Facebook Patent | Privacy setting for sound leakage control

Patent: Privacy setting for sound leakage control

Drawings: Click to check drawins

Publication Number: 20210204058

Publication Date: 20210701

Applicant: Facebook

Abstract

An audio system includes a speaker and a processor. The processor determines a privacy setting for an audio signal. The privacy setting may be selected by a user. The privacy setting may indicate activation of a private mode, or may indicate a privacy level from a range of privacy levels. The processor determines an audio filter that adjusts the audio signal to mitigate sound leakage when presented by the speaker based on the privacy setting. The audio filter may include a low-pass filter and a multiband compressor. The parameters of the audio filter may vary based on the privacy setting. The processor applies the audio filter to the audio signal to generate a filtered audio signal and provides the filtered audio signal to the speaker.

Claims

1. An audio system comprising: a speaker; and a processor configured to: determine a privacy setting for an audio signal; determine an audio filter that adjusts the audio signal to mitigate sound leakage when presented by the speaker based on the privacy setting; apply the audio filter to the audio signal to generate a filtered audio signal; and provide the filtered audio signal to the speaker.

2. The audio system of claim 1, wherein the processor is configured to: determine, based on the privacy setting, an attenuation level for a frequency band; and determine the audio filter based on the attenuation level for the frequency band.

3. The audio system of claim 2, wherein the audio filter includes a low-pass filter and the processor is configured to determine a cutoff frequency of the low-pass filter based on the privacy setting.

4. The audio system of claim 2, wherein the audio filter includes a compressor and the processor is configured to determine a threshold level and a compression ratio of the compressor for the frequency band based on the privacy setting.

5. The audio system of claim 4, wherein processor is configured to determine another threshold level and another compression ratio of the compressor for another frequency band based on the privacy setting.

6. The audio system of claim 1, wherein the audio filter includes a low-pass filter followed by a multiband compressor.

7. The audio system of claim 1, wherein the processor is further configured to: present a user interface for selecting the privacy setting on a display device; and receive a user input indicating the privacy setting.

8. The audio system of claim 7, wherein the audio system is a part of a headset and the display device is a part of a computing device that is separate from the audio system.

9. The audio system of claim 1, further comprising a mechanical control, and wherein the processor is configured to receive a user input provided via the mechanical control indicating the privacy setting.

10. The audio system of claim 1, wherein the privacy setting defines a selection between a private mode or a non-private mode.

11. The audio system of claim 10, wherein the processor is configured to select between the private mode or non-private mode based on a location of the audio system.

12. The audio system of claim 1, wherein the privacy setting defines a selection of a privacy level from a range of privacy levels.

13. The audio system of claim 1, wherein the speaker includes a dipole speaker including an enclosure having an output port and a rear port, a first portion of sound emitted by the speaker is emitted from the output port and a second portion of the sound having a phase offset from the first portion of the sound is emitted from the rear port.

14. A method comprising, by a processor of an audio system: determining a privacy setting for an audio signal; determining determine an audio filter that adjusts the audio signal to mitigate sound leakage when presented by a speaker of the audio system based on the privacy setting; applying the audio filter to the audio signal to generate a filter audio signal; and providing the filtered audio signal to the speaker.

15. The method of claim 14, further comprising, by the processor: determining, based on the privacy setting, an attenuation level for a frequency band; and determining the audio filter based on the attenuation level for the frequency band.

16. Th method of claim 15, wherein the audio filter includes a low-pass filter and the method further comprises, by the processor, determining a cutoff frequency of the low-pass filter based on the privacy setting.

17. The method of claim 15, wherein the audio filter includes a compressor and the method further comprises, by the processor, determining a threshold level and a compression ratio of the compressor for the frequency band based on the privacy setting.

18. The method of claim 14, further comprising, by the processor, receiving a user input indicating the privacy via one of: a user interface presented on a display device; or a user input provided via a mechanical control.

19. The method of claim 14, wherein the privacy setting defines one of: a private mode or a non-private mode; or a privacy level from a range of privacy levels.

20. A non-transitory computer readable medium storing instructions that, when executed by a processor, cause the processor to perform steps comprising: determining a privacy setting for an audio signal, determining an audio filter that adjusts the audio signal to mitigate sound leakage when presented by a speaker based on the privacy setting, applying the audio filter to the audio signal to generate a filtered audio signal, and providing the filtered audio signal to the speaker.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/955,710, filed Dec. 31, 2019, which is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] This disclosure relates generally to artificial reality systems, and more specifically to controlling sound leakage for artificial reality systems.

