EP4646851A1

EP4646851A1 - Active noise reduction (anr) in open-ear headphone

Info

Publication number: EP4646851A1
Application number: EP23853608.0A
Authority: EP
Inventors: Lei Cheng
Original assignee: Bose Corp
Current assignee: Bose Corp
Priority date: 2023-01-04
Filing date: 2023-12-27
Publication date: 2025-11-12
Also published as: WO2024147959A1

Abstract

Aspects include an open-ear headphone with an acoustic module that is configured to be located at least in part in a concha of an outer ear of a user. The headphone includes an error microphone on the acoustic module that is directed toward an ear canal region of the user. An input from the error microphone is used to control an active noise reduction (ANR) setting for the open-ear headphone.

Description

Active Noise Reduction (ANR) in Open-Ear Headphone

PRIORITY CLAIM

[0001] This application claims priority to US Provisional Patent Application No. 63/437,004, filed on lanuary 4, 2023, which is incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates to an open-ear headphone that is carried on the ear and is configured to provide active noise reduction (ANR) in an audio output.

BACKGROUND

[0003] Open-ear headphones typically emit sound at a location close to but not in the ear canal. In certain environments, the non-occluding nature of the headphones can present challenges in controlling noise experienced by the user.

SUMMARY

[0004] Various implementations are directed to an open-ear headphone, including: an acoustic module configured to be located at least in part in a cavum conchae of an outer ear of a user and comprising: a portion that is configured to sit in a lower portion of the cavum conchae, an acoustic transducer, and a first sound-emitting opening that is configured to emit sound produced by the acoustic transducer; a body coupled to the acoustic module and comprising a first portion configured to pass over an outer side of at least one of an anti-helix and a helix or a lobule of the outer ear, and a second portion configured to be located behind the outer ear; and an error microphone on the acoustic module and directed toward an ear canal region of the user, where an input from the error microphone is used to control an active noise reduction (ANR) setting for the open-ear headphone. [0005] Additional aspects and examples are directed to an open-ear headphone with an acoustic module that is configured to be located in the cavum conchae of the outer ear of the user. The acoustic module includes an acoustic transducer and a sound-emitting opening that is configured to emit sound produced by the acoustic transducer. A headphone body coupled to the acoustic module has a first portion that is configured to pass over the outer side of the outer ear, and a second portion that is configured to be located behind the outer ear. The sound-emitting opening is configured to be spaced from and proximate the user’s ear canal opening. In some examples the acoustic module has a lower portion that is outwardly convex and is configured to sit in a lower concavity of the cavum conchae, to support the open-ear headphone in its use position without the need to clamp to the ear. An error microphone is located on the acoustic module and directed toward an ear canal region of the user. An input from the error microphone is used to control an active noise reduction (ANR) setting for the open-ear headphone

[0006] All examples and features mentioned below can be combined in any technically possible way.

[0007] In certain aspects, the error microphone is dedicated to use in controlling the ANR setting for the open-ear headphone.

[0008] In particular cases, the ANR setting is a feedforward ANR setting.

[0009] In some implementations, the input from the error microphone mitigates variation in ANR performance across a group of users with at least one of distinct ear sizes or distinct fits for the open-ear headphone.

[0010] In certain aspects, the variation in ANR performance across the group of users is approximately +/- 2 decibels (dB) to approximately +/- 4 dB.

[0011] In particular cases, the input from the error microphone correlates with a sound pressure level (SPL) in the ear canal region of the user during audio output by the acoustic transducer.

[0012] In certain aspects, the error microphone is approximately 3 millimeters (mm) to approximately 7 mm from the ear canal region of the user. In some aspects, the ear canal region is defined by the entrance of the ear canal of the user.

[0013] In particular cases, the error microphone is approximately 5 mm from the ear canal region of the user.

[0014] In some implementations, the error microphone is vibrationally isolated from the acoustic transducer.

[0015] In certain aspects, the input from the error microphone is outside of a communications circuit loop.

[0016] In particular cases, the communications circuit loop includes one or more communications microphones.

[0017] In some aspects, at least one of the one or more communications microphones provides input for a feedforward ANR circuit.

[0018] In certain implementations, the open-ear headphone further includes a processor coupled with the error microphone and including an ANR circuit for controlling the sound emitted by the transducer according to the ANR setting.

[0019] In particular cases, the ANR setting includes a gain on a transducer control signal. [0020] In some cases, the ANR circuit is configured to adjust the gain on the transducer control signal at least once per use session.

[0021] In certain aspects, the ANR circuit is configured to adjust the gain on the transducer control signal only once per use session.

[0022] In some cases, the use session is defined by at least one trigger.

[0023] In particular cases, the trigger includes at least one of: a power-up event at the open-ear headphone, pairing the open-ear headphone with another device, on/off head detection of the openear headphone, or docking of the open-ear headphone.

[0024] In certain aspects, the open-ear headphone further includes memory coupled with the processor, the memory including a model representing ANR settings for a group of users having distinctions in at least one of ear size or fit for the open-ear headphone.

[0025] In particular cases, the model comprises a machine learning (ML) model.

[0026] In some implementations, the processor is configured to adjust the ANR setting based on a correlation between the model and the input from the error microphone during audio output by the acoustic transducer.

[0027] In certain aspects, the processor is configured to periodically adjust the ANR setting in response to a trigger during use of the open-ear headphone.

[0028] In particular implementations, the processor is configured to continuously adjust the ANR setting in response to a trigger during use of the open-ear headphone.

[0029] In particular cases, the continuous adjustment of the ANR setting includes: receiving an error signal from the error microphone, receiving an input signal representing audio captured by a feedforward microphone at the open-ear headphone, generating an anti-noise signal configured to reduce a noise signal over a frequency range, and applying a gain to at least one of the input signal or the anti-noise signal over the frequency range based on the error signal.

[0030] In certain aspects, the error microphone is located proximate an outermost surface of the open-ear headphone when worn by the user.

[0031] In particular implementations, the first sound-emitting opening is configured to be spaced from and proximate the user’s ear canal opening.

[0032] In some aspects, the portion of the acoustic module that is configured to sit in the lower portion of the cavum conchae is outwardly convex.

[0033] In particular cases, the outwardly convex lower portion of the acoustic module is configured to sit in the lower concavity of the cavum conchae that is adjacent to an antitragus of the user’ s ear. [0034] In certain aspects, the open-ear headphone further includes a pair of microphones in the first portion of the body that are distinct from the error microphone, where the pair of microphones are located in opposed sides of the first portion such that one microphone in the pair is configured to be farther from the user’s mouth than is the second microphone.

[0035] In particular cases, at least one of the antihelix, the helix, and a lobule of the ear is configured to be located between the first portion and second portion of the body.

[0036] In certain aspects, the body is generally “L”-shaped.

[0037] In particular cases, the acoustic module and body together are generally “C”-shaped.

[0038] In certain aspects, a center of gravity of the open-ear headphone is between the acoustic module and the second portion of the body.

[0039] In some implementations, the acoustic module further includes a second sound-emitting opening that is configured to be farther from the ear canal opening than is the first sound-emitting opening.

[0040] In particular cases, the acoustic transducer produces sound pressure in front and back acoustic cavities of the acoustic module, and the first sound-emitting opening is fluidly coupled to the front acoustic cavity and the second sound-emitting opening is fluidly coupled to the back acoustic cavity.

[0041] In certain aspects, the second portion of the body includes a battery housing that is configured to house a battery power source for the open-ear headphone.

[0042] In some cases, the open-ear headphone further includes: a printed circuit board in the first portion of the body and that is electrically coupled to the battery, a flexible circuit element that electrically couples the printed circuit board to the acoustic transducer, and at least one user interface clement including a force touch element, where the force touch element comprises a strain gauge mounted to an inside surface of at least one of the acoustic module and the body.

[0043] In some aspects, a method includes adjusting the ANR setting in the open-ear headphone.

[0044] In particular cases, adjusting the ANR setting is based on the input from the error microphone.

[0045] In certain implementations, adjusting the ANR setting is further based on a model.

