Acoustic device and method of determining a transfer function thereof

Abstract

Embodiments of the present application disclose an acoustic device and a method for determining a transfer function of the acoustic device. The acoustic device comprises a sound generating unit, a first detector, a processor and a fixing structure. The sound generating unit is configured to generate a first sound signal according to a noise reduction control signal. The first detector is configured to obtain a first residual signal. The first residual signal comprises an ambient noise and a residual noise signal formed by superposition of the first sound signal at the first detector. The processor is configured to estimate a second residual signal at a target spatial position according to the first sound signal and the first residual signal, and update the noise reduction control signal according to the second residual signal. The fixing structure is configured to fix the acoustic device at a position near a user's ear and not to block the user's ear canal, and the target spatial position is closer to the user's ear canal than the first detector.

Description

[0001] Cross-referencing

[0002] This specification claims priority to Chinese application No. 202111408329.8, filed on November 19, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This specification relates to the field of acoustic technology, and in particular to an acoustic device and a method for determining its transfer function. Background Technology

[0004] In traditional headphones, the feedback microphone used for active noise cancellation and the target spatial location (such as the eardrum) are considered to be in a pressure field, with a uniform sound pressure distribution throughout the sound field. Therefore, the signal collected by the feedback microphone directly reflects the sound heard by the human ear. However, for open-back headphones, the environment between the feedback microphone and the target spatial location (such as the eardrum) is no longer a pressure field. Consequently, the signal received by the feedback microphone can no longer directly reflect the signal at the target spatial location (such as the eardrum), and thus cannot accurately estimate the inverse sound wave signal emitted by the speaker for active noise cancellation. This results in a reduction in the effectiveness of active noise cancellation, thereby degrading the user's listening experience.

[0005] Therefore, it is desirable to provide an acoustic device that can open up the user's ears and improve the user's auditory experience. Summary of the Invention

[0006] This specification provides an acoustic device including a sound-generating unit, a first detector, a processor, and a fixing structure. The sound-generating unit generates a first sound signal based on a noise reduction control signal. The first detector acquires a first residual signal, which includes ambient noise and residual noise formed by superimposing the first sound signal at the first detector. The processor estimates a second residual signal at a target spatial location based on the first sound signal and the first residual signal, and updates the noise reduction control signal based on the second residual signal. The fixing structure secures the acoustic device near a user's ear without obstructing the user's ear canal, and the target spatial location is closer to the user's ear canal than the first detector.

[0007] Some of the additional features of this application will be described in the following description. These additional features will be apparent to those skilled in the art from the following description and accompanying drawings, or from an understanding of the production or operation of the embodiments. The features of this application can be implemented and obtained through practice or by using various aspects of the methods, tools, and combinations set forth in the following detailed examples. Attached Figure Description

[0008] The present specification will be further described in the manner of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. The embodiments are not restrictive, and in the embodiments, the same numbers refer to the same structures, wherein:

[0009] Figure 1 is a structural schematic diagram of an exemplary acoustic device shown according to some embodiments of the present application;

[0010] Figure 2 is a wearing state schematic diagram of an acoustic device shown according to some embodiments of the present application;

[0011] Figure 3 is an exemplary noise reduction method flowchart of an acoustic device shown according to some embodiments of the present application;

[0012] Figure 4 is an exemplary flowchart of a transfer function determination method of an acoustic device shown according to some embodiments of the present application. Specific embodiments

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present specification, the drawings required to be used in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some examples or embodiments of the present specification, and for those skilled in the art, without paying creative labor, the present specification can also be applied to other similar scenarios according to these drawings. It should be understood that these exemplary embodiments are only given to enable those skilled in the art to better understand and implement the present specification, and do not limit the scope of the present specification in any way. Unless it is obvious from the language environment or otherwise stated, the same numbers in the figures represent the same structure or operation.

[0014] It should be understood that the "system", "device", "unit" and / or "module" used herein is a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0015] As used in the description of the application and the claims, the terms "including", "containing", "having", "including", "characterized by" and the like are to be understood in their open-ended, non-limiting sense, i.e. in the sense of "including but not limited to". As used in the description of the application and the claims, the terms "one", "the" and "said" are not used in a limiting sense. As used in the description of the application and the claims, the term "based on" is meant to mean "based, at least in part, on". The term "one embodiment" is meant to mean "at least one embodiment". The term "another embodiment" is meant to mean "at least one additional embodiment".

[0016] In the description of the application, it is to be understood that the terms "first", "second", "third", "fourth", and the like, merely mean "one", "two", "three", "four", and the like, respectively, and do not connote any actual relationship, order, or importance. Thus, a feature specified as "first" can implicitly or explicitly mean "second", and vice versa. In the description of the application, the meaning of "a plurality" is at least two, such as two, three, and the like, unless otherwise specifically defined.

[0017] In the description of the application, the terms "connected", "fixed", and the like, are to be construed broadly, unless otherwise specifically defined. For example, the term "connected" can mean fixedly connected, or removably connected, or integrated; can mean mechanically connected, or electrically connected; can mean directly connected, or indirectly connected via an intermediate medium; can mean internal communication between two elements, or interaction between two elements, unless otherwise specifically defined. The specific meaning of the above terms in the description of the application can be understood by those skilled in the art according to the specific circumstances.

[0018] Flowcharts have been used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or subsequent operations are not necessarily performed in sequence. On the contrary, each step can be processed in reverse order or simultaneously. Meanwhile, other operations can be added to these processes, or one or more steps of operations can be removed from these processes.

[0019] An open acoustic device (e.g., an open acoustic earphone) is an acoustic device that can open the user's ear. The open acoustic device can fix a speaker to a position near the user's ear by a fixing structure (e.g., an ear hook, a head hook, a glasses leg, etc.) and does not block the user's ear canal. When the user uses the open acoustic device, the ambient environmental noise can also be heard by the user, which makes the user's hearing experience poor. For example, in a place (e.g., a street, a scenic spot, etc.) where the ambient environmental noise is large, when the user uses the open acoustic device to play music, the ambient environmental noise directly enters the user's ear canal, so that the user hears a large amount of environmental noise, which can interfere with the user's experience of listening to music.

[0020] By active noise reduction, the user's hearing experience during use of the acoustic device can be improved. However, for the open acoustic device, the environment in which the feedback microphone and the target spatial position (such as the eardrum, the basilar membrane, etc.) are located is not a pressure field environment, so the signal received by the feedback microphone cannot directly reflect the signal at the target spatial position, and thus cannot accurately perform feedback control on the reverse sound wave signal emitted by the speaker, resulting in that the active noise reduction function cannot be well implemented.

[0021] To solve the above problems, an acoustic device is provided in the embodiments of the present application. The acoustic device can include a sound emitting unit, a first detector, and a processor. The sound emitting unit can be configured to generate a first sound signal according to a noise reduction control signal. The first detector can be configured to obtain a first residual signal. The first residual signal can include ambient noise and a residual noise signal formed by superposition of the first sound signal at the first detector. The processor can be configured to estimate a second residual signal at a target spatial position according to the first sound signal and the first residual signal, and update the noise reduction control signal used to control the sound emitting unit to emit sound according to the second residual signal. The fixing structure can be configured to fix the acoustic device at a position near the user's ear and not to block the user's ear canal, and the target spatial position is closer to the user's ear canal than the first detector.

[0022] In the embodiments of the present application, the processor can accurately estimate the second residual signal at the target spatial position by using the transfer functions between the sound emitting unit, the first detector, the noise source, and the target spatial position and / or the mapping relationship between the transfer functions, and then accurately control the sound emitting unit to generate the noise reduction signal, effectively reduce the ambient noise at the user's ear canal (e.g., the target spatial position), implement the active noise reduction of the acoustic device, and improve the user's hearing experience during use of the acoustic device.

[0023] The acoustic device and the method for determining the transfer function thereof provided in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0024] Figure 1is a structural schematic diagram of an exemplary acoustic device according to some embodiments of the present application. In some embodiments, the acoustic device 100 can be an open acoustic device capable of achieving active noise reduction for ambient noise. In some embodiments, the acoustic device 100 can include a headset, glasses, an augmented reality (AR) device, a virtual reality (VR) device, etc. As shown in Figure 1 The acoustic device 100 can include a sound generating unit 110, a first probe 120, and a processor 130. In some embodiments, the sound generating unit 110 can generate a first sound signal according to a noise reduction control signal. The first probe 120 can pick up an ambient noise and a first residual signal formed by superimposition of the first sound signal at the first probe 120, and convert the picked-up first residual signal into an electrical signal delivered to the processor 130 for processing. The processor 130 can be coupled (e.g., electrically connected) to the first probe 120 and the sound generating unit 110. The processor 130 can receive and process the electrical signal delivered by the first probe 120, for example, estimate a second residual signal at a target spatial location according to the first sound signal and the first residual signal, and then update the noise reduction control signal for controlling the sound generating unit 110 to generate sound according to the second residual signal. The sound generating unit 110 can generate an updated noise reduction signal in response to the updated noise reduction control signal, thereby achieving active noise reduction.

[0025] The sound generating unit 110 can be configured to output a sound signal. For example, the sound generating unit 110 can output a first sound signal according to a noise reduction control signal. For another example, the sound generating unit 110 can output a speech signal according to a speech control signal. In some embodiments, the sound signal generated by the sound generating unit 110 according to the noise reduction control signal (e.g., the first sound signal, the updated first sound signal, etc.) can also be referred to as a noise reduction signal. By generating the noise reduction signal through the sound generating unit 110, the ambient noise delivered to a target spatial location (e.g., a position of a user's ear canal, such as the eardrum, the basilar membrane) can be reduced or cancelled, achieving active noise reduction of the acoustic device 100, thereby improving the auditory experience of the user during use of the acoustic device 100.

