalizer settings based on device class identifier can indicate adjustments to a baseline equalizer setting that is determined based on other factors, such as the type of audio being produced (e.g., music vs. spoken word, particular genre of music, etc.) and/or information about the environment. 
     As another example, some earpieces (or host devices) can provide active noise cancellation. In active noise cancellation, a secondary audio signal is generated that is intended to cancel out ambient sounds that may leak into the user&#39;s ear (e.g., airplane engine noise), and the secondary audio signal can be played in isolation or combined (mixed) with a primary audio signal that the user is listening to. The effectiveness of noise cancellation in a given earpiece can depend on the properties of the cushioning member; for instance, different cushioning members may admit different amounts of ambient sound, and the amount of admitted sound may depend on frequency. 
     Accordingly, in some embodiments, a noise cancellation profile used to generate a secondary audio signal for an earpiece can be modified based on identification data (e.g., a device class identifier) obtained from the cushioning member. In some cases, modifying a noise cancellation profile may include enabling or disabling active noise cancellation, or increasing or decreasing the strength of the secondary audio signal either globally or within specific frequency bands. 
     As another example, some cushioning members may belong to a device class that is designed for use in environments where it is desirable to reduce ambient noise but not to suppress specific sounds (e.g., human speech). In some embodiments, when the identification data indicates that a cushioning member belongs to this device class, appropriate sound-filtering or active noise cancellation algorithms can be automatically applied. 
     As yet another example, some cushioning members may be designed for use by children, who can be particularly vulnerable to hearing damage caused by prolonged exposure to loud sounds. In some embodiments, when the identification data indicates that a cushioning member is designed for children, volume limits can automatically be applied to the speaker of the personal audio device, which can help to protect the user&#39;s ears. It should be understood that volume-limiting operations are not applicable only to children, and volume limits can be associated with any device class. 
     As still another example, some embodiments described above use cushion identification to determine whether a cushioning member is attached to the earpiece. One specific example is described above in the context of acoustic identification techniques, but any of the techniques described above for reading an identification tag can also indicate whether an identification tag (and presumably a cushioning member) is present or not. In some embodiments, an earpiece may be designed for use either with or without a cushioning member, and audio characteristics can be modified based on whether a cushioning member is attached. In other embodiments, an earpiece may be designed for use only with a cushioning member, and the behavior modification when a cushioning member is not detected can include, e.g., notifying the user to attach a cushioning member or not generating sound in the earpiece (or only a low level of sound) when no cushioning member is present. 
     Other behavior modifications can relate to user interface features. For example, a host device with which a personal audio device interoperates can have a graphical user interface that shows an icon or image representing the personal audio device. In some embodiments, the icon or image can be modified based on the identification data. For example, if the identification data identifies the shape, color, or other visual characteristics of the cushioning member that is currently attached, the icon or image can be modified to reflect the actual shape, color, or other visual characteristics of the cushioning member. 
     It should be understood that these examples of device behavior modification are illustrative. Other behavior modifications can be implemented, and different sets of behavior modifications can be associated with different identification data. In some embodiments, the user can have an option to override the behavior modification, e.g., via a user interface of the host device, via voice command, or the like. 
     It should also be understood that in some instances a cushion identification process might fail to read the cushion identification data due to various circumstances, such as absence of or damage to the identification tag, transient errors in a tag sensor, or the like. Accordingly, some embodiments may implement a default behavior mode when cushion identification fails. A default behavior mode can include, for example: operating with default equalizer and/or active noise cancellation profiles; rendering a default cushion image in a graphical user interface; and so on. 
     3.2.2. Assisting User with Cushion Selection 
     In some embodiments, identifying information for a cushioning member that is currently attached to an earpiece can be used to assist a user in selecting a cushioning member to optimize the user&#39;s audio experience. 
     For example, in some embodiments where size of the cushioning member is a characteristic that can be determined from ID tag  308 , the identification data can be used to assist a user in selecting a cushioning member of optimal size.  FIG. 26  shows a flow diagram of a fitting process  2600  according to some embodiments. Fitting process  2600  can be implemented, e.g., in a host device that interoperates with an earpiece, such as host device  350  of  FIG. 3  interoperating with earpiece system  300 . 
     At block  2602 , process  2600  can prompt the user to attach a cushioning member (e.g., an ear tip) to an earpiece (e.g., an earbud) in order to perform size testing. For example, a host device can provide the prompt via a graphical user interface or voice prompt. Once the user has attached the ear tip, at block  2604  process  2600  can obtain identification data from the ear tip. In some embodiments, block  2604  can be similar to block  2404  of process  2400  described above, and any of the identification tags and compatible tag sensors and identification logic described above can be used. Identification data can be varied as desired, provided that the identification data enables determination of a size parameter for the ear tip. 