BACKGROUND

[0003] Headsets, such as artificial reality headsets, include audio systems that provide audio content. The audio systems generate audio content which is presented to a user of the headset. However, the audio content presented by typical audio systems may be audible to other persons or devices close to the headset. For many reasons, such as for privacy, the user may wish to prevent other persons or devices from detecting or understanding the audio content presented by the audio system.

SUMMARY

[0004] An audio system for a headset is configured to decrease sound leakage into a local area of the headset based on a privacy setting. The headset provides audio content to a user of the headset. However, it may be undesirable for the audio content to be audible to other persons or devices near the headset. The audio system may use audio filters to mitigate leakage of the audio content into the local area, particularly for frequency bands in which the (e.g., dipole) speaker is relatively less effective at mitigating sound leakage. The audio system may band-limit the audio content to mitigate leakage of particular frequencies of the audio content into the local area based on the privacy setting. The privacy setting may be set by a user using an application user interface or a mechanical user interface. In one example, the privacy setting defines a selection between a private mode where an audio filter is applied to an audio signal or a non-private mode where the audio filter is not applied. In another example, the privacy setting defines a privacy level from a range of privacy levels, and the characteristics of the audio filter applied to the audio signal is set based on the privacy level. The audio system may include a dipole speaker. The dipole speaker may be relatively effective at mitigating sound leakage below 3,000 Hz, while the audio filter may be used to mitigate sound leakage for higher frequencies depending on the privacy setting.

[0005] Some embodiments include an audio system. The audio system includes a speaker and a processor. The processor determines a privacy setting for an audio signal. The processor determines an audio filter that adjusts the audio signal to mitigate sound leakage when presented by the speaker based on the privacy setting. The processor applies the audio filter to the audio signal to generate a filtered audio signal, and provides the filtered audio signal to the speaker.

[0006] Some embodiments include a method performed by a processor of an audio system. The method includes determining a privacy setting for an audio signal. The method further includes determining determine an audio filter that adjusts the audio signal to mitigate sound leakage when presented by a speaker of the audio system based on the privacy setting. The method further includes applying the audio filter to the audio signal to generate a filtered audio signal, and providing the filtered audio signal to the speaker.

[0007] Some embodiments include a non-transitory computer readable medium storing instructions that, when executed by a processor, cause the processor to perform steps comprising determining a privacy setting for an audio signal, determining an audio filter that adjusts the audio signal to mitigate sound leakage when presented by a speaker based on the privacy setting, applying the audio filter to the audio signal to generate a filtered audio signal, and providing the filtered audio signal to the speaker.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1A is a perspective view of a headset implemented as an eyewear device, in accordance with one or more embodiments.

[0009] FIG. 1B is a perspective view of a headset implemented as a head-mounted display (HMD), in accordance with one or more embodiments.

[0010] FIG. 2 is a block diagram of an audio system, in accordance with one or more embodiments.

[0011] FIG. 3A is a perspective view is of a portion of a temple with a dipole speaker, in accordance with one or more embodiments.

[0012] FIG. 3B is a rear view of the portion of the temple of FIG. 3A, in accordance with one or more embodiments.

[0013] FIGS. 4A and 4B are application user interfaces for selecting a privacy setting, in accordance with one or more embodiments.

[0014] FIGS. 5A and 5B are mechanical user interfaces for selecting a privacy setting, in accordance with one or more embodiments.

[0015] FIG. 6 is a flowchart illustrating a process for mitigating sound leakage, in accordance with one or more embodiments.

[0016] FIG. 7 is a flowchart illustrating a process for mitigating sound leakage based on a privacy setting, in accordance with one or more embodiments.

[0017] FIG. 8 is a system that includes a headset, in accordance with one or more embodiments.

[0018] The figures depict various embodiments for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein.

DETAILED DESCRIPTION

[0019] An audio system is configured to mitigate sound leakage into a local environment based on a privacy setting. Leakage refers to the effect of sound from a speaker (e.g., headphones) escaping into the outside world. Mitigating sound leakage increases the privacy for a user of the audio system and also decreases disturbances for others in the local area, but there may be a trade off in sound quality. As such, the privacy setting allows a user to select between higher privacy or sound quality. The privacy setting may be selected by the user using an application user interface or a mechanical user interface. The privacy setting may define a selection of a privacy level from a range of privacy levels, or may define a selection between a private mode being on or off.