[0046] Some examples include one of the above and/or below features, or any combination thereof. In an example the second portion of the body comprises a battery housing that is configured to house a battery power source for the open-ear headphone. In an example the acoustic module comprises a lower portion that is outwardly convex and is configured to sit in a lower concavity of the cavum conchae that is adjacent to an antitragus of the user’s ear. [0047] Two or more features described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein. [0048] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects and benefits will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Various aspects of at least one example are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the inventions. In the figures, identical or nearly identical components illustrated in various figures may be represented by a like reference character or numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures:

[0050] Figs. 1A-1G are perspective, front, right side, left side, rear, top, and bottom views, respectively, of an open-ear headphone.

[0051] Figs. 1H and II are additional perspective views of the open-ear headphone of Figs. 1A- 1G, but with elements of the open-ear headphone identified.

[0052] Fig. 2 illustrates how the open-ear headphone of Figs. 1A-1G interfaces with the outer ear.

[0053] Figs. 3A and 3B are side and rear perspective views, respectively, of the open-ear headphone in place on an ear.

[0054] Fig. 4 is a rear view of the open-ear headphone in place on an ear, illustrating its center of gravity.

[0055] Fig. 5 is a schematic partial cross-sectional view of an open-ear headphone.

[0056] Fig. 6 is a schematic cross-sectional view of the acoustic module of an open-ear headphone.

[0057] Fig. 7 is a perspective, partially transparent view of an open-ear headphone according to various implementations.

[0058] Fig. 8 is a perspective, partially transparent view of an open-ear headphone according to various additional implementations.

[0059] Fig. 9 is a schematic front view of another open-ear headphones according to implementations. [0060] Fig. 10 shows example signal flow topologies for an ANR device in an open-ear headphone according to certain implementations.

[0061] Fig. 1 1 is a graphical depiction of total insertion gain (TIG) comparison between a conventional open-ear headphone and an open-ear headphone according to various implementations. [0062] Fig. 12 is graphical depiction of a log standard deviation of the insertion gain from FIG. 11.

[0063] Fig. 13 illustrates an example ANR device (or, ANR circuit) according to various disclosed implementations.

[0064] Fig. 14 is a flow diagram illustrating processes performed by an ANR device according to various implementations.

[0065] Fig. 15 illustrates example sub-components in the gain control block 304 for performing the processes illustrated in Fig. 14.

[0066] It is noted that the drawings of the various implementations are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the implementations. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION

[0067] Various disclosed implementations include open-car headphones that are configured to provide active noise reduction (ANR) to an audio output, for example, using feedforward ANR. In particular cases, an open-ear headphone includes an error microphone that is directed toward an ear canal region of the user (during use), where an input from the error microphone is used to control an ANR setting for the headphone. In more particular cases, the error microphone is not part of a communications control loop in the open-car headphone. In further cases, the error microphone is dedicated to use in controlling the ANR setting for the open-ear headphone. In certain aspects, the open-ear headphone uses the input from the error microphone to mitigate variation in ANR performance across a group of users with distinct ear sizes and/or fits for the open-ear headphone. [0068] The present open-ear headphones provide high-quality sound, are stable on the ear, are comfortable to wear for long periods of time, are unobtrusive, and look stylish. The acoustic transducer or driver is in an acoustic module that is configured to be located in the cavum conchae of the outer ear, close to the ear canal. The acoustic module has a sound-emitting opening on the side closest to the ear canal, leading to higher quality sound. The acoustic module is shaped to nestle in the lower concavity of the cavum conchae. A body section that carries the acoustic module is shaped to pass over the outer side of the anti-helix/helix/lobule of the ear, and ends in a distal portion that is located behind the outer ear. The center of gravity of the open-ear headphone is between the acoustic module and the distal portion, and is thus in or very close to the anti-helix, helix, or lobule; this leads to greater stability on the ear without the need to clamp on the ear. The open-ear headphone is thus comfortable for long-term wear.

[0069] Examples of the headphones described herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The headphones are capable of implementation in other examples and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, functions, components, elements, and features discussed in connection with any one or more examples are not intended to be excluded from a similar role in any other examples. [0070] Examples disclosed herein may be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and references to “an example,” “some examples,” “an alternate example,” “various examples,” “one example” or the like are not necessarily mutually exclusive and are intended to indicate that a particular’ feature, structure, or characteristic described may be included in at least one example. The appearances of such terms herein are not necessarily all referring to the same example.

[0071] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to examples, components, elements, acts, or functions of the devices herein referred to in the singular may also embrace embodiments including a plurality, and any references in plural to any example, component, element, act, or function herein may also embrace examples including only a singularity. Accordingly, references in the singular or plural form are not intended to limit the presently disclosed devices, their components, acts, or elements. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms.

[0072] Commonly labeled components in the FIGURES are considered to be substantially equivalent components for the purposes of illustration, and redundant discussion of those components is omitted for clarity.

[0073] Various disclosed implementations relate to open-ear headphones, certain aspects of which are described in US Patent Application No. 17/306,208, (“Open-Ear Headphone,” filed on May 3, 2021), US Patent Application No. 17/590,321, (“Open-Ear Headphone,” filed on February 1, 2022), US Patent Application No. 17/837,482, (“Active Noise Reduction Control for Non- Occluding Wearable Audio Devices”, filed on June 10, 2022), and US Patent No. 11,483,655 (“Gain- Adaptive Active Noise Reduction (ANR) Device”, issued on October 25, 2022), each of which is entirely incorporated by reference herein.

[0074] This disclosure features an open-ear headphone with an acoustic module configured to be located at least in part in a concha of an outer ear of a user and comprising an acoustic transducer and a first sound-emitting opening that is configured to emit sound produced by the acoustic transducer, and a body coupled to the acoustic module and comprising a first portion configured to pass over an outer side of the outer ear, and a second portion configured to be located behind the outer ear. The first sound-emitting opening is configured to be spaced from and proximate the user’s ear canal opening, preferably in the cavum conchae and proximate the ear canal opening. In some examples the acoustic module is configured to be located in the cavum conchae. In a specific example the acoustic module has lower portion that is outwardly convex and is configured to sit in a lower concavity of the cavum conchae that is adjacent to the antitragus and lobule of the user’s ear. The open-ear headphone is configured such that when the acoustic module is placed into the cavum conchae of the ear the body passes over at least one of the antihelix, the helix, and the lobule of the ear. In an example the body is generally “L”-shaped and the acoustic module and body together (i.e. , the entire open-ear headphone) is generally “C”-shaped. In an example the center of gravity of the open-ear headphone is between the acoustic module and the second portion of the body. The center of gravity can be located in or near the part of the outer ear that is between the acoustic module and the second portion of the body (e.g., the helix or lobule).

[0075] In some examples the acoustic module includes a second sound-emitting opening that is configured to be farther from the ear canal opening than is the first sound-emitting opening. The sound-emitting openings can be arranged to accomplish a dipole-like pattern that can result in sound cancelation that reduces spillage of the sound that can be heard by others. In one example the acoustic transducer produces sound pressure in front and back acoustic cavities of the acoustic module, and the first sound-emitting opening is fluidly coupled to the front acoustic cavity and the second sound-emitting opening is fluidly coupled to the back acoustic cavity. In some examples the second portion of the body includes a battery housing that is configured to house a battery power source for the open-ear headphone. There can be a printed circuit board in the first portion of the body that is electrically coupled to the battery, and a flexible circuit element that electrically couples the printed circuit board to the acoustic transducer. In some examples the open-car headphone also includes a pair of microphones in the first portion of the body. These microphones can be located in opposed sides of the first portion of the body such that one microphone is configured to be farther from the user’s mouth than is the second microphone. The microphones can be arrayed, such as by beam- steering, to improve the pickup of the user’s voice in the presence of noise or other external sounds.

[0076] In particular implementations, the open-ear headphone further includes an error microphone that is distinct from the pair of microphones in the first portion of the body. That is, an additional (e.g., third) microphone is located on the acoustic module and directed toward an ear' canal region of the user. In some cases, the input from the additional (error) microphone is used to adjust an ANR setting, e.g., a feedforward ANR setting in the open-ear headphone.

