Open wearable acoustic device and active noise reduction method

Abstract

The present application provides an open wearable acoustic device and an active noise reduction method, wherein the acoustic device includes a first sound sensor module, a speaker and a noise reduction circuit. The first sound sensor module includes N sound sensors. The noise reduction circuit determines N weights corresponding to the N sound sensors based on the target direction from which the ambient noise comes, so that the phase of the comprehensive ambient noise signal measured by the first sound sensor module based on the N weights is ahead of the phase of the ambient noise reaching the sound output end of the speaker. The noise reduction circuit generates a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights. The speaker converts the first noise cancellation signal into a first noise cancellation frequency, thereby achieving the purpose of noise reduction. Regardless of the direction from which the ambient noise comes, this solution can ensure that the first sound sensor module has a phase lead relative to the speaker, improves the causality of the feedforward noise reduction system, and thus can improve the active noise reduction effect.

Description

Technical Field

[0001] This specification relates to the field of audio technology, and in particular to an open wearable acoustic device and an active noise reduction method. Background Art

[0002] Nowadays, wearable devices with acoustic output functions (such as headphones) are used by more and more users. In particular, a listening method in which an acoustic device does not form a closed space with the human body (i.e., an open-ear listening method, for example, there is no need to insert the acoustic device into the ear canal or cover the ear, or the surface of the acoustic device is provided with sound-transmitting holes, so that an open space is formed between the eardrum and the acoustic device) is increasingly used in wearable acoustic devices because of its comfort and safety. Such wearable acoustic devices are called open wearable devices.

[0003] When worn on the user's head, the aforementioned open-type wearable acoustic device does not form a closed space with the user's eardrum. Therefore, compared to closed-type acoustic devices (such as in-ear headphones), the sound emitted by noise sources outside the ear will enter the ear more. This makes the user hear more ambient noise when wearing an open-type acoustic device, reducing the user's auditory experience. Therefore, it is necessary to provide an active noise reduction design based on an open-type wearable acoustic device. Summary of the Invention

[0004] This specification provides an open wearable acoustic device and an active noise reduction method, which can improve the active noise reduction effect.

[0005] In a first aspect, the present specification provides an open wearable acoustic device, comprising: a support member, a speaker, a first sound sensor module, and a noise reduction circuit; wherein the speaker is physically connected to the support member, and an open space is formed between the speaker and the user's eardrum when the acoustic device is worn on the user's head; the first sound sensor module includes N sound sensors, each physically connected to the support member and distributed on a side of the speaker away from the eardrum, the N sound sensors having different directions relative to a target point of the speaker, where N is an integer greater than or equal to 2; and the noise reduction circuit is configured to: determine a target direction from which ambient noise comes; based on the target direction, determine N weights corresponding to the N sound sensors so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights leads the phase of the ambient noise reaching the sound output end of the speaker; generate a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights; and send the first noise cancellation signal to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

[0006] In some embodiments, the integrated environmental noise signal is a signal obtained by weighted summing the N individual environmental noise signals based on the N weights.

[0007] In some embodiments, for the i-th sound sensor among the N sound sensors, the angle between the direction of the i-th sound sensor relative to the target point and the target direction is θ i , the corresponding weight and the θ i Negative correlation, wherein i is any positive integer less than or equal to N.

[0008] In some embodiments, the noise reduction circuit includes: N feedforward filters, corresponding one-to-one to the N sound sensors, wherein the i-th feedforward filter is connected to the i-th sound sensor and the speaker, and is configured to filter the individual environmental noise signal collected by the i-th sound sensor, where i is any positive integer less than or equal to N.

[0009] In some embodiments, in order to generate the first noise cancellation signal, the noise reduction circuit: for the i-th sound sensor among the N sound sensors, based on the weight corresponding to the i-th sound sensor, adjusts the filtering parameters of the i-th feedforward filter, and filters the individual environmental noise signal collected by the i-th sound sensor through the adjusted i-th feedforward filter to generate the i-th individual noise cancellation signal, where i is any positive integer less than or equal to N; and superimposes the N individual noise cancellation signals generated by the N feedforward filters to obtain the first noise cancellation signal.

[0010] In some embodiments, the target direction is the direction of arrival of full-band ambient noise. In order to determine the target direction, the noise reduction circuit: obtains the N individual ambient noise signals collected by the N sound sensors; and obtains the target direction by performing full-band waveguide direction DOA analysis on the N individual ambient noise signals.

[0011] In some embodiments, the ambient noise includes M sub-band noises corresponding to M sub-bands, and the target direction includes M incoming wave directions corresponding to the M sub-bands, where M is an integer greater than 1. In order to determine the target direction, the noise reduction circuit: obtains the N individual ambient noise signals collected by the N sound sensors, and for the j-th sub-band among the M sub-bands: extracts the sub-band noise signals corresponding to the j-th sub-band from the N individual ambient noise signals, respectively, to obtain N sub-band noise signals corresponding to the j-th sub-band, and obtains the incoming wave direction corresponding to the j-th sub-band by performing DOA analysis on the N sub-band noise signals, where j is any positive integer less than or equal to M.

[0012] In some embodiments, the first noise cancellation signal includes M sub-band noise cancellation signals corresponding to the M sub-bands. To generate the first noise cancellation signal, the noise reduction circuit determines, for a j-th sub-band among the M sub-bands, N sub-band weights corresponding to the N sound sensors based on the incoming wave direction corresponding to the j-th sub-band, so that a phase of a comprehensive sub-band noise signal measured by the first sound sensor module based on the N sub-band weights leads a phase of the ambient noise corresponding to the j-th sub-band reaching the sound output end of the speaker. Based on the N sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors and the N sub-band weights, N individual sub-band noise cancellation signals corresponding to the j-th sub-band are generated. The N individual sub-band noise cancellation signals are superimposed to obtain a sub-band noise cancellation signal corresponding to the j-th sub-band, where j is any positive integer less than or equal to M.

[0013] In some embodiments, N=2, and the N sound sensors are located at the acoustic zero point of the speaker and in opposite directions relative to the target point.

[0014] In some embodiments, N=3, and the N sound sensors are distributed in a triangle shape at the acoustic zero point of the speaker.

[0015] In some embodiments, at least some of the N sound sensors are omnidirectional microphones or directional microphones.

[0016] In some embodiments, the noise reduction circuit includes: at least one storage medium and at least one processor, wherein the storage medium stores at least one instruction set for performing noise reduction; the processor is communicatively connected to the speaker, the first sound sensor module and the at least one storage medium, wherein when the acoustic device is running, the at least one processor reads the at least one instruction set and executes according to the instructions of the at least one instruction set: determining a target direction from which the ambient noise comes, and based on the target direction, determining N weights corresponding to the N sound sensors so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights is ahead of the phase of the ambient noise reaching the sound output end of the speaker, generating a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights, and sending the first noise cancellation signal to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

[0017] In some embodiments, the acoustic device is one of headphones, silencers, hearing aids, and acoustic glasses.

[0018] In a second aspect, this specification also provides an active noise reduction method, which is applied to the open wearable acoustic device as described in the first aspect, and the method includes: determining, through the noise reduction circuit: a target direction from which the ambient noise comes; based on the target direction, determining N weights corresponding to the N sound sensors, so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights is ahead of the phase of the ambient noise reaching the sound output end of the speaker; generating a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights; and sending the first noise cancellation signal to the speaker, so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

[0019] In some embodiments, the integrated environmental noise signal is a signal obtained by weighted summing the N individual environmental noise signals based on the N weights.

[0020] In some embodiments, the angle between the direction of the i-th sound sensor of the N sound sensors relative to the target point and the target direction is θ i , the corresponding weight and the θ i Negative correlation, wherein i is any positive integer less than or equal to N.

[0021] In some embodiments, the noise reduction circuit includes: N feedforward filters, corresponding one-to-one to the N sound sensors, wherein the i-th feedforward filter is connected to the i-th sound sensor and the speaker, and is configured to filter the individual environmental noise signal collected by the i-th sound sensor, where i is any positive integer less than or equal to N; and generating the first noise reduction signal includes: for the i-th sound sensor among the N sound sensors, based on the weight corresponding to the i-th sound sensor, adjusting the filtering parameters of the i-th feedforward filter, and filtering the individual environmental noise signal collected by the i-th sound sensor through the adjusted i-th feedforward filter to generate the i-th individual noise reduction signal, where i is any positive integer less than or equal to N; and superimposing the N individual noise reduction signals generated by the N feedforward filters to obtain the first noise reduction signal.

[0022] In some embodiments, the target direction is the direction of arrival of full-band ambient noise; and determining the target direction from which the ambient noise comes includes: obtaining the N individual ambient noise signals collected by the N sound sensors, and obtaining the target direction by performing full-band direction of arrival (DOA) analysis on the N individual ambient noise signals.

[0023] In some embodiments, the ambient noise includes M sub-band noises corresponding to M sub-bands, the target direction includes M incoming wave directions corresponding to the M sub-bands, where M is an integer greater than 1; and determining the target direction from which the ambient noise comes includes: obtaining N individual ambient noise signals collected by the N sound sensors, and for the j-th sub-band in the M sub-bands: extracting the sub-band noise signals corresponding to the j-th sub-band from the N individual ambient noise signals, respectively, to obtain N sub-band noise signals corresponding to the j-th sub-band, and obtaining the incoming wave direction corresponding to the j-th sub-band by performing DOA analysis on the N sub-band noise signals, where j is any positive integer less than or equal to M.

[0024] In some embodiments, the first noise cancellation signal includes M sub-band noise cancellation signals corresponding to the M sub-bands; and generating the first noise cancellation signal includes, for the j-th sub-band of the M sub-bands: determining, based on the incoming wave direction corresponding to the j-th sub-band, N sub-band weights corresponding to the N sound sensors, so that the phase of the integrated sub-band noise signal measured by the first sound sensor module based on the N sub-band weights leads the phase of the ambient noise corresponding to the j-th sub-band reaching the sound output end of the speaker; generating, based on the N sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors and the N sub-band weights, N individual sub-band noise cancellation signals corresponding to the j-th sub-band; and superimposing the N individual sub-band noise cancellation signals to obtain a sub-band noise cancellation signal corresponding to the j-th sub-band, wherein j is any positive integer less than or equal to M.

[0025] As can be seen from the above technical solutions, the open wearable acoustic device and active noise reduction method provided in this specification include a first sound sensor module, a speaker, and a noise reduction circuit. The first sound sensor module includes N sound sensors. The noise reduction circuit determines N weights corresponding to the N sound sensors based on the target direction from which the ambient noise comes, so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights is ahead of the phase of the ambient noise reaching the sound output end of the speaker. The noise reduction circuit generates a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights. The speaker converts the first noise cancellation signal into a first noise cancellation frequency, thereby achieving the purpose of noise reduction. Regardless of the direction from which the ambient noise comes, this solution can ensure that the first sound sensor module has a phase lead relative to the speaker, improve the causality of the feedforward noise reduction system, and thus can enhance the active noise reduction effect.

[0026] Other features of the open wearable acoustic device and active noise reduction method provided in this specification are partially listed in the following description. The creative aspects of the open wearable acoustic device and active noise reduction method provided in this specification can be fully explained by practicing or using the methods, devices, and combinations described in the following detailed examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1AA schematic diagram of a wearing scenario of an acoustic device provided according to an embodiment of this specification is shown;

[0029] Figure 1B A schematic diagram of an acoustic device in an in-ear wearing manner is shown;

[0030] Figure 1C A schematic diagram of an acoustic device using an ear-hanging wearing method is shown;

[0031] Figure 1D A schematic diagram of an acoustic device using an ear clip wearing method is shown;

[0032] Figure 2 A schematic diagram of the hardware structure of an acoustic device provided according to an embodiment of this specification is shown;

[0033] Figure 3 A schematic diagram showing leakage signals collected by sound sensors at different positions in an acoustic device;

[0034] Figure 4 A flowchart of an active noise reduction method provided according to an embodiment of this specification is shown;

[0035] Figure 5 A schematic diagram of the active noise reduction principle of an acoustic device provided according to an embodiment of this specification is shown;

[0036] Figure 6 A schematic diagram illustrating a noise reduction effect of an active noise reduction method provided according to an embodiment of this specification;

[0037] Figure 7 A flowchart of another active noise reduction method provided according to an embodiment of this specification is shown;

[0038] Figure 8A A schematic diagram showing a frequency response curve of feedforward noise reduction of ambient noise at the eardrum using different feedforward filter gains when a first user wears an acoustic device;

[0039] Figure 8B A schematic diagram showing frequency response curves of feedforward noise reduction performed on a second sound signal using different feedforward filter gains when a first user wears an acoustic device;

[0040] Figure 9A A schematic diagram showing a frequency response curve of feedforward noise reduction of ambient noise at the eardrum using different feedforward filter gains when a second user wears the acoustic device;

[0041] Figure 9BA schematic diagram showing frequency response curves of feedforward noise reduction performed on a second sound signal using different feedforward filter gains when a second user wears an acoustic device;

[0042] Figure 10 A schematic diagram showing the distribution of the sound sensors when the first sound sensor module includes two sound sensors is shown;

[0043] Figure 11 A schematic diagram showing the distribution of the sound sensors when the first sound sensor module includes three sound sensors is shown;

[0044] Figure 12 A flowchart of another active noise reduction method provided according to an embodiment of this specification is shown;

[0045] Figure 13 A schematic diagram of the active noise reduction principle of another acoustic device provided according to an embodiment of this specification is shown;

[0046] Figure 14 A schematic diagram showing a set of frequency response curves provided according to an embodiment of this specification is shown;

[0047] Figure 15 A schematic diagram showing another set of frequency response curves provided according to an embodiment of this specification; and

[0048] Figure 16 FIG2 shows a flow chart of another active noise reduction method provided according to an embodiment of this specification. DETAILED DESCRIPTION

[0049] The following description provides specific application scenarios and requirements for this specification, with the goal of enabling those skilled in the art to make and use the contents of this specification. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but is intended to be accorded the broadest scope consistent with the claims.

[0050] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. For example, as used herein, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. When used in this specification, the terms "comprise," "include," and / or "contain" are intended to refer to the presence of the associated integers, steps, operations, elements, and / or components, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups or the addition of other features, integers, steps, operations, elements, components, and / or groups in the system / method.

[0051] These and other features of this specification, as well as the operation and function of the associated elements of the structure, and the economical assembly and manufacture of the components, can be significantly improved with consideration of the following description. Reference is made to the accompanying drawings, all of which form a part of this specification. However, it should be expressly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0052] The flowcharts used in this specification illustrate operations implemented by systems according to some embodiments of the present specification. It should be clearly understood that the operations of the flowcharts may not be implemented in sequence. Rather, the operations may be implemented in reverse order or simultaneously. Furthermore, one or more additional operations may be added to the flowcharts. One or more operations may be removed from the flowcharts.

[0053] For the convenience of description, the terms appearing in this manual are first explained:

[0054] Closed acoustic devices: When some acoustic devices are worn, a closed space is formed between the acoustic device and the user's eardrum. Such acoustic devices can be called closed acoustic devices. For example, the acoustic device can adopt an in-ear design (such as earbud headphones), a closed earmuff design, or other similar designs to form a closed space between it and the user's eardrum. When the user wears a closed acoustic device, the above-mentioned closed space can physically isolate external noise and reduce the interference of external noise on the user. However, users usually feel uncomfortable when wearing closed acoustic devices for a long time.

[0055] Open-type acoustic devices: Some acoustic devices, when worn, create an open space between the device and the user's eardrum. These devices are referred to as open-type acoustic devices. For example, the device may not be inserted into or cover the ear canal, or may have sound-transmitting holes on its surface, creating an open space between the device and the eardrum. Open-type acoustic devices can improve wearing comfort and make the sound heard by the user more transparent and natural.

[0056] Noise: In this application, any sound that is unwelcome, unwanted, or disturbs the user's hearing can be called noise.

[0057] Passive noise reduction: This refers to technology that uses passive methods to reduce noise. The above passive methods include but are not limited to: eliminating (or partially eliminating) the noise source, preventing the spread of noise, or preventing the user's ears from hearing the noise, or any combination thereof. For example, the technology that achieves noise reduction by forming a closed space in the ear belongs to passive noise reduction technology. Passive noise reduction technology can also be called passive noise reduction technology. Passive noise reduction does not eliminate noise, but suppresses noise through physical means.