[0020] The audio system includes one or more speakers and a circuitry (e.g., audio controller or processor) that controls audio content output by the audio system. The audio system may be a component of a device worn and/or carried by a user that includes the audio system, and is configured to present audio to a user via the audio system. A personal audio device may be, e.g., an artificial reality headset, a cellphone, some other device configured to present audio to a user via the audio system, or some combination thereof.

[0021] The audio system may include a dipole speaker. The dipole speaker may mitigate sound leakage into the local area by canceling sounds with destructive interference in the far field (e.g., 50 cm or more.) Dipole speakers typically are relatively more effective at canceling sound waves at lower frequencies, such as below 3,000 Hz. The audio system applies audio filters to attenuate sounds at various frequencies, including frequencies over 3,000 Hz, to mitigate sound leakage into the local area. The audio system may dynamically select filters to attenuate the audio content based on the privacy setting. In some embodiments, the privacy setting may be determined programmatically, such as based on environmental conditions, the type of audio content being presented, the presence of other people in a local area, the frequency of the audio content being presented, or some combination thereof.

[0022] Embodiments of the invention may include or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality (VR), an augmented reality (AR), a mixed reality (MR), a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to create content in an artificial reality and/or are otherwise used in an artificial reality. The artificial reality system that provides the artificial reality content may be implemented on various platforms, including a wearable device (e.g., headset) connected to a host computer system, a standalone wearable device (e.g., headset), a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

[0023] FIG. 1A is a perspective view of a headset 100 implemented as an eyewear device, in accordance with one or more embodiments. In some embodiments, the eyewear device is a near eye display (NED). In general, the headset 100 may be worn on the face of a user such that content (e.g., media content) is presented using a display assembly and/or an audio system. However, the headset 100 may also be used such that media content is presented to a user in a different manner. Examples of media content presented by the headset 100 include one or more images, video, audio, or some combination thereof. The headset 100 includes a frame, and may include, among other components, a display assembly including one or more display elements 120, a depth camera assembly (DCA), an audio system, and a position sensor 190. While FIG. 1A illustrates the components of the headset 100 in example locations on the headset 100, the components may be located elsewhere on the headset 100, on a peripheral device paired with the headset 100, or some combination thereof. Similarly, there may be more or fewer components on the headset 100 than what is shown in FIG. 1A.

[0024] The frame 110 holds the other components of the headset 100. The frame 110 includes a front part that holds the one or more display elements 120 and end pieces (e.g., temples) to attach to a head of the user. The front part of the frame 110 bridges the top of a nose of the user. The length of the end pieces may be adjustable (e.g., adjustable temple length) to fit different users. The end pieces may also include a portion that curls behind the ear of the user (e.g., temple tip, ear piece). 0

[0025] The one or more display elements 120 provide light to a user wearing the headset 100. As illustrated the headset includes a display element 120 for each eye of a user. In some embodiments, a display element 120 generates image light that is provided to an eyebox of the headset 100. The eyebox is a location in space that an eye of user occupies while wearing the headset 100. For example, a display element 120 may be a waveguide display. A waveguide display includes a light source (e.g., a two-dimensional source, one or more line sources, one or more point sources, etc.) and one or more waveguides. Light from the light source is in-coupled into the one or more waveguides which outputs the light in a manner such that there is pupil replication in an eyebox of the headset 100. In-coupling and/or outcoupling of light from the one or more waveguides may be done using one or more diffraction gratings. In some embodiments, the waveguide display includes a scanning element (e.g., waveguide, mirror, etc.) that scans light from the light source as it is in-coupled into the one or more waveguides. Note that in some embodiments, one or both of the display elements 120 are opaque and do not transmit light from a local area around the headset 100. The local area is the area surrounding the headset 100. For example, the local area may be a room that a user wearing the headset 100 is inside, or the user wearing the headset 100 may be outside and the local area is an outside area. In this context, the headset 100 generates VR content. Alternatively, in some embodiments, one or both of the display elements 120 are at least partially transparent, such that light from the local area may be combined with light from the one or more display elements to produce AR and/or MR content.

[0026] In some embodiments, a display element 120 does not generate image light, and instead is a lens that transmits light from the local area to the eyebox. For example, one or both of the display elements 120 may be a lens without correction (non-prescription) or a prescription lens (e.g., single vision, bifocal and trifocal, or progressive) to help correct for defects in a user’s eyesight. In some embodiments, the display element 120 may be polarized and/or tinted to protect the user’s eyes from the sun.

[0027] In some embodiments, the display element 120 may include an additional optics block (not shown). The optics block may include one or more optical elements (e.g., lens, Fresnel lens, etc.) that direct light from the display element 120 to the eyebox. The optics block may, e.g., correct for aberrations in some or all of the image content, magnify some or all of the image, or some combination thereof.