[0026] In the present application, the noise reduction signal can be a sound signal whose phase is opposite or substantially opposite to that of the ambient noise, and the sound waves of the noise reduction signal partially or wholly cancel the sound waves of the ambient noise, thereby achieving active noise reduction. It can be understood that the user can select the degree of active noise reduction according to actual needs. For example, the degree of active noise reduction can be adjusted by adjusting the amplitude of the noise reduction signal. In some embodiments, the absolute value of the phase difference between the phase of the noise reduction signal and the phase of the ambient noise at the target spatial position can be within a preset phase range. The preset phase range can be within the range of 90-180 degrees. The absolute value of the phase difference between the phase of the noise reduction signal and the phase of the ambient noise at the target spatial position can be adjusted within the range according to the needs of the user. For example, when the user does not want to be disturbed by the sound of the surrounding environment, the absolute value of the phase difference can be a larger value, for example, 180 degrees, so that the phase of the noise reduction signal is opposite to the phase of the ambient noise at the target spatial position. For another example, when the user wants to remain sensitive to the surrounding environment, the absolute value of the phase difference can be a smaller value, for example, 90 degrees. It should be noted that the more sound (i.e., ambient noise) of the surrounding environment the user wants to receive, the closer the absolute value of the phase difference can be to 90 degrees; the less sound of the surrounding environment the user wants to receive, the closer the absolute value of the phase difference can be to 180 degrees. In some embodiments, when the phase of the noise reduction signal and the phase of the ambient noise at the target spatial position satisfy a certain condition (e.g., opposite phase), the amplitude difference between the amplitude of the noise reduction signal and the amplitude of the ambient noise at the target spatial position can be within a preset amplitude range. For example, when the user does not want to be disturbed by the sound of the surrounding environment, the amplitude difference can be a smaller value, for example, 0 dB, i.e., the amplitude of the noise reduction signal is equal to the amplitude of the ambient noise at the target spatial position. For another example, when the user wants to remain sensitive to the surrounding environment, the amplitude difference can be a larger value, for example, approximately equal to the amplitude of the ambient noise at the target spatial position. It should be noted that the more sound of the surrounding environment the user wants to receive, the closer the amplitude difference can be to the amplitude of the ambient noise at the target spatial position, and the less sound of the surrounding environment the user wants to receive, the closer the amplitude difference can be to 0 dB.

[0027] In some embodiments, the sound emitting unit 110 can be located at a position close to the user's ear when the user wears the acoustic device 100. In some embodiments, according to the working principle of the sound emitting unit 110, the sound emitting unit 110 can include one or more of an electric dynamic speaker (e.g., a moving coil speaker), a magnetic speaker, an ionic speaker, an electrostatic speaker (or a capacitive speaker), a piezoelectric speaker, etc. In some embodiments, according to the propagation mode of the sound output by the sound emitting unit 110, the sound emitting unit 110 can include an air conduction speaker and / or a bone conduction speaker. In some embodiments, when the sound emitting unit 110 is a bone conduction speaker, the target spatial position can be the user's basilar membrane position. When the sound emitting unit 110 is an air conduction speaker, the target spatial position can be the user's eardrum position, thereby ensuring that the acoustic device 100 can have a good active noise reduction effect.

[0028] In some embodiments, the number of sound emitting units 110 can be one or more. When the number of sound emitting units 110 is one, the sound emitting unit 110 can be used to output a noise reduction signal to cancel ambient noise and can be used to deliver sound information (e.g., device media audio, call far-end audio) that the user needs to hear to the user. For example, when the number of sound emitting units 110 is one and is an air conduction speaker, the air conduction speaker can be used to output a noise reduction signal to cancel ambient noise. In this case, the noise reduction signal can be a sound wave (i.e., vibration of air) that can be transmitted through air to the target spatial position and mutually cancel ambient noise at the target spatial position. At the same time, the air conduction speaker can also be used to deliver sound information that the user needs to hear to the user. For another example, when the number of sound emitting units 110 is one and is a bone conduction speaker, the bone conduction speaker can be used to output a noise reduction signal to cancel ambient noise. In this case, the noise reduction signal can be a vibration signal (e.g., vibration of the speaker housing) that can be transmitted through bone or tissue to the user's basilar membrane and mutually cancel ambient noise at the user's basilar membrane. At the same time, the bone conduction speaker can also be used to deliver sound information that the user needs to hear to the user. When the number of sound emitting units 110 is more than one, a part of the sound emitting units 110 can be used to output a noise reduction signal to cancel ambient noise, and another part can be used to deliver sound information (e.g., device media audio, call far-end audio) that the user needs to hear to the user. For example, when the number of sound emitting units 110 is more than one and includes a bone conduction speaker and an air conduction speaker, the air conduction speaker can be used to output a sound wave to reduce or cancel ambient noise, and the bone conduction speaker can be used to deliver sound information that the user needs to hear to the user. Compared with the air conduction speaker, the bone conduction speaker can directly transmit mechanical vibration to the user's auditory nerve through the user's body (e.g., bone, skin tissue, etc.), and the interference to the air conduction microphone that picks up ambient noise is small.

[0029] It is to be noted that the sound generating units 110 can be independent functional devices or part of a single device capable of implementing multiple functions. By way of example only, the sound generating units 110 can be integrated with the processor 130 and / or formed as one piece. In some embodiments, when the number of sound generating units 110 is more than one, the arrangement of the plurality of sound generating units 110 can include a linear array (e.g., straight line, curved line), a planar array (e.g., cross shape, net shape, circle, ring, polygon, and regular and / or irregular shapes), a three-dimensional array (e.g., cylinder, sphere, hemisphere, polyhedron, etc.), or any combination thereof, without being limited thereto. In some embodiments, the sound generating units 110 can be disposed at the left and / or right ears of the user. For example, the sound generating units 110 can include a first sub-speaker and a second sub-speaker. The first sub-speaker can be located at the left ear of the user, and the second sub-speaker can be located at the right ear of the user. The first sub-speaker and the second sub-speaker can be simultaneously in an active state or only one of them can be controlled to be in an active state. In some embodiments, the sound generating units 110 can be speakers with a directional sound field, and the main lobe of which is directed to the user's ear canal.

[0030] The first detector 120 can be configured to pick up a sound signal. For example, the first detector 120 can pick up a voice signal of the user. For another example, the first detector 120 can pick up a first residual signal. In some embodiments, the first residual signal can include an ambient noise and a residual noise signal formed by superimposing a first sound signal (i.e., a noise reduction signal) generated by the sound generating unit 110 at the first detector 120. In other words, the first detector 120 can simultaneously pick up the ambient noise and the noise reduction signal emitted by the sound generating unit 110. Further, the first detector 120 can convert the first residual signal into an electrical signal and transmit it to the processor 130 for processing.

[0031] In the present application, the ambient noise can refer to a combination of various external sounds in the environment in which the user is located. By way of example only, the ambient noise can include one or more of traffic noise, industrial noise, construction noise, social noise, etc. The traffic noise can include, but is not limited to, driving noise, horn noise, etc. of motor vehicles. The industrial noise can include, but is not limited to, power machinery operation noise, etc. of a factory. The construction noise can include, but is not limited to, power machinery excavation noise, hole drilling noise, mixing noise, etc. The social life environment noise can include, but is not limited to, mass gathering noise, entertainment and propaganda noise, crowd noise, household appliance noise, etc.

[0032] In some embodiments, the environmental noise can include the sound of the user speaking. For example, the first detector 120 can pick up the environmental noise according to the talk state of the acoustic device 100. When the acoustic device 100 is in the non-talk state, the sound generated by the user speaking by himself / herself can be regarded as the environmental noise, and the first detector 120 can pick up the sound of the user speaking by himself / herself and other environmental noise at the same time. When the acoustic device 100 is in the talk state, the sound generated by the user speaking by himself / herself can not be regarded as the environmental noise, and the first detector 120 can pick up the environmental noise except the sound of the user speaking by himself / herself. For example, the first detector 120 can pick up the noise emitted by the noise source at a distance (e.g., 0.5 meters, 1 meter) away from the first detector 120. For another example, the first detector 120 can pick up the noise that is significantly different (e.g., the frequency, volume or sound pressure is different by more than a certain threshold) from the sound generated by the user speaking by himself / herself.

[0033] In some embodiments, the first detector 120 can be arranged at a position near the ear canal of the user to pick up the environmental noise and / or the first sound signal transmitted to the ear canal of the user. For example, when the user wears the acoustic device 100, the first detector 120 can be located at the side of the sound generating unit 110 facing the ear canal of the user (as shown in the first detector 220 and the sound generating unit 210 in FIG. 1B). In some embodiments, the first detector 120 can be arranged at the left ear and / or the right ear of the user. In some embodiments, the first detector 120 can include one or more air conduction microphones (which can also be referred to as feedback microphones), for example, the first detector 120 can include a first sub-microphone (or microphone array) and a second sub-microphone (or microphone array). The first sub-microphone (or microphone array) can be located at the left ear of the user, and the second sub-microphone (or microphone array) can be located at the right ear of the user. The first sub-microphone (or microphone array) and the second sub-microphone (or microphone array) can enter the working state at the same time or only one of them can be controlled to enter the working state. Figure 2

[0034] In some embodiments, according to the working principle of the microphone, the first detector 120 can include a moving coil microphone, a ribbon microphone, a condenser microphone, an electret microphone, an electromagnetic microphone, a carbon microphone, etc., or any combination thereof. In some embodiments, the arrangement of the first detector 120 can include a linear array (e.g., straight line shape, curved line shape), a planar array (e.g., cross shape, circular shape, ring shape, polygonal shape, mesh shape, etc. regular and / or irregular shape), a three-dimensional array (e.g., cylindrical shape, spherical shape, hemispherical shape, polyhedron, etc.), etc., or any combination thereof.