[0077] Figs. 1A-1I illustrate an exemplary open-ear headphone 10 according to various implementations (labeling in FIGS. 1H and II). Open-ear headphone 10 includes acoustic module 12 that is sized, shaped, and located relative to the open-ear headphone body 14 such that the acoustic module 12 is configured to be located in the concha of the outer ear of the user. Generally, the outer ear (also known as the auricle or pinna) of a human includes a concha that is immediately adjacent to the entrance to the ear canal, which is underneath (or, behind) the tragus. The concha is divided by the helix crus into a lower portion termed the cavum conchae and an upper portion termed the cymba conchae. The cavum conchae is a generally bowl-shaped feature that is directly adjacent to the ear’ canal. The cavum conchae typically includes a depression bordered by the antitragus, which is the lower part of the anti-helix and/or bordered by the lobule. The lobule (i.e., the earlobe), which is at the lower end of the helix, is typically just below the anti-tragus.

[0078] Open -ear headphone 10 body 14 is coupled to acoustic module 12 and includes a first portion 16 that is configured to pass over the outer side of the ear (e.g., at least one of the anti-helix and helix and lobule of the outer ear), and a second portion 18 that is configured to be located behind the outer ear. Body 14 can be generally “L”-shaped from the side (as shown in Fig. 2) with portion 16 running at about a right angle to acoustic module 12, connecting portion 17 running at about a right angle to portion 16 and leading to distal portion 18. In an example portion 18 can be generally cylindrical such that it is configured to hold a generally cylindrical battery power source (e.g., a rechargeable battery). Overall, open-ear headphone 10 is generally “C”-shaped, as shown in Fig. 2. In an example acoustic module 12 and body 14 are parts of a unitary molded plastic housing that is constructed and arranged to contain the transducer, the battery, and any necessary electronics for operation of the headphone.

[0079] Fig. 2 illustrates how the open-ear headphone of Figs. 1A-1I interfaces with the outer ear. As shown in Fig. 2, acoustic module 12 sits in the cavum conchae 51 of outer ear 50. As explained in more detail elsewhere herein, in certain implementations there is a first sound-emitting opening 100 that emits sound produced by an acoustic transducer in acoustic module 12. Sound-emitting opening 100 is spaced from and proximate the user’s ear canal opening (not shown). In this example acoustic module 12 has lower portion 13 that is outwardly convex and is configured to sit in lower concavity 52 of cavum conchae 51. In certain cases, the weight of the open-ear headphone hangs from and is suspended from the cavum conchae; this holds the open-ear headphone 10 on the ear without the need for it to clamp to the ear. To add compliance to lower portion 13 such that it sits on the uneven surface of concavity 52, there may be a cushion or other compliant or compressible member (not shown) on all or part of lower portion 13, or lower portion 13 can be made from a compliant material such as a foam. If light clamping of the open-ear headphone 10 to the ear is desirable, compliance can be built in. For example, at least portion 17 could be made of an elastomer or include a hinge element so that it can flex relative to portion 16, thus altering the location of portion 18 and altering the thickness of the gap between portions 16 and 17 that encompass ear portion 54. A suitable compliant elastomer may have a hardness of 80 durometer shore A.

[0080] The open-ear headphone is configured such that when the acoustic module is placed into the cavum conchae of the ear the body passes over at least one of the antihelix, the helix, and the lobule of the ear, any one or more of these portions of ear 50 designated generally as 54 in Fig. 2. The user is able to pivot the body to a comfortable or otherwise desirable position of the body on the outer ear. See Fig. 3 A for a more complete description of the outer ear and the manner in which body portion 16 overlies the outer ear. Second body portion 18 is behind the outer ear. In other words, it is located between outer ear 50 and the adjacent portion of head 55, as shown in Fig. 2. Portion 17 connects portions 16 and 18 and is configured to pass over edge 59 of outer ear 50. [0081] Figs. 3A and 3B are side and rear perspective views, respectively, of the open-ear headphone 10 in place on outer ear 50. The manner in which open-ear headphone 10 interacts with outer ear 50 may be better understood with reference to parts of outer ear 50 illustrated in Fig. 3A. Outer ear 50 includes helix 56, anti-helix 57, lobule 64, tragus 62, and concha 60 that includes cavum conchae 51 with anti-tragus 58 forming the lower border of cavum conchae 51. Depending on the user’ s outer ear anatomy and the user’ s preference for the fit of the open-ear headphone, body portion 16 can be configured to pass over one or more of helix 56, anti-helix 57, lobule 64, and antitragus 58. Body portion 17 passes over the outer edge 59 of the ear at the location of one or more of helix 56, anti-helix 57, and lobule 64. The ear canal region, or ear canal entrance, is indicated by leading line 67 in FIG. 3B. As described herein, in certain implementations, open-ear headphone 10 is positioned to detect noise proximate the ear canal region 67.

[0082] In some examples, open-ear headphone 10 carries one or more external microphones. External microphones can be used to sense the user’ s voice and/or sense environmental sounds and/or as feed-forward microphones of an active noise cancelation system; these and other functions of external microphones of a headphone are known in the technical field and so are not further described herein. In this example, external microphones 71 and 72 are located in opposed sides of body portion 16 such that they lie generally along axis 73 that intersects or passes close to the expected location of the user’s mouth. This way the microphones can be beam- formed if desired. Beamforming is also known in the technical field and so is not further described herein.

[0083] Fig. 4 is a rear view of the open-ear headphone 10 in place on outer ear 50, illustrating its center of gravity 70. The center of gravity is between acoustic module 12 (only partially visible in this view) and body portion 18. In some examples the center of gravity is in the outer ear, e.g., in the helix 56.

[0084] Fig. 5 is a schematic partial cross-sectional view of open-ear headphone 10 illustrating battery 80 carried inside of body portion 18. Acoustic module 12 carries acoustic transducer 82 that generates sound pressure in acoustic cavity 90. Sound-emitting opening 100 is in the end of acoustic module 12 that is closest to car canal opening 63. Sound is emitted through opening 100, as indicated by arrow 92. Depending on the location of opening 100 and the specific configuration and the symmetry of acoustic module 12, open-ear headphone 10 may be able to be carried on either the left or the right ear. Alternatively, a set of headphones can include one left headphone and one right headphone, with configurations that are specific for the designated ear. Printed circuit board (PCB) 84 is located in body portion 16 and is electrically coupled to battery 80. Flex circuit element 86 leads from PCB 84 to transducer 82, to carry at least power and audio signals to the transducer. User interface elements can be built into the body portion if desired. For example, force touch elements (e.g., front to back or top to bottom squeezing) may be interpreted by a controller (not shown) to accomplish user interface elements of types known in the technical field. In some examples strain gauges are used for force touch sensing elements. In an example the strain gauges are mounted to the inside surface of headphone 10. Two possible locations arc illustrated in Fig. 5, where strain gauge 88 is mounted in acoustic module 12 and strain gauge 89 is mounted in body portion 16.

[0085] Fig. 6 is a schematic cross-sectional view of the acoustic module 12 with transducer 82. In some examples the acoustic module includes a second sound-emitting opening 102 that is configured to be farther from the ear canal opening than is the first sound-emitting opening 100. The sound-emitting openings can be arranged to accomplish a dipole-like pattern that can result in sound cancelation that reduces spillage of the sound that can be heard by others. In one example the acoustic transducer produces sound pressure in front 96 and back 98 acoustic cavity portions of the acoustic cavity 90 of the acoustic module, and the first sound-emitting opening 100 is fluidly coupled to the front acoustic cavity 96 and the second sound-emitting opening 102 (also illustrated in FIG. 9) is fluidly coupled to the back acoustic cavity 98. As is known in the technical field, sound-emitting openings can be covered by resistive or environmentally-protective elements such as cloths or weaves.