[0058] Active noise reduction: It may refer to a technology that actively reduces noise by generating a noise cancellation signal (for example, a signal with a phase opposite to the noise to be suppressed). Specifically, an acoustic device using active noise reduction technology can collect noise signals through a sound sensor, generate a noise cancellation signal for offsetting the noise signal through a noise reduction circuit, and play the noise cancellation signal through a speaker so that the noise cancellation signal offsets the noise signal, thereby eliminating the noise. Active noise reduction technology can also be called active noise reduction technology. Active noise reduction technology can be divided into feedforward noise reduction, feedback noise reduction and hybrid noise reduction.

[0059] Feedforward noise reduction: A sound sensor is placed on the outside of the acoustic device, and the ambient noise is collected through the sound sensor to generate an ambient noise signal. The ambient noise signal is filtered through a feedforward filter to generate a noise cancellation signal, and the noise cancellation signal is played through the speaker. In this way, the noise cancellation signal and the ambient noise at the eardrum are offset (or partially offset), thereby reducing the volume of the ambient noise heard by the user. The above-mentioned feedforward filter is mainly used to compensate for the difference between the ambient noise at the eardrum and the ambient noise collected by the sound sensor. In the feedforward noise reduction system, an open-loop noise reduction control system is formed between the speaker and the sound sensor.

[0060] Feedback noise reduction: A sound sensor is placed inside the acoustic device. The sound sensor collects the ambient noise in the area near the eardrum, filters the ambient noise through a feedback filter to generate a noise cancellation signal, and plays the noise cancellation signal through the speaker. In this way, the noise cancellation signal and the ambient noise at the eardrum are offset (or partially offset), thereby reducing the volume of the ambient noise heard by the user. In the feedback noise reduction system, a closed-loop noise reduction control system is formed between the speaker and the sound sensor.

[0061] Hybrid noise reduction: Hybrid noise reduction combines feedforward and feedback noise reduction techniques. Generally speaking, hybrid noise reduction can further improve noise reduction effectiveness compared to either feedforward or feedback noise reduction alone.

[0062] The present application provides an open wearable acoustic device (hereinafter referred to as "acoustic device") and an active noise reduction method thereof, which can reduce the volume of ambient noise heard by the user and reduce the interference of ambient noise on the user in a scenario where the user wears the acoustic device.

[0063] Figure 1AA schematic diagram of a wearing scenario of an acoustic device provided according to an embodiment of the present specification is shown. In scenario 001, the acoustic device 100 is worn on the user's ear 200. The ear 200 may include an auricle 201 and an eardrum 202. The acoustic device 100 can be worn on the auricle 201, and the acoustic device 100 and the eardrum 202 are not closed, forming an open space. In scenario 001, a noise source 300 may also be included, and the number of noise sources 300 may be one or more. The noise source 300 is configured to emit ambient noise (for example, sound that is not welcomed by the user, is not wanted by the user, or interferes with the user's hearing). The acoustic device 100 is configured to suppress or eliminate ambient noise heard by the human ear. Specifically, the acoustic device 100 adopts an active noise reduction method to suppress or eliminate ambient noise by generating and outputting a noise cancellation signal (a signal with a phase opposite to the ambient noise).

[0064] In some embodiments, the acoustic device 100 may be headphones, mufflers, hearing aids, acoustic glasses, etc., or any combination thereof. Figure 1A The acoustic device 100 is illustrated as an example of headphones. When the acoustic device 100 is acoustic glasses, the area of ​​the temples of the acoustic glasses near the ears can be provided with a sound output device, which is configured to output sound to the user's ears. It should be noted that the acoustic device 100 can be worn on the user's ears 200 in any manner, and this application does not limit this. For example, the wearing methods of the acoustic device 100 may include head-mounted, in-ear wearing, around-the-neck wearing, ear-hanging wearing, ear-clip wearing, etc., or any combination thereof.

[0065] In some embodiments, scene 001 may also include: a network and a target device ( Figure 1A (not shown). The target device may be an electronic device with an audio output function. The acoustic device 100 and the target device may be connected via a network communication, and data or signals may be transmitted between the two via the network. For example, the target device may send target audio (e.g., music, voice, etc.) to be played to the acoustic device 100 via the network, so that the acoustic device 100 can output the target audio to the user.

[0066] In some embodiments, the target device may be equipped with an audio acquisition device, and the target audio may be acquired through the audio acquisition device. In some embodiments, the target device may receive the target audio from another device. In some embodiments, the target device may include a mobile device, a tablet computer, a laptop computer, a built-in device in a motor vehicle, or the like, or any combination thereof. In some embodiments, the mobile device may include a smart home device, a smart mobile device, a virtual reality device, an augmented reality device, or the like, or any combination thereof. In some embodiments, the smart home device may include a smart TV, a desktop computer, a smart speaker, or the like, or any combination thereof. In some embodiments, the smart mobile device may include a smartphone, a personal digital assistant, a gaming device, a navigation device, or the like, or any combination thereof. In some embodiments, the virtual reality device or augmented reality device may include a virtual reality helmet, virtual reality glasses, a virtual reality patch, an augmented reality helmet, augmented reality glasses, an augmented reality patch, or the like, or any combination thereof. For example, the virtual reality device or augmented reality device may include Google Glass, a head-mounted display, VR, or the like. In some embodiments, the built-in device in the motor vehicle may include an onboard computer, an onboard television, or the like.

[0067] In some embodiments, the network can be any type of wireless network. For example, the network can include a telecommunications network, an intranet, the Internet, a local area network (LAN), a wide area network (WAN), a wireless local area network (WLAN), a metropolitan area network (MAN), a wide area network (WAN), a public switched telephone network (PSTN), a Bluetooth network, a ZigBee network, a near field communication (NFC) network, or the like. In some embodiments, the network can be a Bluetooth network, in which case the acoustic device 100 and the target device can communicate based on the Bluetooth protocol.

[0068] Continue to see Figure 1A The acoustic device 100 may include: a support 101, a speaker 102, a noise reduction circuit 105, and at least one sound sensor module. The speaker 102 and the at least one sound sensor module may be physically connected to the support 101.

[0069] The support member 101 can be used to assist in securing the acoustic device 100 to the user's ear. For example, the support member 101 can be the housing of the acoustic device 100 or other additional structure. It should be noted that this application does not limit the specific form of the support member 101. It should be understood that the specific form of the support member 101 is related to the wearing method supported by the acoustic device 100.

[0070] Figure 1BA schematic diagram of an acoustic device in an in-ear wearing mode is shown. In this case, the support member 101 can be designed to fit the auricle 201 , with one or more support points on the support member 101 fitting with preset points on the auricle 201 . Figure 1C FIG2 is a schematic diagram of an acoustic device in an ear-hanging wearing mode. In this case, the support member 101 may adopt a suspension structure so that the acoustic device 100 can be suspended on the auricle 201 . Figure 1D Schematic diagram of an acoustic device using an ear clip wearing method is shown. In this case, the support member 101 can adopt a clamping structure so that the support member 101 can be clamped on the auricle 201.

[0071] Continue to see Figure 1A , the speaker 102 can be arranged on a side of the acoustic device 100 close to the ear canal opening. When the acoustic device 100 is worn on the user's head, an open space is formed between the speaker 102 and the user's eardrum 202. In some embodiments, when the acoustic device 100 is worn on the user's head, the speaker 102 can be close to the user's ear canal opening without blocking the ear canal opening, so that an open space is formed between the speaker 102 and the eardrum 202. In some embodiments, the shell of the acoustic device 100 can adopt a non-enclosed shell, for example, a sound-transmitting hole is provided on the shell, so that an open space is formed between the speaker 102 and the eardrum 202.

[0072] The speaker 102 can be configured to generate audio based on the audio signal (or convert the audio signal into audio). The audio signal here is an electrical signal that carries sound information, and audio refers to the sound signal played through the speaker. After the sound is emitted from the original sound source (such as an ambient noise source, a person's throat, etc.), it is converted into an electrical signal that carries the sound information through a sensor that collects the sound (such as a microphone), that is, the audio signal. The speaker 102 can also be called an electroacoustic transducer, which can receive the audio signal that carries the sound information when working, and then convert it into a sound signal to play it out. In some embodiments, the acoustic device 100 may include a plurality of speakers 102. In this case, the above-mentioned plurality of speakers 102 can be arranged in an array, for example, a linear array, a planar array, a spherical array or other array.

[0073] In some embodiments, the at least one sound sensor module may include a first sound sensor module 103. Figure 1AAs shown, the first sound sensor module 103 is away from the eardrum 202 relative to the speaker 102. That is, the first sound sensor 103 can be arranged on the outside of the acoustic device 100 (when the acoustic device 100 is worn on the user's head, the side of the acoustic device 100 away from the eardrum 202 is regarded as the outside). In some embodiments, the first sound sensor module 103 may include one or more sound sensors. When the first sound sensor module 103 includes multiple sound sensors, the multiple sound sensors can be arranged in an array, for example, a linear array, a planar array, a spherical array or other arrays. In some embodiments, the above-mentioned sound sensor is a device for collecting sound and converting sound into an electrical signal, such as a microphone.

[0074] In some embodiments, the at least one sound sensor module may include a second sound sensor module 104. The second sound sensor module 104 is close to (or near) the eardrum 202 relative to the speaker 102. That is, the second sound sensor module 104 is arranged on the inner side of the acoustic device 100 (when the acoustic device 100 is worn on the user's head, the side of the acoustic device 100 close to the eardrum 202 is regarded as the inner side). In some embodiments, the second sound sensor module 104 may include one or more sound sensors. When the second sound sensor module 104 includes multiple sound sensors, the multiple sound sensors may be arranged in an array, for example, a linear array, a planar array, a spherical array or other arrays.

[0075] In some embodiments, the at least one sound sensor module may include both a first sound sensor module 103 and a second sound sensor module 104 .

[0076] The first sound sensor module 103 is configured to collect a first sound and generate a first sound signal corresponding to the first sound. The first sound may be an analog sound signal, and the first sound signal may be an electrical signal. It should be understood that since the noise source 300 exists in the environment in which the acoustic device 100 is located, the first sound sensor module 103 can collect the ambient noise emitted by the noise source 300. In addition, since an open space is formed between the speaker 102 and the eardrum 202, the first sound sensor module 103 can also collect the sound emitted by the speaker 102. For ease of description, the sound from the speaker 102 collected by the first sound sensor module 103 is referred to as leakage sound in this application. Therefore, the first sound collected by the first sound sensor module 103 includes ambient noise and leakage sound. Accordingly, the first sound signal generated by the first sound sensor module 103 includes: the ambient noise signal from the noise source 300 and the leakage signal from the speaker 102.

[0077] The first sound sensor module 103 is located farther from the eardrum 202 than the speaker 102. In other words, the first sound sensor module 103 is closer to the noise source 300 than the speaker 102. Therefore, the ambient noise reaches the first sound sensor module 103 earlier than the sound output of the speaker 102. In other words, the phase of the ambient noise reaching the first sound sensor module 103 is ahead of the phase of the ambient noise reaching the sound output of the speaker 102. Therefore, the first sound signal collected by the first sound sensor module 103 can be used for feedforward noise reduction.

[0078] The second sound sensor module 104 is configured to collect a second sound and generate a second sound signal corresponding to the second sound. The second sound may be a sound analog signal, and the second sound signal may be an electrical signal. For an open acoustic device, the second sound sensor module 104 can collect the ambient noise emitted by the noise source 300 on the one hand, and the sound emitted by the speaker 102 on the other hand. Therefore, the second sound collected by the second sound sensor module 104 includes components of ambient noise and components of the sound emitted by the speaker 102. In an active noise reduction scenario, the ambient noise emitted by the noise source 300 is conducted along the air to reach the open space, and a portion of the ambient noise in the open space is offset or weakened by the sound of the speaker 102 during the active noise reduction process. Therefore, the second sound collected by the second sound sensor module 104 can also be called residual noise, that is, the ambient noise remaining in the open space.

[0079] The second sound sensor module 104 is closer to the eardrum 202 than the speaker 102. In other words, the second sound sensor module 104 is farther from the noise source 300 than the speaker 102. Therefore, the ambient noise arrives at the second sound sensor module 104 later than the sound output of the speaker 102. In other words, the phase of the ambient noise arriving at the second sound sensor module 104 lags behind the phase of the ambient noise arriving at the sound output of the speaker 102. Therefore, the second sound signal collected by the second sound sensor module 104 can be used for feedback noise reduction.

[0080] Continue to see Figure 1A The noise reduction circuit 105 is connected to the first sound sensor module 103, the second sound sensor module 104, and the speaker 102, and is configured to perform active noise reduction to reduce the volume of ambient noise heard by the human ear. The active noise reduction can be any one of feedforward noise reduction, feedback noise reduction, and hybrid noise reduction.

[0081] In some embodiments, the noise reduction circuit 105 may be configured to perform feed-forward noise reduction. In this case, the noise reduction circuit 105 may obtain a first sound signal from the first sound sensor module 103 and perform active noise reduction based on the first sound signal.

[0082] In some embodiments, the noise reduction circuit 105 performing active noise reduction based on the first sound signal may include: the noise reduction circuit 105 generating a first noise cancellation signal based on the first sound signal. The noise reduction circuit 105 transmits the first noise cancellation signal to the speaker 102, causing the speaker 102 to convert the first noise cancellation signal into a first noise cancellation frequency. The phase of the first noise cancellation signal may be set to be opposite, approximately opposite, or have a predetermined phase difference with the phase of the ambient noise in the space at the eardrum 202, so that the phase of the first noise cancellation frequency is opposite, approximately opposite, to the phase of the ambient noise at the eardrum 202 and the surrounding space, thereby reducing the volume of the ambient noise at the eardrum 202. In some embodiments, the noise reduction circuit 105 may include a feedforward filter connected to the first sound sensor module 103 and the speaker 102. After receiving the first sound signal from the first sound sensor 103, the noise reduction circuit 105 may input the first sound signal into the feedforward filter, filter the first sound signal through the feedforward filter to obtain the first noise cancellation signal, and output the first noise cancellation signal to the speaker 102. The feedforward filter is configured to adjust at least one of the gain or the phase of the first sound signal so that the obtained first noise cancellation signal can offset at least part of the ambient noise at the eardrum 202 .

[0083] In some embodiments, the noise reduction circuit 105 may also be configured to perform feedback noise reduction. In this case, the noise reduction circuit 105 may obtain a second sound signal from the second sound sensor module 104 and perform active noise reduction based on the second sound signal.

[0084] In some embodiments, the process of the noise reduction circuit 105 performing active noise reduction based on the second sound signal may include: the noise reduction circuit 105 generating a second noise cancellation signal based on the second sound signal. The noise reduction circuit 105 transmits the second noise cancellation signal to the speaker 102, causing the speaker 102 to convert the second noise cancellation signal into a second noise cancellation frequency. The second noise cancellation signal may be configured to have a phase opposite to, approximately opposite to, or with a predetermined phase difference from the ambient noise at the eardrum 202, such that the phase of the second noise cancellation frequency is opposite to, or approximately opposite to, the phase of the ambient noise at the eardrum 202 and the surrounding space, thereby reducing the volume of the ambient noise at the eardrum 202. In some embodiments, the noise reduction circuit 105 may include a feedback filter connected to the second sound sensor module 103 and the speaker 102. After receiving the second sound signal from the second sound sensor 103, the noise reduction circuit 105 may input the second sound signal into the feedback filter, filter the second sound signal through the feedback filter, obtain the second noise cancellation signal, and output the second noise cancellation signal to the speaker 102. The feedback filter is configured to adjust at least one of the gain or the phase of the second sound signal so that the obtained second noise cancellation signal can offset at least part of the ambient noise at the eardrum 202 .

[0085] In some embodiments, the noise reduction circuit 105 may also be configured to perform hybrid noise reduction. In this case, the noise reduction circuit 105 may obtain a first sound signal from the first sound sensor module 103 and a second sound signal from the second sound sensor module 104, and perform active noise reduction based on the first sound signal and the second sound signal.