[0035] ​The processor 130 can be configured to estimate a noise cancellation signal of the sound emitting unit 110 according to the noise signal of the outside world, so that the noise cancellation signal emitted by the sound emitting unit 110 can reduce or cancel the environmental noise heard by the user, and realize active noise cancellation. Specifically, the processor 130 can estimate a second residual signal at a target spatial position according to the first sound signal generated by the sound emitting unit 110 and the first residual signal (containing environmental noise and residual noise signals formed by superimposing the first sound signal at the first detector 120) obtained by the first detector 120. The processor 130 can further update the noise cancellation control signal for controlling the sound emitting unit 110 to emit sound according to the second residual signal. The sound emitting unit 110 can generate a new noise cancellation signal in response to the updated noise cancellation control signal, so as to realize real-time correction of the noise cancellation signal, and realize good active noise cancellation effect.

[0036] In the present application, the target spatial position can refer to a spatial position close to the eardrum of the user by a certain distance. The target spatial position can be closer to the ear canal (e.g., eardrum) of the user than the first detector 120. The certain distance here can be a fixed distance, for example, 0 cm, 0.5 cm, 1 cm, 2 cm, 3 cm, etc. In some embodiments, the target spatial position can be inside the ear canal or outside the ear canal. For example, the target spatial position can be the eardrum position, the basilar membrane position, or other positions outside the ear canal. In some embodiments, the number of microphones in the first detector 120 and the distribution position relative to the ear canal of the user can be related to the target spatial position. The number of microphones in the first detector 120 and / or the distribution position relative to the ear canal of the user can be adjusted according to the target spatial position. For example, when the target spatial position is closer to the ear canal of the user, the number of microphones in the first detector 120 can be increased. For another example, when the target spatial position is closer to the ear canal of the user, the spacing of the microphones in the first detector 120 can also be reduced. For another example, when the target spatial position is closer to the ear canal of the user, the arrangement of the microphones in the first detector 120 can also be changed.

[0037] In some embodiments, the processor 130 may acquire a first transfer function between the sound-emitting unit 110 and the first detector 120, a second transfer function between the sound-emitting unit 110 and the target spatial location, a third transfer function between the ambient noise source and the first detector 120, and a fourth transfer function between the ambient noise source and the target spatial location. The processor 130 may estimate a second residual signal at the target spatial location based on the first, second, third, and fourth transfer functions, the first sound signal, and the first residual signal. In some embodiments, the processor 130 may not need to acquire the third and fourth transfer functions separately; it may only need to acquire the ratio between the fourth and third transfer functions to determine the second residual signal. In this case, the processor 130 may acquire the first transfer function between the sound-emitting unit 110 and the first detector 120, the second transfer function between the sound-emitting unit 110 and the target spatial location, and a fifth transfer function reflecting the relationship between the ambient noise source and the first detector 120, and the target spatial location (e.g., the ratio between the fourth and third transfer functions). Processor 130 can estimate a second residual signal at the target spatial location based on a first transfer function, a second transfer function, a fifth transfer function, a first sound signal, and a first residual signal. In some embodiments, processor 130 can acquire only the first transfer function between the sound-emitting unit 110 and the first detector 120, and further estimate the second residual signal at the target spatial location based on the first transfer function, the first sound signal, and the first residual signal. Further details regarding processor 130's estimation of the second residual signal at the target spatial location can be found elsewhere in this description (e.g., Figure 3 (This section and its related discussions will not be explained in detail here.)

[0038] In some embodiments, the processor 130 may include hardware modules and software modules. By way of example only, the hardware module may include a Digital Signal Processor (DSP) chip or an Advanced Reduced Instruction Set Machine (ARM), and the software module may include an algorithm module.

[0039] In some embodiments, the acoustic device 100 can further comprise one or more third detectors (not shown). In some embodiments, the third detector can also be referred to as a feed-forward microphone. The third detector can be further away from the target space location than the first detector 120, i.e. the feed-forward microphone can be closer to the noise source than the feedback microphone. The third detector can be configured to pick up the ambient noise transmitted to the third detector and convert the picked-up ambient noise into an electrical signal for transmission to the processor 130 for processing. The processor 130 can determine the noise reduction control signal based on the ambient noise picked up by the third detector and the estimated signal at the target space location as described above. Specifically, the processor can receive the electrical signal converted from the ambient noise transmitted by the third detector and process it to estimate the ambient noise signal (e.g. the amplitude, phase, etc. of the noise) at the target space location. The processor 130 can further generate the noise reduction control signal based on the estimated noise signal at the target space location. Further, the processor 130 can send the noise reduction control signal to the sound emitting unit 110. The sound emitting unit 110 can generate a new noise reduction signal in response to the noise reduction control signal. The parameters (e.g. the amplitude, phase, etc.) of the noise reduction signal can correspond to the parameters of the ambient noise. For example only, the amplitude of the noise reduction signal can be approximately equal to the amplitude of the ambient noise, and the phase of the noise reduction signal can be approximately opposite to the phase of the ambient noise, so as to ensure that the noise reduction signal emitted by the sound emitting unit 110 can maintain a good active noise reduction effect.

[0040] In some embodiments, the third detector can be disposed at the left ear and / or the right ear of the user. For example, there can be one third detector, and when the acoustic device 100 is used by the user, the third detector can be located at the left ear of the user. For another example, there can be multiple third detectors, and when the acoustic device 100 is used by the user, the third detectors can be distributed at the left ear and the right ear of the user, so that the acoustic device 100 can better receive the spatial noise transmitted from different sides. In some embodiments, the third detectors can be distributed at various positions of the acoustic device 100, and when the acoustic device 100 is used by the user, the multiple third detectors can be located at the left ear, the right ear of the user, or can be disposed around the head of the user.

[0041] In some embodiments, the third detector can be disposed at a target region so that the third detector is least disturbed by the interference signal from the sound emitting unit 110. When the sound emitting unit 110 is a bone conduction speaker, the interference signal can include the leakage signal and the vibration signal of the bone conduction speaker, and the target region can be a region where the total energy of the leakage signal and the vibration signal of the bone conduction speaker transmitted to the third detector is least. When the sound emitting unit 110 is an air conduction speaker, the target region can be a region where the sound pressure level of the radiation sound field of the air conduction speaker is least.

[0042] In some embodiments, the third detector can include one or more air conduction microphones. For example, when the user is listening to music using the acoustic device 100, the air conduction microphone can simultaneously acquire the noise of the external environment and the sound when the user speaks and acquire the noise of the external environment and the sound when the user speaks together as environmental noise. In some embodiments, the third detector can include one or more bone conduction microphones. The bone conduction microphone can be in direct contact with the user's skin, and the vibration signal generated by the user's bones or muscles when speaking can be directly transmitted to the bone conduction microphone, and then the bone conduction microphone converts the vibration signal into an electrical signal and transmits the electrical signal to the processor 130 for processing. In some embodiments, the bone conduction microphone can also not be in direct contact with the human body, and the vibration signal generated by the user's bones or muscles when speaking can first be transmitted to the housing structure of the acoustic device 100, and then transmitted to the bone conduction microphone by the housing structure. In some embodiments, when the user is in a call state, the processor 130 can acquire the sound signal of the air conduction microphone as environmental noise and use the environmental noise for noise reduction, and the sound signal of the bone conduction microphone is transmitted to the terminal device as a voice signal, thereby ensuring the call quality (i.e., the sound quality of the object speaking to the current user to the current user) when the user is calling.

[0043] In some embodiments, the processor 130 can control the on-off state of the bone conduction microphone and / or the air conduction microphone in the third detector based on the working state of the acoustic device 100. The working state of the acoustic device 100 can refer to the use state when the user wears the acoustic device 100. For example only, the working state of the acoustic device 100 can include, but is not limited to, a call state, a non-call state (e.g., a music playing state), a voice message sending state, etc. In some embodiments, when the third detector picks up environmental noise and voice signals, the on-off state of the bone conduction microphone and the on-off state of the air conduction microphone in the third detector can be determined according to the working state of the acoustic device 100. For example, when the user wears the acoustic device 100 to play music, the on-off state of the bone conduction microphone can be in a standby state, and the on-off state of the air conduction microphone can be in a working state. For another example, when the user wears the acoustic device 100 to send a voice message, the on-off state of the bone conduction microphone can be in a working state, and the on-off state of the air conduction microphone can be in a working state. In some embodiments, the processor 130 can control the on-off state of the microphone (e.g., bone conduction microphone, air conduction microphone) in the third detector by sending a control signal.

[0044] In some embodiments, when the working state of the acoustic device 100 is the non-talking state (e.g., the music playing state), the processor 130 can control the bone conduction microphone in the third probe to be in the standby state and the air conduction microphone to be in the working state. In the non-talking state of the acoustic device 100, the user's own voice signal can be regarded as the environmental noise. In this case, the user's own voice signal included in the environmental noise picked up by the air conduction microphone can not be filtered out, so that the user's own voice signal can also be cancelled with the noise reduction signal output by the sound generating unit 110 as part of the environmental noise. When the working state of the acoustic device 100 is the talking state, the processor 130 can control the bone conduction microphone and the air conduction microphone in the third probe to be in the working state. In the talking state of the acoustic device 100, the user's own voice signal needs to be retained. In this case, the processor 130 can send a control signal to control the bone conduction microphone to be in the working state, and the bone conduction microphone can pick up the user's voice signal. The processor 130 can remove the user's voice signal picked up by the bone conduction microphone from the environmental noise picked up by the air conduction microphone, so that the user's own voice signal is not cancelled with the noise reduction signal output by the sound generating unit 110, thereby ensuring the normal talking state of the user.

[0045] In some embodiments, when the working state of the acoustic device 100 is the talking state, if the sound pressure of the environmental noise is greater than a preset threshold, the processor 130 can control the bone conduction microphone in the third probe to remain in the working state. The sound pressure of the environmental noise can reflect the intensity of the environmental noise. The preset threshold here can be a value pre-stored in the acoustic device 100, for example, 50 dB, 60 dB, or 70 dB, or any other arbitrary value. When the sound pressure of the environmental noise is greater than the preset threshold, the environmental noise will affect the user's talking quality. The processor 130 can control the bone conduction microphone to remain in the working state by sending a control signal, and the bone conduction microphone can obtain the vibration signal of the facial muscles when the user talks, and basically will not pick up the external environmental noise. At this time, the vibration signal picked up by the bone conduction microphone is taken as the voice signal when talking, thereby ensuring the normal talking of the user.

