Acoustic system

Abstract

Embodiments of the present specification provide an acoustic system, comprising: a loudspeaker, a first sound sensor, a second sound sensor, and a signal processing circuit. The first sound sensor works to collect ambient sound and generate a first signal, the ambient sound comprising a first sound from the loudspeaker and a second sound from a target sound source; the second sound sensor works to collect ambient sound and generate a second signal, wherein the first signal and the second signal satisfy k2≥2k1, k1 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the first signal, and k2 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the second signal; the signal processing circuit works to reduce a signal component corresponding to the first sound in the first signal based on the second signal to obtain a target signal, and perform a target operation on the target signal. The acoustic system can reduce or eliminate feedback components in the target signal.

Description

TECHNICAL FIELD

[0001] The present specification relates to the field of acoustics, and in particular, to an acoustic system. BACKGROUND

[0002] Some acoustic systems include both a loudspeaker and a sound sensor. There is usually a problem of acoustic feedback in these acoustic systems. The acoustic feedback refers to that the sound signal collected by the sound sensor is played through the loudspeaker after a certain processing, and the sound emitted by the loudspeaker is re-collected by the sound sensor, so that the acoustic system forms a closed loop of “loudspeaker->sound sensor->loudspeaker”. In the above acoustic system, the sound of the loudspeaker picked up by the sound sensor can be referred to as feedback sound. The existence of the feedback sound causes some problems in the acoustic system. For example, it causes the acoustic system to produce howling and other problems, and it can also restrict the maximum forward gain that the acoustic system can achieve. Therefore, it is necessary to provide an acoustic system that can reduce or eliminate the feedback sound. SUMMARY

[0003] The present specification provides an acoustic system that can reduce or eliminate feedback sound, thereby avoiding howling and other problems caused by feedback sound, and improving the maximum forward gain that the acoustic system can achieve.

[0004] In a first aspect, the present specification provides an acoustic system, comprising: a loudspeaker, a first sound sensor, a second sound sensor and a signal processing circuit, wherein the loudspeaker receives a driving signal and converts it into a first sound when working, the first sound sensor collects an environment sound and generates a first signal when working, the environment sound includes the first sound and a second sound from a target sound source, the target sound source includes other sound sources except the loudspeaker, the second sound sensor collects the environment sound and generates a second signal when working, wherein the first signal and the second signal satisfy k2≥2k1, where k1 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the first signal, k2 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the second signal, the signal processing circuit is connected with the first sound sensor and the second sound sensor respectively, and when working, it reduces the signal component corresponding to the first sound in the first signal based on the second signal to obtain a target signal, and performs a target operation on the target signal.

[0005] In some embodiments, to satisfy k2≥2k1, the first signal and the second signal satisfy at least one of the following conditions: a ratio of signal energy in the second signal corresponding to the first sound to signal energy in the second signal corresponding to the second sound is greater than or equal to 2; a ratio of signal energy in the second signal corresponding to the first sound to signal energy in the first signal corresponding to the first sound is greater than or equal to 2; and a ratio of signal energy in the first signal corresponding to the second sound to signal energy in the first signal corresponding to the first sound is greater than or equal to 2.

[0006] In some embodiments, a positional relationship among the first sound sensor, the second sound sensor, and the loudspeaker satisfies a preset condition, so that the first signal and the second signal satisfy k2≥2k1.

[0007] In some embodiments, the preset condition comprises: L1≥2L2, where L2 is a distance between the second sound sensor and the loudspeaker, and L1 is a distance between the first sound sensor and the loudspeaker.

[0008] In some embodiments, the acoustic system further comprises a housing, a partial area of the housing forms an acoustic cavity, the loudspeaker and the second sound sensor are both located inside the acoustic cavity, and the first sound sensor is located outside the acoustic cavity.

[0009] In some embodiments, a sound generating component of the loudspeaker divides the acoustic cavity into a first acoustic cavity and a second acoustic cavity, a sound emitting surface of the sound generating component faces the first acoustic cavity, and the second sound sensor is located inside the first acoustic cavity or the second acoustic cavity.

[0010] In some embodiments, the second sound sensor is coupled to the sound generating component of the loudspeaker.

[0011] In some embodiments, the acoustic system further comprises a housing, a sound pickup surface of the second sound sensor and a sound pickup surface of the first sound sensor are both located in a free space outside the housing, and the second sound sensor is closer to the loudspeaker relative to the first sound sensor.

[0012] In some embodiments, the acoustic system further comprises a housing, a partial area of the housing forms a first acoustic cavity and a second acoustic cavity, the loudspeaker is located in the first acoustic cavity, the second sound sensor is located in the second acoustic cavity, and the second sound sensor is closer to the loudspeaker relative to the first sound sensor.