[0086] Fig. 7 illustrates additional features of an open-ear headphone 10, further including an error microphone (mic) 110 located on the acoustic module 12. In various implementations, the error microphone 110 is directed toward the ear canal region 67 of the user (Fig. 3B), for example. In particular cases, the error microphone 110 is physically directed toward the ear canal region 67. In further cases, the error microphone 110 can include a set of microphones that are configured to detect noise at the ear canal region 67, e.g., via microphone directivity approaches such as beamforming. In various implementations, as noted herein, an input from the error microphone 110 is used to control an ANR setting for the open-ear headphone 10.

[0087] In certain cases, the error microphone 110 is located on, or in, the outer casing 120 of the acoustic module 12. In certain cases, the error microphone 110 is located proximate an outermost surface of the open-ear headphone 10 when worn by the user. In particular cases, during use of the open-ear headphone 10, the error microphone 110 is positioned to be approximately three millimeters (mm) to approximately 7 mm from the ear canal region of the user (e.g., the entrance of the ear canal of the user). As used herein, the term “approximately” can refer to a defined value, plus or minus several percent. In a particular case, during use of the open-ear headphone 10, the error microphone 110 is positioned to be approximately 5 mm from the ear canal region of the user. In particular cases, the error microphone 110 is located in or on the outer casing 120 of a section of the acoustic module 12 that is directed toward the ear canal entrance, e.g., proximate the first soundemitting opening 100. In some cases, the error microphone 110 is located on an inner portion 130 of the acoustic module 12 (when worn), as illustrated in Fig. 7. In other cases, the error microphone 110 is located on an outer portion 140 of the acoustic module 12 (when worn), as illustrated in Fig. 8. In particular aspects, the error microphone 110 is vibrationally isolated from the transducer 82. That is, the error microphone 110 can be located proximate a portion of the outer casing 120 that is mechanically dampened or decoupled from the transducer 82. In certain cases where the outer casing 120 include multiple sections, the error microphone is located proximate a section of the outer casing 120 that is separate from a section coupled with the transducer 82. In various implementations, the error microphone 110 is aligned with the first sound-emitting opening 100, e.g., overlapping a span of the first sound-emitting opening in at least one dimension along the outer casing 120. For example, where the first sound-emitting opening is positioned toward the ear canal entrance of the user, the error microphone 110 is also positioned toward that ear canal entrance. Fig. 9 illustrates certain implementations of the open-ear headphone 10, showing in particular an inner casing 150 that has wiring lines 160 for connecting a controller (or control circuit) such as the PCB 84 (Fig. 5) with an error microphone 110. In some cases, the wiring lines 160 are integral to the inner casing 150, e.g., molded or otherwise manufactured in the inner casing 150. In various implementations, the inner casing 150 is covered by the outer casing 120 in the finished open-ear headphone 10.

[0088] In certain cases, the PCB 84 (Fig. 5) can include or otherwise be coupled with an ANR device 200 in the open-ear headphone 10 (FIG. 10). The ANR device 200 can include a configurable digital signal processor (DSP), which can be used for implementing various signal flow topologies and filter configurations. Examples of such DSPs are described in U.S. Pat. Nos. 10,580,398, 8,073,150 and 8,073,151, which are incorporated herein by reference in their entirety. Fig. 10 illustrates example signal flow topologies according to certain implementations. In various implementations, the ANR device 200 can use one or more microphones to control and/or provide anti-noise signals to the transducer 82. In particular cases, one or both of external microphones 71, 72 can act as a feedforward microphone to the ANR device 200. The error microphone 110 can act as a feedback microphone in certain cases. In other cases, the error microphone 110 is not used in the feedback microphone loop illustrated in Fig. 13. For example, the error microphone 110 can be used as the error signal for a feedforward noise reduction path to periodically, or continuously, adapt the feedforward coefficient(s) in a feedforward compensator. In such cases, adaptive feedforward coefficient adjustment can minimize the error from acoustic energy at the user’s ear canal region, as compared with a reference (e.g., a zero reference for error microphone 110). In more particular cases, the error microphone 110 is dedicated to use in controlling the ANR setting, e.g., a feedforward ANR setting. In still further embodiments, the input from the error microphone 110 is only used to adjust the feedforward and/or feedback microphone loop during audio output by the transducer 82.

[0089] Various signal flow topologies can be implemented in an ANR device (also called an ANR circuit) 200 to enable functionalities such as audio equalization, feedback noise cancellation, feedforward noise cancellation, etc. For example, as shown in the example block diagram of ANR device 200 in Fig. 10, the signal flow topologies can include a feedforward noise reduction path 210 that drives the output transducer 82 to generate an anti-noise signal (using, for example, a feedforward compensator 212) to reduce the effects of a noise signal picked up by the feedforward microphone(s) 71, 72. In another example, the signal flow topologies can include a feedback noise reduction path 214 that drives the output transducer 82 to generate an anti-noise signal (using, for example, a feedback compensator 216) to reduce the effects of a noise signal picked up by the error microphone 110 (or other feedback microphone). The signal flow topologies can also include an audio path 218 that includes circuitry (e.g., equalizer 220) for processing input audio signals 208 such as music or communication signals, for playback over the output transducer 82. As described herein, in various implementations, the error microphone 110 is outside (or separate from) a communications circuit loop, e.g., a feedforward path 210 and in additional cases, the error microphone 110 is outside of the audio path 218.

[0090] As noted herein, the input to the error microphone 110 is used to control an ANR setting for the open-ear headphone 10, e.g., a feedforward ANR setting. In particular cases, the input from the error microphone 110 can be used to mitigate variation in ANR performance across a group of users with distinct ear sizes and/or distinct fits for the open-ear headphone 10. For example, due to the open-ear configuration of the open-ear headphone 10 and the positioning of the acoustic module 12 relative to the cavum conchae 51 of outer ear 50, users of varying ear sizes and/or shapes can experience distinctions in the fit of the open-ear headphone 10. Adjusting the ANR setting (e.g., feedforward settings) can aid in enhancing desirable noise cancelation for audio output to the transducer 82 across a group of users. In a particular implementation, adjusting the ANR setting using the error microphone 110 can mitigate variation in ANR performance to several decibels (dB), and in some cases, a few decibels (dB), across a population of users with distinct fits and/or ear sizes. Fig. 11 is a graphical depiction of total insertion gain (TIG) for two types of open-ear headphones: i) a conventional open-ear headphone that does not utilize a third (e.g., error microphone), and ii) open-ear headphone 10 disclosed according to various implementations that uses error microphone 110 to control at least one ANR setting. The solid curves (i), (ii) illustrate a mean response across a population of users with distinct ear- sizes and/or shapes. Faded curves, shown as (i’) for the conventional open-ear headphone and (ii’) for the open-ear headphone 10, illustrate individual user responses. Fig. 12 shows a log standard deviation of the insertion gain from FIG. 11, with the conventional open-ear headphone (i) and the open-ear headphone 10 according to various implementations (ii). As is evident in Figs. 11 and 12 the open-ear headphone 10 can mitigate variation in TIG relative to a conventional open-ear headphone, e.g., across particular frequency ranges such as 200 Hz to approximately 1 kilo-hertz (kHz). In certain cases, the open-ear headphone can reduce variation in ANR performance across the group of users to approximately +/- 2 decibels (dB) to approximately +/- 4 dB, and in particular cases, +/- 3 dB. [0091] In order to effectively control the ANR in the output to transducer 82 in the open-ear headphone 10, the ANR device 200 is configured to correlate the input from the error microphone 110 with noise (e.g., a sound pressure level (SPL) of noise, acoustic signature of noise(s), etc.) in the ear canal region of the user during audio output by the acoustic transducer 82. In particular cases, the input of the error microphone 110 represents an estimate of noise at the ear canal region of the user. Because the open-ear headphone 10 does not occlude the user’s ear canal, and because the physical configuration of the open-ear headphone 10 does not allow for direct measurement of noise (e.g., SPL, frequency, etc.) at the ear canal region, the ANR device 200 is configured to correlate the input from the error microphone 110 with an estimate of noise at the ear canal region during audio output by the acoustic transducer 82. As described herein, the input from the error microphone 110 can be correlated with one or more acoustic characteristics of noise (e.g., SPL, frequency, tone, etc.) at the ear canal region to compensate for estimated noise at that ear canal region, and adjust the ANR setting accordingly. In particular cases, as described herein, the input from the error microphone 110 can be correlated with noise characteristics during audio output by the acoustic transducer 82 using a model such as a machine learning model.