[0086] In some embodiments, the process of the noise reduction circuit 105 performing active noise reduction based on the first sound signal and the second sound signal may include: the noise reduction circuit 105 generating a first noise cancellation signal based on the first sound signal, and generating a second noise cancellation signal based on the second sound signal. The noise reduction circuit 105 transmits the first and second noise cancellation signals to the speaker 102, so that the speaker 102 converts the first and second noise cancellation signals into noise cancellation frequencies to reduce the volume of ambient noise at the eardrum 202 and the surrounding space. In some embodiments, the noise reduction circuit 105 may include a feedforward filter and a feedback filter. The feedforward filter is connected to the first sound sensor module 103 and the speaker 102. The feedback filter is connected to the second sound sensor module 104 and the speaker 102. The noise reduction circuit 105 may input the first sound signal into the feedforward filter, filter the first sound signal through the feedforward filter to obtain the first noise cancellation signal, and input the second sound signal into the feedback filter, filter the second sound signal through the feedback filter to obtain the second noise cancellation signal. The noise reduction circuit 105 then transmits the first and second noise cancellation signals to the speaker 102. The feedforward filter is configured to adjust at least one of the gain or phase of the first sound signal so that the audio generated by the first noise cancellation signal after conversion by the speaker 102 can offset at least part of the ambient noise at the eardrum 202 and the surrounding space (i.e., the phase of the audio is opposite or approximately opposite to the phase of at least part of the ambient noise at the eardrum 202 and the surrounding space). The feedback filter is configured to adjust at least one of the gain or phase of the second sound signal so that the audio generated by the first noise cancellation signal after conversion by the speaker 102 can offset at least part of the ambient noise at the eardrum 202 (i.e., the phase of the audio is opposite or approximately opposite to the phase of at least part of the ambient noise at the eardrum 202 and the surrounding space). In some embodiments, the noise reduction circuit 105 can send the first noise cancellation signal and the second noise cancellation signal to the speaker 102, respectively. In some embodiments, the noise reduction circuit 105 can first synthesize the first noise cancellation signal and the second noise cancellation signal to obtain a synthesized noise cancellation signal, and then send the synthesized noise cancellation signal to the speaker 102.

[0087] In some embodiments, the noise reduction circuit 105 can be configured to perform the active noise reduction method described herein. In this case, the noise reduction circuit 105 can store data or instructions for performing the active noise reduction method described herein and can execute or be used to execute the data or instructions. In some embodiments, the noise reduction circuit 105 can include a hardware device with data information processing capabilities and the necessary programs to operate the hardware device. The above-described active noise reduction method will be described in detail below.

[0088] Figure 2FIG1 shows a hardware structure diagram of an acoustic device provided according to an embodiment of this specification. Figure 2 As shown, in some embodiments, the noise reduction circuit 105 may include: at least one storage medium 106 and at least one processor 107. The at least one processor 107 is communicatively connected to the speaker 102, the first sound sensor module 103, and the second sound sensor module 104. It should be noted that the noise reduction circuit 105 in this application includes at least one storage medium 106 and at least one processor 107 for the purpose of illustration only. One of ordinary skill in the art will understand that the noise reduction circuit 105 may also include other hardware circuit structures, which are not limited in this application, as long as they can meet the functions mentioned in this application without departing from the spirit of this application.

[0089] In some embodiments, the acoustic device 100 may further include a communication port 108. The communication port 108 is used for data communication between the acoustic device 100 and the outside world. For example, the communication port 108 may be used for data communication between the acoustic device 100 and other devices.

[0090] In some embodiments, the acoustic device 100 may further include an internal communication bus 109. The internal communication bus 109 may connect various system components. For example, the speaker 102, the first sound sensor module 103, the second sound sensor module 104, the processor 107, the storage medium 106, and the communication port 108 may all be connected via the internal communication bus 109.

[0091] The storage medium 106 may include a data storage device. The data storage device may be a non-transitory storage medium or a temporary storage medium. For example, the data storage device may include one or more of a disk 1061, a read-only storage medium (ROM) 1062, or a random access storage medium (RAM) 1063. The storage medium 106 also includes at least one instruction set stored in the data storage device. The instruction set includes instructions, which are computer program code. The computer program code may include programs, routines, objects, components, data structures, processes, modules, etc. that execute the active noise reduction method provided in this specification.

[0092] At least one processor 107 is used to execute the at least one instruction set mentioned above. When the acoustic device 100 is running, the at least one processor 107 reads the at least one instruction set and executes the active noise reduction method provided in this specification according to the instructions of the at least one instruction set. The processor 107 can execute all or part of the steps included in the communication method. The processor 107 can be in the form of one or more processors. In some embodiments, the processor 107 may include one or more hardware processors, such as a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application-specific integrated circuit (ASIC), an application-specific instruction set processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physical processing unit (PPU), a microcontroller unit, a digital signal processor (DSP), a field programmable gate array (FPGA), an advanced RISC machine (ARM), a programmable logic device (PLD), any circuit or processor capable of performing one or more functions, etc., or any combination thereof. Just for illustration, Figure 2 The acoustic device 100 shown in the figure illustrates a case where only one processor 107 is included. However, it should be noted that the acoustic device 100 in this specification may also include multiple processors. Therefore, the operations and / or method steps disclosed in this specification may be performed by a single processor as described in this specification, or may be performed jointly by multiple processors. For example, if the processor 107 of the acoustic device 100 in this specification performs step A and step B, it should be understood that step A and step B may also be performed jointly or separately by two different processors 120 (for example, the first processor performs step A and the second processor performs step B, or the first and second processors perform steps A and B together).

[0093] Those skilled in the art will know that Figure 2 This is just one design of the noise reduction circuit 105. The noise reduction circuit 105 can also be designed in other hardware forms without departing from the spirit of the invention disclosed in this application. The specific design of the noise reduction circuit 105 is not limited in this application.

[0094] As previously mentioned, in an open acoustic device, the first sound signal collected and generated by the first sound sensor module 103 is not simply the ambient noise signal, but rather a mixed sound signal comprising both the ambient noise signal and the leakage signal. Therefore, if the noise reduction circuit 105 performs feedforward noise reduction directly based on the first sound signal, the leakage signal will affect the feedforward noise reduction process, resulting in poor feedforward noise reduction results.

[0095] In some embodiments, to reduce the impact of leakage signals on the feedforward noise reduction effect, the acoustic device 100 can employ physical isolation, placing the first acoustic sensor module 103 at the acoustic null point of the speaker 102. For example, the speaker 102 can employ a dipole speaker design, with the first acoustic sensor module 103 located at the acoustic null point of the dipole speaker. This prevents the first acoustic sensor module 103 from collecting leakage signals from the speaker 102, or only collects minimal leakage signals.

[0096] Figure 3 The figure shows the leakage signals collected by the sound sensors at different positions in the acoustic device. FF1 and FF2 represent the sound sensors located at the acoustic zero point of the speaker 102, and FF3 represents the sound sensor located near the speaker 102. During the test, after the speaker 102 is stimulated by the signal, the leakage signal collected by FF1 is obtained as follows: Figure 3 As shown in the curve 301, the leakage signal collected by FF2 is obtained as follows Figure 3 The curve 302 shown in FIG. 3 is used to obtain the leakage signal collected by FF3. Figure 3 The curve 303 shown. Figure 3 It can be seen that when the ambient frequency is low (for example, below 1500 Hz), the leakage signals collected by FF1 and FF2 are reduced by more than 20 dB compared with the leakage signal collected by FF3, which can achieve a certain noise reduction effect.

[0097] In some embodiments, the distance between the first acoustic sensor module 103 and the acoustic null point of the speaker 102 can be within a non-zero preset range. In other words, the first acoustic sensor module 103 can be positioned relatively close to the acoustic null point of the speaker 102, rather than being located strictly at the acoustic null point of the speaker 102. This can reduce the requirements for the structural design and assembly process of the acoustic device 100.

[0098] The present application provides an active noise reduction method P100, which can reduce the influence of the leakage signal on the feedforward noise reduction by cutting the leakage signal component in the first sound signal, thereby improving the noise reduction effect. The above-mentioned active noise reduction method P100 can be applied to the scenario of "the first sound sensor module 103 is not set at the acoustic zero point position of the speaker 102", and can also be applied to the scenario of "the first sound sensor module 103 is set at the acoustic zero point position of the speaker 102". In the scenario of "the first sound sensor module 103 is set at the acoustic zero point position of the speaker 102", since there is still a problem of the speaker signal leaking to the first sound sensor module in some frequency bands (for example Figure 3When the frequency is above 5000 Hz, the leakage signals collected by FF1 and FF2 are substantially equivalent to the leakage signal collected by FF3. Therefore, the active noise reduction method P100 provided in this application can be used to perform active noise reduction for the specific frequency band where leakage occurs to improve the noise reduction effect. The active noise reduction method P100 can be applied independently to the acoustic device 100 provided in this application, or it can be combined with other active noise reduction methods described elsewhere in this document.

[0099] Figure 4 FIG1 shows a flow chart of an active noise reduction method according to an embodiment of the present specification. The active noise reduction method P100 can be executed by the noise reduction circuit 105 in the acoustic device 100. For example, when the noise reduction circuit 105 adopts Figure 2 In the structure shown, the processor 107 in the noise reduction circuit 105 can read the instruction set stored in its local storage medium, and then execute the active noise reduction method P100 described in this specification according to the instruction set. Figure 4 As shown, the active noise reduction method P100 may include:

[0100] S11: Acquire a first sound signal from a first sound sensor module, where the first sound signal includes an ambient noise signal from ambient noise and a leakage signal from a speaker.

[0101] As previously described, the first sound sensor module 103 collects the first sound and converts it into a first sound signal. The first sound is actually a mixture of ambient noise from the noise source 300 and leakage sound from the speaker 102. Therefore, the first sound signal includes both the ambient noise signal corresponding to the ambient noise and the leakage signal corresponding to the leakage sound. The noise reduction circuit 105 is connected to the first sound sensor module 103 and can obtain the first sound signal from the first sound sensor module 103.

[0102] S12: Generate a quasi-ambient noise signal by reducing the leakage signal component in the first sound signal.

[0103] Specifically, the noise reduction circuit 105 can measure the components of the leakage signal contained in the first sound signal in some way, and then subtract the components of the leakage signal from the first sound signal to obtain a quasi-environmental noise signal. It should be noted that the components of the leakage signal obtained by the above measurement may deviate from the actual leakage signal. Therefore, the result obtained by subtracting the components of the leakage signal obtained by the above measurement from the first sound signal is not strictly equal to the actual environmental noise signal, but is approximately equal to the actual environmental noise signal. Therefore, in this application, the reduction result is referred to as a quasi-environmental noise signal. The quasi-environmental noise signal can be understood as a compensation signal obtained by leakage compensation of the first sound signal.

[0104] Figure 5 FIG1 shows a schematic diagram of the active noise reduction principle of an acoustic device provided according to an embodiment of this specification. Figure 5 As shown, assuming:

[0105] The transfer function between the sound emitted by the noise source 300 and the audio signal measured by the first sound sensor module 103 is denoted as h1;

[0106] The transfer function between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensor module 104 is denoted as h2;

[0107] The transfer function between the sound emitted by the speaker 102 and the audio signal measured by the first sound sensor module 103 is denoted as h3;

[0108] The transfer function between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is denoted as h4;

[0109] The transfer function between the input and output of the feedforward filter is denoted as h5;

[0110] The transfer function between the input and output of the feedback filter is denoted as h6;

[0111] The acoustic transfer function between the sound emitted by the speaker 102 and the eardrum 202 is recorded as h7; and

[0112] The acoustic transfer function between the sound emitted by the noise source 300 and the eardrum 202 is recorded as h8.

[0113] The ambient noise emitted by noise source 300 is denoted as S0; the first sound signal collected by first sound sensor module 103 is denoted as S1; the second sound signal collected by second sound sensor module 104 is denoted as S2; the noise cancellation signal emitted by speaker 102 is denoted as S3; and the ambient noise at eardrum 202 is denoted as S4. It should be noted that in this application, S4 refers to the ambient noise actually heard by the human ear, that is, the ambient noise remaining at eardrum 202 after noise reduction processing.

[0114] Depend on Figure 5 In the acoustic transmission process shown in FIG, there is the following relationship between S0, S1, S2, S3 and S4:

[0115] S4=S3*h7+S0*h8 Formula (0)

[0116] S3=S1*h5 formula (1-1)

[0117] S3=S2*h6 Formula (1-2)

[0118] S3=S1*h5+S2*h6 Formula (1-3)

[0119] S1=S0*h1+S3*h3 Formula (2)

[0120] S2=S3*h4+S0*h2 Formula (3)

[0121] Among them, the above formula (1-1) corresponds to the feedforward noise reduction mode, the above formula (1-2) corresponds to the feedback noise reduction mode, and the above formula (1-3) corresponds to the hybrid noise reduction mode.

[0122] The following takes the feedforward noise reduction mode as an example to analyze the design principles of the feedforward filter h5.

[0123] In the feedforward noise reduction mode, substituting the above formula (2) into formula (1-1) yields:

[0124]

[0125] Substituting formula (4) into formula (0), we get:

[0126]

[0127] In an ideal situation (where the sound emitted by the speaker 102 does not leak to the first sound sensor module 103 ), h3=0. Substituting into formula (5) yields:

[0128] S4=S0*(h8+h1*h5*h7) Formula (6)

[0129] Typically, the noise reduction goal of active noise reduction technology is to minimize S4. Based on formula (6), it can be seen that, ideally, h5 needs to compensate for h1, h7, and h8. In this case, the first sound sensor module can be called an ideal feedforward sound sensor module, and the feedforward filter can be called an ideal feedforward filter.

[0130] In non-ideal conditions, especially when the first sound sensor module 103 in an open acoustic device is not located at the acoustic zero point of the speaker 102, h3≠0. Therefore, the noise reduction circuit 105 can measure the transfer function h3′ between the speaker 102 and the first sound sensor module 103 through internal model control, where h3′≈h3. In the present application, considering that the transfer function h3′ is measured and there may be a certain error between it and the true transfer function h3, the transfer function h3′ can also be referred to as the measured transfer function. During the feedforward noise reduction process, the noise reduction circuit 105 can use h3′ to compensate for the first sound signal to obtain a quasi-ambient noise signal. Furthermore, the noise reduction circuit 105 can filter the quasi-ambient noise signal through an ideal feedforward filter to obtain a first noise-canceled signal.

[0131] In some embodiments, h3′ can be measured as follows: the noise reduction circuit 105 transmits a test audio signal to the speaker 102, causing the speaker 102 to emit a corresponding test audio signal, which is then collected by the first sound sensor module 103. The noise reduction circuit 105 obtains the collected audio signal collected by the first sound sensor module 103 and determines the transfer function h3′ based on the test audio signal and the collected audio signal. For example, assuming the test audio signal is Y1 and the collected audio signal is Y2, then h3′ = Y2 / Y1. Thus, the noise reduction circuit 105 can measure h3′ by controlling the speaker 102 to transmit the test audio signal. This method of measuring h3′ is simple to implement and does not affect the noise reduction performance of the noise reduction circuit 105.

[0132] In some embodiments, considering that h3 is generally related to the wearing posture of the acoustic device 100, the corresponding h3 may be different when the same acoustic device 100 is worn by different users, and the corresponding h3 may also be different when the same acoustic device is worn multiple times by the same user. Therefore, the noise reduction circuit 105 can perform the above measurement process when it detects that the acoustic device 100 is turned on or when it detects that the acoustic device 100 is being worn by the user, thereby improving the accuracy of h3′.

[0133] In some embodiments, after measuring h3′, the noise reduction circuit 105 can generate a quasi-ambient noise signal in the following manner: the noise reduction circuit 105 obtains the input signal corresponding to the speaker 102 (i.e., S3) and applies a first gain to the input signal (S3) to obtain a first gain signal, where the first gain is h3′. Thus, the first gain signal is S3*h3′. Furthermore, the noise reduction circuit 105 obtains the first sound signal from the first sound sensor module 103 (i.e., S1 = S0*h1 + S3*h3) and subtracts the first gain signal from the first sound signal to obtain the quasi-ambient noise signal. The quasi-ambient noise signal can be expressed as: S1′ = S0*h1 + S3*h3 - S3*h3′.

[0134] S13: Generate a first noise cancellation signal based on the quasi-ambient noise signal.