     At block  2606 , process  2600  can determine the size parameter for the ear tip based on the identification data. In some embodiments, the identification data may include a numerical value that maps directly to a size (e.g., numerical values 0, 1, 2 can map to sizes small, medium, and large). In other embodiments, size can be determined by a lookup operation on the identification data (e.g., using table  2500  of  FIG. 25 ) or the like. 
     At block  2608 , process  2600  can perform an audio leakage test. Examples of leakage tests for earpieces are known in the art and can include detecting external sounds leaking in through the earpiece and/or detecting sounds produced by the earpiece leaking out to the environment. A particular test is not relevant to understanding the present disclosure. At block  2610 , process  2600  can determine whether the leakage test was successful. For instance, success or failure of a leakage test can be defined based on whether the level of sound leakage is below or above some preset threshold. In the event of failure, at block  2612  process  2600  can provide a recommendation for another size to try next. Because process  2600  has determined the size of the ear tip that was tested, the recommendation can be more specific than a general suggestion to try a different size. For instance, based on the current size and the leakage test result, process  2600  can provide a recommendation to try a larger (or smaller) size or to try a specific size. If, at block  2610 , the leakage test succeeds, then at block  2614  process  2600  can confirm that the currently-attached size provides appropriate protection against sound leakage. 
     It will be appreciated that process  2600  is illustrative and can be modified. Process  2600  can be used with a variety of leakage tests and a variety of earpieces and cushioning members (including cushions for ear cups). Similar processes can also be used to assess whether a particular cushioning member is providing satisfactory audio performance and to recommend a different cushioning member that may provide improved performance. For example, in addition to or instead of having different sizes, different types of cushioning members may be made of different materials that provide different levels of insulation from external sounds, and a recommendation for a cushioning member made of a particular material can be made based on leakage tests and/or user feedback regarding the subjective audio experience. In some embodiments, a process such as process  2600  can be implemented entirely within the earpiece, e.g., using indicator lights or voice prompts to communicate test results and recommendations. 
     3.2.3. Additional Uses of Cushioning Member Identification Data 
     Embodiments described above can leverage a variety of data encoding and reading technologies to encode and read identification data for a cushion. As described above, different technologies can enable different amounts of information to be encoded, from 1 or 2 bits up to several kilobytes. Accordingly, many types of information can be encoded, including materials, manufacturer name, date of manufacture, and/or a unique cushion identifier (e.g., a serial number). Where available, detailed identification data, such as a unique cushion identifier, can be used for a variety of purposes. For example, some embodiments, a cushioning member can be made (entirely or in part) of foam and/or elastic materials that may degrade (e.g., become rigid or excessively pliant) after a long period of use or even without use due to aging of the materials. In embodiments where the identification data uniquely identifies a specific cushioning member (e.g., by serial number), a personal audio device or an associated host device can monitor and track usage history of that cushioning member, e.g., by tracking cumulative hours of use. In some embodiments, the personal audio device or associated host device can generate a notification to the user when the usage history indicates that the cushioning member may be due for maintenance (e.g., cleaning) or replacement. Similarly, if the identification data provides information usable to determine the age of the cushioning member (e.g., a date of manufacture), the personal audio device or associated host device can determine whether the cushioning member should be replaced due to age (with or without reference to any usage history information). In some embodiments, usage monitoring can be performed with less-granular cushion identification data. For example, referring to  FIG. 25 , it may be assumed that a particular user has only one set of large red ear tips from manufacturer MFR 1, and usage monitoring can be based on that assumption. 
     As another example, where the identification data uniquely identifies a specific cushioning member, the behavior of the personal audio device can be modified according to user-specific preferences when a particular cushioning member is identified as being attached. For instance, while a particular cushioning member is attached, a user may adjust equalizer settings, noise cancellation preferences, volume settings, volume limits, or other operating parameters for the personal audio device. In some embodiments, the personal audio device (or a host device with which the personal audio device interoperates) can save the user preferences in association with the identification data for the cushioning member. The next time the same cushioning member is identified by the personal audio device (or by the host device, as the case may be), the saved user preferences can be automatically retrieved and applied. In other embodiments, user preferences can be saved in association with identification data at a less granular level; for instance user preferences can be stored in association with an identifier of a specific device class rather than a specific cushioning member, and the stored preferences can be applied whenever a cushioning member is identified as having that device class. In some embodiments, a host device that saves user preferences associated with a particular cushioning member (or device class) can share the saved preferences with other devices that can act as host devices (e.g., other personal electronic devices belonging to the same user). Accordingly, a user can easily transfer user preferences associated with a particular cushioning member (or device class) to another host device. 