[0092] Fig. 13 illustrates an example ANR device (or, ANR circuit) 300 according to various disclosed implementations. As described herein, the ANR device 300 can be implemented in one or more of the noise reduction paths illustrated in Fig. 10, e.g., the feedforward noise reduction path 110. Additionally, while not illustrated in Fig. 13, the ANR device 300 can be implemented in systems with multiple feedforward microphones (e.g., feedforward microphones 71, 72), e.g., in one or more feedforward noise reduction paths. As described herein, the ANR device 300 is configured to control the gain applied to the input signal and/or the anti-noise signal over a frequency range to enhance performance. In some cases, the ANR device 300 is configured to perform the functions described herein using fixed controllers (i.e., a fixed set of filter coefficients), thereby mitigating processing and/or power consumption. However, in additional implementations, the filter coefficients can be dynamic, for example, varying based on one or more input conditions or updates to filter models.

[0093] In various implementations, the ANR device 300 is connected with a feedforward microphone 71, 72 and an electro-acoustic transducer 82 as described with respect to Fig. 10. In certain cases, the ANR device 300 is connected with an error measurement sensor (EMS) 302 that is configured to detect an audio signal from in or around the user’s ear canal. In certain cases, the EMS 302 includes one or more microphones. In particular cases, the EMS 302 includes the error microphone 110 (Fig. 10). In various implementations, external noise detected proximate the ear canal region is also detected at EMS 302 (noise signal path N_so shown). In certain additional implementations, the input to the error microphone 110 can also be used in a feedforward noise reduction path, as indicated in Figs. 10 and 13.

[0094] The ANR device 300 also includes a gain control block 304 for receiving an error signal 306 representing the audio captured by EMS 302. The gain control block 304 is also configured to receive an anti-noise signal (K_ncout) 308 from an ANR filter 310. In various implementations, the ANR filter 310 includes a feedforward compensator (or, controller) similar to Ks 112 shown and illustrated in Fig. 10. In certain cases, the feedforward compensator will ideally have a frequency response of - N_S0/G_Sd (which is not always practically achieved). As noted herein, the feedforward compensator filters the input signal 314 received at the feed forward microphone(s) 71, 72 (and in some cases, error microphone 110) such that when the filtered signal (anti-noise signal 308) is passed through the output transducer 82 it cancels the acoustic signal at the ear (or at the error sensor such as EMS 302, or at a feedback microphone).

[0095] The ANR filter 310 may be implemented as a finite-impulse-response (FIR) filter, as an infinite-impulse-response (HR) filter, or as a series of two or more FIR and/or HR filters. The ANR filter 310 has a feedforward input for receiving an input signal 314 that represents audio captured by the feedforward microphone(s) 71, 72 (e.g., external noise 312). The ANR filter 310 generates an anti-noise signal 308 that is configured to reduce a noise signal (e.g., external noise 12) over a frequency range, e.g., a defined frequency range. In various implementations, the ANR filter 310 has a fixed set of filter coefficients for generating the anti-noise signal 308. In certain cases, the ANR filter 310 has a voltage or magnitude limit for generating the anti-noise signal 308. However, as noted herein, in additional implementations, the ANR filter 310 can include or be coupled with a filter coefficient generator that is configured to generate filter coefficients based on one or more inputs.

[0096] As described herein, the gain control block 304 is configured to apply a gain 316 to the input signal 314 and/or the anti-noise signal 308 over the frequency range, based on the error signal 306 and the anti-noise signal 308. In various implementations, the gain control block 304 is configured to apply the gain 316 by controlling a signal input to a gain control element 318. Gain control element 318 can be configured to amplify and/or attenuate the output of the ANR filter 310 according to filter gain 316. The filter gain 316 can be applied as a linear or logarithmic gain factor, or a linear or logarithmic change to a gain factor. In some cases, the gain control element 318 is implemented as a multiplier (e.g., within the processor 320), as a variable gain amplifier (VGA) in the feedforward signal flow path to the transducer 82, or within the signal flow path of feedforward microphone(s) 71, 72, and/or error microphone 110.

[0097] In particular implementations, the ANR device 300 is beneficially configured to control the feedforward signal flow path to the transducer 82 in an open-ear headphone such as open-ear headphone 10. In such cases, the ANR device 300 is configured to control (e.g., adjust or maintain) the filter gain 316 to the gain control element 318 during audio output at the transducer 82. In particular cases, the ANR device 300 is configured to use the input 314 from the error microphone 110 as a feedforward input to ANR filter 310 only while audio output is occurring at the transducer 82. This configuration can be beneficial in open-ear headphones such as the open-ear headphone 10 because of variations in anatomy and/or fit of the open-ear headphone 10. For example, when a user wears an open-ear device such as the open-ear headphone 10 in an environment with noise 312, the feedforward microphones 71, 72, detect (pick up) the external noise signal as input 314, and send that input 314 through the ANR filter 310 to generate the anti-noise signal 308, which acts as an input to transducer 82 for playing an anti-noise output. In an open-ear configuration (e.g., open-ear headphone 10), the noise 312 (e.g., noise in a room or other space) detected by the feedforward microphone(s) 71, 72 is approximately equivalent to the noise detected by the user’s ear (e.g., at ear canal region). As such, the feedforward microphone(s) 71, 72 can accurately assess the noise at the user’s ear. As noted herein, in conventional open-ear configurations, when an anti-noise signal (e.g., anti-noise signal 308) is sent to the transducer 82 for output based on the input from feedforward microphones (e.g., feedforward microphones 71, 72), the anti-noise audio detected at the ear by a group of users (e.g., two, three, four, or more users) can vary. In some cases, variation in the received anti-noise output from the transducer 82 can vary significantly, e.g., due to differences in fit, anatomy, etc. This variation can be referred to as the driver (transducer)-to-ear transfer function (or G_ed) variation.

[0098] In a basic non-limiting example, if the external noise 312 has a value of one (1), the feedforward microphone(s) 71, 72 and the user’s ear- drum detect noise at a value of (1). In this example, the gain control element 318 uses a fixed controller for a reference (e.g., average) user’s ear (e.g., an average measured or otherwise derived from a population of users) with an anti-noise output of 0.8. When output as audio at transducer 82, this should produce an 80% cancelation in the noise detected by the user’s ear. However, distinct users will experience distinct levels of noise cancelation from the same (reference) anti-noise output value of 0.8. For example, a user with a larger than average ear (where transducer 82 is farther from the ear canal entrance) may experience less than average noise cancelation, e.g., a value of 0.4. A user with a smaller than average ear (where transducer 82 is closer to the ear canal entrance) may experience greater than average noise cancelation, e.g., a value of 0.9. In such examples, an ANR device relying on only the feedforward microphones 71, 72 can cancel approximately 80% of the noise on average, but can experience a variation between 40% cancelation and 90% cancelation across a population.

[0099] In contrast, the open-ear headphone 10 including ANR device 300 uses the input from the error microphone 110 during audio output from the transducer 82 to control (e.g., adjust) the gain 316 applied by the gain control element 318. That is, during audio output at the transducer 82, the ANR device 300 is configured to detect the signal (e.g., pressure) at the error microphone 110 and adjust the gain 316 applied to the output signal based on a deviation in the error microphone input from the reference, or average pressure for a population of users. In a non-limiting, ideal case as an example, the pressure detected at the error microphone 110 is equal to the pressure at the user’s ear drum during audio output at transducer 82. In this example, the open-ear headphone 10 is configured to detect a trigger or other indicator of a use session (e.g., donning of the open-ear headphone 10), and output a signal at the transducer 82 (e.g., audio output such as a tone, chime, music, speech, etc.). During output at the transducer 82, the ANR device 300 receives the input 314 from the error microphone 110. The ANR device 300 then compares that input 314 with an expected input from the error microphone 110 for a population of users, e.g., a reference such as an average input from an error microphone 110 based on a model such as ANR settings model 340. In response to the input 314 from error microphone 110 deviating from the expected input, the gain controller 304 is configured to adjust the gain 316 to modify the anti-noise signal 308 that will be output to the transducer 82. For example, if the input 314 from the error microphone 110 is higher (e.g., higher pressure) than the reference, the gain controller 304 may reduce the gain 316 to reduce the anti-noise signal 308, and if the input 314 from the error microphone 110 is lower (e.g., lower pressure) than the reference, the gain controller 304 may increase the gain 316 to increase the antinoise signal 308. As noted herein, this gain adjustment can be performed periodically, continuously, and/or on a per use-session basis.