[0046] In some embodiments, when the working state of the acoustic device 100 is the call state, the processor 130 can control the bone conduction microphone to switch from the working state to the standby state if the sound pressure of the ambient noise is less than a preset threshold. When the sound pressure of the ambient noise is less than the preset threshold, the sound pressure of the ambient noise is relatively small compared to the sound pressure of the sound signal generated by the user's speech, and in this case, the remaining user's speech sound after the user's speech sound transmitted to the user's ear through the first acoustic path is offset by a part of the noise reduction signal output by the sound generating unit 110 transmitted to the user's ear through the second acoustic path is still sufficient to ensure normal call of the user (for example, the user's speech sound after noise reduction signal offset can be used as a call voice signal, and it is converted into an electrical signal to transmit to another acoustic device, and converted into a sound signal by the sound generating unit in the acoustic device, so that the opposite user can hear the local user's speech sound clearly during the call). In this case, the processor 130 can control the bone conduction microphone in the third detector to switch from the working state to the standby state by sending a control signal, thereby reducing the signal processing complexity and power consumption of the acoustic device 100. It should be noted that when the sound generating unit 110 is an air conduction loudspeaker, the specific position where the noise reduction signal and the ambient noise offset each other can be the user's ear canal or its vicinity, for example, the eardrum position (i.e. the target space position). The first acoustic path can be the path of the ambient noise from the noise source to the target space position, and the second acoustic path can be the path of the noise reduction signal from the air conduction loudspeaker to the target space position. When the sound generating unit 110 is a bone conduction loudspeaker, the specific position where the noise reduction signal and the ambient noise offset each other can be the user's basilar membrane. The first acoustic path can be the path of the ambient noise from the noise source, through the user's ear canal, eardrum to the user's basilar membrane, and the second acoustic path can be the path of the noise reduction signal from the bone conduction loudspeaker, through the user's bone or tissue to the user's basilar membrane.

[0047] In some embodiments, the acoustic device 100 can further include one or more sensors 140. The one or more sensors 140 can be electrically connected with other components of the acoustic device 100 (e.g., the processor 130). The one or more sensors 140 can be used to acquire physical location and / or motion information of the acoustic device 100. By way of example only, the one or more sensors 140 can include an inertial measurement unit (IMU), a global position system (GPS), a radar, etc. The motion information can include a motion trajectory, a motion direction, a motion speed, a motion acceleration, a motion angular velocity, motion related time information (e.g., a motion start time, an end time), etc., or any combination thereof. By way of example of the IMU, the IMU can include a microelectro mechanical system (MEMS). The microelectro mechanical system can include a multi-axis accelerometer, a gyroscope, a magnetometer, etc., or any combination thereof. The IMU can be used to detect the physical location and / or motion information of the acoustic device 100 to enable control of the acoustic device 100 based on the physical location and / or motion information.

[0048] In some embodiments, the one or more sensors 140 can include a distance sensor. The distance sensor can be used to detect a distance from the acoustic device 100 to a user’s ear (e.g., a distance between the sound emitting unit 110 and the target spatial location), to determine a current wearing posture or a use scenario of the acoustic device 100 based on the distance, and to further determine the transfer function among the sound emitting unit 110, the first probe 120, and the target spatial location. More details about determining the transfer function based on the distance can be found in Figure 3 or Figure 4 and the description thereof, which will not be repeated here.

[0049] In some embodiments, the acoustic device 100 can include a memory 150. The memory 150 can store data, instructions, and / or any other information. For example, the memory 150 can store the transfer function among the sound emitting unit 110, the first probe 120, and the target spatial location for different users and / or different wearing postures. As another example, the memory 150 can store a mapping relationship among the transfer functions among the sound emitting unit 110, the first probe 120, and the target spatial location for different users and / or different wearing postures. As yet another example, the memory 150 can store instructions for implementing Figure 3The data and / or computer programs of the illustrated flow 300 can be stored in the memory 150. For another example, the memory 150 can also be used to store a trained neural network. It is to be understood that different users can have different body shapes (e.g., different sizes of heads, different compositions of muscle tissue, fat tissue, bones, etc.), and the corresponding first transfer function, second transfer function, third transfer function, and fourth transfer function can be different. Different wearing postures can refer to different positions at which the user wears the acoustic device 100, different wearing directions of the acoustic device 100, different forces between the acoustic device 100 and the user, etc., and the corresponding first transfer function, second transfer function, third transfer function, and fourth transfer function can also be different.

[0050] In some embodiments, the memory 150 can include a mass storage, a removable storage, a volatile read-write memory, a read-only memory (ROM), or any combination thereof. The memory 150 can be in signal communication with the processor 130. When the user wears the acoustic device 100, the processor 130 can obtain the corresponding first transfer function, second transfer function, third transfer function, and fourth transfer function from the memory 150 according to the body shape of the user, the wearing posture, etc. The processor 130 can estimate the second residual signal at the target spatial position (e.g., the eardrum) based on the corresponding first transfer function, second transfer function, third transfer function, and fourth transfer function to generate a more accurate noise reduction control signal, so that the counter sound waves emitted by the sound emitting unit 110 in response to the noise reduction control signal have a better active noise reduction effect.

[0051] In some embodiments, the acoustic device 100 can include a signal transceiver 160. The signal transceiver 160 can be electrically connected to other components (e.g., the processor 130) of the acoustic device 100. In some embodiments, the signal transceiver 160 can include a Bluetooth, an antenna, etc. The acoustic device 100 can communicate with other external devices (e.g., a mobile phone, a tablet, a smart watch) through the signal transceiver 160. For example, the acoustic device 100 can wirelessly communicate with other devices through Bluetooth.

[0052] In some embodiments, the acoustic device 100 can include a housing structure 170. The housing structure 170 can be configured to carry other components of the acoustic device 100 (e.g., the sound emitting unit 110, the first probe 120, the processor 130, the distance sensor 140, the memory 150, the signal transceiver 160, etc.). In some embodiments, the housing structure 170 can be an enclosed or semi-enclosed structure that is hollow inside, and other components of the acoustic device 100 are located within or on the housing structure. In some embodiments, the housing structure can be a regular or irregular shaped solid structure with a cuboid, cylinder, frustum, etc. shape. When the acoustic device 100 is worn by a user, the housing structure can be located near the user’s ear. For example, the housing structure can be located on the lateral side (e.g., front side or back side) of the user’s pinna. For another example, the housing structure can be located on the user’s ear but not block or cover the user’s ear canal. In some embodiments, the acoustic device 100 can be a bone conduction earphone, and at least one side of the housing structure can be in contact with the user’s skin. In a bone conduction earphone, an acoustic driver (e.g., a vibration speaker) converts an audio signal into mechanical vibrations, which can be transmitted through the housing structure and the user’s bone to the user’s auditory nerve. In some embodiments, the acoustic device 100 can be an air conduction earphone, and at least one side of the housing structure can be in contact or not in contact with the user’s skin. At least one sound guide hole is included on the side wall of the housing structure, and a speaker in an air conduction earphone converts an audio signal into air conduction sound, which can be radiated through the sound guide hole towards the user’s ear.

[0053] In some embodiments, the acoustic device 100 can include a fixing structure 180. The fixing structure 180 can be configured to fix the acoustic device 100 in a position near the user’s ear without blocking the user’s ear canal. In some embodiments, the fixing structure 180 can be physically connected (e.g., clamped, threaded, etc.) with the housing structure 170 of the acoustic device 100. In some embodiments, the housing structure 170 of the acoustic device 100 can be part of the fixing structure 180. In some embodiments, the fixing structure 180 can include an ear hook, a back hook, an elastic band, a glasses leg, etc., such that the acoustic device 100 can be better fixed in a position near the user’s ear, preventing the acoustic device 100 from falling off when in use. For example, the fixing structure 180 can be an ear hook, which can be configured to be worn around the ear region. In some embodiments, the ear hook can be a continuous hook, and can be elastically stretched to be worn around the user’s ear, while the ear hook can also exert pressure on the user’s auricle, such that the acoustic device 100 is firmly fixed in a specific position on the user’s ear or head. In some embodiments, the ear hook can be a discontinuous band. For example, the ear hook can include a rigid portion and a flexible portion. The rigid portion can be made of a rigid material (e.g., plastic or metal), and the rigid portion can be fixed with the housing structure 170 of the acoustic device 100 by physical connection (e.g., clamping, threading, etc.). The flexible portion can be made of an elastic material (e.g., cloth, composite material, or / and neoprene). For another example, the fixing structure 180 can be a neckband, which can be configured to be worn around the neck / shoulder region. For yet another example, the fixing structure 180 can be a glasses leg, which is part of glasses and is erected on the user’s ear.