[0028] The DCA determines depth information for a portion of a local area surrounding the headset 100. The DCA includes one or more imaging devices 130 and a DCA controller (not shown in FIG. 1A), and may also include an illuminator 140. In some embodiments, the illuminator 140 illuminates a portion of the local area with light. The light may be, e.g., structured light (e.g., dot pattern, bars, etc.) in the infrared (IR), IR flash for time-of-flight, etc. In some embodiments, the one or more imaging devices 130 capture images of the portion of the local area that include the light from the illuminator 140. As illustrated, FIG. 1A shows a single illuminator 140 and two imaging devices 130. In alternate embodiments, there is no illuminator 140 and at least two imaging devices 130.

[0029] The DCA controller computes depth information for the portion of the local area using the captured images and one or more depth determination techniques. The depth determination technique may be, e.g., direct time-of-flight (ToF) depth sensing, indirect ToF depth sensing, structured light, passive stereo analysis, active stereo analysis (uses texture added to the scene by light from the illuminator 140), some other technique to determine depth of a scene, or some combination thereof.

[0030] The audio system provides audio content. The audio system includes a transducer array, a sensor array, and an audio controller 150. However, in other embodiments, the audio system may include different and/or additional components. Similarly, in some cases, functionality described with reference to the components of the audio system can be distributed among the components in a different manner than is described here. For example, some or all of the functions of the controller may be performed by a remote server.

[0031] The transducer array presents sound to user. The transducer array includes a plurality of transducers. A transducer may be a speaker 160 or a tissue transducer (e.g., a bone conduction transducer or a cartilage conduction transducer). In some embodiments, instead of individual speakers for each ear, the headset 100 includes a speaker array comprising multiple speakers integrated into the frame 110 to improve directionality of presented audio content. The tissue transducer couples to the head of the user and directly vibrates tissue (e.g., bone or cartilage) of the user to generate sound. The number and/or locations of transducers may be different from what is shown in FIG. 1A.

[0032] As shown in FIG.1A, the audio system of the headset 100 includes an audio assembly coupled to each side of the frame 110, including speakers 160 and enclosures 170, corresponding to the right and left ears of the user. Each of the speakers 160 is contained in a respective enclosure 170. In FIG. 1A, each of the enclosures 170 is shown integrated into a temple 182 of the frame 110, but an enclosure may be coupled to the frame in a different configuration, according to some embodiments. Each of the enclosures 170 includes an output port 175 coupled to a front cavity of the respective enclosure and at least one rear port 155 coupled to a rear cavity of the enclosure. In other embodiments, an enclosure may include more than one output port and one or more rear ports. In some embodiments, at least one of the rear ports is a resistive port configured to dampen the sound emitted from the rear cavity of the enclosure 170. The speaker 160 emits sound, in response to an electronic audio signal received from the audio controller 150. The audio controller 150 may provide and transmit instructions for the audio system to present audio content to the user. The output port 175 is configured to output a first portion of the sound from the front cavity of the enclosure 170, and the rear ports 155 are configured to output a second portion of the sound from the rear cavity of the enclosure 170. The first portion of the sound and the second portion of the sound may destructively interfere with each other, such that a portion of the sound is canceled in the far field.

[0033] The distance between the output port 175 and a rear port 155 may vary. If the output port 175 and rear port 155 are relatively close, the high frequency in the far field is canceled more effectively, but this may result in worse playback in the near field as potential for destructive interference increases.

[0034] The audio controller 150 applies audio filters to the audio content to mitigate the leakage of the audio content into the local area. The audio controller 150 determines a privacy setting for an audio signal, determines an audio filter that adjusts the audio signal to mitigate sound leakage when presented by a speaker 160 based on the privacy setting, applies the audio filter to the audio signal, and provides the audio signal to the speaker 160. The privacy setting may be set by a user using an application user interface (e.g., presented by the imaging device 130) and/or a mechanical user interface (e.g., on the frame 110). The privacy setting may define a selection between a private mode where the audio filter is applied to the audio signal or a non-private mode where the audio filter is not applied. The private mode provides increased privacy by reducing sound leakage, but with reduced quality of playback for the audio content. The non-private mode provides improved quality of playback, but with more sound leakage than the private mode. In another example, the privacy setting defines a privacy level from a range of privacy levels. The audio controller 150 determines the characteristics of the audio filter based on the privacy level. Here, the audio controller 150 provides for sliding amount in the tradeoff between reduction in sound leakage and audio playback quality.