[00100] Fig. 14 shows a flow diagram illustrating processes performed by the gain control block 304 in calculating the gain 316 (Fig. 13). Fig. 15 illustrates sub-components in the gain control block 304 for performing the processes illustrated in Fig. 14. In various implementations, the gain control block 304 is configured to: [00101] Process 401 A: Filter (with filter 502, Fig. 15) the anti-noise signal 308 from the ANR filter 310 over a frequency range to generate a filtered feedforward signal 504; and [00102] Process 401B: Filter (with filter 506, Fig. 15) the error signal 306 over the frequency range to generate a filtered error signal 508. In certain implementations, the anti-noise signal 308 and error signal 306 are filtered over the frequency range simultaneously, or approximately simultaneously. In other implementations, processes 401A and 401B are performed sequentially, in any order. As noted herein, in various implementations, the anti-noise signal 308 and error signal 306 are filtered over the same frequency range. In certain implementations, filters 502 and 506 are the same or substantially identical filter components. In other cases, filters 502 and 506 are distinct components. In various implementations, at least one filter 502, 506 includes a bandpass filter. In particular cases, both filters 502 and 506 include a bandpass filter. In some specific cases, the bandpass filter is applied across a frequency range that is predetermined, e.g., based on the design of the open-ear headphone 10. In certain cases, the frequency range is predetermined based on the type of open-ear headphone 10, e.g., a shape, style, and/or fit location of the open-ear headphone.

According to some example implementations, the frequency range is equal to approximately 50 Hertz (Hz) to approximately 800 Hz. In various implementations, the frequency range of the bandpass filter(s) is determined by the phase variation as a function of the frequency of G_sa measured on a sample data set (e.g., a sample of (n) headsets and users). In certain cases, the frequency threshold(s)/range(s) for bandpass filtering are based on a standard deviation correlating to that data set, and/or a minimum/maximum correlating to that data set. In some cases, the phases of the anti-noise signal 308 and the error signal 306 vary by less than a threshold, e.g., +/- 90 degrees from a nominal response. In certain cases, the phases of the anti-noise signal 308 and the error signal 306 vary by significantly less than +/- 90 degrees from the nominal response. The frequency range and phase variation can be based on a statistical mean and/or median from a set of test subjects, and can be stored for application by filters 502 and 506. The frequency range and phase variation can also be configured to be updated according to changes and/or additions in test subject data.

[00103] Following filtering (processes 401 A, B), in process 402: the control block 304 performs:

[00104] Process 402: Estimate (with estimator filter 510, also referred to as a cancelation path estimator filter or a plant estimator filter) a feedforward path contribution to the error signal 306. That is, the cancelation path estimator filter 510 (Fig. 15) estimates the signal that will arrive at the EMS 302 based on the anti-noise signal 308 that passes through the gain control element 318 and is output at transducer 106. According to various implementations, assigning the feedforward path contribution to the error signal 306 is performed using an estimated system transfer function (Gsd) that is applied to the anti-noise signal 308 (as generated by ANR filter 310). As is known in the art, the estimated system transfer function (Gsd) is an estimate based on measured transfer function components. That is, as described herein, the gain control block 304 (e.g., at cancelation path estimator filter 510) is configured to estimate the system transfer function (Gsd), which is a quantity that is calculated based upon measured transfer function components. In a laboratory setting, this system transfer function (Gsd) can be measured by computing a transfer function between the driver signal (voltage) and feedback microphone signal (voltage) in the absence of noise or other sound, that is, without ANR functionality running. However, in practice, it is difficult to directly measure the system transfer function (Gsd) in a wearable audio device because ANR functionality is often employed. As such, the system transfer function (Gsd) described herein is noted as an estimated function that is based upon other measured transfer function components. This “system transfer function (Gsd)” differs from measured transfer function values, and is denoted as such herein. [00105] Process 403: Determine the gain (e.g., with gain calculator 512, Fig. 15) based on a correlation between the filtered error signal 508 and the filtered feedforward signal 504 with the assigned feedforward path contribution to the error signal (+FF path assignment).

[00106] As noted herein, in various implementations, the gain calculator 512 is configured to determine the gain 316 based on the correlation between the filtered error signal 508 and the filtered feedforward signal 504 with the assigned feedforward path contribution (+FF path). In certain cases, the gain calculator 512 includes or otherwise applies a least mean squares (LMS) algorithm, to update the gain over time. In certain cases, the gain calculator 512 iteratively updates the gain, e.g., computing a delta (or, increment) that is added to the previous gain value. Update types can include standard, normalized, sign, etc. In certain examples, the gain formula is represented by g(n+l) = g(n) + F(u(n),e(n)), where u(n) is the feedforward path contribution (+FF path) and e(n) is the filtered error signal 508. Certain examples of LMS filtering are disclosed in Melvin Hick’s lecture (Lecture 5) on “Variants of the LMS algorithm” published in 2017, which is incorporated by reference in its entirety and can be accessed at: https://www.cs.tut.fi/~tabus/course/ASP/SGN2206LectureNew5.pdf.

[00107] In certain implementations, the gain 316 is calculated over only a select frequency range, e.g., a predetermined frequency range between approximately 50 Hertz (Hz) to approximately 800 Hz. In some cases, the gain control block 304 down-samples the anti-noise signal 308 and the error signal 306 to mitigate power usage in the headphone 100. That is, the gain control block 304 is configured in various implementations to process the anti-noise signal 308 and error signal 306 at a lower rate than the sampling rate, conserving resources (e.g., power) for later use.

[00108] In certain implementations, the gain 316 may have an upper limit (maximum). This upper limit can be based on physical and/or system limitations in the open-ear headphone 10, e.g., system stability constraints and/or in order to control undesirable system behaviors if the FF microphone 102 is blocked or damaged. In certain implementations, the gain control block 304 is configured to modify the gain 316 based on an overload control adjustment, e.g., to address an overload event such as those described herein. For example, in practice, the voltage applied to the driver 106 or the mechanical displacement of the driver 106 all have maximum magnitudes which cannot be exceeded without causing “clipping” or other distortions (described herein). In order to prevent such “clipping” or other distortions, the gain control block 304 can be configured to limit or otherwise reduce the gain 316 in response to detecting that the feedforward anti-noise signal 308 and/or the total output signal sent to the driver 106 exceeds a threshold (e.g., a threshold correlated with clipping and/or distortion). In these cases, the gain control block 304 can be configured to compare the feedforward anti-noise signal 308 and/or the calculated output signal to the driver 106 (based on calculated gain 316 and feedforward anti-noise signal 308) with a threshold before assigning the gain 316 to the gain control element 318. In additional or alternative cases, the gain control block 304 can include an independent gain control element/element(s) for adjusting to detected overload events. In certain of these cases, the gain control block 304 applies an additional (distinct) gain to the gain control element 318 in response to determining that the feedforward antinoise signal 308 and/or the calculated output signal deviates from a threshold that indicates an overload event. In some cases, the gain control block 304 is configured to mn the overload gain control in parallel with the primary gain control functions described herein, and in certain cases, can disable or suspend the primary gain control functions in response to detecting an overload event (enabling control of the gain control element 318 strictly with the overload gain control topology). Examples of such parallel compensation are described in US Patent No. 10,580,398 (previously incorporated by reference herein).