[0013] In some embodiments, the acoustic system further comprises a housing, a sound pickup surface of the first sound sensor is located in a free space outside the housing, a sound pickup surface of the second sound sensor is located in an internal space of the housing, and the second sound sensor is closer to the loudspeaker relative to the first sound sensor.

[0014] In some embodiments, the acoustic system further comprises a first housing and a second housing, wherein,

[0015] the second housing is located inside the first housing, and the second housing is formed with an acoustic cavity, and the loudspeaker and the second sound sensor are located inside the acoustic cavity.

[0016] In some embodiments, the acoustic system further comprises a barrier, the second sound sensor and the loudspeaker are located on a first side of the barrier, and the first sound sensor is located on a second side of the barrier.

[0017] In some embodiments, sound pickup directivities of the first sound sensor and the second sound sensor satisfy a preset condition, so that the first signal and the second signal satisfy k2≥2k1.

[0018] In some embodiments, sound pickup directivities of the first sound sensor and the second sound sensor satisfy at least one of the following conditions: sound pickup sensitivity of the first sound sensor in a first direction is greater than sound pickup sensitivity in a second direction; and sound pickup sensitivity of the second sound sensor in the first direction is less than sound pickup sensitivity in the second direction, wherein the first direction points to the target sound source, and the second direction points to the loudspeaker.

[0019] In some embodiments, the first sound sensor is located at a first position within a target area, and the second sound sensor is located at a second position within the target area, wherein the first position and the second position satisfy at least one of the following conditions: sound energy from the loudspeaker at the first position is less than sound energy from the loudspeaker at other positions within the target area except the first position; and sound energy from the loudspeaker at the second position is greater than sound energy from the loudspeaker at other positions within the target area except the second position.

[0020] In some embodiments, to obtain the target signal, the signal processing circuit: performs an adaptive filtering operation on the second signal to obtain a third signal, and subtracts the third signal from the first signal to obtain the target signal.

[0021] In some embodiments, the signal processing circuit is further configured to update a filter parameter corresponding to the adaptive filtering operation based on at least one of the second signal and the target signal.

[0022] In some embodiments, to obtain the target signal, the signal processing circuit is configured to perform a first pre-processing operation on the first signal to obtain a first intermediate signal, perform a second pre-processing operation on the second signal to obtain a second intermediate signal, and subtract a signal component corresponding to the first sound in the first intermediate signal based on the second intermediate signal to obtain the target signal.

[0023] In some embodiments, the first pre-processing operation comprises at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation, and the second pre-processing operation comprises at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation.

[0024] In some embodiments, the signal processing circuit is further connected with the loudspeaker, and when performing the target operation, the signal processing circuit is configured to amplify the target signal by a gain and send the amplified signal to the loudspeaker to drive the loudspeaker to produce sound.

[0025] From the above technical solutions, it can be seen that the acoustic system provided by the present specification comprises a loudspeaker, a first sound sensor, a second sound sensor, and a signal processing circuit. When the loudspeaker is working, it receives a driving signal and converts it into a first sound. When the first sound sensor is working, it collects environmental sound and generates a first signal, the environmental sound including the first sound and a second sound from a target sound source. When the second sound sensor is working, it collects environmental sound and generates a second signal, the first signal and the second signal satisfying k2≥2k1, where k1 is the ratio of the signal energy corresponding to the first sound to the signal energy corresponding to the second sound in the first signal, and k2 is the ratio of the signal energy corresponding to the first sound to the signal energy corresponding to the second sound in the second signal. The signal processing circuit is connected with the first sound sensor and the second sound sensor respectively, and when working, it subtracts a signal component corresponding to the first sound in the first signal based on the second signal to obtain a target signal, and performs a target operation on the target signal. As can be seen, the acoustic system provided by the present specification can reduce or eliminate feedback components in the target signal, thereby avoiding problems such as howling caused by feedback sound, and can also improve the maximum forward gain that can be achieved by the acoustic system.