[0135] In some embodiments, see Figure 5 , the noise reduction circuit 105 can input the quasi-environmental noise signal S1′ into the feedforward filter (h5), and filter the quasi-environmental noise signal (S1′) through the feedforward filter to obtain a first noise reduction signal. The feedforward filter is configured to adjust at least one of the gain or phase of the quasi-environmental noise signal (S1′) so that the obtained first noise reduction signal can offset at least part of the environmental noise at the eardrum 202 and / or in the surrounding space. It should be understood that the above-mentioned feedforward filter can be an ideal feedforward filter, that is, the ideal amplitude and phase response of the above-mentioned feedforward filter can be designed based on formula (6).

[0136] S14: Sending the first noise cancellation signal to a speaker, so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

[0137] As previously described, the noise reduction circuit 105 is in communication with the speaker 102. After generating a first noise cancellation signal, the noise reduction circuit 105 can send the first noise cancellation signal to the speaker 102. In this way, the speaker 102 plays the first noise cancellation audio corresponding to the first noise cancellation signal, so that the first noise cancellation audio cancels or partially cancels the ambient noise at the eardrum 202, thereby achieving the purpose of noise reduction.

[0138] Figure 6 FIG1 shows a schematic diagram of the noise reduction effect of an active noise reduction method provided according to an embodiment of this specification. Figure 6 As shown, curve 601 and curve 602 correspond to the noise reduction results of two test scenarios respectively. The test process corresponding to curve 601 is as follows: the noise reduction circuit 105 obtains Figure 3The first sound signal collected by FF1 (located at the acoustic zero point of the speaker 102) in FIG. 1 contains no or substantially no leakage signal from the speaker 102. The noise reduction circuit 105 uses an ideal feedforward filter to perform feedforward noise reduction based on the first sound signal, and obtains the noise reduction result shown in curve 601. The test process corresponding to curve 602 is as follows: the noise reduction circuit 105 obtains Figure 3 The first sound signal collected by FF3 (not located at the acoustic zero point of the speaker 102, or located outside the acoustic zero point of the speaker 102) contains a leakage signal from the speaker 102. The noise reduction circuit 105 adopts Figure 4 The active noise reduction method shown in the figure first reduces the leakage signal component in the first sound signal to obtain a quasi-ambient noise signal, and then uses an ideal feedforward filter to perform feedforward noise reduction based on the quasi-ambient noise signal. Figure 6 As can be seen, the noise reduction results of curve 601 and curve 602 are basically the same. This shows that the noise reduction circuit 105 can effectively improve the noise reduction effect of the open acoustic device by first reducing the leakage signal component in the first sound signal to obtain a quasi-ambient noise signal, and then generating the first noise cancellation signal based on the quasi-ambient noise signal.

[0139] above Figure 4In the active noise reduction method P100 shown, after the noise reduction circuit 105 obtains the first sound signal from the first sound sensor module, it first reduces the leakage signal component from the first sound signal to generate a quasi-ambient noise signal, and then performs feedforward noise reduction based on the quasi-ambient noise signal to generate a first noise reduction signal. In some embodiments, the noise reduction circuit 105 can interchange the above-mentioned reduction step and the feedforward noise reduction step. Specifically, after the noise reduction circuit 105 obtains the first sound signal (S1) from the first sound sensor module, it first performs feedforward noise reduction (h5) on the first sound signal to generate an intermediate noise reduction signal (S1*h5). Since the first sound signal includes the ambient noise signal and the leakage signal, when the noise reduction circuit 105 performs feedforward noise reduction on the first sound signal, it will simultaneously perform feedforward noise reduction on the ambient noise signal and the leakage signal. The intermediate noise reduction signal (S1*h5) obtained in this way contains both the feedforward noise reduction results of the ambient noise signal and the feedforward noise reduction results of the leakage signal. The feedforward noise reduction result of the leakage signal can be estimated as follows: obtain the input signal (S3) corresponding to the speaker, provide a first gain (h3′) to the input signal to obtain a first gain signal (S3*h3′). It should be understood that the first gain signal S3*h3′ can be regarded as an estimated value of the leakage signal. The first gain signal (S3*h3′) is filtered based on the feedforward noise reduction parameter (h5) to obtain the filtered result of the leakage signal (S3*h3′*h5). Furthermore, the noise reduction circuit 105 subtracts the feedforward noise reduction result (S3*h3′*h5) of the leakage signal from the intermediate noise reduction signal (S1*h5) to obtain the first noise reduction signal (S1*h5-S3*h3′*h5). It should be noted that in the above method, h3′ is the transfer function between the speaker and the first sound sensor module. Its measurement method can be found in the description of the relevant content above and will not be repeated here.

[0140] In summary, in the active noise reduction method P100 provided in this specification, when the first sound signal includes both an ambient noise signal and a leakage signal, the noise reduction circuit 105 can generate a quasi-ambient noise signal by first reducing the leakage signal component in the first sound signal, then generate a first noise cancellation signal based on the quasi-ambient noise signal, and then convert the first noise cancellation signal into a first noise cancellation frequency through a speaker, thereby achieving the purpose of noise reduction. Because the noise reduction circuit 105 reduces the leakage signal component in the first sound signal during the feedforward noise reduction process, the impact of the leakage signal on the feedforward noise reduction is reduced, and therefore, the noise reduction effect of the active noise reduction can be improved.

[0141] Typically, the noise reduction circuit 105 should design / adjust the noise reduction parameters of the noise reduction circuit 105 with "minimizing the ambient noise (S4) at the eardrum 202" as the noise reduction target. In a closed acoustic device, the second sound signal (S2) collected by the second sound sensor module 104 is equal to or approximately equal to the ambient noise (S4) at the eardrum 202. Therefore, in a closed acoustic device, "minimizing the second sound signal (S2)" can be used as a noise reduction target. However, in an open acoustic device, due to the open space formed between the speaker 102 and the eardrum 202, the second sound signal (S2) measured by the second sound sensor module 104 and the ambient noise (S4) at the eardrum 202 are no longer equal or approximately equal.

[0142] During the research process of this application, it was found that the reasons why S2 and S4 are no longer equal or approximately equal are as follows: Figure 5 In the acoustic transmission process shown, the second sound signal (S2) measured by the second sound sensor module 104 can be expressed as formula (3), and the ambient noise (S4) at the eardrum 202 can be expressed as formula (0), as follows:

[0143] S2=S3*h4+S0*h2 Formula (3)

[0144] S4=S3*h7+S0*h8 Formula (0)

[0145] As can be seen from the above formulas (3) and (0), both S2 and S4 can be considered as mixed signals of two sound signals, wherein the first sound signal comes from the noise cancellation signal (S3) emitted by the speaker 102, and the second sound signal comes from the ambient noise signal (S0) emitted by the noise source 300. With respect to the second sound signal, considering that under normal circumstances, within the frequency band to be reduced, the transfer function (h2) between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensor module 104 is equal to or approximately equal to the transfer function (h8) between the sound emitted by the noise source 300 and the eardrum 202, that is, h2≈h8, therefore, the components of the second sound signal in S2 and S4 are equivalent, and the difference between S2 and S4 mainly comes from the difference between the noise cancellation signal component (S3*h4) in S2 and the noise cancellation signal component (S3*h7) in S4.

[0146] In a closed acoustic device, the transfer function (h4) between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is equal to or approximately equal to the transfer function (h7) between the sound emitted by the speaker 102 and the eardrum 202, that is, h4≈h7. Therefore, S2 obtained based on formula (3) and S4 obtained based on formula (0) are also equal to or approximately equal to each other. In an open acoustic device, the transfer function (h4) between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 and the transfer function (h7) between the sound emitted by the speaker 102 and the eardrum 202 are no longer equal to or approximately equal to each other. Therefore, S2 obtained based on formula (3) and S4 obtained based on formula (0) are no longer equal to or approximately equal to each other.

[0147] It is understandable that, since S2 and S4 are no longer equal or approximately equal in an open acoustic device, if "minimizing S2" is still used as the noise reduction goal, the noise reduction effect will be poor.

[0148] To solve the above technical problems, the inventors of this application proposed the following technical concept during the research process: by specially designing the structure of the acoustic device 100 and the position of each component, it is achieved that: although S4 and S2 are not equal, S4 can be estimated based on S2 (or in other words, S4 and S2 have the same change trend). In this way, S4 can be estimated based on S2, and active noise reduction can be performed with minimizing S4 as the noise reduction target. Alternatively, the noise reduction parameters required for "minimizing S4 as the noise reduction target" can be derived based on the noise reduction parameters required for "minimizing S2 as the noise reduction target", thereby improving the active noise reduction effect.

[0149] Based on the above analysis, the difference between S4 and S2 mainly comes from: the difference between the component of the noise cancellation signal in S2 (S3*h4) and the component of the noise cancellation signal in S4 (S3*h7). If you want to estimate S4 based on S2, the general consideration is that you need to know h4 and h7 respectively. However, during the research process of the inventor, it was found that h7 and h4 are both quantities that are strongly correlated with the posture of the acoustic device 100, that is, when different users wear the acoustic device, h4 is different from each other, and h7 is also different from each other. Even when the same user wears the acoustic device multiple times, h4 is also different from each other, and h7 is also different from each other. In addition, since there is no acoustic sensor at the user's eardrum 202 in actual application scenarios, it is difficult to measure h7, which makes it difficult to estimate S4. After further research by the inventors, it was found that although h4 and h7 are both strongly correlated with the posture of the acoustic device 100, the positions of the second sound sensor module 104 and the speaker 102 can be designed so that: h4 and h7 satisfy the first preset relationship, and the first preset relationship is independent of the posture of the acoustic device 100. The first preset relationship is independent of the posture of the acoustic device 100, which means that no matter in what posture the acoustic device 100 is worn by the user, the first preset relationship is satisfied between h4 and h7. For example, when the acoustic device 100 is worn by different users, the first preset relationship is satisfied between h4 and h7. For another example, when the acoustic device 100 is worn by the same user multiple times, the first preset relationship is satisfied between h4 and h7.

[0150] This application does not limit the specific form of the first preset relationship. During the design phase of the acoustic device 100, the first preset relationship between h4 and h7 can be obtained by testing a large number of users wearing the acoustic device multiple times. In some embodiments, the above-mentioned first preset relationship can be: h7 / h4=h9. It should be noted that this application does not limit the value of h9. It should be understood that when the first preset relationship is satisfied between h4 and h7, the following relationship may be satisfied between S2 and S4: the component of the noise cancellation signal in S4 (S3*h7) and the component of the noise cancellation signal in S2 (S3*h4) have the following relationship: (S3*h7) / (S3*h4)=h9; or, the component of the noise cancellation signal in S2 (S3*h4) is xdB lower in intensity than the component of the noise cancellation signal in S4 (S3*h7), where the value of x can be 1, 2 or any other value.

[0151] It should be noted that the present application does not limit the specific positions of the second sound sensor module 104 and the speaker 102, as long as the positions of the two can satisfy the first preset relationship between h4 and h7, and the first preset relationship is independent of the posture of the acoustic device 100. In some embodiments, the speaker 102 can be set at a position close to the ear canal opening, and the sound output surface (i.e., the surface where the sound output end is located) faces the ear canal opening. For example, due to the shape and mass distribution of the acoustic device 100, no matter what posture the acoustic device 100 is worn in, a certain position of the acoustic device 100 is close to the ear canal opening, so the speaker 102 can be set at this position. The second sound sensor module 104 can be set on the sound output surface of the speaker 102. In addition, when designing the specific position of the second sound sensor module 104 on the sound output surface, the following principles can be considered: (1) the sound sampling end of the second sound sensor module 104 is away from the user's skin, and (2) the sound sampling end of the second sound sensor module 104 is as close to the ear canal opening as possible. It should be understood that the positions of the speaker 102 and the second sound sensor module 104 determined in the above manner can make h4 and h7 less susceptible to the influence of the wearing posture. That is, regardless of the posture in which the acoustic device 100 is worn, h4 and h7 satisfy the same first preset relationship. In addition, the positions of the speaker 102 and the second sound sensor module 104 determined in the above manner can also make the second sound signal S2 collected by the second sound sensor module 104 closer to the ambient noise S4 at the eardrum 202, and the second sound signal S2 is less susceptible to skin reflection. In this way, the estimated S4 based on the first preset relationship and the second sound signal S2 is more accurate.

[0152] When a first preset relationship is satisfied between h4 and h7, and this first preset relationship is independent of the position of the acoustic device 100, the present application provides an active noise reduction method P200. Regardless of the position in which the acoustic device 100 is worn by the user, the noise reduction parameters can be adjusted based on the second sound signal (S2) and the first preset relationship, thereby improving the active noise reduction effect. The active noise reduction method P200 can be independently applied to the acoustic device 100 provided in this application, or it can be combined with other active noise reduction methods described elsewhere in this application.

[0153] Figure 7 FIG2 shows a flow chart of another active noise reduction method P200 provided according to an embodiment of the present specification. The active noise reduction method P200 can be executed by the noise reduction circuit 105 in the acoustic device 100. For example, the processor 107 in the noise reduction circuit 105 can read the instruction set stored in its local storage medium, and then execute the active noise reduction method P200 described in the present specification according to the instruction set. Figure 7 As shown, the active noise reduction method P200 may include:

[0154] S21: Acquire a second sound signal from a second sound sensor module.

[0155] S22: Adjusting noise reduction parameters of the noise reduction circuit based on the second sound signal and the first preset relationship.

[0156] In some embodiments, the noise reduction circuit 105 may determine the ambient noise (S4) at the eardrum 202 based on the second sound signal (S2) and the first predetermined relationship. Furthermore, the noise reduction circuit 105 adjusts the noise reduction parameters with the goal of minimizing the ambient noise (S4) at the eardrum 202.

[0157] In some embodiments, the noise reduction circuit 105 may estimate S4 in the following manner:

[0158] (1) A first transfer function h4′ between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 is measured.

[0159] In some embodiments, h4′ can be measured as follows: the noise reduction circuit 105 transmits a test audio signal to the speaker 102, causing the speaker 102 to emit a corresponding test audio signal, which is then collected by the second sound sensor module 104. The noise reduction circuit 105 obtains the collected audio signal collected by the second sound sensor module 104 and determines a first transfer function h4′ based on the test audio signal and the collected audio signal. For example, assuming the test audio signal is Y1 and the collected audio signal is Y2, then h4′ = Y2 / Y1. Thus, the noise reduction circuit 105 can measure h4′ by controlling the speaker 102 to transmit the test audio signal. This method of measuring h4′ is simple and does not affect the noise reduction performance of the noise reduction circuit 105. In some embodiments, considering that h4 is generally related to the wearing posture of the acoustic device 100, the corresponding h4 may be different when the same acoustic device 100 is worn by different users. Furthermore, the corresponding h4 may also be different when the same acoustic device is worn multiple times by the same user. Therefore, the noise reduction circuit 105 may perform the above measurement process when detecting that the acoustic device 100 is powered on or when detecting that the acoustic device 100 is worn by the user, thereby improving the accuracy of h4′.

[0160] (2) Determine the ambient noise at the eardrum based on the first transfer function, the first preset relationship, and the second sound signal.

[0161] Specifically, based on the first transfer function h4 ′ and the first preset relationship, a second transfer function h7 ′ between the sound emitted by the speaker 102 and the eardrum 202 may be determined.

[0162] For example, assuming that the first preset relationship is: h7 / h4=h9, then based on the first transfer function h4' and the above first preset relationship, the second transfer function h7'=h4'*h9 can be obtained.

[0163] Furthermore, S4 can be determined based on the first transfer function h4′, the second transfer function h7′, and S2, as follows:

[0164] First, based on formula (3), we can get:

[0165] S0*h2=S2-S3*h4 Formula (12)

[0166] Based on the previous analysis, the component of the ambient noise in S2 (S0*h2) is approximately equal to the component of the ambient noise in S4 (S0*h8), that is:

[0167] S0*h8≈S0*h2=S2-S3*h4 Formula (13)

[0168] Substituting formula (13) into formula (0), we get:

[0169] S4≈S3*h7+(S2-S3*h4) Formula (14)

[0170] In formula (14), S3 is the input signal of speaker 102, h4 can be replaced by the first transfer function h4′, h7 can be replaced by the second transfer function h7′, and S2 is the second sound signal collected by second sound sensor module 104. Thus, noise reduction circuit 105 can estimate S4 based on the first transfer function h4′, the second transfer function h7′, the second sound signal S2, and the input signal S3 of speaker 102.