[00109] In certain implementations, as shown in phantom in Fig. 13, the gain control block 304 and/or ANR device 300 include a processor (PU) 320, or are otherwise coupled with a processor 320 (e.g., a central processor in the open-ear headphone 10) that is configured to control additional device functions based on the determined gain 316. Description of certain additional device functions is included in US Patent No. 11,483,655 (“Gain- Adaptive Active Noise Reduction (ANR) Device”, issued on October 25, 2022), previously incorporated by reference herein. In certain cases, the processor 320 is coupled with memory 330 that includes an ANR settings model 340 that represents ANR settings for a group of users.

[00110] In particular cases, the ANR settings model 340 represents ANR settings (e.g., gain settings, such as applied gain 316) for a group of users that have distinctions in ear size and/or fit for the open-ear headphone 10. In particular cases, the ANR settings model (or, model) 340 includes a machine learning (ML) model that is configured to be periodically, or continuously updated (e.g., during use of open-ear headphone 10, and/or between use sessions of the open-ear headphone 10). The model 340 can be built or otherwise trained using a set of test (or, subject) data that correlates feedback microphone signals detected at or near the entrance to a user’ s ear canal with error microphone signals detected by the error microphone 110 during audio output by the transducer 82. For example, the model 340 can be trained by correlating feedback microphone signals from an external (or, test) microphone placed in or next to the user’s ear canal entrance with signals detected by the error microphone 110 during audio output by transducer 82. As noted herein, the open-ear configuration of the headphone 10 can present challenges in detecting real-time noise at the user’s ear canal entrance. By training the model 340 with correlations between the signals detected by error microphone 110 and noise detected by a test feedback microphone in or near a user’s ear canal entrance (which can be updated over time and/or usage) during audio output, the model 340 is configured to provide a beneficial ANR setting adjustment for the ANR device 300 during use of the open-ear headphone 10. In some cases, the ML model is configured to adjust ANR setting outputs based on particular user conditions, e.g., based on fit for a particular user or users over time, and/or based on detected noise conditions such as frequency bands or acoustic signatures of detected noise. As described herein, during use of the open-ear headphone 10 by a user, the ANR device 300 can adjust an ANR setting (e.g., gain 316) based on input(s) from the error microphone 110.

[00111] In particular implementations, the ANR setting (e.g., gain 316) is adjusted at least once per use session. In some examples, a use session is defined by at least one trigger, e.g., indicating use of the open-ear headphone 10 by a user. Example triggers can include one or more of: a power- up event at the open-ear headphone 10, pairing the open-ear headphone 10 with another device (e.g., a small device, an audio gateway, a speaker system), on/off head detection of the open-ear headphone 10, or docking of the open-ear headphone 10 (e.g., in a storage and/or charging location such as a case).

[00112] In some examples, the ANR device 300 is configured to adjust the gain 316 on the transducer control signal only once per use session. In these cases, the ANR device 300 can mitigate power usage for the open-ear headphone 10, for example, by making a once-per-use session adjustment to the gain 316, e.g., in response to a trigger such as power-up, pairing or on-head event. [00113] In some additional examples, the ANR device 300 can be configured to adjust the gain 316 on the transducer control signal at least once per use session. For example, the ANR device 300 can be configured to adjust the gain 316 on the transducer control signal multiple times per use session, e.g., between triggers. In some cases, the ANR device 300 is configured to adjust the gain 316 on the transducer control signal periodically, or continuously, during use. In periodic adjustment scenarios, the ANR device 300 is configured to adjust the gain 316 on the transducer control signal at regular or irregular intervals, e.g., intervals of 30 seconds, one minute, several minutes, etc. In various implementations, the ANR device 300 is configured to adjust the gain on the transducer control signal in response to detected changes in the error signal 306 (FIG. 13), e.g., to provide gain-adaptive output control based on dynamic changes in detected signals at the error microphone 110 (shown as EMS 302 in Fig. 13).

[00114] In any case, relative to conventional devices, the open-ear headphones shown and described herein are configured to improve noise reduction for a group of users (e.g., across varying fits). In some cases, the open-ear headphones shown and described herein include ANR devices that rely on fixed filter coefficients. In other cases, such ANR devices rely on dynamically generated filter coefficients. In particular cases, open-ear headphones shown and described herein can efficiently respond to changes in ambient noise conditions while conserving power and processing resources. Additionally, the ANR devices shown and described herein can effectively mitigate noise in open-ear headphone configurations, with pronounced benefits over certain frequency ranges.

[00115] As noted herein the open-ear headphone 10 including ANR device 300 can include one or more circuit components for performing processes according to various implementations. In certain cases, the ANR device 300 includes a control circuit coupled with a processor and/or logic engine for adjusting a gain on one or more signals for producing an acoustic output. In some particular cases, a control circuit is contained in one or both earpieces in a headset, and receive commands from a logic engine for performing functions described herein. In additional cases, a logic engine is located remotely relative to earpieces in the ANR headphone, e.g., in a connected small devices such as a small phone, smart watch, wearable smart device, etc., or in a cloud-based logic engine that is accessible via communications components at the ANR headpiece (not shown). [00116] The controller(s) in the ANR device 300 can execute instructions (e.g., software), including instructions stored in a memory or in a secondary storage device (e.g., a mass storage device). The controller(s) in the ANR device 300 may be implemented as a chipset of chips that include separate and multiple analog and digital processors. The controllers in ANR device 300 may provide, for example, for coordination of other components in the ANR headpiece, such as control of user interfaces, applications run by additional electronics in the ANR headpiece, and network communication by the ANR headpiece. The controller in the ANR device 300 may manage communication with a user through a connected display and/or a conventional user input interface. [00117] In various implementations, electronic components described as being “coupled” can be linked via conventional hard-wired and/or wireless means such that these electronic components can communicate data with one another. Additionally, sub-components within a given component can be considered to be linked via conventional pathways, which may not necessarily be illustrated. [00118] The term “approximately” as used with respect to values herein can allot for a nominal variation from absolute values, e.g., of several percent or less. Unless expressly limited by its context, the term “signal” is used herein to indicate any of its ordinary meanings, including a state of a memory location (or set of memory locations) as expressed on a wire, bus, or other transmission medium. Unless expressly limited by its context, the term “generating” is used herein to indicate any of its ordinary meanings, such as computing or otherwise producing. Unless expressly limited by its context, the term “calculating” is used herein to indicate any of its ordinary meanings, such as computing, evaluating, smoothing, and/or selecting from a plurality of values. Unless expressly limited by its context, the term “obtaining” is used to indicate any of its ordinary meanings, such as calculating, deriving, receiving (e.g., from an external device), and/or retrieving (e.g., from an array of storage elements). Where the term “comprising” is used in the present description and claims, it does not exclude other elements or operations. The term “based on” (as in “A is based on B”) is used to indicate any of its ordinary meanings, including the cases (i) “based on at least” (e.g., “A is based on at least B”) and, if appropriate in the particular context, (ii) “equal to” (e.g., “A is equal to B”). Similarly, the term “in response to” is used to indicate any of its ordinary meanings, including “in response to at least.”

[00119] Unless indicated otherwise, any disclosure of an operation of an apparatus having a particular feature is also expressly intended to disclose a method having an analogous feature (and vice versa), and any disclosure of an operation of an apparatus according to a particular configuration is also expressly intended to disclose a method according to an analogous configuration (and vice versa). The term “configuration” may be used in reference to a method, apparatus, and/or system as indicated by its particular context. The terms “method,” “process,” “procedure,” and “technique” are used generically and interchangeably unless otherwise indicated by the particular context. The terms “apparatus” and “device” are also used generically and interchangeably unless otherwise indicated by the particular context. The terms “element” and “module” are typically used to indicate a portion of a greater configuration. Any incorporation by reference of a portion of a document shall also be understood to incorporate definitions of terms or variables that are referenced within the portion, where such definitions appear elsewhere in the document, as well as any figures referenced in the incorporated portion.

[00120] The functionality described herein, or portions thereof, and its various modifications (hereinafter “the functions”) can be implemented, at least in part, via a computer program product, e.g., a computer program tangibly embodied in an information carrier, such as one or more non- transitory machine-readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components.

[00121] A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a network.