[0054] In some embodiments, the acoustic device 100 may further include an interactive module (not shown) for adjusting the sound pressure level of the noise-reducing signal. In some embodiments, the interactive module may include a button, a voice assistant, a gesture sensor, etc. The user can adjust the noise reduction mode of the acoustic device 100 by controlling the interactive module. Specifically, the user can adjust (e.g., amplify or reduce) the amplitude information of the noise-reducing signal by controlling the interactive module to change the sound pressure level of the noise-reducing signal emitted by the sound-emitting unit 110, thereby achieving different noise reduction effects. As an example only, the noise reduction mode may include a strong noise reduction mode, a medium noise reduction mode, a weak noise reduction mode, etc. For example, when the user wears the acoustic device 100 indoors, where the ambient noise is relatively low, the user can turn off the noise reduction mode of the acoustic device 100 or adjust it to a weak noise reduction mode through the interactive module. For example, when a user wears the acoustic device 100 while walking in public places such as on the street, the user needs to maintain a certain level of awareness of the surrounding environment while listening to audio signals (e.g., music, voice information) to cope with emergencies. In this case, the user can select a medium noise reduction mode through an interactive module (e.g., a button or voice assistant) to preserve ambient noise (such as alarm sounds, impact sounds, car horns, etc.). As another example, when a user is taking public transportation such as a subway or airplane, the user can select a strong noise reduction mode through the interactive module to further reduce ambient noise. In some embodiments, the processor 130 can also send prompts to the acoustic device 100 or a terminal device (e.g., a mobile phone, smartwatch, etc.) communicatively connected to the acoustic device 100 based on the ambient noise intensity range to remind the user to adjust the noise reduction mode.

[0055] It should be noted that the above regarding Figure 1 The description provided is for illustrative purposes only and is not intended to limit the scope of this application. Various changes and modifications can be made by those skilled in the art based on the guidance of this application. In some embodiments, one or more components of the acoustic device 100 (e.g., distance sensor 140, transceiver 160, fixing structure 180, interaction module, etc.) may be omitted. In some embodiments, one or more components of the acoustic device 100 may be replaced by other elements that perform similar functions. For example, the acoustic device 100 may not include the fixing structure 180, and the housing structure 170 or a portion thereof may be a housing structure with a shape adapted to the human ear (e.g., annular, elliptical, polygonal (regular or irregular), U-shaped, V-shaped, semi-circular) so that the housing structure can be attached near the user's ear. In some embodiments, a component of the acoustic device 100 may be divided into multiple sub-components, or multiple components may be combined into a single component. These changes and modifications do not depart from the scope of this application.

[0056] Figure 2is a schematic diagram of a wearing state of an acoustic device according to some embodiments of the present application. As shown in Figure 2 When a user wears the acoustic device 200, the acoustic device 200 can be fixed near the user's ear 230 (or head) and does not block the user's ear canal. The acoustic device 200 can include a sound emitting unit 210 and a first detector 220.

[0057] In some embodiments, the first detector 220 can be located on the side of the sound emitting unit 210 facing the user's ear canal. In some embodiments, the ratio of the acoustic path from the first detector 220 to the target spatial position A to the acoustic path from the first detector 220 to the sound emitting unit 210 can be between 0.5 and 20. In some embodiments, the acoustic path between the first detector 220 and the target spatial position A can be 5mm to 50mm. In some embodiments, the acoustic path between the first detector 220 and the target spatial position A can be 15mm to 40mm. In some embodiments, the acoustic path between the first detector 220 and the target spatial position A can be 25mm to 35mm. In some embodiments, the number and / or distribution position of the microphones in the first detector 220 relative to the user's ear canal can be adjusted according to the acoustic path between the first detector 220 and the target spatial position A.

[0058] Since the acoustic device 200 is an open acoustic device (for example, an open earphone), the environment in which the first detector 220 and the target spatial position A (for example, a position close to the user's ear canal and having a certain distance from the eardrum) are located is no longer a pressure field environment, and thus the signal received by the first detector 220 cannot be completely equivalent to the signal at the target spatial position A. In this case, by obtaining the corresponding relationship between the sound signal at the first detector 220 and the sound signal at the target spatial position A, and then determining the sound signal at the target spatial position A, the target spatial position A can be more accurately de-noised.

[0059] It should be noted that, Figure 2 The schematic diagram of the wearing state of the acoustic device shown in is only illustrative. In embodiments of the present application, the relative positional relationship between the first detector 220, the target spatial position A, and the sound emitting unit 210 can be, but is not limited to, the case shown in Figure 2 For example, in some embodiments, the sound emitting unit 210, the first detector 220, and the target spatial position A can not be on the same straight line. For another example, in some embodiments, the first detector 220 can be located on the side of the sound emitting unit 210 away from the target spatial position A, and the distance from the first detector 220 to the target spatial position A can be greater than the distance from the sound emitting unit 210 to the target spatial position A.

[0060] Figure 3is an exemplary noise reduction method flowchart of an acoustic device according to some embodiments of the present application. In some embodiments, flowchart 300 can be performed by acoustic device 100.

[0061] In step 310, a first sound signal generated by sound generating unit 110 according to a noise reduction control signal can be acquired. In some embodiments, step 310 can be performed by processor 130.

[0062] In some embodiments, the noise reduction control signal can be generated according to the ambient noise picked up by the third probe (i.e., the feed-forward microphone). Processor 130 can generate a noise reduction electrical signal (which contains the information in the first sound signal) according to the ambient noise picked up by the third probe, and generate the noise reduction control signal according to the noise reduction electrical signal. Further, processor 130 can transmit the noise reduction control signal to sound generating unit 110 to make it generate the first sound signal. It is to be understood that the acquisition of the first sound signal by processor 130 can be understood as the acquisition of the noise reduction electrical signal by processor 130. The noise reduction electrical signal and the first sound signal are only different in form, the former is an electrical signal and the latter is a vibration signal. In some embodiments, sound generating unit 110 can also generate an updated first sound signal according to an updated noise reduction control signal.

[0063] In step 320, a first residual signal picked up by first probe 120 can be acquired. The first residual signal can include the ambient noise and the residual noise signal formed by the superposition of the first sound signal at first probe 120. In some embodiments, step 320 can be performed by processor 130.

[0064] According to the related description in Figure 1 The ambient noise can refer to the combination of various external sounds (e.g., traffic noise, industrial noise, construction noise, social noise) in the environment in which the user is located, according to the related description in some embodiments. First probe 120 can be located near the user's ear canal to pick up the first residual signal delivered to the user's ear canal. Further, first probe 120 can convert the picked-up first residual signal into an electrical signal and deliver it to processor 130 for processing.

[0065] In step 330, a second residual signal at a target spatial location can be estimated based on the first sound signal and the first residual noise. In some embodiments, step 330 can be performed by processor 130.

[0066] The second residual signal can include ambient noise and a residual noise signal formed by superposition of the first sound signal at the target spatial location. It is to be understood that, since the acoustic device 100 is an open acoustic device, the environment in which the first probe 120 (i.e., the feedback microphone) and the target spatial location (e.g., the eardrum) are located is no longer a pressure field environment, and thus the noise signal received by the first probe 120 can no longer directly reflect the noise signal of the target spatial location. Therefore, the processor 130 can determine the second residual signal according to at least one transfer function between the sound generating unit 110, the first probe 120, the ambient noise source, and the target spatial location. In some embodiments, the transfer function between any two of the sound generating unit 110, the first probe 120, the ambient noise source, and the target spatial location can represent a relationship between sound signals of the corresponding positions of the two, which can reflect, for example, a transmission quality in a transmission process in which a sound signal generated by one is transmitted to the other, or a relationship between a sound signal acquired by one and a sound signal generated by the other. For example, the transfer function between the sound generating unit 110 and the first probe 120 can represent a transmission quality in a transmission process in which the first sound signal generated by the sound generating unit 110 is transmitted to the first probe 120, or a relationship between the first residual signal acquired by the first probe 120 and the first sound signal generated by the sound generating unit 110. For another example, the transfer function between the ambient noise source and the first probe 120 can represent a transmission quality in a transmission process in which ambient noise is transmitted from the ambient noise source to the first probe 120, or a relationship between the first residual signal acquired by the first probe 120 and the ambient noise generated by the ambient noise source.

[0067] In some embodiments, the first sound signal (also referred to as a noise reduction signal) emitted by the sound generating unit 110 can be S, and the ambient noise can be N, and at this time, the signal at the first probe 120 (i.e., the first residual signal) M and the signal at the target spatial location (i.e., the second residual signal) D can be represented by formula (1) and formula (2), respectively:

[0068] M = H SM S + H NM N, (1)

[0069] D = H SD S + H ND N, (2)

[0070] wherein H SM represents a first transfer function between the sound generating unit 110 and the first probe 120, H NM represents a second transfer function between the sound generating unit 110 and the target spatial location, H NDa fourth transfer function between the ambient noise source and the target spatial location.

[0071] To achieve the goal of active noise reduction, the second residual signal D at the target spatial location needs to be estimated. The second residual signal D at the target spatial location can be regarded as the magnitude of the noise heard by the user after active noise reduction (e.g., the signal that can be received by the user's eardrum). At this time, the above formulas (1) and (2) can be simplified as the following formula (3):

[0072]

[0073] In some embodiments, the processor 130 can directly obtain a first transfer function H SM between the sound generating unit 110 and the first probe 120, a second transfer function H SD between the sound generating unit 110 and the target spatial location, a third transfer function H NM between the ambient noise source and the first probe 120, and a fourth transfer function H ND between the ambient noise source and the target spatial location. Further, the processor 130 can estimate the second residual signal D at the target spatial location based on the first transfer function, the second transfer function, the third transfer function, the fourth transfer function, and the aforementioned first sound signal S and first residual signal M, and according to formula (3). In some embodiments, the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function can be related to the user category. The processor 130 can directly call the corresponding first transfer function, the second transfer function, the third transfer function, and the fourth transfer function from the memory 150 according to the current user category (e.g., adult or child).

[0074] In some embodiments, the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function can be related to the wearing posture of the acoustic device 100. The processor 130 can directly call the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function corresponding to the current wearing posture from the memory 150. For example, the acoustic device 100 can include one or more sensors, such as a distance sensor, a position sensor. The sensor can detect the distance between the acoustic device 100 and the user's ear and / or the relative position of the acoustic device 100 and the user's ear. Different wearing postures of the acoustic device 100 can correspond to different distances between the acoustic device 100 and the user's ear and / or different relative positions of the acoustic device 100 and the user's ear. The processor 130 can determine the current wearing posture of the acoustic device 100 according to the distance data and / or position data obtained by the sensor, so as to further determine the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function corresponding to the current wearing posture.