[0171] The above-mentioned active noise reduction process first determines the ambient noise (S4) at the eardrum 202 based on the second sound signal (S2) and the first preset relationship, and then sets minimizing the ambient noise (S4) at the eardrum 202 as the noise reduction target, thereby improving the accuracy of the noise reduction target and thus improving the effect of active noise reduction.

[0172] The above embodiment is based on the following assumption when determining S4: the transfer function (h2) between the sound emitted by the noise source 300 and the audio signal measured by the second sound sensor module 104 is approximately equal to the transfer function (h8) between the sound emitted by the noise source 300 and the eardrum 202, that is, h2≈h8. The inventors have taken into account that in actual application scenarios, h2 and h8 are usually not strictly equal, which leads to a certain error in S4 determined by the above embodiment. Therefore, in order to further improve the accuracy of S4, h2 and h8 can also be considered in the process of determining S4. However, h2 and h8 are also quantities related to the posture of the acoustic device 100. When different users wear the acoustic device, h2 and h8 are different. Even when the same user wears the acoustic device multiple times, h2 and h8 are different. Therefore, it is difficult to measure h2 and h8 separately. After further research by the inventors, it was found that when designing the positions of the second sound sensor module 104 and the speaker 102, in addition to satisfying the first preset relationship between h4 and h7, the second preset relationship can also be satisfied between h2 and h8, and the second preset relationship is also independent of the posture of the acoustic device 100. The second preset relationship is independent of the posture of the acoustic device 100, which means that no matter in what posture the acoustic device 100 is worn by the user, the second preset relationship is satisfied between h2 and h8. For example, when the acoustic device 100 is worn by different users, the second preset relationship is satisfied between h2 and h8. For another example, when the acoustic device 100 is worn by the same user multiple times, the second preset relationship is satisfied between h2 and h8.

[0173] This application does not limit the specific form of the second preset relationship. During the design phase of the acoustic device 100, the relationship between h2 / h1 and h8 / h1 can be obtained by testing a large number of users wearing the acoustic device multiple times. Based on this relationship, the second preset relationship between h2 and h8 can be obtained. In some embodiments, the above-mentioned second preset relationship can be: h8 / h2=h10. It should be noted that this application does not limit the value of h10. It should be understood that when the second preset relationship is satisfied between h2 and h8, the following relationship may be satisfied between S2 and S4: the component (S0*h8) of the ambient noise signal in S4 and the component (S0*h2) of the ambient noise signal in S2 have the following relationship: (S0*h8) / (S0*h2)=h10; or, the component (S0*h2) of the ambient noise signal in S2 is ydB lower in intensity than the component (S0*h8) of the ambient noise signal in S4, where the value of y can be 1, 2 or any other value.

[0174] In some embodiments, when a first preset relationship is satisfied between h4 and h7, a second preset relationship is satisfied between h2 and h8, and both the first preset relationship and the second preset relationship are independent of the position of the acoustic device 100, S4 can be estimated based on the first preset relationship, the second preset relationship, and S2. The specific method is as follows:

[0175] (1) Measure and obtain a first transfer function h4′ between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104. The measurement process of the first transfer function h4′ can be found in the description of the related content above and will not be repeated here.

[0176] (2) Determine the ambient noise at the eardrum based on the first transfer function, the first preset relationship, the second preset relationship, and the second sound signal.

[0177] Specifically, based on the first transfer function h4' and the first preset relationship, a second transfer function h7' between the sound emitted by the speaker 102 and the eardrum 202 can be determined. The process of determining the second transfer function h7' can be found in the previous description of the relevant content and will not be repeated here.

[0178] Furthermore, S4 may be determined based on the second preset relationship, the first transfer function h4′, the second transfer function h7′, and S2, as follows:

[0179] First, based on formula (3), we can get:

[0180] S0*h2=S2-S3*h4 Formula (12)

[0181] Based on the second preset relationship, we can get:

[0182] S0*h8=S0*h2*h10=(S2-S3*h4)*h10 Formula (15)

[0183] Substituting formula (15) into formula (0), we get:

[0184] S4=S3*h7+(S2-S3*h4)*h10 Formula (16)

[0185] In formula (16), S3 is the input signal from speaker 102, h4 can be replaced by the first transfer function h4′, h7 can be replaced by the second transfer function h7′, S2 is the second sound signal collected by second sound sensor module 104, and h10 can be obtained based on the second preset relationship. Thus, S4 can be determined based on the first transfer function h4′, the second transfer function h7′, the second preset relationship, the second sound signal S2, and the input signal S3 from speaker 102.

[0186] After estimating S4, the noise reduction parameters of the noise reduction circuit 105 can be adjusted with minimizing S4 as the noise reduction target. In some embodiments, the noise reduction circuit 105 may include a feedforward filter, in which case the noise reduction parameters may include the filtering parameters of the feedforward filter. In some embodiments, the noise reduction circuit 105 may include a feedback filter, in which case the noise reduction parameters may include the filtering parameters of the feedback filter. In some embodiments, the noise reduction circuit 105 may include a feedforward filter and a feedback filter, in which case the noise reduction parameters may include at least one of the filtering parameters of the feedforward filter or the filtering parameters of the feedback filter.

[0187] In some embodiments, the filter parameters of the feedforward filter or feedback filter may include at least one of a filter gain, a filter phase, or a quality factor. The quality factor may be expressed as the ratio of the filter's center frequency F (in Hz) to its -3dB bandwidth B (in Hz), i.e., quality factor Q = F / B, which describes the filter's ability to separate adjacent frequency components in a signal. A higher quality factor indicates a higher ability of the filter to resolve adjacent frequency components.

[0188] In some embodiments, the noise reduction parameters of the noise reduction circuit 105 may include the filter gain of the feedforward filter. In this case, for ease of description, the filter gain of the feedforward filter required for "minimizing the second sound signal (S2) as the noise reduction target" is referred to as the first filter gain, and the filter gain of the feedforward filter required for "minimizing the ambient noise (S4) at the eardrum 202 as the noise reduction target" is referred to as the second filter gain. Then, when h4 and h7 satisfy the first preset relationship, there will be a certain relationship between the signal strengths of S2 and S4, for example, the signal strength of S2 is xdB lower than the signal strength of S4. In this case, the first filter gain and the second filter gain also satisfy this relationship.

[0189] For example, Figure 8A A schematic diagram shows a frequency response curve of feedforward noise reduction of ambient noise at the eardrum using different feedforward filter gains when a first user wears an acoustic device. Figure 8BA schematic diagram illustrates frequency response curves for feedforward noise reduction of a second sound signal using different feedforward filter gains when a first user is wearing an acoustic device. Assuming that h4 and h7 satisfy a first predetermined relationship, the second sound signal (S2) is 2 dB lower than the ambient noise (S4) at the eardrum 202.

[0190] See also Figure 8A and Figure 8B When the acoustic device 100 is worn by the first user, the feedforward filter in the noise reduction circuit 105 uses different filter gains (increasing from 0dB to 4dB) to perform active noise reduction. Under different filter gains, the frequency response curves obtained by feedforward noise reduction based on the ambient noise (S4) at the eardrum 202 are as follows: Figure 8A As shown. Under different filter gains, the frequency response curves obtained by feedforward noise reduction based on the second sound signal (S2) are as follows Figure 8B As shown. Figure 8A It can be seen that if the noise reduction target is to minimize the ambient noise (S4) at the eardrum 202, the second filter gain required by the feedforward filter is 4dB. Figure 8B It can be seen that if minimizing the second sound signal ( S2 ) is used as the noise reduction target, the first filter gain required by the feedforward filter is 2 dB.

[0191] Figure 9A A schematic diagram shows a frequency response curve of feedforward noise reduction of ambient noise at the eardrum using different feedforward filter gains when a second user wears the acoustic device. Figure 9B A schematic diagram illustrates frequency response curves for feedforward noise reduction of a second sound signal using different feedforward filter gains when user B is wearing an acoustic device. Assuming that h4 and h7 satisfy a first predetermined relationship, the intensity of the second sound signal (S2) is 2 dB lower than the ambient noise (S4) at the eardrum 202.

[0192] See also Figure 9A and Figure 9B When the acoustic device 100 is worn by the second user, the feedforward filter in the noise reduction circuit 105 uses different filter gains (increasing from 0dB to 4dB) to perform active noise reduction. Under different filter gains, the frequency response curves obtained by feedforward noise reduction based on the ambient noise (S4) at the eardrum 202 are as follows: Figure 9A As shown. Under different filter gains, the frequency response curves obtained by feedforward noise reduction based on the second sound signal (S2) are as follows Figure 9B As shown. Figure 9A It can be seen that if the noise reduction target is to minimize the ambient noise (S4) at the eardrum 202, the second filter gain required by the feedforward filter is 3dB. Figure 8BIt can be seen that if minimizing the second sound signal ( S2 ) is used as the noise reduction target, the first filter gain required by the feedforward filter is 1 dB.

[0193] Depend on Figures 8A to 9B It can be seen that the relationship between the first and second filter gains is the same as the relationship between the intensity of the second sound signal (S2) and the intensity of the ambient noise (S4) at the eardrum 202. In other words, if the intensity of the second sound signal (S2) is x dB lower than the intensity of the ambient noise (S4) at the eardrum 202, then the first filter gain is x dB lower than the second filter gain.

[0194] Therefore, the noise reduction circuit 105 can also adjust the filter gain of the feedforward filter in the following manner: first, the first filter gain of the feedforward filter is determined by minimizing the second sound signal (S2) as the noise reduction target. Then, the noise reduction circuit 105 determines the above-mentioned second filter gain based on the first filter gain and the first preset relationship, and adjusts the current filter gain of the feedforward filter to the second filter gain. For example, assume that the first preset relationship makes the intensity of the second sound signal (S2) 2dB lower than the intensity of the ambient noise (S4) at the eardrum 202. The noise reduction circuit 105 first determines the first filter gain to be 2dB with minimizing the second sound signal (S2) as the noise reduction target. Then, the noise reduction circuit 105 can add 2dB to the first filter gain to obtain a second filter gain of 4dB. Therefore, the current filter gain of the feedforward filter is adjusted to 4dB.

[0195] In some embodiments, the acoustic device 100 may provide the user with multiple operating modes. Each operating mode has default noise reduction parameters associated with the noise reduction circuit 105, and different operating modes may have different default noise reduction parameters. In some embodiments, the acoustic device 100 may be provided with interactive controls that the user can operate to switch between different operating modes. In some embodiments, the acoustic device 100 may provide an interactive interface that can be displayed on the screen of the acoustic device 100 or on a target device connected to the acoustic device 100. The user can select different operating modes through the interactive interface. In some embodiments, the multiple operating modes correspond to different environment types. The user can interactively indicate the current environment type to the acoustic device 100, and the noise reduction circuit 105 can then switch to the corresponding operating mode based on the current environment type. In some embodiments, the multiple operating modes may correspond to different user types. The user can interactively indicate their user type to the acoustic device 100, and the noise reduction circuit 105 can then switch to the corresponding operating mode based on the user type.

[0196] Thus, in S22, the noise reduction circuit 105 can obtain the target operating mode indicated by the user from the multiple operating modes, and then adjust the default noise reduction parameters corresponding to the target operating mode based on the second sound signal (S2) and the first preset relationship. It should be understood that by providing multiple operating modes, the acoustic device 100 can meet the noise reduction needs of different users or in different environments.

[0197] S23: Perform active noise reduction based on the adjusted noise reduction parameters.

[0198] In some embodiments, the noise reduction circuit 105 may further obtain a first sound signal from the first sound sensor module and filter at least one of the first sound signal or the second sound signal based on the adjusted noise reduction parameter to generate a noise reduction signal. Furthermore, the noise reduction circuit 105 transmits the noise reduction signal to a speaker, causing the speaker to convert the noise reduction signal into a noise reduction frequency to reduce the volume of ambient noise at the eardrum.

[0199] In some embodiments, when the acoustic device 100 operates in the feedforward noise reduction mode, the noise reduction circuit 105 can filter the first sound signal based on the adjusted noise reduction parameters to generate a noise reduction signal. For example, the noise reduction circuit 105 can input the first sound signal into the feedforward filter, and filter the first sound signal through the feedforward filter to obtain a noise reduction signal. In some embodiments, when the first sound signal includes both an ambient noise signal and a leakage signal, the noise reduction circuit 105 can first generate a quasi-ambient noise signal by reducing the component of the leakage signal in the first sound signal, and then filter the quasi-ambient noise signal based on the adjusted noise reduction parameters to obtain a noise reduction signal. On the one hand, since the accuracy of the noise reduction target is guaranteed when adjusting the noise reduction parameters, active noise reduction based on the adjusted noise reduction parameters can improve the effect of active noise reduction. On the other hand, by reducing the component of the leakage signal in the first sound signal, the influence of the leakage signal on the feedforward noise reduction process is reduced, which can further improve the effect of active noise reduction.

[0200] In some embodiments, when the acoustic device 100 operates in the feedback noise reduction mode, the noise reduction circuit 105 may filter the second sound signal based on the adjusted noise reduction parameters to generate a noise reduction signal. For example, the noise reduction circuit 105 may input the second sound signal into a feedback filter, and filter the second sound signal through the feedback filter to obtain a noise reduction signal.

[0201] In some embodiments, when the acoustic device 100 operates in a hybrid noise reduction mode, the noise reduction circuit 105 can filter the first sound signal based on the adjusted noise reduction parameters to obtain a first noise reduction signal. For example, the noise reduction circuit 105 inputs the first sound signal into a feedforward filter, filters the first sound signal through the feedforward filter, and obtains a first noise reduction signal. The noise reduction circuit 105 can also filter the second sound signal based on the adjusted noise reduction parameters to obtain a second noise reduction signal. For example, the noise reduction circuit 105 inputs the second sound signal into a feedback filter, filters the second sound signal through the feedback filter, and obtains a second noise reduction signal. Further, the noise reduction circuit 105 synthesizes the first noise reduction signal and the second noise reduction signal to obtain a noise reduction signal. In some embodiments, when the first sound signal includes both an ambient noise signal and a leakage signal, the noise reduction circuit 105 can first generate a quasi-ambient noise signal by reducing the leakage signal component in the first sound signal, and then filter the quasi-ambient noise signal based on the adjusted noise reduction parameters to obtain the first noise reduction signal. On the one hand, since the accuracy of the noise reduction target is guaranteed when adjusting the noise reduction parameters, active noise reduction based on the adjusted noise reduction parameters can improve the effectiveness of active noise reduction. On the other hand, by reducing the leakage signal component in the first sound signal, the impact of the leakage signal on the feedforward noise reduction process is reduced, which can further improve the effectiveness of active noise reduction.

[0202] In summary, in the active noise reduction method P200 provided in this specification, since the acoustic transfer function (h4) between the sound emitted by the speaker 102 and the audio signal measured by the second sound sensor module 104 and the acoustic transfer function (h7) between the sound emitted by the speaker 102 and the eardrum 202 satisfy a first preset relationship, and the first preset relationship is independent of the position of the acoustic device 100, the noise reduction circuit 105 can adjust the noise reduction parameters based on the second sound signal (S2) and the first preset relationship, and perform active noise reduction based on the adjusted noise reduction parameters. Since the noise reduction circuit 105 adjusts the noise reduction parameters based on the second sound signal (S2) and the first preset relationship, the adjusted noise reduction parameters meet the most essential noise reduction target, thereby improving the noise reduction effect of active noise reduction.

[0203] As previously mentioned, in some embodiments, the first sound sensor module 103 may include a sound sensor. In this case, since the ambient noise may come from any direction, the following situation may occur: the ambient noise has already reached the speaker 102 or the eardrum 202 before reaching the sound sensor. For example, assuming that the sound sensor is set on the first side of the acoustic device 100 (for example, the side facing the front of the user), and the noise source 300 is located on the second side of the acoustic device 100 (for example, the side facing the back of the user), since the sound sensor is far away from the noise source 300, the ambient noise emitted by the noise source 300 first reaches the speaker 102 or the eardrum 202, and is then collected by the sound sensor. In this way, the causality of the feedforward noise reduction performed by the noise reduction circuit 105 deteriorates, resulting in a worse noise reduction effect of the feedforward noise reduction, especially the worse feedforward noise reduction effect in certain frequency bands (for example, mid-high frequency bands), and may even cause the noise heard by the human ear to increase.