[00122] Actions associated with implementing all or part of the functions can be performed by one or more programmable processors executing one or more computer programs to perform the functions of the calibration process. All or part of the functions can be implemented as special purpose logic circuitry, e.g., an FPGA and/or an ASIC (application- specific integrated circuit). Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Components of a computer include a processor for executing instructions and one or more memory devices for storing instructions and data.

[00123] Elements of figures are shown and described as discrete elements in a block diagram. These may be implemented as one or more of analog circuitry or digital circuitry. Alternatively, or additionally, they may be implemented with one or more microprocessors executing software instructions. The software instructions can include digital signal processing instructions.

Operations may be performed by analog circuitry or by a microprocessor executing software that performs the equivalent of the analog operation. Signal lines may be implemented as discrete analog or digital signal lines, as a discrete digital signal line with appropriate signal processing that is able to process separate signals, and/or as elements of a wireless communication system. [00124] When processes are represented or implied in the block diagram, the steps may be performed by one element or a plurality of elements. The steps may be performed together or at different times. The elements that perform the activities may be physically the same or proximate one another, or may be physically separate. One element may perform the actions of more than one block. Audio signals may be encoded or not, and may be transmitted in either digital or analog form. Conventional audio signal processing equipment and operations are in some cases omitted from the drawings.

[00125] Other embodiments not specifically described herein are also within the scope of the following claims. Elements of different implementations described herein may be combined to form other embodiments not specifically set forth above. Elements may be left out of the structures described herein without adversely affecting their operation. Furthermore, various separate elements may be combined into one or more individual elements to perform the functions described herein.

[00126] Having described above several aspects of at least one example, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only, and the scope of the invention should be determined from proper construction of the appended claims, and their equivalents.

Claims

CLAIMS I claim:

1. An open-ear headphone, comprising: an acoustic module configured to be located at least in part in a cavum conchae of an outer ear of a user and comprising: a portion that is configured to sit in a lower portion of the cavum conchae, an acoustic transducer, and a first sound-emitting opening that is configured to emit sound produced by the acoustic transducer; a body coupled to the acoustic module and comprising a first portion configured to pass over an outer side of at least one of an anti-helix and a helix or a lobule of the outer ear, and a second portion configured to be located behind the outer ear; and an error microphone on the acoustic module and directed toward an ear canal region of the user, wherein an input from the error microphone is used to control an active noise reduction (ANR) setting for the open-ear headphone.

2. The opcn-car headphone of claim 1, wherein the error microphone is dedicated to use in controlling the ANR setting for the open-ear headphone.

3. The open-ear headphone of claim 1, wherein the ANR setting is a feedforward ANR setting.

4. The open-ear headphone of claim 1, wherein the input from the error microphone mitigates variation in ANR performance across a group of users with at least one of distinct ear sizes or distinct fits for the open-ear headphone.

5. The open-ear headphone of claim 4, wherein the variation in ANR performance across the group of users is approximately +/- 2 decibels (dB) to approximately +/- 4 dB.

6. The open-ear headphone of claim 1, wherein the input from the error microphone correlates with a sound pressure level (SPL) in the ear canal region of the user during audio output by the acoustic transducer.

7. The open-ear headphone of claim 1, wherein the error microphone is approximately 3 millimeters (mm) to approximately 7 mm from the ear canal region of the user.

8. The open-ear headphone of claim 7, wherein the error microphone is approximately 5 mm from the ear canal region of the user.

9. The open-ear headphone of claim 1, wherein the error microphone is vibrationally isolated from the acoustic transducer.

10. The open-ear headphone of claim 1, wherein the input from the error microphone is outside of a communications circuit loop.

11. The open-ear headphone of claim 10, wherein the communications circuit loop comprises one or more communications microphones.

12. The open-ear headphone of claim 11, wherein at least one of the one or more communications microphones provides input for a feedforward ANR circuit.

13. The open-ear headphone of claim 1, further comprising a processor coupled with the error microphone and including an ANR circuit for controlling the sound emitted by the transducer according to the ANR setting.

14. The open-ear headphone of claim 13, wherein the ANR setting includes a gain on a transducer control signal.

15. The open-ear headphone of claim 14, wherein the ANR circuit is configured to adjust the gain on the transducer control signal at least once per use session.

16. The open-ear headphone of claim 14, wherein the ANR circuit is configured to adjust the gain on the transducer control signal only once per use session.

17. The open-ear headphone of claim 16, wherein the use session is defined by at least one trigger.

18. The open-ear headphone of claim 17, wherein the trigger includes at least one of: a power-up event at the open-ear headphone, pairing the open-ear headphone with another device, on/off head detection of the open-ear headphone, or docking of the open-ear headphone.

19. The open-ear headphone of claim 13, further comprising memory coupled with the processor, the memory including a model representing ANR settings for a group of users having distinctions in at least one of ear size or fit for the open-ear headphone.

20. The open-ear headphone of claim 19, wherein the model comprises a machine learning (ML) model.

21. The open-ear headphone of claim 19, wherein the processor is configured to adjust the ANR setting based on a correlation between the model and the input from the error microphone during audio output by the acoustic transducer.

22. The open-ear headphone of claim 21, wherein the processor is configured to periodically adjust the ANR setting in response to a trigger during use of the open-ear headphone.

23. The open-ear headphone of claim 21, wherein the processor is configured to continuously adjust the ANR setting in response to a trigger during use of the open-ear headphone.

24. The open-ear headphone of claim 21, wherein the continuous adjustment of the ANR setting includes: receiving an error signal from the error microphone, receiving an input signal representing audio captured by a feedforward microphone at the open-ear headphone, generating an anti-noise signal configured to reduce a noise signal over a frequency range, and applying a gain to at least one of the input signal or the anti-noise signal over the frequency range based on the error signal.

26. The open-ear headphone of claim 1, wherein the error microphone is located proximate an outermost surface of the open-ear headphone when worn by the user.

26. The open-ear headphone of claim 1, wherein the first sound-emitting opening is configured to be spaced from and proximate the user’s ear canal opening.

27. The open-ear headphone of claim 1, wherein the portion of the acoustic module that is configured to sit in the lower portion of the cavum conchae is outwardly convex.

28. The open-ear headphone of claim 27, wherein the outwardly convex lower portion of the acoustic module is configured to sit in the lower concavity of the cavum conchae that is adjacent to an antitragus of the user’ s ear.

29. The open-ear headphone of claim 1, further comprising a pair of microphones in the first portion of the body that a e distinct from the error microphone, wherein the microphones are located in opposed sides of the first portion such that one microphone in the pair is configured to be farther from the user’s mouth than is the second microphone.

30. The open-ear headphone of claim 1, wherein at least one of the antihelix, the helix, and a lobule of the car is configured to be located between the first portion and second portion of the body.

31. The open-ear headphone of claim 1, wherein the body is generally “L”-shaped.

32. The open-ear headphone of claim 1, wherein the acoustic module and body together are generally “C”-shaped.

33. The open-ear headphone of claim 1, wherein a center of gravity of the open-ear headphone is between the acoustic module and the second portion of the body.

34. The open-ear headphone of claim 1, wherein the acoustic module further comprises a second sound-emitting opening that is configured to be farther from the ear canal opening than is the first sound-emitting opening.

35. The open-ear headphone of claim 34, wherein the acoustic transducer produces sound pressure in front and back acoustic cavities of the acoustic module, and wherein the first sound-emitting opening is fluidly coupled to the front acoustic cavity and the second sound-emitting opening is fluidly coupled to the back acoustic cavity.

36. The open-ear headphone of claim 1, wherein the second portion of the body comprises a battery housing that is configured to house a battery power source for the open-ear headphone.

37. The open-ear headphone of claim 36, further comprising: a printed circuit board in the first portion of the body and that is electrically coupled to the battery, a flexible circuit element that electrically couples the printed circuit board to the acoustic transducer, and at least one user interface element comprising a force touch element, wherein the force touch element comprises a strain gauge mounted to an inside surface of at least one of the acoustic module and the body.

38. A method of adjusting the ANR setting in the open-ear headphone of claim 1.

39. The method of claim 38, wherein adjusting the ANR setting is based on the input from the error microphone.

40. The method of claim 39, wherein adjusting the ANR setting is further based on a model.