[0035] The audio filter defined by the privacy setting may include one or more filters and one or more compressors. The audio controller 150 determines an attenuation level a frequency band of the audio signal, and determines the audio filter based on the attenuation level. Different frequency bands of the audio signal may include different attenuation levels based on the privacy setting. The audio controller 150 may associate different privacy settings with different attenuation levels of frequency bands, and adjust the audio filter based on the attenuation levels of the frequency bands.

[0036] In some embodiments, the privacy setting may be determined based on factors such as the content being presented and/or environmental conditions in the local area. For example, if the audio content being presented includes speech, the audio controller 150 may increase the privacy setting to apply filters which minimize leakage while maintaining intelligibility of the speech for the user. If an environmental condition indicates that increased mitigation is desirable, such as if the headset is in a quiet environment or if there are other people near the user, the audio controller may increase the privacy setting and the amount of sound leakage mitigation. In contrast, if an environmental condition indicates that the headset is in a loud environment or that the user is alone, the audio controller may decrease the privacy setting and apply less restrictive audio filters to improve the audio experience for the user. In some embodiments, the audio controller 150 determines an environmental condition programmatically, such as based on data received from one or more sensors of the headset 100.

[0037] The audio controller 150 processes information from the sensor array that describes sounds detected by the sensor array. The audio controller 150 may be a circuitry, such as a processor and a computer-readable storage medium. In other examples, the circuitry may include an application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or some other type of processing circuit. The audio controller 150 may be configured to generate direction of arrival (DOA) estimates, generate acoustic transfer functions (e.g., array transfer functions and/or head-related transfer functions), track the location of sound sources, form beams in the direction of sound sources, classify sound sources, generate audio filters for the speakers 160, or some combination thereof.

[0038] The sensor array detects sounds within the local area of the headset 100. The sensor array includes a plurality of acoustic sensors 180. An acoustic sensor 180 captures sounds emitted from one or more sound sources in the local area (e.g., a room). Each acoustic sensor is configured to detect sound and convert the detected sound into an electronic format (analog or digital). The acoustic sensors 180 may be acoustic wave sensors, microphones, sound transducers, or similar sensors that are suitable for detecting sounds.

[0039] In some embodiments, one or more acoustic sensors 180 may be placed in an ear canal of each ear (e.g., acting as binaural microphones). In some embodiments, the acoustic sensors 180 may be placed on an exterior surface of the headset 100, placed on an interior surface of the headset 100, separate from the headset 100 (e.g., part of some other device), or some combination thereof. The number and/or locations of acoustic sensors 180 may be different from what is shown in FIG. 1A. For example, the number of acoustic detection locations may be increased to increase the amount of audio information collected and the sensitivity and/or accuracy of the information. The acoustic detection locations may be oriented such that the microphone is able to detect sounds in a wide range of directions surrounding the user wearing the headset 100.

[0040] Some embodiments of the headset 100 and audio system have different components than those described here. For example, the enclosure 170 may include a different configuration of ports, for example, with a different number, shape, type, and/or size of ports. The example of the audio system shown in FIG. 1A includes two enclosures 170, each enclosure containing a speaker, corresponding to a left and right ear for presenting stereo sound. In some embodiments, the audio system comprises a speaker array including a plurality of enclosures 170 (e.g. more than two) coupled to the frame 110 of the headset 100. In this case, each enclosure may contain one or more speakers. Similarly, in some cases, functions can be distributed among the components in a different manner than is described here. Additionally, the dimensions or shapes of the components may be different.

[0041] The position sensor 190 generates one or more measurement signals in response to motion of the headset 100. The position sensor 190 may be located on a portion of the frame 110 of the headset 100. The position sensor 190 may include an inertial measurement unit (IMU). Examples of position sensor 190 include: one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects motion, a type of sensor used for error correction of the IMU, or some combination thereof. The position sensor 190 may be located external to the IMU, internal to the IMU, or some combination thereof.

[0042] In some embodiments, the headset 100 may provide for simultaneous localization and mapping (SLAM) for a position of the headset 100 and updating of a model of the local area. For example, the headset 100 may include a passive camera assembly (PCA) that generates color image data. The PCA may include one or more RGB cameras that capture images of some or all of the local area. In some embodiments, some or all of the imaging devices 130 of the DCA may also function as the PCA. The images captured by the PCA and the depth information determined by the DCA may be used to determine parameters of the local area, generate a model of the local area, update a model of the local area, or some combination thereof. Furthermore, the position sensor 190 tracks the position (e.g., location and pose) of the headset 100 within the room. Additional details regarding the components of the headset 100 are discussed below in connection with FIG. 5.