[0075] In some embodiments, the processor 130 can directly determine the first transfer function, the second transfer function, the third transfer function and the fourth transfer function corresponding to the acoustic device 100 according to the sensor data (e.g., the relative positional relationship, the distance relationship, etc. between the acoustic device 100 and the user's ear) of the sensor. Specifically, different distances between the acoustic device 100 and the user's ear and / or different relative positions of the acoustic device 100 and the user's ear can correspond to different first transfer functions, second transfer functions, third transfer functions and fourth transfer functions. The processor 130 can directly call the first transfer function, the second transfer function, the third transfer function and the fourth transfer function corresponding to the distance data and / or the position data obtained by the sensor.

[0076] In some embodiments, the first transfer function can have a mapping relationship with the second transfer function, the third transfer function and the fourth transfer function, respectively. The processor 130 can obtain the first transfer function, and determine the second transfer function, the third transfer function and the fourth transfer function according to the mapping relationship between the first transfer function and the second transfer function, the third transfer function and the fourth transfer function, respectively, to further determine the second residual signal D at the target spatial position. In some embodiments, the mapping relationship between the first transfer function and the second transfer function, the third transfer function and the fourth transfer function can be determined by a trained neural network. Specifically, the processor 130 can determine the first transfer function between the sound generating unit 110 and the first probe 120 based on the relationship between the first sound signal (or the noise control signal used to generate the first sound signal) and the first residual signal. For example, when the user wears the acoustic device 100, the first transfer function can be determined according to the following formula (4) in the case of no noise:

[0077]

[0078] Further, the processor 130 can input the first transfer function into the trained neural network, and obtain the second transfer function, the third transfer function and / or the fourth transfer function from the output of the trained neural network.

[0079] In some embodiments, the mapping relationship between the first transfer function and the second transfer function, the third transfer function, the fourth transfer function can be generated based on test data of the acoustic device 100 in different wearing scenarios (or different wearing postures) and stored in the memory 150. The processor 130 can directly call for use. It can be understood that in different wearing scenarios or use states, the acoustic device 100 can correspond to different first transfer functions, second transfer functions, third transfer functions and fourth transfer functions. In addition, the first transfer function and the second transfer function, the third transfer function, the fourth transfer function can have different mapping relationships, and the mapping relationship can change with the change of the wearing scenario (or the wearing posture), for example. More details about the mapping relationship between the first transfer function and the second transfer function, the third transfer function, the fourth transfer function can refer to the section and its related discussion, which will not be described in detail here. Figure 4

[0080] In some embodiments, the processor 130 can determine the relationship between the second residual signal and the first transfer function, the first sound signal and the first residual signal based on the mapping relationship between the first transfer function and the second transfer function, the third transfer function, the fourth transfer function, respectively. In other words, the second residual signal can be regarded as a function with the first transfer function as the variable. When the first transfer function is determined, the processor 130 can estimate the second residual signal at the target spatial position according to the function and the first sound signal generated by the sound generating unit 110 and the first residual signal received by the first detector 120.

[0081] In some embodiments, according to formula (3), the ratio between the third transfer function H NM and the fourth transfer function H ND can be regarded as a whole (also can be called the fifth transfer function), which is used to reflect the relationship between the environmental noise source and the first detector, the target spatial position. In other words, the processor 130 can no longer separately obtain the third transfer function H ND and the fourth transfer function H NM , but only needs to obtain the ratio between the third transfer function H ND and the fourth transfer function H NM . Specifically, the processor 130 can obtain the first transfer function between the sound generating unit 110 and the first detector 120, the second transfer function between the sound generating unit 110 and the target spatial position, and the fifth transfer function reflecting the relationship between the environmental noise source and the first detector 120, the target spatial position (i.e., ). The processor 130 can estimate the second residual signal D at the target spatial position based on the first transfer function, the second transfer function, the fifth transfer function, the first sound signal and the first residual signal according to formula (3).​

[0082] In some embodiments, the second transfer function can have a first mapping relationship with the first transfer function, and the fifth transfer function can have a second mapping relationship with the first transfer function. After determining the first transfer function, the processor 130 can determine the second transfer function according to the first transfer function and the first mapping relationship between the first transfer function and the second transfer function, and determine the fifth transfer function (i.e., the ratio of the fourth transfer function and the third transfer function) according to the second mapping relationship between the ratio of the fourth transfer function and the third transfer function and the first transfer function. More details about the first mapping relationship and the second mapping relationship can be found in Figure 4 and the description thereof, which will not be repeated here.

[0083] In some embodiments, the acoustic device 100 can also include an adjustment button or can be adjusted through an application (APP) of a user terminal. Through the adjustment button or the APP on the user terminal, the user can select the transfer function or the mapping relationship between the transfer functions related to the acoustic device 100 that the user needs. For example, the user can select the distance (i.e., adjust the wearing posture) from the acoustic device 100 to the user's ear (or face) through the adjustment button or the APP on the user terminal. The processor 130 can obtain the corresponding first transfer function, second transfer function, third transfer function and fourth transfer function or the mapping relationship between the first transfer function and the second transfer function, the third transfer function and / or the fourth transfer function according to the distance from the acoustic device 100 to the user's ear (or face). Further, the processor 130 can estimate the second residual signal D of the target spatial position according to the obtained transfer function or the mapping relationship between the transfer functions, and the first sound signal S of the sound emitting unit 110 and the first residual signal M detected by the first detector 120. In other words, the user can adjust the active noise reduction performance of the acoustic device 100, for example, complete noise reduction or partial noise reduction, through the adjustment button or the APP on the user terminal.

[0084] In step 340, the noise control signal of the sound emitting unit 110 can be updated based on the second residual signal of the target spatial position. In some embodiments, step 340 can be performed by the processor 130.

[0085] In some embodiments, the processor 130 can generate a new noise reduction electrical signal based on the estimated second residual signal D in step 330, and generate a new noise reduction control signal based on the new noise reduction electrical signal. Alternatively, the processor 130 can update the noise reduction control signal for controlling the sound generation unit 110 to generate sound. Specifically, in some embodiments, when full active noise reduction is required, the second residual signal D at the target spatial location can be substantially considered as 0, i.e., the acoustic device 100 can substantially eliminate the noise from the outside world, so that the user cannot hear the noise from the outside world, and a good active noise reduction effect is achieved. At this time, the first sound signal S emitted by the sound generation unit 110 can be simplified as:

[0086]

[0087] In other words, the processor 130 can calculate the size of the noise reduction signal required to be emitted by the sound generation unit 110 according to the first transfer function H SM between the sound generation unit 110 and the first probe 120, the second transfer function H SD between the sound generation unit 110 and the target spatial location, the third transfer function H NM between the ambient noise source and the first probe 120, the fourth transfer function H ND between the ambient noise source and the target control location, and the first residual signal M at the first probe 120, to correct the existing noise reduction signal emitted by the sound generation unit 110, so as to realize real-time correction of the noise reduction signal of the sound generation unit 110, and ensure that the noise reduction signal emitted by the sound generation unit 110 can achieve a good active noise reduction effect.

[0088] It should be noted that the above description of the process 300 is only for example and illustration, and does not limit the scope of the present specification. Those skilled in the art can make various modifications and changes to the process 300 under the guidance of the present specification. These modifications and changes are still within the scope of the present application. For example, in some embodiments, the acoustic device 100 can be a closed acoustic device, i.e., the first probe 120 and the target spatial location are located in a pressure sound field. At this time, H NM = H ND , H SD = H SM According to formula (3), the signal M at the first probe 120 (i.e., the first residual signal) is the same as the signal D at the target spatial location (i.e., the second residual signal). The noise reduction signal S (i.e., the first sound signal) emitted by the sound generation unit 110 can satisfy the following relationship:

[0089]

[0090] At this time, the processor 130 can estimate the noise reduction signal required to be emitted by the sound emitting unit 110 according to the first transfer function H SM , the third transfer function H NM , the acquired signal M at the first probe 120 and the ambient noise signal N, correct the noise reduction signal emitted by the sound emitting unit 110, and realize real-time correction of the noise reduction signal emitted by the sound emitting unit 110, so as to realize a good active noise reduction effect.

[0091] In some embodiments, when the acoustic device 100 is a closed acoustic device and needs to realize complete active noise reduction, the second residual signal D at the target space position and the first residual signal M at the first probe 120 can be considered as 0. At this time, the noise reduction signal S (i.e. the first sound signal) emitted by the sound emitting unit 110 can satisfy the following relationship:

[0092]

[0093] At this time, the external noise can be completely eliminated by the noise reduction signal emitted by the sound emitting unit 110. The processor 130 can estimate the size of the noise reduction signal required to be emitted by the sound emitting unit 110 according to the first transfer function H SM , the third transfer function H NM , the ambient noise signal N, correct the noise reduction signal emitted by the sound emitting unit 110, and realize real-time correction of the noise reduction signal emitted by the sound emitting unit 110, so as to realize a good active noise reduction effect.

[0094] It should be noted that the above description of the process 300 is only for example and illustration, and does not limit the scope of application of the present specification. Those skilled in the art can make various modifications and changes to the process 300 under the guidance of the present specification. These modifications and changes are still within the scope of the present application. In some embodiments, the process 300 can be stored in a computer readable storage medium in the form of computer instructions. When the computer instructions are executed, the above-mentioned noise reduction method can be realized.

[0095] Figure 4is an exemplary flowchart of a method for determining a transfer function of an acoustic device according to some embodiments of the present disclosure. In some embodiments, the acoustic device can include at least a sound emitting unit, a first detector, a processor, and a fixing structure. When a user wears the acoustic device, the fixing structure can fix the acoustic device in a position near the user's ear and not block the user's ear canal, and make a target spatial position (e.g., the user's eardrum or basilar membrane) closer to the user's ear canal than the first detector. More details about the sound emitting unit, the first detector, the processor, the target spatial position, etc. can refer to the related description of the acoustic device 100 in Figure 1 In some embodiments, the steps in the flowchart 400 can be invoked and / or executed by the processor 130 in the acoustic device 100 or other processing devices other than the processor 130.