[0204] To this end, in some embodiments, the first sound sensor module 103 may include multiple sound sensors. For ease of description, the number of sound sensors included in the first sound sensor module 103 is recorded as N, where N is an integer greater than or equal to 2. The N sound sensors are physically connected to the support member 101, respectively, and are distributed on a side away from the eardrum relative to the speaker 102. Without considering the leakage of the speaker 102, each sound sensor is configured to collect ambient noise from the noise source 300 and generate an ambient noise signal. For the sake of distinction, in the following text, the ambient noise signal collected by each sound sensor is referred to as an individual ambient noise signal, and the ambient noise signal collected by the first sound sensor module 103 is referred to as a comprehensive ambient noise signal.

[0205] The N sound sensors are oriented in different directions relative to a target point on speaker 102. In some embodiments, the target point may be the center point or the sound output point of speaker 102. Because the N sound sensors are oriented in different directions relative to the target point, when ambient noise arrives from different directions, at least one of the N sound sensors will be able to detect the ambient noise before speaker 102.

[0206] In some embodiments, N=2. Figure 10 FIG. 1 shows a schematic diagram of the distribution of each sound sensor when the first sound sensor module includes two sound sensors. Figure 10As shown, when N=2, the first sound sensor module 103 may include: a sound sensor 1031 and a sound sensor 1032. The two sound sensors may be located on two sides of the acoustic device 100 facing opposite directions, or in other words, the directions of the two sound sensors relative to the target point are opposite. For example, when the acoustic device 100 is worn on the user's head, the sound sensor 1031 is located on the first side of the acoustic device 100 facing the front of the user, and the sound sensor 1032 is located on the second side of the acoustic device 100 facing the rear of the user. In this way, when the ambient noise is emitted by the noise source in front of the user, the phase of the ambient noise reaching the sound sensor 1031 (or the phase of the individual ambient noise signal measured by the sound sensor 1031) is ahead of the phase of the ambient noise reaching the sound output end of the speaker 102. When ambient noise originates from a noise source behind the user, the phase of the ambient noise reaching the sound sensor 1032 (or the phase of the individual ambient noise signal measured by the sound sensor 1032) precedes the phase of the ambient noise reaching the sound output of the speaker 102. In some embodiments, the two sound sensors can be located at the acoustic null point of the speaker 102. This ensures that the signals collected by the two sound sensors do not contain any leakage signals from the speaker 102, thereby enhancing the active noise reduction effect.

[0207] In some embodiments, N=3. Figure 11 FIG. 1 shows a schematic diagram of the distribution of the sound sensors when the first sound sensor module includes three sound sensors. Figure 11As shown, when N=3, the first sound sensor module 103 may include: a sound sensor 1031, a sound sensor 1032, and a sound sensor 1033. The three sound sensors may be distributed on three sides of the acoustic device 100 facing different directions. For example, when the acoustic device 100 is worn on the user's head, the sound sensor 1031 is located on the first side of the acoustic device 100 facing the front of the user, the sound sensor 1032 is located on the second side of the acoustic device 100 facing the back of the user, and the sound sensor 1033 is located on the third side of the acoustic device 100 facing the ground. In this way, when the ambient noise is emitted by the noise source in front of the user, the phase of the ambient noise reaching the sound sensor 1031 (or the phase of the individual ambient noise signal measured by the sound sensor 1031) is ahead of the phase of the ambient noise reaching the sound output end of the speaker 102. When the ambient noise is emitted by the noise source behind the user, the phase of the ambient noise reaching the sound sensor 1032 (or the phase of the individual ambient noise signal measured by the sound sensor 1032) is ahead of the phase of the ambient noise reaching the sound output end of the speaker 102. When the ambient noise is emitted by the noise source below the acoustic device, the phase of the ambient noise reaching the sound sensor 1033 (or the phase of the individual ambient noise signal measured by the sound sensor 1033) is ahead of the phase of the ambient noise reaching the sound output end of the speaker 102. In some embodiments, the above-mentioned three sound sensors can be distributed in a triangular form at the acoustic zero point position of the speaker 102. In this way, the signals collected by the three sound sensors do not contain leakage signals from the speaker 102, thereby improving the active noise reduction effect.

[0208] It should be noted that the above Figure 10 and Figure 11 These are just two possible distribution methods. In actual design, the N sound sensors can also be distributed in other ways, which are not illustrated here. In addition, this application does not impose any specific restrictions on the value of N. For example, the value of N can also be 4, 5, or any other integer.

[0209] In some embodiments, the N sound sensors may be arranged in an array, such as a linear array, a planar array, a spherical array, or other arrays. Arranging the sound sensors in an array also helps reduce the complexity of signal processing within the noise reduction circuit 105, thereby improving the active noise reduction performance.

[0210] At least some of the N sound sensors may be omnidirectional microphones. Omnidirectional microphones are highly sensitive to ambient noise in all directions and can collect ambient noise in any direction. At least some of the N sound sensors may also be directional microphones. Directional microphones can only collect ambient noise in a specified direction. For example, Figure 10As shown, sound sensor 1031 can be directional in front of the user and is configured to collect ambient noise from the front of the user. Sound sensor 1032 can be directional in the back of the user and is configured to collect ambient noise from the back of the user. The directional microphones described above may include, but are not limited to, cardioid microphones, near-cardioid microphones, or other directional microphones. The directional microphones may have the same or different directivities for different frequencies.

[0211] When the first sound sensor module 103 includes N sound sensors, the present application provides an active noise reduction method P300. When performing active noise reduction, the noise reduction circuit 105 can assign weights to the N sound sensors so that the first sound sensor module 103 has phase leadership in all directions. This solution improves the causality of feedforward noise reduction, thereby enhancing the active noise reduction effect. The active noise reduction method P300 can be applied independently to the acoustic device 100 provided in this application, or it can be combined with other active noise reduction methods described elsewhere in this document.

[0212] Figure 12 FIG. 1 shows a flow chart of another active noise reduction method P300 provided according to an embodiment of the present specification. The active noise reduction method P300 can be executed by the noise reduction circuit 105 in the acoustic device 100. For example, when the noise reduction circuit 105 adopts Figure 2 In the structure shown, the processor 107 in the noise reduction circuit 105 can read the instruction set stored in its local storage medium, and then execute the active noise reduction method P300 described in this specification according to the instruction set. Figure 12 As shown, the active noise reduction method P300 may include:

[0213] S31: Determine the target direction from which the ambient noise comes.

[0214] The target direction refers to the direction from which the ambient noise comes, that is, the direction of the noise source 300. In some embodiments, the direction of a ray pointing from the target point on the speaker 102 to the noise source 300 can be called the target direction.

[0215] In some embodiments, the noise reduction circuit 105 can obtain N individual ambient noise signals collected by N sound sensors, and estimate the target direction from which the ambient noise comes based on the N individual ambient noise signals. In some embodiments, the noise reduction circuit 105 can obtain the target direction by performing a full-band Direction of Arrival (DOA) analysis on the N individual ambient noise signals. In this case, the target direction represents the direction of arrival of the full-band ambient noise (i.e., the overall ambient noise).

[0216] It should be noted that this application does not specifically limit the DOA algorithm. For example, one or more of the Estimating Signal Parameter via Rotational Invariance Techniques (ESPRIT) algorithm, the Multiple Signal Classification (MUSIC) algorithm, etc. can be used.

[0217] S32: Based on the target direction, determine N weights corresponding to the N sound sensors in the first sound sensor module, so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights leads the phase of the ambient noise reaching the sound output end of the speaker.

[0218] In some embodiments, the integrated environmental noise signal is a signal obtained by weighted summing N individual environmental noise signals collected by N sound sensors based on the N weights.

[0219] Combine Figure 10 Let's take an example. The first sound sensor module 103 includes a sound sensor 1031 and a sound sensor 1032. The individual environmental noise signal collected by the sound sensor 1031 is: The individual environmental noise signal collected by the sound sensor 1032 is:

[0220] Assuming that the weight of the sound sensor 1031 is α1 and the weight of the sound sensor 1032 is α2, the comprehensive environmental noise signal measured by the first sound sensor module 103 based on the above two weights can be expressed as:

[0221]

[0222] The phase of the above-mentioned integrated environmental noise signal can be expressed as:

[0223]

[0224] It can be seen that the noise reduction circuit 105 can set weights for the N sound sensors based on the target direction, so that the phase of the above-mentioned integrated noise signal is ahead of the phase of the ambient noise reaching the sound output end of the speaker 102.

[0225] In some embodiments, the weight associated with the i-th sound sensor is related to the phase lead of the individual ambient noise signal collected by the i-th sound sensor. For example, the further ahead the phase of the individual ambient noise signal collected by the i-th sound sensor is compared to the phase of the ambient noise reaching the sound output of the speaker 102, the greater the weight associated with the i-th sound sensor. Conversely, the smaller the weight associated with the i-th sound sensor, the further ahead the phase of the individual ambient noise signal collected by the i-th sound sensor is. Here, i is any positive integer less than or equal to N.

[0226] In some embodiments, it is assumed that the angle between the direction of the i-th sound sensor relative to the target point on the speaker 102 and the target direction is θ i , then the weight corresponding to the i-th sound sensor is equal to the θ i Negative correlation. That is, θ i The smaller the value (indicating that the deviation between the direction of the sound sensor relative to the target point and the target direction is smaller), the greater the weight, θ i The larger the value is (indicating that the deviation between the direction of the sound sensor relative to the target point and the target direction is greater), the smaller the weight is.

[0227] Combine Figure 10 For example, assuming the ambient noise comes from in front of the user, the weight of sound sensor 1031 is greater than the weight of sound sensor 1032. Thus, during active noise reduction, sound sensor 1031 plays a primary role, ensuring phase leadership. If the ambient noise comes from behind the user, the weight of sound sensor 1032 is greater than the weight of sound sensor 1031. Thus, during active noise reduction, sound sensor 1032 plays a primary role, also ensuring phase leadership.

[0228] S33: Generate a first noise cancellation signal based on the N individual environmental noise signals collected by the N sound sensors and the N weights.

[0229] In some embodiments, the noise reduction circuit 105 may include N feedforward filters, corresponding one-to-one to the N sound sensors. The i-th feedforward filter is connected to the i-th sound sensor and the speaker 102 and is configured to filter the individual ambient noise signal collected by the i-th sound sensor. i is any positive integer less than or equal to N. In other words, the N feedforward filters in the noise reduction circuit 105 are connected in parallel.

[0230] Because the N feedforward filters are connected in parallel, the active noise reduction process does not increase the filter order or latency. Furthermore, these N parallel feedforward filters can also help increase filtering complexity. For example, the N feedforward filters can be responsible for noise reduction in different frequency bands, thereby enhancing the feedforward noise reduction capability.

[0231] Figure 13 FIG2 shows a schematic diagram of the active noise reduction principle of another acoustic device provided according to an embodiment of this specification. Figure 13 As shown, it is assumed that the first sound sensor module 103 includes a sound sensor 1031 and a sound sensor 1032, and the noise reduction circuit includes a feedforward filter h51 and a feedforward filter h52. The feedforward filter h51 is connected to the sound sensor 1031 and the speaker 102, and the feedforward filter h52 is connected to the sound sensor 1032 and the speaker 102.

[0232] Continue to see Figure 13 , assuming:

[0233] The transfer function between the sound emitted by the noise source 300 and the audio signal measured by the sound sensor 1031 is denoted as h11;

[0234] The transfer function between the sound emitted by the noise source 300 and the audio signal measured by the sound sensor 1032 is denoted as h12;

[0235] The acoustic transfer function between the sound emitted by the speaker 102 and the eardrum 202 is denoted as h7; and

[0236] The acoustic transfer function between the sound emitted by the noise source 300 and the eardrum 202 is denoted as h8.

[0237] The noise signal emitted by the noise source 300 is recorded as S0; the individual environmental noise signal collected by the sound sensor 1031 is recorded as S11; the individual environmental noise signal collected by the sound sensor 1032 is recorded as S12; the noise cancellation signal emitted by the speaker 102 is recorded as S3; and the noise signal received by the eardrum 202 is recorded as S4.

[0238] Depend on Figure 13 In the acoustic transmission process shown in FIG, there is the following relationship between S0, S11, S12, S3 and S4:

[0239] S4=S0*h8+S3*h7 Formula (0)

[0240] S3=S11*h51+S12*h52 Formula (7)

[0241] S11=S0*h11 formula (8)

[0242] S12=S0*h12 formula (9)

[0243] Substituting formula (8) and formula (9) into formula (7), we can obtain:

[0244] S3=S0*h11*h51+S0*h12*h52 Formula (10)

[0245] Substituting formula (10) into formula (0) yields:

[0246] S4=S0*h8+S0*(h11*h51+h12*h52)*h7 Formula (11)

[0247] It can be seen from formula (11) that the feedforward noise reduction effect is jointly determined by hS1 and h52.

[0248] In some embodiments, when the noise reduction circuit 105 performs active noise reduction, it can adjust the filtering parameters of the feedforward filter h51 based on the weight of the sound sensor 1031, and filter the individual environmental noise signal S11 collected by the sound sensor 1031 through the adjusted feedforward filter h51 to generate an individual noise reduction signal. Furthermore, the noise reduction circuit 105 can also adjust the filtering parameters of the feedforward filter h52 based on the weight of the sound sensor 1032, and filter the individual environmental noise signal S12 collected by the sound sensor 1032 through the adjusted feedforward filter h52 to generate an individual noise reduction signal. Furthermore, the noise reduction circuit 105 synthesizes the two individual noise reduction signals generated by the two feedforward filters to obtain a first noise reduction signal.

[0249] In some embodiments, adjusting the filter parameters of the feedforward filter h51 or the feedforward filter h52 may include adjusting the filter gain of the feedforward filter h51 or the feedforward filter h52. For example, the weight of the sound sensor 1031 may be multiplied by the current filter gain of the feedforward filter h51 to obtain the adjusted filter gain of the feedforward filter h51. The weight of the sound sensor 1032 may be multiplied by the current filter gain of the feedforward filter h52 to obtain the adjusted filter gain of the feedforward filter h52.

[0250] It should be understood that the noise reduction circuit 105 adjusts the filtering parameters of N feedforward filters based on N weights, so that during the active noise reduction process, the sound sensors with higher weights (sound sensors with higher phase leading properties) and their corresponding feedforward filters contribute more to the overall noise reduction, while the sound sensors with lower weights (sound sensors with lower phase leading properties) and their corresponding feedforward filters contribute less to the overall noise reduction, thereby improving the active noise reduction effect.

[0251] In some embodiments, the above N sound sensors may be N directional microphones with different directivities. Continuing to refer to Figure 13 , assuming that the directivity of the sound sensor 1031 is in front of the user and the directivity of the sound sensor 1032 is behind the user. When the ambient noise comes from in front of the user, the directivities of the above two sound sensors make h11 much greater than h12 (i.e., h11 >> h12). According to the above formula (11), it can be seen that in the active noise reduction process, mainly the sound sensor 1031 is functioning. Therefore, the first sound sensor module 103 has a phase lead, thereby being able to improve the active noise reduction effect. When the ambient noise comes from behind the user, the directivities of the above two sound sensors make h11 much smaller than h12 (i.e., h11 << h12). According to the above formula (11), it can be seen that in the active noise reduction process, mainly the sound sensor 1032 is functioning. Therefore, the first sound sensor module 103 has a phase lead, thereby being able to improve the active noise reduction effect.

[0252] Thus, it can be seen that in the case where the N sound sensors have different directivities, the different directivities of the N sound sensors enable the active noise reduction process to automatically select the optimal sound sensor, and without having to adjust the filtering parameters of the feedforward filter, the phase lead of the first sound sensor module in all directions can be achieved.

[0253] S34: Send the first noise cancellation signal to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation audio to reduce the volume of the ambient noise at the eardrum.