     In some embodiments, a cushioning member (referred to herein as an “advanced” cushioning member) may include active circuitry implementing additional capabilities beyond cushioning and/or sound insulation. For example, one or more sensors can be embedded into a cushioning member to detect a user&#39;s pulse, temperature, perspiration, or other biometric information. (The particular type or capability of the sensor(s) embedded in a cushioning member may be varied as desired.) Identification data for an advanced cushioning member can include data indicating the particular capabilities of the advanced cushioning member (e.g., the sensor type(s) of embedded sensor(s)), and the earpiece (and/or a host device) can modify a behavior accordingly. For example, the earpiece can enable supplying of power to the cushioning member when an advanced cushioning member is identified and disable supplying of power otherwise. As another example, based on the identification data for a particular cushioning member, an earpiece (or a host device) can determine when to read sensor data from the cushioning member and/or how to interpret received sensor data. It will be appreciated that a wide variety of advanced capabilities can be selectively enabled or disabled based on identification data obtained from a particular cushioning member. 
     4. Additional Embodiments 
     While the invention has been described with respect to specific embodiments, one skilled in the art will recognize that numerous modifications are possible. For example, although the description makes reference to ear tips that may be positioned at least partially within the user&#39;s ear canal and to cushions that may be worn on the ear or over the ear, similar principles can be applied to any cushioning member that can be detachably attached to an earpiece of a personal audio device. The particular size and shape of a cushioning member or an earpiece can be modified as desired. 
     The amount, content, and format of identification data or identification information can be varied as desired. Identification data can range from a small amount of data (e.g., two or three bits) specifying size or color to an arbitrarily long number (which can be represented, e.g., as bit string) that uniquely identifies a particular cushioning member. In some embodiments, identification data can be structured. For instance, if the identification data is represented as a bit string, one portion of the bit string may identify a device class, another portion may identify a manufacturer, and so on. Lookup tables or the like can also be used to map arbitrary numerical identification data to a particular combination of properties of a cushioning member. 
     As described above, identification data can be used to modify device behavior, including the production of sound by the earpiece, user interface features, interactions between the earpiece and cushioning member (e.g., reading sensor data), and so on. Identification data can also be used to monitor the condition of a particular cushioning member and to notify the user when a cushioning member may benefit from maintenance (e.g., cleaning) or replacement. Other behavior modifications and/or user-supportive operations can be implemented based on the identification data. 
     Some embodiments described above refer to a single earpiece and a single cushioning member. It should be understood that a personal audio device may include a pair of earpieces of like design (e.g., as shown in  FIGS. 1 and 2 ) and that cushioning members may likewise be provided in pairs of like design. Where cushioning members are provided in pairs, an identification tag can be included in either or both cushioning members of the pair, and reader circuitry to read the identification tag may be included in either or both earpieces. If reader circuitry in the two earpieces of a pair detect a discrepancy in identification data between their respective cushioning members (e.g., identification data indicating different device classes or sizes), various responsive actions can be taken. For example, the user can be notified of the discrepancy; audio settings for the two earpieces can be modified differently based on the identification data of their respective cushion members; or audio settings for both earpieces can be selected based on blending audio settings associated with the two cushioning members. 
     Various features described herein, e.g., methods, apparatus, computer-readable media and the like, can be realized using any combination of dedicated components and/or programmable processors and/or other programmable devices. The various processes described herein can be implemented on the same processor or different processors in any combination. Where components are described as being configured to perform certain operations, such configuration can be accomplished, e.g., by designing electronic circuits to perform the operation, by programming programmable electronic circuits (such as microprocessors) to perform the operation, or any combination thereof. Further, while the embodiments described above may make reference to specific hardware and software components, those skilled in the art will appreciate that different combinations of hardware and/or software components may also be used and that particular operations described as being implemented in hardware might also be implemented in software or vice versa. 
     Computer programs incorporating various features described herein may be encoded and stored on various computer readable storage media; suitable media include magnetic disk or tape, optical storage media such as compact disk (CD) or DVD (digital versatile disk), flash memory, and other non-transitory media. Computer readable media encoded with the program code may be packaged with a compatible electronic device, or the program code may be provided separately from electronic devices (e.g., via Internet download or as a separately packaged computer-readable storage medium). 
     In some embodiments, the identification data can uniquely identify a particular cushioning member that belongs to a particular user; where this is the case, the identification data might be regarded as personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. For instance, in some embodiments, identification data for a cushion or tip need not be provided to any entity other than the earpiece or (optionally) a user-owned host device with which the earpiece interoperates. Users may be informed of and prompted to opt in to any sharing of data that may occur. 
     Thus, although the invention has been described with respect to specific embodiments, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Metadata:
Filing Date: 20200916
Publication Date: 20220201
Grant Date: 20220201
Priority Date: 20190918
Inventors: TERLIZZI, JEFFREY J.
BERGERON, KATHLEEN A.
ERGUN, ALI N.
HATFIELD, DUSTIN A.
HUWE, ETHAN L.
MARCO, TODD P.
LEBLANC, JASON JOSEPH
ZUPKE, Robert D.
MINERBI, MICHAEL B.
BHAGWAT, PRATHAMESH R.
BLOOM, DANIEL R.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R2460/15", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1008", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2420/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R25/652", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2460/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2420/07", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/77", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 74869950