[0096] In step 410, the processor 130 can obtain a first signal emitted by the sound emitting unit based on the control signal in the absence of environmental noise, and a second signal picked up by the first detector.

[0097] Specifically, the control signal can be input to the sound emitting unit 110 after the tester wears the acoustic device 100. In response to receiving the control signal, the sound emitting unit 110 can output the first signal S0. Further, the first signal S0 output by the sound emitting unit 110 can be transmitted to and picked up by the first detector 120. It is to be understood that due to energy loss in the transmission process, reflection between the signal and the tester and / or the acoustic device 100, noise in the environment, etc., the signal M0 (e.g., the second signal) picked up by the first detector 120 can be different from the first signal S0. In addition, for different testers, their body tissue morphology can be different (e.g., the size of the head, the composition of muscle tissue, fat tissue, bone, etc.), resulting in different wearing postures (e.g., different wearing positions, different contact forces with the tester) when they wear the acoustic device. In some embodiments, for the same tester, the wearing posture (e.g., the wearing position) when they wear the acoustic device 100 can also be different. For different wearing postures, although the relative positions of the sound emitting unit 110 and the first detector 120 do not change, due to the different wearing postures of the tester, the transmission conditions of the signal emitted by the sound emitting unit 110 change (e.g., the reflection of the signal is different) in the transmission process to the first detector 120. Therefore, for different wearing postures, the first transfer function between the sound emitting unit 110 and the first detector 120 of the acoustic device 100 can also be different.

[0098] In some embodiments, the tester can be a simulated human head in a lab or a user. For example, when the acoustic device 100 is worn on a simulated human head, the first probe 120 and the sound emitting unit 110 of the acoustic device 100 can be located near the ear canal of the simulated human head. In some embodiments, the control signal can be an electrical signal containing any sound signal. It should be understood that in this application, a sound signal (e.g., a first signal, a second signal, etc.) can include frequency information, amplitude information, phase information, and the like. In some embodiments, the first signal and / or the second signal can refer to a sound signal or an electrical signal obtained after converting the sound signal.

[0099] In step 420, the processor 130 can determine a first transfer function between the sound emitting unit 110 and the first probe 120 based on the first signal and the second signal.

[0100] It can be understood that in the absence of environmental noise, the second signal M0 detected by the first probe 120 is entirely transmitted from the sound emitting unit 110. The ratio between the second signal M0 picked up by the first probe 120 and the first signal S0 output by the sound emitting unit 110 can directly reflect the transmission quality or transmission efficiency of the first signal generated by the sound emitting unit 110 in the transmission process from the sound emitting unit 110 to the first probe 120. In some embodiments, the first transfer function H SM is positively correlated with the ratio of the second signal M0 and the first signal S0. For example only, the first transfer function H SM The relationship between the first signal S0 and the second signal M0 can satisfy:

[0101]

[0102] In step 430, the processor 130 can obtain a third signal picked up by a second probe. The second probe can be disposed at a target spatial position to simulate the eardrum (or the basilar membrane) of the human ear to pick up a sound signal. The target spatial position is closer to the ear canal of the tester than the first probe 120. In some embodiments, the target spatial position can be the position of the eardrum or the basilar membrane of the tester. For example, when the sound emitting unit 110 is an air conduction loudspeaker, the target spatial position can be the position of or near the eardrum of the tester. When the sound emitting unit 110 is a bone conduction loudspeaker, the target spatial position can be the position of or near the basilar membrane of the tester. In some embodiments, the second probe can be a micro microphone (e.g., a MEMS microphone) that can enter the ear canal of the user and collect sound inside the ear canal.

[0103] Specifically, the first signal S0 output by the sound generating unit 110 can be transmitted to the target spatial position and picked up by the second probe at the target spatial position. Similar to the transmission of the first signal to the first probe 120, the signal D0 (e.g., the third signal) picked up by the second probe can be different from the first signal S0 due to energy loss in the transmission process, reflection between the signal and the tester and / or the acoustic device 100, noise in the environment, etc. In addition, for different wearing postures, the second transfer function between the sound generating unit 110 of the acoustic device 100 and the target spatial position (or the second probe) can be different.

[0104] In step 440, the processor 130 can determine the second transfer function between the sound generating unit 110 and the target spatial position based on the first signal and the third signal.

[0105] It can be understood that in the scenario where there is no environmental noise, the third signal D0 detected by the second probe is entirely transmitted from the sound generating unit 110. The ratio between the third signal D0 picked up by the second probe and the first signal S0 output by the sound generating unit 110 can directly reflect the transmission quality or transmission efficiency of the first signal generated by the sound generating unit 110 in the transmission process from the sound generating unit 110 to the second probe (i.e., the target spatial position). In some embodiments, the second transfer function H SD may be positively correlated with the ratio of the third signal D0 and the first signal S0. By way of example only, the second transfer function H SD The relationship between the first signal S0 and the third signal D0 can satisfy:

[0106]

[0107] In step 450, the processor 130 can obtain a fourth signal picked up by the first probe 120 and a fifth signal picked up by the second probe in a scenario where there is environmental noise and the sound generating unit 110 does not emit any signal. The environmental noise can be generated by one or more environmental noise sources. During the test, the environmental noise source can be any sound source other than the sound generating unit. For example, the environmental noise N0 can be simulated by other sound generating devices in the test environment.

[0108] Specifically, the ambient noise N0 emitted by the ambient noise source can be transmitted to the first detector 120 and the second detector, and picked up by the first detector 120 and the second detector respectively. Similar to the transmission of the first signal to the first detector 120, due to the energy loss in the transmission process, the reflection between the signal and the tester (or the acoustic device), etc., the signal M'0 (i.e., the fourth signal) picked up by the first detector 120 and the signal D'0 (i.e., the fifth signal) picked up by the second detector can not be the same as the ambient noise signal. In addition, for different wearing postures, the third transfer function between the ambient noise source and the first detector 120 can be different, and the fourth transfer function between the ambient noise source and the target spatial position (or the second detector) can be different.

[0109] In step 460, the processor 130 can determine the third transfer function between the ambient noise source and the first detector 120 based on the ambient noise and the fourth signal.

[0110] It can be understood that in the scenario where there is ambient noise and the sound emitting unit 110 does not emit any signal, at this time, the fourth signal M'0 detected by the first detector 120 is all transmitted from the ambient noise source. The ratio between the fourth signal M'0 picked up by the first detector 120 and the ambient noise N0 generated by the ambient noise source can directly reflect the transmission quality or transmission efficiency in the transmission process of the ambient noise generated by the ambient noise source from the ambient noise source to the first detector 120. In some embodiments, the third transfer function H NM may be positively correlated with the ratio of the fourth signal M'0 and the ambient noise N0. Just as an example, the third transfer function H NM The relationship between the ambient noise N0 and the fourth signal M'0 can satisfy:

[0111]

[0112] In step 470, the processor 130 can determine the fourth transfer function between the ambient noise source and the target spatial position based on the ambient noise and the fifth signal.

[0113] It can be understood that in the scenario where there is ambient noise and the sound emitting unit does not emit any signal, at this time, the fifth signal D'0 detected by the second detector is all transmitted from the ambient noise source. The ratio between the fifth signal D'0 picked up by the second detector and the ambient noise N0 generated by the ambient noise source can directly reflect the transmission quality or transmission efficiency in the transmission process of the ambient noise generated by the ambient noise source from the ambient noise source to the second detector (i.e., the target spatial position). In some embodiments, the fourth transfer function H ND may be positively correlated with the ratio of the fifth signal D'0 and the ambient noise N0. Just as an example, the fourth transfer function H NDThe relationship between the ambient noise N0and the fifth signal D'0may satisfy:

[0114]

[0115] In some embodiments, the first transfer function, the second transfer function, the third transfer function and the fourth transfer function measured for a certain type of tester (e.g. adult, child) can be stored in the memory 150. When the user wears the acoustic device 100, the processor 130 can directly call the first transfer function, the second transfer function, the third transfer function and the fourth transfer function measured for a certain typical tester to roughly estimate the second residual signal at the target spatial position (e.g. at the eardrum of the user), so as to roughly estimate the noise reduction signal of the sound generating unit, and achieve active noise reduction. For example, a set of first transfer functions, second transfer functions, third transfer functions and fourth transfer functions can correspond to adult males, and another set of first transfer functions, second transfer functions, third transfer functions and fourth transfer functions can correspond to children. When the user is a child, the processor 130 can call a set of first transfer functions, second transfer functions, third transfer functions and fourth transfer functions corresponding to children.

[0116] In some embodiments, the processor 130 can repeat the above steps 410 to 470 for different wearing scenarios (e.g. different wearing positions) or different testers, determine a plurality of sets of transfer functions of the acoustic device 100 in different wearing postures, and store the plurality of sets of transfer functions corresponding to different wearing postures in the memory 150 for calling. Each set of transfer functions can include corresponding first transfer functions, second transfer functions, third transfer functions and fourth transfer functions. When the user wears the acoustic device 100, the processor 130 can call the first transfer function, the second transfer function, the third transfer function and the fourth transfer function corresponding to the wearing posture according to the wearing posture of the acoustic device 100. Further, the processor 130 can estimate the second residual signal at the target spatial position according to the called transfer function and the first sound signal of the sound generating unit 110 and the first residual signal picked up by the first detector 120, and update the noise reduction control signal for controlling the sound generating unit 110 to generate sound according to the second residual signal. More about the determination of the second residual signal according to the transfer function can be referred to the description of Figure 3 and the description thereof, which will not be repeated here.