[0043] FIG. 1B is a perspective view of a headset 105 implemented as an HIVID, in accordance with one or more embodiments. In embodiments that describe an AR system and/or a MR system, portions of a front side of the HIVID are at least partially transparent in the visible band (-380 nm to 750 nm), and portions of the HIVID that are between the front side of the HIVID and an eye of the user are at least partially transparent (e.g., a partially transparent electronic display). The HIVID includes a front rigid body 115 and a band 185. The headset 105 includes many of the same components described above with reference to FIG. 1A, but modified to integrate with the HIVID form factor. For example, the HIVID includes a display assembly, a DCA, an audio system, and a position sensor 190. FIG. 1B shows the illuminator 140, a plurality of the speakers 160, a plurality of the imaging devices 130, a plurality of acoustic sensors 180, and the position sensor 190. The speakers 160 may be located in various locations, such as coupled to the band 185 (as shown), coupled to front rigid body 115, or may be configured to be inserted within the ear canal of a user. One or more of the speakers 160 may be a dipole speaker configured to mitigate sound leakage. Additionally, the audio system may be configured to selectively apply audio filters to the audio content presented by the speakers 160 to mitigate sound leakage, such as based on a privacy setting.

[0044] FIG. 2 is a block diagram of an audio system 200, in accordance with one or more embodiments. The audio system in FIG. 1A or FIG. 1B may be an embodiment of the audio system 200. The audio system 200 mitigates sound leakage based on a privacy setting. The audio system 200 further generates one or more acoustic transfer functions for a user. The audio system 200 may then use the one or more acoustic transfer functions to generate audio content for the user. In the embodiment of FIG. 2, the audio system 200 includes a transducer array 210, a sensor array 220, and an audio controller 230. Some embodiments of the audio system 200 have different components than those described here. Similarly, in some cases, functions can be distributed among the components in a different manner than is described here.

[0045] The transducer array 210 is configured to present audio content. The transducer array 210 includes a plurality of transducers. A transducer is a device that provides audio content. A transducer may be, e.g., a speaker (e.g., the speaker 160), a tissue transducer, some other device that provides audio content, or some combination thereof. A tissue transducer may be configured to function as a bone conduction transducer or a cartilage conduction transducer. The transducer array 210 may present audio content via air conduction (e.g., via one or more speakers), via bone conduction (via one or more bone conduction transducer), via cartilage conduction (via one or more cartilage conduction transducers), or some combination thereof. In some embodiments, the transducer array 210 may include one or more transducers to cover different parts of a frequency range. For example, a piezoelectric transducer may be used to cover a first part of a frequency range and a moving coil transducer may be used to cover a second part of a frequency range.

[0046] The bone conduction transducers generate acoustic pressure waves by vibrating bone/tissue in the user’s head. A bone conduction transducer may be coupled to a portion of a headset, and may be configured to be behind the auricle coupled to a portion of the user’s skull. The bone conduction transducer receives vibration instructions from the audio controller 230, and vibrates a portion of the user’s skull based on the received instructions. The vibrations from the bone conduction transducer generate a tissue-borne acoustic pressure wave that propagates toward the user’s cochlea, bypassing the eardrum.

[0047] The cartilage conduction transducers generate acoustic pressure waves by vibrating one or more portions of the auricular cartilage of the ears of the user. A cartilage conduction transducer may be coupled to a portion of a headset, and may be configured to be coupled to one or more portions of the auricular cartilage of the ear. For example, the cartilage conduction transducer may couple to the back of an auricle of the ear of the user. The cartilage conduction transducer may be located anywhere along the auricular cartilage around the outer ear (e.g., the pinna, the tragus, some other portion of the auricular cartilage, or some combination thereof). Vibrating the one or more portions of auricular cartilage may generate: airborne acoustic pressure waves outside the ear canal; tissue born acoustic pressure waves that cause some portions of the ear canal to vibrate thereby generating an airborne acoustic pressure wave within the ear canal; or some combination thereof. The generated airborne acoustic pressure waves propagate down the ear canal toward the ear drum. A small portion of the acoustic pressure waves may propagate into the local area.

[0048] The transducer array 210 generates audio content in accordance with instructions from the audio controller 230. In some embodiments, the audio content is spatialized. Spatialized audio content is audio content that appears to originate from a particular direction and/or target region (e.g., an object in the local area and/or a virtual object). For example, spatialized audio content can make it appear that sound is originating from a virtual singer across a room from a user of the audio system 200. The transducer array 210 may be coupled to a wearable device (e.g., the headset 100 or the headset 105). In alternate embodiments, the transducer array 210 may be a plurality of speakers that are separate from the wearable device (e.g., coupled to an external console).