[0254] It should be understood that S31 to S34 described above are for estimating the incoming wave direction of the ambient noise in the full frequency band and performing active noise reduction in the full frequency band based on the estimated target direction. In some embodiments, when estimating the target direction, the noise reduction circuit 105 can also estimate in sub-frequency bands. For example, the full frequency band is divided into M sub-frequency bands, and the ambient noise includes M sub-frequency band noises corresponding to the M sub-frequency bands. The noise reduction circuit 105 can separately estimate the incoming wave directions of the M sub-frequency band noises for each sub-frequency band. In this case, the target direction obtained in S31 includes M incoming wave directions corresponding to the M sub-frequency bands. It should be noted that the present application does not limit the division method of the M sub-frequency bands. In some embodiments, the above M sub-frequency bands may include: a low frequency band (e.g., 0 - 150 Hz), a middle frequency band (e.g., 150 - 500 Hz), and a high frequency band (e.g., 500 - 2000 Hz).

[0255] In some embodiments, the noise reduction circuit 105 may obtain N individual ambient noise signals collected by N sound sensors, and then estimate the direction of arrival of the j-th sub-frequency band in the following manner: extract the sub-band noise signal corresponding to the j-th sub-frequency band from the N individual ambient noise signals to obtain N sub-band noise signals corresponding to the j-th sub-frequency band, and perform DOA analysis on the N sub-band noise signals to obtain the direction of arrival of the j-th sub-frequency band. Wherein, j is any positive integer less than or equal to M.

[0256] After obtaining the M incoming wave directions corresponding to the M sub-bands, the noise reduction circuit 105 can perform active noise reduction based on each sub-band. Specifically, for the j-th sub-band, based on the incoming wave directions corresponding to the j-th sub-band, the noise reduction circuit 105 determines N sub-band weights corresponding to the N sound sensors, so that the phase of the integrated sub-band noise signal measured by the first sound sensor module 103 based on the N sub-band weights advances the phase of the ambient noise of the j-th sub-band arriving at the sound output of the speaker 102. The integrated sub-band noise signal is a signal obtained by weighted summing the sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors based on the N sub-band weights. Furthermore, the noise reduction circuit 105 generates N individual sub-band noise cancellation signals corresponding to the j-th sub-band based on the sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors and the N sub-band weights. The noise reduction circuit superimposes the N individual sub-band noise cancellation signals to obtain a sub-band noise cancellation signal corresponding to the jth sub-band. Here, j is any positive integer less than or equal to M. The noise reduction circuit 105 performs the above process for each of the M sub-bands to obtain M sub-band noise cancellation signals corresponding to the M sub-bands. Furthermore, the noise reduction circuit 105 transmits the M sub-band noise cancellation signals to the speaker 102, so that the speaker 102 converts the M sub-band noise cancellation signals into noise cancellation audio to reduce the volume of the ambient noise at the eardrum 202.

[0257] It should be understood that the process of performing active noise reduction for each sub-band is similar to the active noise reduction process for the full frequency band described above and will not be described in detail here. It should be noted that each feedforward filter may include M filtering units corresponding to M sub-bands. When performing active noise reduction for the j-th sub-band, the filtering parameters corresponding to the j-th filtering unit in the feedforward filter may be adjusted based on the weights, for example, the filtering gain corresponding to the j-th filtering unit may be adjusted.

[0258] Figure 14 FIG1 shows a schematic diagram of a set of frequency response curves provided according to an embodiment of this specification. Figure 14As shown, curve 141 illustrates the frequency response of acoustic device 100 using a single sound sensor FF1 in conjunction with a feedforward filter. Curve 142 illustrates the frequency response of acoustic device 100 using a single sound sensor FF2 in conjunction with a feedforward filter. Curve 143 illustrates the frequency response of acoustic device 100 using both sound sensors FF1 and FF2 in conjunction with two parallel feedforward filters. Curves 141 and 142 show that individual sound sensors FF1 and FF2 each achieve noise reduction effects in different frequency bands. Curve 143 shows that combining sound sensors FF1 and FF2 achieves noise reduction across a wider frequency band and achieves a deeper noise reduction depth.

[0259] As mentioned above, in an open acoustic device, the ambient noise signal collected by the sound sensor may contain leakage signals (ie, leakage signals from the speaker 102). By providing multiple sound sensors in the first sound sensor 103, the acoustic device 100 can reduce the leakage to a certain extent. Figure 15 FIG2 shows another schematic diagram of a set of frequency response curves provided according to an embodiment of this specification. Figure 15 As shown, curve 153 illustrates the frequency response of the acoustic device 100 when it uses both sound sensor FF1 and sound sensor FF2 and cooperates with two parallel feedforward filters for noise reduction. Curve 151 illustrates the frequency response of FF1 and its corresponding feedforward filter, and curve 152 illustrates the frequency response of FF2 and its corresponding feedforward filter. Figure 15 As can be seen, when using two sound sensors, the feedforward filter gain required for each sound sensor is significantly smaller than when using a single sound sensor to achieve the same filtering effect. This reduction in feedforward filter gain can reduce leakage, thereby avoiding system divergence problems caused by leakage and noise amplification problems caused by some users wearing acoustic devices.

[0260] In summary, in the active noise reduction method P300 provided herein, when the first sound sensor module 103 includes N sound sensors, the noise reduction circuit 105, when performing active noise reduction, can determine N weights corresponding to the N sound sensors based on the target direction of the ambient noise, so that the phase of the integrated ambient noise signal measured by the first sound sensor module 103 based on the N weights leads the phase of the ambient noise reaching the sound output of the speaker. The noise reduction circuit 105 then generates a first noise cancellation signal based on the N individual ambient noise signals collected by the N sound sensors and the N weights, and transmits the first noise cancellation signal to the speaker 102. Thus, by introducing N sound sensors and assigning weights to the N sound sensors, this solution ensures that the first sound sensor module 103 maintains a phase lead relative to the sound output of the speaker 102 regardless of the direction of the ambient noise, thereby improving the causal nature of feedforward noise reduction and, in turn, enhancing the active noise reduction effect, particularly high-frequency noise reduction performance. Furthermore, using multiple sound sensors can reduce gain compared to a single sound sensor, thereby reducing leakage in certain frequency bands (such as high frequencies) in open-air scenarios. This avoids system divergence issues caused by leakage in these frequency bands, as well as noise amplification issues experienced by some users wearing acoustic devices. Furthermore, this solution estimates the direction of incoming waves at a sub-band granularity and performs active noise reduction on each sub-band, helping to increase the depth of noise reduction in each sub-band, further enhancing the effectiveness of active noise reduction.

[0261] Typically, after the active noise reduction function is enabled, the acoustic device 100 performs active noise reduction across the entire frequency band based on pre-designed noise reduction parameters. However, in actual applications, due to the diverse external environments in which the acoustic device 100 operates, these pre-designed noise reduction parameters are often not suitable for active noise reduction in various external environments. For example, in some special external environments, the noise reduction effect of the acoustic device may be poor, or the speaker 102 may experience distortion.

[0262] To this end, the noise reduction circuit 105 can provide multiple noise reduction modes. Thus, during active noise reduction, the noise reduction circuit 105 can adaptively select a target noise reduction mode from the multiple noise reduction modes based on the noise conditions of the external environment and execute the target noise reduction mode. Adaptively selecting the target noise reduction mode means that the noise reduction mode can be switched autonomously, flexibly, intelligently, and / or adaptively based on the noise conditions of the external environment. It should be understood that the process of switching noise reduction modes is automatically performed by the noise reduction circuit 105, without manual user intervention.

[0263] In some embodiments, the multiple noise reduction modes may include at least one of a passive noise reduction mode, an anti-breaking noise reduction mode, a narrowband noise reduction mode, and a normal noise reduction mode.

[0264] In the passive noise reduction mode, the active noise reduction function of the acoustic device 100 is turned off.

[0265] In the normal noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on, and the noise reduction circuit 105 uses pre-designed noise reduction parameters to perform active noise reduction in the full frequency band based on at least one of the first sound signal or the second sound signal.

[0266] In the narrowband noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on. The active noise reduction process includes: the noise reduction circuit 105 determines the target frequency band based on the first sound signal, and the energy concentration in the target frequency band exceeds the preset threshold. The energy concentration in the target frequency band refers to the concentration degree of the noise signal energy in the target frequency band. In some embodiments, the bandwidth corresponding to the target frequency band is smaller than the preset bandwidth, so the target frequency band can be called a narrowband. Furthermore, the noise reduction circuit 105 can perform active noise reduction in the target frequency band (narrowband) based on at least one of the first sound signal or the second sound signal.

[0267] In some embodiments, after determining the target frequency band, the noise reduction circuit 105 can adjust the noise reduction parameters of the noise reduction circuit 105 based on the target frequency band. The adjusted noise reduction parameters can specify that active noise reduction is performed on the target frequency band (for example, the noise reduction depth of the target frequency band is greater than the noise reduction depth of other frequency bands), or the adjusted noise reduction parameters can specify that active noise reduction is performed only on the target frequency band and not on other frequency bands. In some embodiments, the above-mentioned "adjusting the noise reduction parameters of the noise reduction circuit 105" can include: converting the full-band filter in the noise reduction circuit 105 into a narrowband filter. By adjusting the noise reduction parameters based on the target frequency band, the above-mentioned embodiment can increase the noise reduction depth within the target frequency band and improve the noise reduction effect within the target frequency band.

[0268] In the anti-breaking sound noise reduction mode, the active noise reduction function of the acoustic device 100 is turned on. The active noise reduction process includes: the noise reduction circuit 105 generates a noise cancellation signal based on at least one of the first sound signal or the second sound signal, and makes the amplitude of the noise cancellation signal fall within the amplitude range supported by the speaker 102. Further, the noise reduction circuit 105 sends a noise cancellation signal to the speaker 102, so that the speaker 102 converts the noise cancellation signal into a noise cancellation frequency to reduce the volume of the ambient noise at the eardrum 202. Among them, the above-mentioned amplitude range refers to the signal amplitude range supported by the speaker 102 when it can sound normally without breaking sound. The breaking sound refers to the phenomenon that the vibration of the speaker diaphragm exceeds its linear range, resulting in serious sound distortion. When the amplitude of the signal input to the speaker 102 exceeds the above-mentioned amplitude range, it will cause the speaker 102 to break. When the amplitude of the signal input to the speaker 102 is within the said amplitude range, it will not cause the speaker 102 to break. It should be understood that, since the noise reduction circuit 105 ensures that the amplitude of the noise cancellation signal is within the amplitude range supported by the loudspeaker 102 when generating the noise cancellation signal, distortion of the sound from the loudspeaker 102 can be avoided.

[0269] In some embodiments, the noise reduction circuit 105 can generate a noise cancellation signal in the following manner so that the amplitude of the noise cancellation signal falls within the amplitude range supported by the speaker 102: the noise reduction circuit 105 filters at least one of the first sound signal or the second sound signal to obtain a candidate noise cancellation signal. The filtering process has been described in the relevant section above and is not repeated here. Furthermore, the noise reduction circuit 105 corrects the amplitude of the candidate noise cancellation signal based on the amplitude range so that the corrected amplitude falls within the amplitude range, and uses the corrected signal as the noise cancellation signal. In some embodiments, the output end of the noise reduction circuit 105 (i.e., the interface between the noise reduction circuit 105 and the speaker 102) can be provided with a dynamic range control (DRC). The dynamic range control is configured to adjust the amplitude of the input signal so that the amplitude of the output signal falls within the amplitude range. In this case, after obtaining the candidate noise cancellation signal, the noise reduction circuit 105 inputs the candidate noise cancellation signal into the dynamic range controller, which corrects the amplitude of the candidate noise cancellation signal to obtain the noise cancellation signal.

[0270] In this manner, the noise reduction circuit 105 does not need to adjust the original noise reduction parameters, but only needs to add a post-amplitude correction link (such as adding a dynamic range controller) to avoid the speaker 102 from sound distortion.

[0271] In some embodiments, the noise reduction circuit 105 can generate a noise cancellation signal in the following manner so that the amplitude of the noise cancellation signal is within the amplitude range supported by the speaker 102: the noise reduction circuit 105 adjusts the corresponding filter gain of the noise reduction circuit 105 based on the first sound signal so that the amplitude of the output signal obtained after filtering is within the amplitude range. Furthermore, the noise reduction circuit 105 filters at least one of the first sound signal or the second sound signal based on the adjusted noise reduction parameter to obtain the noise cancellation signal.

[0272] In this manner, the noise reduction circuit 105 only needs to adjust the filter gain to make the amplitude of the noise reduction signal fall within the amplitude range, without changing the circuit structure of the noise reduction circuit 105 .

[0273] In some embodiments, in the adjusted filter gain, the first filter gain corresponding to the first preset frequency band is less than the second filter gain corresponding to the second preset frequency band. In some embodiments, the frequency in the first preset frequency band is lower than the frequency in the second preset frequency band. In some embodiments, the frequency in the first preset frequency band is lower than the preset frequency, wherein the preset frequency can be 500Hz, 200Hz, 150Hz or other frequency values. In some embodiments, the first preset frequency band can be a low frequency band (for example, a frequency band with a frequency less than 150Hz). Since the first preset frequency band corresponds to a smaller filter gain, the amplitude of the filtered noise cancellation signal corresponding to the first preset frequency band can be smaller, thereby avoiding distortion of the speaker 102 in the first preset frequency band.

[0274] In some embodiments, when adjusting the filter gain, the noise reduction circuit 105 may reduce the first filter gain corresponding to the first preset frequency band based on the default filter gain, while maintaining the second filter gain corresponding to the second preset frequency band unchanged. This prevents the speaker 102 from sound distortion without reducing the noise reduction effect corresponding to the second preset frequency band.

[0275] When the acoustic device 100 provides multiple noise reduction modes, the present application provides an active noise reduction method P400 that can adaptively switch to a noise reduction mode suitable for the current environment based on the noise conditions of the current environment, thereby enabling the acoustic device 100 to achieve good noise reduction effects in different environments. The active noise reduction method P400 can be applied independently to the acoustic device 100 provided in the present application, or it can be combined with other active noise reduction methods described elsewhere in this document.

[0276] Figure 16FIG2 shows a flow chart of another active noise reduction method P400 provided according to an embodiment of the present specification. The active noise reduction method P400 can be executed by the noise reduction circuit 105 in the acoustic device 100. For example, the processor 107 in the noise reduction circuit 105 can read the instruction set stored in its local storage medium, and then execute the active noise reduction method P400 described in the present specification according to the instruction set. Figure 16 As shown, the active noise reduction method P400 may include:

[0277] S41: Acquire a first sound signal from a first sound sensor module.

[0278] S42: Adaptively selecting a target noise reduction mode from a plurality of noise reduction modes of an acoustic device based on the first sound signal.

[0279] In some embodiments, the noise reduction circuit 105 can adaptively select a target noise reduction mode from multiple noise reduction modes based on at least one of the intensity or bandwidth type of the first sound signal. The bandwidth type of the first sound signal can be categorized into two types: narrowband and non-narrowband. The narrowband type indicates that the bandwidth occupied by the first sound signal is smaller than a preset bandwidth. Compared to the non-narrowband type, the signal energy of the narrowband type is concentrated within a narrower frequency band.

[0280] In some embodiments, the process of the noise reduction circuit 105 adaptively selecting the target noise reduction mode may include at least one of the following S42 - 1 , S42 - 2 , and S42 - 3 .

[0281] S42-1: Determine that the intensity of the first sound signal is less than or equal to a second intensity threshold, and select a passive noise reduction mode from the multiple noise reduction modes.

[0282] The second intensity threshold may correspond to the upper limit of noise intensity in a relatively quiet environment. For example, the second intensity threshold may be 40 dB. That is, when the noise intensity in the external environment is low (e.g., less than 40 dB), the noise reduction circuit 105 selects the passive noise reduction mode and disables the active noise reduction function. This can reduce the power consumption of the acoustic device 100.

[0283] S42-2: Determine whether the intensity of the first sound signal is greater than or equal to a first intensity threshold, and select an anti-breaking noise reduction mode from the multiple noise reduction modes.

[0284] The first intensity threshold is greater than the second intensity threshold. For example, the first intensity threshold may be 90 dB. When the noise level in the external environment is high (e.g., greater than or equal to 90 dB), the noise reduction circuit 105 may select an anti-crackling noise reduction mode. This can prevent the speaker 102 from cracking.

[0285] S42-3: Determine that the intensity of the first sound signal is greater than a second intensity threshold, and the bandwidth type of the first sound signal is a narrowband type, and select a narrowband noise reduction mode from the multiple noise reduction modes.