[0117] In some embodiments, since the transfer function changes according to the wearing posture of the acoustic device 100, when the user wears the acoustic device 100, the processor 130 can directly determine the first transfer function based on the first sound signal output by the sound-emitting unit 110 and the first residual signal detected by the first detector 120, but cannot directly obtain the second, third, and fourth transfer functions. In this case, the processor 130 can determine the second, third, and fourth transfer functions respectively based on the first transfer function and the relationships between the first transfer function and the second, third, and fourth transfer functions respectively. Specifically, the processor 130 can determine the relationships between the first transfer function and the second, third, and fourth transfer functions respectively based on multiple sets of transfer functions corresponding to different wearing postures, and store them in the memory 150 for later retrieval. In some embodiments, the processor 130 can determine the relationships between the first transfer function and the second, third, and fourth transfer functions respectively through statistical methods. In some embodiments, the processor 130 can use multiple sets of sample transfer functions as training samples to train the neural network. Each set of sample transfer functions can be actually measured by the acoustic device 100 under different wearing states through test signals. The processor 130 can use the trained neural network as a first transfer function to establish relationships with the second, third, and fourth transfer functions. For example, regarding the relationship between the first and second transfer functions, the processor 130 can use the first sample transfer function from each set of sample transfer functions as the input to the first neural network, and the second sample transfer function from that set as the output of the first neural network, to train the first neural network. The processor 130 can use the trained first neural network as a relationship between the first and second transfer functions. Specifically, in application, the processor 130 can input the first transfer function into the trained first neural network to determine the second transfer function.

[0118] In some embodiments, according to formula (3), the third transfer function H NM and the fourth transfer function H ND The ratio between them can be considered as a whole; in this case, it is not necessary to obtain the third transfer function H separately. NM and the fourth transfer function H ND The second residual signal can also be determined. In this case, the processor 130 can determine the first transfer function H based on multiple sets of transfer functions corresponding to different wearing postures. SM With the second transfer function H SD The first mapping relationship between them, and the third transfer function H NM and the fourth transfer function H ND The ratio between them and the first transfer function HSM a second mapping relationship between the first transfer function and the third transfer function, and store the first mapping relationship and the second mapping relationship in the memory 150 for calling. Exemplarily, the first mapping relationship and the second mapping relationship can be respectively represented as:

[0119] H SD = g(H SM ), (12)

[0120]

[0121] When the user wears the acoustic device 100, the processor 130 can determine the second transfer function according to the first transfer function and the first mapping relationship, and determine the ratio of the fourth transfer function to the third transfer function according to the first transfer function and the second mapping relationship. Further, the processor 130 can estimate the second residual signal of the target spatial position according to the first transfer function, the second transfer function, the ratio of the fourth transfer function to the third transfer function, and the first sound signal emitted by the sound emitting unit 110 and the first residual signal detected by the first detector 120, and update the noise control signal according to the second residual signal of the target spatial position. The sound emitting unit 110 generates a new first sound signal (i.e., a noise reduction signal) in response to the updated noise control signal.

[0122] In some embodiments, the processor 130 can train the neural network by taking multiple sets of sample transfer functions as training samples, obtain a trained neural network, and take the trained neural network as the second mapping relationship. Specifically, the processor 130 can take the first sample transfer function in each set of sample transfer functions as the input of the second neural network, and take the ratio between the first sample transfer function and the third sample transfer function in the set of sample transfer functions as the output of the second neural network, to train the second neural network. The processor 130 can take the trained second neural network as the second mapping relationship. In application, the processor 130 can input the first transfer function into the trained second neural network to determine the ratio between the fourth transfer function and the third transfer function.

[0123] In some embodiments, the acoustic device 100 can include one or more sensors (may also be referred to as fourth detectors). For example, a distance sensor, a position sensor, etc. The sensor can detect the distance between the acoustic device 100 and the user’s ear (or face) and / or the relative position of the acoustic device 100 and the user’s ear. For ease of description, the sensor will be described herein by taking the distance sensor as an example. In some embodiments, different wearing postures can correspond to different distances between the acoustic device 100 and the user’s ear (or face). The processor 130 can store the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function corresponding to different distances in the memory 150 for calling. In some embodiments, the processor 130 can store different wearing postures of the acoustic device 100, corresponding distances, and transfer functions in the memory 150. When the user wears the acoustic device 100, the processor 130 can first determine the wearing posture of the acoustic device 100 by the distance between the acoustic device 100 and the user’s ear detected by the distance sensor (i.e., the fourth detector). The processor 130 can further determine the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function according to the wearing posture. Alternatively, the processor 130 can directly determine the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function according to the distance between the acoustic device 100 and the user’s ear detected by the distance sensor (i.e., the fourth detector). In some embodiments, the processor 130 can determine the mapping relationship between the first transfer function and the second transfer function, the third transfer function, and the fourth transfer function according to the distance between the acoustic device 100 and the user’s ear detected by the distance sensor and the first transfer function.

[0124] In some embodiments, the processor 130 can obtain the second transfer function, the third transfer function, and / or the fourth transfer function by taking the distance data obtained by the distance sensor (or the distance data together with the first transfer function) as the input of the trained third neural network. Specifically, the processor 130 can train the third neural network by taking the sample distance obtained by the distance sensor (or the sample distance together with the first sample transfer function in the corresponding set of sample transfer functions) as the input of the third neural network, and the sample second transfer function, the sample third transfer function, and / or the sample fourth transfer function in the set of sample transfer functions as the output of the third neural network. In application, the processor 130 can input the distance data obtained by the distance sensor (or the distance data together with the first transfer function) into the trained third neural network to determine the second transfer function, the third transfer function, and / or the fourth transfer function.

[0125] It should be noted that the above description of the flow 400 is merely for example and illustration, and does not limit the scope of the present specification. Various modifications and changes can be made to the flow 400 under the guidance of the present specification by those skilled in the art. Such modifications and changes are still within the scope of the present application. For example, in some embodiments, during the test process, the second signal can be obtained first, or the third signal can be obtained first, or the second signal and the third signal can be obtained simultaneously. In some embodiments, the flow 400 can be stored in a computer readable storage medium in the form of computer instructions. When the computer instructions are executed, the test method of the transfer function described above can be implemented.

[0126] The beneficial effects that the embodiments of the present application can bring include but are not limited to: (1) an open acoustic device is proposed, through the transfer function or the relationship between the transfer functions between the sound emitting unit, the first detector, the target space position and the environmental noise source, the second residual signal at the target space position can be accurately estimated in an open scene to generate a more accurate noise reduction control signal, so that the reverse sound wave emitted by the sound emitting unit in response to the noise reduction control signal has a better active noise reduction effect; (2) by detecting the distance or relative position between the sensor and the user's ear or face, the transfer function of the acoustic device is further corrected, and the active noise reduction performance of the acoustic device is improved; (3) a method for determining the transfer function of an open acoustic device is proposed, which can accurately obtain the relationship between the transfer functions. It should be noted that different embodiments can have different beneficial effects, and in different embodiments, the beneficial effects that can be produced can be any one or a combination of the above, or any other beneficial effects that can be obtained.

[0127] The above has described the basic concepts, and it is obvious that the above detailed disclosure is only for example and does not limit the present application. Although it is not explicitly stated here, those skilled in the art can make various modifications, improvements and corrections to the present application. Such modifications, improvements and corrections are suggested in the present application, so such modifications, improvements and corrections are still within the spirit and scope of the exemplary embodiments of the present application.

Claims

1. An acoustic device comprising a sound emitting unit, a first probe, a processor, and a fixing structure, wherein, the sound emitting unit is configured to generate a first sound signal according to a noise reduction control signal; the first probe is configured to obtain a first residual signal, the first residual signal comprising an ambient noise and a residual noise signal formed by superposition of the first sound signal at the first probe; the processor is configured to estimate a second residual signal at a target spatial position according to the first sound signal and the first residual signal, and update the noise reduction control signal according to the second residual signal; and the fixing structure is configured to fix the acoustic device at a position near a user’s ear and not to block the user’s ear canal, and the target spatial position is closer to the user’s ear canal than the first probe; wherein the estimating the second residual signal at the target spatial position according to the first sound signal and the first residual signal comprises: the processor is configured to obtain a first transfer function between the sound emitting unit and the first probe, a second transfer function between the sound emitting unit and the target spatial position, a third transfer function between an ambient noise source and the first probe, and a fourth transfer function between the ambient noise source and the target spatial position, and calculate the second residual signal by the following formula: the processor is configured to obtain the first transfer function; and wherein the D is the second residual signal, the M is the first residual signal, the S is the first sound signal, the H SM is the first transfer function, the H SD is the second transfer function, the H NM is the third transfer function, and the H ND is the fourth transfer function.

2. The acoustic device of claim 1, wherein, determine the second transfer function, the third transfer function, and the fourth transfer function according to the first transfer function, and a mapping relationship between the first transfer function and the second transfer function, the third transfer function, and the fourth transfer function. The mapping relationship between the first transfer function and the second transfer function, the third transfer function, and the fourth transfer function is generated based on test data of the acoustic device in different wearing scenarios. The processor is configured to obtain the first transfer function; and 3. The acoustic device of claim 2, wherein, input the first transfer function into a trained neural network, and obtain an output of the trained neural network as the second transfer function, the third transfer function, and the fourth transfer function.

4. The acoustic device of claim 1, wherein, The obtaining the first transfer function comprises: calculating the first transfer function according to the noise reduction control signal and the first residual signal. The acoustic device further comprises a distance sensor configured to detect a distance between the acoustic device and the user’s ear, 5. An acoustic device according to any one of claims 2 to 4, wherein, the processor is further configured to determine the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function according to the distance. 8.The acoustic device of claim 7, wherein, 6. The acoustic device of claim 1, wherein, the first transfer function and the second transfer function have a first mapping relationship; and the fifth transfer function and the first transfer function have a second mapping relationship.

7. The acoustic device of claim 1, wherein, The is represented by a fifth transfer function. ​ ​ ​

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