[0049] The transducer array 210 may include one or more speakers in a dipole configuration. The speakers may be located in an enclosure having a front port and a rear port. A first portion of the sound emitted by the speaker is emitted from the front port. The rear port allows a second portion of the sound to be emitted outwards from the rear cavity of the enclosure in a rear direction. The second portion of the sound is substantially out of phase with the first portion emitted outwards in a front direction from the front port.

[0050] In some embodiments, the second portion of the sound has a (e.g., 180.degree.) phase offset from the first portion of the sound, resulting overall in dipole sound emissions. As such, sounds emitted from the audio system experience dipole acoustic cancellation in the far-field where the emitted first portion of the sound from the front cavity interfere with and cancel out the emitted second portion of the sound from the rear cavity in the far-field, and leakage of the emitted sound into the far-field is low. This is desirable for applications where privacy of a user is a concern, and sound emitted to people other than the user is not desired. For example, since the ear of the user wearing the headset is in the near-field of the sound emitted from the audio system, the user may be able to exclusively hear the emitted sound.

[0051] The sensor array 220 detects sounds within a local area surrounding the sensor array 220. The sensor array 220 may include a plurality of acoustic sensors that each detect air pressure variations of a sound wave and convert the detected sounds into an electronic format (analog or digital). The plurality of acoustic sensors may be positioned on a headset (e.g., headset 100 and/or the headset 105), on a user (e.g., in an ear canal of the user), on a neckband, or some combination thereof. An acoustic sensor may be, e.g., a microphone, a vibration sensor, an accelerometer, or any combination thereof. In some embodiments, the sensor array 220 is configured to monitor the audio content generated by the transducer array 210 using at least some of the plurality of acoustic sensors. Increasing the number of sensors may improve the accuracy of information (e.g., directionality) describing a sound field produced by the transducer array 210 and/or sound from the local area.

[0052] The sensor array 220 detects environmental conditions of the headset. For example, the sensor array 220 detects an ambient noise level. The sensor array 220 may also detect sound sources in the local environment, such as persons speaking. The sensor array 220 detects acoustic pressure waves from sound sources and converts the detected acoustic pressure waves into analog or digital signals, which the sensor array 220 transmits to the audio controller 230 for further processing.

[0053] The audio controller 230 controls operation of the audio system 200. In the embodiment of FIG. 2, the audio controller 230 includes a data store 235, a DOA estimation module 240, a transfer function module 250, a tracking module 260, a beamforming module 270, an audio filter module 280, and a sound leakage attenuation module. The audio controller 230 may be located inside a headset, in some embodiments. Some embodiments of the audio controller 230 have different components than those described here. Similarly, functions can be distributed among the components in different manners than described here. For example, some functions of the controller may be performed external to the headset. The user may opt in to allow the audio controller 230 to transmit data captured by the headset to systems external to the headset, and the user may select privacy settings controlling access to any such data.

[0054] The data store 235 stores data for use by the audio system 200. Data in the data store 235 may include a privacy setting, attenuation levels of frequency bands associated with privacy settings, and audio filters and related parameters. The data store 235 may further include sounds recorded in the local area of the audio system 200, audio content, head-related transfer functions (HRTFs), transfer functions for one or more sensors, array transfer functions (ATFs) for one or more of the acoustic sensors, sound source locations, virtual model of local area, direction of arrival estimates, and other data relevant for use by the audio system 200, or any combination thereof. The data store 235 may include observed or historical ambient noise levels in a local environment of the audio system 200. The data store 235 may include properties describing sound sources in a local environment of the audio system 200, such as whether sound sources are typically humans speaking; natural phenomenon such as wind, rain, or waves; machinery; external audio systems; or any other type of sound source.

[0055] The DOA estimation module 240 is configured to localize sound sources in the local area based in part on information from the sensor array 220. Localization is a process of determining where sound sources are located relative to the user of the audio system 200. The DOA estimation module 240 performs a DOA analysis to localize one or more sound sources within the local area. The DOA analysis may include analyzing the intensity, spectra, and/or arrival time of each sound at the sensor array 220 to determine the direction from which the sounds originated. In some cases, the DOA analysis may include any suitable algorithm for analyzing a surrounding acoustic environment in which the audio system 200 is located.