[0026] Other functions of the acoustic system provided by the present specification will be partially listed in the following description. The creative aspects of the acoustic system provided by the present specification can be fully explained by practicing or using the methods, devices, and combinations described in the following detailed examples. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of an application scenario provided according to an embodiment of this specification is shown;

[0029] Figure 2 A schematic diagram of a design for an acoustic system provided according to an embodiment of this specification is shown;

[0030] Figure 3 A schematic diagram of another design for an acoustic system provided according to an embodiment of this specification is shown;

[0031] Figure 4 A schematic diagram of yet another design of an acoustic system provided according to an embodiment of this specification is shown;

[0032] Figure 5 A schematic diagram of yet another design of an acoustic system provided according to an embodiment of this specification is shown;

[0033] Figures 6A to 6F Several structural schematic diagrams of acoustic systems provided according to embodiments of this specification are shown;

[0034] Figures 7A to 7G Several other structural schematic diagrams of acoustic systems provided according to embodiments of this specification are shown;

[0035] Figures 8A to 8F Several more schematic diagrams of acoustic systems provided according to embodiments of this specification are shown;

[0036] Figure 9 A schematic diagram of the pickup direction of an acoustic system provided according to an embodiment of this specification is shown;

[0037] Figure 10A A schematic diagram showing the positions of a first sound sensor and a second sound sensor in a target area in an acoustic system provided according to an embodiment of this specification is shown.

[0038] Figure 10B A schematic diagram showing the feedback sound energy at various locations within the target area of ​​the acoustic system is presented; and

[0039] Figure 11A diagram showing test results of acoustic systems provided according to embodiments of the present specification in terms of adaptive filtering performance is shown. DETAILED DESCRIPTION

[0040] The following description provides specific applications and requirements of the present specification, which is intended to enable a person skilled in the art to manufacture and use the content of the present specification. Various local modifications of the disclosed embodiments are apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present specification. Therefore, the present specification is not limited to the embodiments shown, but is consistent with the widest scope of the claims.

[0041] The terms used herein are only for the purpose of describing specific example embodiments, and are not limiting. For example, unless the context clearly indicates otherwise, as used herein, the singular forms "a", "an", and "the" can also include the plural forms. When used in the present specification, the terms "comprise", "include" and / or "contain" mean that the associated whole, step, operation, element and / or component exists, but do not exclude the presence of one or more other features, whole, step, operation, element, component and / or group or other features, whole, step, operation, element, component and / or group can be added to the system / method.

[0042] These features of the present specification and other features, as well as the operation and function of related elements of the structure, and the combination and economy of manufacture of components can be significantly improved in view of the following description. Referring to the drawings, all of which form part of the present specification. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of the present specification. It should also be understood that the drawings are not drawn to scale.

[0043] The flowchart used in the present specification shows the operation of system implementation according to some embodiments of the present specification. It should be clearly understood that the operations of the flowchart can not be implemented in sequence. On the contrary, the operations can be implemented in reverse order or simultaneously. In addition, one or more other operations can be added to the flowchart. One or more operations can be removed from the flowchart.

[0044] Before the specific embodiments of the present specification are described, the application scenario of the present specification is introduced as follows. The acoustic system provided by the present specification can be applied to scenarios that require feedback sound to be reduced or eliminated. The following is illustrated by way of example. Figure 1

[0045] Figure 1 A diagram showing an application scenario provided according to embodiments of the present specification is shown. As shown in FIG. 1, the acoustic system provided by the present specification can be applied to a scenario where a user is in a room 100 and a sound source 110 is in the room 100. The sound source 110 can be a speaker, a microphone, or any other device that generates sound. The acoustic system provided by the present specification can be used to reduce or eliminate feedback sound in the room 100. Figure 1 ​As shown, the application scenario 001 can be a sound amplification scenario, an auxiliary listening scenario, a hearing assistance scenario, etc. In this scenario, the sound sensor 120 works to collect ambient sound. In this process, if the loudspeaker 110 also plays sound synchronously, the sound played by the loudspeaker 110 will also be collected by the sound sensor 120. In this way, the ambient sound collected by the sound sensor 120 includes not only the sound from the target sound source 160 but also the sound from the loudspeaker 110. Further, the sound signal collected by the sound sensor 120 is input to the loudspeaker 110 after being amplified by the forward gain (G), so as to drive the loudspeaker 110 to produce sound. In this way, a closed loop of "loudspeaker -> sound sensor -> loudspeaker" is formed in the acoustic system. In this case, when the sound signal of some frequency is self-excited and oscillated, a howling phenomenon will occur. Such howling will make the user feel uncomfortable, and when the howling is serious, it can also cause damage to the devices in the acoustic system. In addition, the existence of the howling also limits the forward gain amplification multiple of the acoustic system, thereby restricting the maximum forward gain that the acoustic system can achieve.

[0046] It should be noted that the application scenarios described above are only part of the application scenarios to which the present application is applicable. The acoustic system provided by the present application can also be applied to other similar scenarios, which are not described in the specification. Those skilled in the art should understand that the acoustic system provided by the present application is also applicable to other use scenarios within the protection scope of the present application. Figure 1 The application scenarios shown are only part of the application scenarios to which the present application is applicable. The acoustic system provided by the present application can also be applied to other similar scenarios, which are not described in the specification. Those skilled in the art should understand that the acoustic system provided by the present application is also applicable to other use scenarios within the protection scope of the present application.