[0286] The condition for enabling the active noise reduction function is that the intensity of the first sound signal is greater than the second intensity threshold. Based on this, if the bandwidth type of the first sound signal is narrowband, the noise reduction circuit 105 selects the narrowband noise reduction mode. This allows active noise reduction to be performed only in the target frequency band where the energy of the first sound signal is concentrated, rather than across the entire frequency band. This helps to increase the depth of noise reduction within the target frequency band and enhance the active noise reduction effect.

[0287] In some embodiments, the judgment logic of the noise reduction circuit 105 for adaptively selecting the target noise reduction mode may be as follows: the noise reduction circuit 105 first determines whether the intensity of the first sound signal is less than the second intensity threshold. If so, the passive noise reduction mode is selected. If not, the active noise reduction function is turned on. Afterwards, the noise reduction circuit 105 respectively determines whether the following two conditions are met: Condition 1: The intensity of the first sound signal is greater than or equal to the first intensity threshold, Condition 2: The bandwidth type of the first sound signal is a narrowband type. At this time, the judgment result includes the following four cases: If only Condition 1 is met, the anti-breaking noise reduction mode is selected; if only Condition 2 is met, the narrowband noise reduction mode is selected; if both Condition 1 and Condition 2 are met, the anti-breaking noise reduction mode and the narrowband noise reduction mode can be selected at the same time. If neither Condition 1 nor Condition 2 is met, the normal noise reduction mode is selected.

[0288] In some embodiments, when the first sound signal includes both an ambient noise signal and a leakage signal, the noise reduction circuit 105 may first reduce the leakage signal component in the first sound signal to generate a quasi-ambient noise signal. Then, based on the quasi-ambient noise signal, the noise reduction circuit 105 may adaptively select a target noise reduction mode from multiple noise reduction modes. The aforementioned method for reducing the leakage signal component in the first sound signal has been described above and is not further elaborated here.

[0289] The noise reduction circuit 105 reduces the leakage signal component in the first sound signal so that the obtained quasi-ambient noise signal is closer to the actual ambient noise. Therefore, the target noise reduction mode is adaptively selected based on the quasi-ambient noise signal, so that the selected target noise reduction mode is more in line with the current environment, thereby improving the noise reduction effect.

[0290] S43: Execute the target noise reduction mode.

[0291] In some embodiments, the acoustic device 100 operates in a feedforward noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the first sound signal. In some embodiments, the acoustic device 100 operates in a feedback noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the second sound signal. In some embodiments, the acoustic device 100 operates in a hybrid noise reduction mode, and the noise reduction circuit 105 performs a target noise reduction mode based on the first sound signal and the second sound signal.

[0292] In summary, the active noise reduction method P400 provided in this specification can adaptively adjust the noise reduction mode based on the noise conditions of the external environment in which the acoustic device 100 is located, so that the active noise reduction process of the acoustic device 100 is more consistent with the noise conditions of the current environment, which helps to improve the overall performance of the acoustic device 100. For example, when the noise in the current environment is low, the acoustic device 100 can turn off the active noise reduction function to reduce power consumption; when the noise in the current environment is high, the acoustic device 100 can select the anti-crackling noise reduction mode to prevent the speaker 102 from cracking; when the noise in the current environment is narrowband, the acoustic device 100 can select the narrowband noise reduction mode to increase the noise reduction depth and improve the noise reduction effect.

[0293] In the case where the acoustic device 100 provides multiple noise reduction modes, the present application also provides another active noise reduction method that can be performed by the noise reduction circuit 105. In this active noise reduction method, the noise reduction circuit 105 can obtain the user's instructions and select a target noise reduction mode from multiple noise reduction modes according to the user's instructions, and then execute the target noise reduction mode. For example, the acoustic device 100 can be provided with an interactive control, and the user can switch between different noise reduction modes through the interactive control. For another example, the acoustic device 100 can provide an interactive interface, which can be presented on the screen of the acoustic device 100, or on a target device connected to the acoustic device 100 for communication, and the user can select different noise reduction modes through the interactive interface. In some embodiments, the user's instructions can indicate a specific noise reduction mode, so that the noise reduction circuit 105 can determine the noise reduction mode indicated by the instructions as the target noise reduction mode. In some embodiments, the user's instructions can specifically indicate the ambient noise conditions in which the user is located, and the noise reduction circuit 105 can select the target noise reduction mode from multiple noise reduction modes based on the ambient noise conditions indicated by the instructions. In this way, users can independently select a suitable active noise reduction mode based on their preferences and / or the current ambient noise conditions, thereby meeting the personalized needs of different users.

[0294] Another aspect of this specification provides a non-transitory storage medium storing at least one set of executable instructions for performing active noise reduction. When the executable instructions are executed by a processor, the executable instructions direct the processor to implement the steps of the active noise reduction method described in this specification. In some possible implementations, various aspects of this specification may also be implemented in the form of a program product comprising program code. When the program product is executed on an acoustic device 100, the program code is used to cause the acoustic device 100 to perform the steps of the active noise reduction method described in this specification. The program product for implementing the above method may include the program code in a portable compact disc read-only memory (CD-ROM) and may be executed on the acoustic device 100. However, the program product of this specification is not limited to this. In this specification, a readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system. The program product may utilize any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples of computer-readable storage media include: an electrical connection having one or more conductors, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The computer-readable storage medium may include a data signal propagated in baseband or as part of a carrier wave, which carries readable program code. Such a propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. The computer-readable storage medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the foregoing. Program code for performing the operations described herein may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may execute entirely on the acoustic device 100, partially on the acoustic device 100, as a stand-alone software package, partially on the acoustic device 100 and partially on a remote computing device, or entirely on the remote computing device.

[0295] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0296] In summary, after reading this detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not expressly stated herein, those skilled in the art will understand that this specification encompasses various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are intended to be suggested by this specification and are within the spirit and scope of the exemplary embodiments of this specification.

[0297] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, “one embodiment,” “an embodiment,” and / or “some embodiments” mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is emphasized and should be understood that two or more references to “an embodiment,” “one embodiment,” or “an alternative embodiment” in various parts of this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be appropriately combined in one or more embodiments of this specification.

[0298] It should be understood that in the foregoing descriptions of the embodiments of this specification, to facilitate understanding of a feature and to simplify this specification, various features are combined in a single embodiment, figure, or description thereof. However, this does not necessarily mean that these features are combined. When reading this specification, a person skilled in the art may label some of the devices as separate embodiments. In other words, the embodiments of this specification can also be understood as the integration of multiple sub-embodiments. This also applies when each sub-embodiment contains fewer than all the features of a single previously disclosed embodiment.

[0299] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, articles, and the like, cited herein is hereby incorporated by reference in its entirety for all purposes, except for any prosecution document history related thereto, any equivalent that may be inconsistent or conflicting with this document, or any equivalent prosecution document history that may have a limiting effect on the broadest scope of the claims now or hereafter associated with this document. For example, if there is any inconsistency or conflict between the descriptions, definitions, and / or usage of terms associated with any incorporated material and the terminology, descriptions, definitions, and / or usage associated with this document, the terminology in this document shall control.

[0300] Finally, it should be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can adopt alternative configurations based on the embodiments in this specification to implement the application in this specification. Therefore, the embodiments of this specification are not limited to the embodiments precisely described in the application.

Claims

1. An open wearable acoustic device, characterized in that: include: Support members; a speaker, physically connected to the support member, wherein when the acoustic device is worn on the user's head, the speaker is located on a side of the acoustic device close to the ear canal opening, with a sound output end of the speaker facing the ear canal opening and forming an open space between the speaker and the user's eardrum; a first sound sensor module, comprising N sound sensors, each physically connected to the support member and distributed on a side of the speaker away from the eardrum, wherein the N sound sensors are oriented in different directions relative to a target point of the speaker, where N is an integer greater than or equal to 2; as well as The noise reduction circuit is communicatively connected to the first sound sensor module and the speaker, and is configured to: Determine the target direction from which the ambient noise comes, Based on the target direction, determine N weights corresponding to the N sound sensors so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights leads the phase of the ambient noise reaching the sound output end of the speaker, generating a first noise cancellation signal based on the N individual environmental noise signals collected by the N sound sensors and the N weights, and The first noise cancellation signal is sent to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

2. The acoustic device according to claim 1, characterized in that The integrated environmental noise signal is a signal obtained by weighted summing the N individual environmental noise signals based on the N weights.

3. The acoustic device according to claim 1, wherein For the i-th sound sensor among the N sound sensors, the angle between the direction of the i-th sound sensor relative to the target point and the target direction is θ i , the corresponding weight and the θ i Negative correlation, wherein i is any positive integer less than or equal to N.

4. The acoustic device according to claim 1, wherein The noise reduction circuit includes: N feedforward filters, corresponding one to one to the N sound sensors, The i-th feedforward filter is connected to the i-th sound sensor and the speaker, and is configured to filter the individual environmental noise signal collected by the i-th sound sensor, where i is any positive integer less than or equal to N.

5. The acoustic device according to claim 4, characterized in that To generate the first noise cancellation signal, the noise reduction circuit: For an i-th sound sensor among the N sound sensors, adjusting a filtering parameter of an i-th feedforward filter based on the weight corresponding to the i-th sound sensor, and filtering the individual environmental noise signal collected by the i-th sound sensor using the adjusted i-th feedforward filter to generate an i-th individual noise-cancelled signal, where i is any positive integer less than or equal to N; as well as The N individual denoised signals generated by the N feedforward filters are superimposed to obtain the first denoised signal.

6. The acoustic device according to claim 1, wherein The target direction is the direction of incoming waves of full-band ambient noise. To determine the target direction, the noise reduction circuit: Acquiring the N individual environmental noise signals collected by the N sound sensors; and The target direction is obtained by performing full-band direction of arrival (DOA) analysis on the N individual environmental noise signals.

7. The acoustic device according to claim 1, wherein The environmental noise includes M sub-band noises corresponding to the M sub-bands, and the target direction includes M incoming wave directions corresponding to the M sub-bands, where M is an integer greater than 1. Wherein, in order to determine the target direction, the noise reduction circuit: Obtaining the N individual environmental noise signals collected by the N sound sensors, and For the j-th sub-band among the M sub-bands: extracting the sub-band noise signals corresponding to the j-th sub-band from the N individual environmental noise signals respectively, to obtain N sub-band noise signals corresponding to the j-th sub-band, and By performing DOA analysis on the N sub-band noise signals, the direction of arrival corresponding to the j-th sub-band is obtained. Wherein, j is any positive integer less than or equal to M.

8. The acoustic device according to claim 7, characterized in that The first noise reduction signal includes M sub-band noise reduction signals corresponding to the M sub-bands, wherein: To generate the first noise cancellation signal, the noise reduction circuit performs the following operation on the j-th sub-band of the M sub-bands: Based on the incoming wave direction corresponding to the j-th sub-band, N sub-band weights corresponding to the N sound sensors are determined, so that the phase of the integrated sub-band noise signal measured by the first sound sensor module based on the N sub-band weights is ahead of the phase of the ambient noise corresponding to the j-th sub-band reaching the sound output end of the speaker. generating N individual sub-band noise cancellation signals corresponding to the j-th sub-band based on the N sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors and the N sub-band weights, and The N individual sub-band denoised signals are superimposed to obtain a sub-band denoised signal corresponding to the j-th sub-band, Wherein, j is any positive integer less than or equal to M.

9. The acoustic device according to claim 1, wherein Said N=2, said N sound sensors are located at the acoustic zero point of said loudspeaker and in opposite directions relative to said target point.

10. The acoustic device according to claim 1, wherein The N=3, and the N sound sensors are distributed in a triangle shape at the acoustic zero point position of the speaker.

11. The acoustic device according to claim 1, wherein At least some of the N sound sensors are omnidirectional microphones or directional microphones.

12. The acoustic device according to claim 1, wherein The noise reduction circuit comprises: at least one storage medium storing at least one instruction set for performing noise reduction; and at least one processor, in communication with the speaker, the first sound sensor module, and the at least one storage medium, When the acoustic device is running, the at least one processor reads the at least one instruction set and executes according to the instructions of the at least one instruction set: Determine the target direction from which the ambient noise comes, Based on the target direction, determine N weights corresponding to the N sound sensors so that the phase of the integrated ambient noise signal measured by the first sound sensor module based on the N weights leads the phase of the ambient noise reaching the sound output end of the speaker, generating a first noise cancellation signal based on the N individual environmental noise signals collected by the N sound sensors and the N weights, and The first noise cancellation signal is sent to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

13. The acoustic device according to claim 1, wherein The acoustic device is one of earphones, mufflers, hearing aids, and acoustic glasses.

14. An active noise reduction method, characterized in that: Applied to the open wearable acoustic device according to claim 1, the method comprises, by the noise reduction circuit: Determine the target direction from which the ambient noise comes; Determining, based on the target direction, N weights corresponding to the N sound sensors so that a phase of a comprehensive ambient noise signal measured by the first sound sensor module based on the N weights leads a phase of the ambient noise reaching a sound output end of the speaker; generating a first noise cancellation signal based on the N individual environmental noise signals collected by the N sound sensors and the N weights; as well as The first noise cancellation signal is sent to the speaker so that the speaker converts the first noise cancellation signal into a first noise cancellation frequency to reduce the volume of the ambient noise at the eardrum.

15. The method according to claim 14, characterized in that The integrated environmental noise signal is a signal obtained by weighted summing the N individual environmental noise signals based on the N weights.

16. The method according to claim 14, characterized in that The angle between the direction of the i-th sound sensor of the N sound sensors relative to the target point and the target direction is θ i , the corresponding weight and the θ i Negative correlation, wherein i is any positive integer less than or equal to N.

17. The method according to claim 14, characterized in that The noise reduction circuit includes: N feedforward filters, corresponding one-to-one to the N sound sensors, wherein the i-th feedforward filter is connected to the i-th sound sensor and the speaker and is configured to filter the individual environmental noise signal collected by the i-th sound sensor, where i is any positive integer less than or equal to N; and Generating a first noise cancellation signal includes: For an i-th sound sensor among the N sound sensors, adjusting a filtering parameter of an i-th feedforward filter based on the weight corresponding to the i-th sound sensor, and filtering the individual environmental noise signal collected by the i-th sound sensor using the adjusted i-th feedforward filter to generate an i-th individual noise-cancelled signal, where i is any positive integer less than or equal to N; and The N individual denoised signals generated by the N feedforward filters are superimposed to obtain the first denoised signal.

18. The method according to claim 14, characterized in that The target direction is the incoming direction of the full-band ambient noise; and Determining the target direction from which the ambient noise comes includes: Obtaining the N individual environmental noise signals collected by the N sound sensors, and The target direction is obtained by performing full-band direction of arrival (DOA) analysis on the N individual environmental noise signals.

19. The method according to claim 14, wherein The environmental noise includes M sub-band noises corresponding to the M sub-bands, and the target direction includes M incoming wave directions corresponding to the M sub-bands, where M is an integer greater than 1; as well as Determining the target direction from which the ambient noise comes includes: Obtaining N individual environmental noise signals collected by the N sound sensors, and For the j-th sub-band among the M sub-bands: extracting the sub-band noise signals corresponding to the j-th sub-band from the N individual environmental noise signals respectively, to obtain N sub-band noise signals corresponding to the j-th sub-band, and By performing DOA analysis on the N sub-band noise signals, the direction of arrival corresponding to the j-th sub-band is obtained. Wherein, j is any positive integer less than or equal to M.

20. The method according to claim 19, wherein The first noise cancellation signal includes M sub-band noise cancellation signals corresponding to the M sub-bands; and The generating the first noise cancellation signal comprises: for the j-th sub-frequency band among the M sub-frequency bands: Based on the incoming wave direction corresponding to the j-th sub-band, N sub-band weights corresponding to the N sound sensors are determined, so that the phase of the integrated sub-band noise signal measured by the first sound sensor module based on the N sub-band weights is ahead of the phase of the ambient noise corresponding to the j-th sub-band reaching the sound output end of the speaker. generating N individual sub-band noise cancellation signals corresponding to the j-th sub-band based on the N sub-band noise signals corresponding to the j-th sub-band collected by the N sound sensors and the N sub-band weights, and The N individual sub-band denoised signals are superimposed to obtain a sub-band denoised signal corresponding to the j-th sub-band, Wherein, j is any positive integer less than or equal to M.

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