[0056] For example, the DOA analysis may be designed to receive input signals from the sensor array 220 and apply digital signal processing algorithms to the input signals to estimate a direction of arrival. These algorithms may include, for example, delay and sum algorithms where the input signal is sampled, and the resulting weighted and delayed versions of the sampled signal are averaged together to determine a DOA. A least mean squared (LMS) algorithm may also be implemented to create an adaptive filter. This adaptive filter may then be used to identify differences in signal intensity, for example, or differences in time of arrival. These differences may then be used to estimate the DOA. In another embodiment, the DOA may be determined by converting the input signals into the frequency domain and selecting specific bins within the time-frequency (TF) domain to process. Each selected TF bin may be processed to determine whether that bin includes a portion of the audio spectrum with a direct path audio signal. Those bins having a portion of the direct-path signal may then be analyzed to identify the angle at which the sensor array 220 received the direct-path audio signal. The determined angle may then be used to identify the DOA for the received input signal. Other algorithms not listed above may also be used alone or in combination with the above algorithms to determine DOA.

[0057] In some embodiments, the DOA estimation module 240 may also determine the DOA with respect to an absolute position of the audio system 200 within the local area. The position of the sensor array 220 may be received from an external system (e.g., some other component of a headset, an artificial reality console, a mapping server, a position sensor (e.g., the position sensor 190), etc.). The external system may create a virtual model of the local area, in which the local area and the position of the audio system 200 are mapped. The received position information may include a location and/or an orientation of some or all of the audio system 200 (e.g., of the sensor array 220). The DOA estimation module 240 may update the estimated DOA based on the received position information.

[0058] The transfer function module 250 is configured to generate one or more acoustic transfer functions. Generally, a transfer function is a mathematical function giving a corresponding output value for each possible input value. Based on parameters of the detected sounds, the transfer function module 250 generates one or more acoustic transfer functions associated with the audio system. The acoustic transfer functions may be array transfer functions (ATFs), head-related transfer functions (HRTFs), other types of acoustic transfer functions, or some combination thereof. An ATF characterizes how the microphone receives a sound from a point in space.

[0059] An ATF includes a number of transfer functions that characterize a relationship between the sound source and the corresponding sound received by the acoustic sensors in the sensor array 220. Accordingly, for a sound source there is a corresponding transfer function for each of the acoustic sensors in the sensor array 220. And collectively the set of transfer functions is referred to as an ATF. Accordingly, for each sound source there is a corresponding ATF. Note that the sound source may be, e.g., someone or something generating sound in the local area, the user, or one or more transducers of the transducer array 210. The ATF for a particular sound source location relative to the sensor array 220 may differ from user to user due to a person’s anatomy (e.g., ear shape, shoulders, etc.) that affects the sound as it travels to the person’s ears. Accordingly, the ATFs of the sensor array 220 are personalized for each user of the audio system 200.

[0060] In some embodiments, the transfer function module 250 determines one or more HRTFs for a user of the audio system 200. The HRTF characterizes how an ear receives a sound from a point in space. The HRTF for a particular source location relative to a person is unique to each ear of the person (and is unique to the person) due to the person’s anatomy (e.g., ear shape, shoulders, etc.) that affects the sound as it travels to the person’s ears. In some embodiments, the transfer function module 250 may determine HRTFs for the user using a calibration process. In some embodiments, the transfer function module 250 may provide information about the user to a remote system. The user may adjust privacy settings to allow or prevent the transfer function module 250 from providing the information about the user to any remote systems. The remote system determines a set of HRTFs that are customized to the user using, e.g., machine learning, and provides the customized set of HRTFs to the audio system 200.

[0061] The tracking module 260 is configured to track locations of one or more sound sources. The tracking module 260 may compare current DOA estimates and compare them with a stored history of previous DOA estimates. In some embodiments, the audio system 200 may recalculate DOA estimates on a periodic schedule, such as once per second, or once per millisecond. The tracking module may compare the current DOA estimates with previous DOA estimates, and in response to a change in a DOA estimate for a sound source, the tracking module 260 may determine that the sound source moved. In some embodiments, the tracking module 260 may detect a change in location based on visual information received from the headset or some other external source. The tracking module 260 may track the movement of one or more sound sources over time. The tracking module 260 may store values for a number of sound sources and a location of each sound source at each point in time. In response to a change in a value of the number or locations of the sound sources, the tracking module 260 may determine that a sound source moved. The tracking module 260 may calculate an estimate of the localization variance. The localization variance may be used as a confidence level for each determination of a change in movement. The tracking module 260 may transmit the locations of sound sources to the sound leakage attenuation module 290.

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