[0047] As can be seen from the above, the existence of feedback sound can cause a series of problems in the acoustic system, including but not limited to: producing howling, restricting the maximum forward gain that the acoustic system can achieve, etc. Therefore, the present application provides an acoustic system with reduced or eliminated feedback sound, thereby avoiding the above series of problems.

[0048] The acoustic system provided by the present application can use an acoustic feedback cancellation (AFC) technique to reduce or eliminate feedback sound. In order to facilitate subsequent description, the principle of the AFC technique will be introduced first as follows. Figure 2 The principle of the AFC technique will be introduced first as follows.

[0049] Figure 2 A design schematic of an acoustic system provided by an embodiment of the present application is shown. The acoustic system 10 can be one of a hearing assistance / auxiliary listening system, a sound amplification system, etc. The acoustic system 10 can use an AFC technique to reduce or eliminate feedback components (i.e., signal components corresponding to feedback sound). As shown, Figure 2 The acoustic system 10 can include a loudspeaker 110, a sound sensor 120, and a signal processing circuit 150.

[0050] The speaker 110 is a device for converting an electrical signal into a sound, which can also be referred to as an electro-acoustic transducer. For example, the speaker 110 can be a loudspeaker. The speaker 110 can be a device for making sound based on at least one of a gas, a liquid, and a solid. The speaker 110 can be connected with the signal processing circuit 150, and in operation, receives the electrical signal from the signal processing circuit 150 and converts it into a sound to be played out. In some embodiments, the acoustic system 10 can further include a first peripheral circuit (not shown in Figure 2 The first peripheral circuit is connected between the signal processing circuit 150 and the speaker 110. The first peripheral circuit can include all or part of the circuit between the output of the signal processing circuit 150 and the speaker 110. The first peripheral circuit can perform some processing on the electrical signal output by the signal processing circuit 150, so that the processed electrical signal is suitable for the speaker 110 to play. The first peripheral circuit can include, but is not limited to, at least one of an operational amplifier device, a power amplifier device, a digital-to-analog converter device, a capacitor, an inductor, a resistor, and the like.

[0051] The sound sensor 120 is a device for picking up a sound and converting the sound into an electrical signal, which can also be referred to as an acoustic-electric transducer. For example, the sound sensor 120 can be a microphone (MIC). The sound sensor 120 can be a device for picking up sound based on at least one of a gas, a liquid, and a solid. The sound sensor 120 can be connected with the signal processing circuit 150, and in operation, collects an ambient sound and converts it into an electrical signal, which is then sent to the signal processing circuit 150. In some embodiments, the acoustic system 10 can further include a second peripheral circuit (not shown in Figure 2 The second peripheral circuit is connected between the sound sensor 120 and the signal processing circuit 150. The second peripheral circuit can include all or part of the circuit between the sound sensor 120 and the input of the signal processing circuit 150. The second peripheral circuit can perform some processing on the electrical signal picked up by the sound sensor 120, so as to be converted into a signal suitable for processing by the signal processing circuit 150. The second peripheral circuit can include, but is not limited to, at least one of a power amplifier device, an operational amplifier device, an analog-to-digital converter device, a capacitor, an inductor, a resistor, and the like.

[0052] Continuing to refer to Figure 2The sound sensor 120 collects an ambient sound to generate a pickup signal y, and inputs the pickup signal y to the signal processing circuit 150. The ambient sound at least includes a second sound emitted by a target sound source 160. The target sound source 160 refers to a sound source other than the loudspeaker 110. For example, the target sound source 160 can include an electronic device (such as a television, a sound box, a mobile phone, etc.) having a sound playing function; for another example, the target sound source 160 can also include a human throat. The pickup signal y can be referred to as an input signal of the signal processing circuit 150. The signal processing circuit 150 performs a series of processing on the pickup signal y to obtain a driving signal u, and sends the driving signal u to the loudspeaker 110. The driving signal u can be referred to as an output signal of the signal processing circuit 150. The loudspeaker 110 receives the driving signal u and converts it into a first sound. The first sound is re-collected by the sound sensor 120 after being transmitted through the feedback path, and thus the first sound can also be referred to as a feedback sound. As can be seen, the ambient sound collected by the sound sensor 120 not only includes the second sound from the target sound source 160, but also includes the first sound from the loudspeaker 110. That is, the pickup signal y includes a signal component x corresponding to the first sound (i.e., the feedback sound) and a signal component v corresponding to the second sound.

[0053] The signal processing circuit 150 can be a circuit having a certain signal processing capability. The input end of the signal processing circuit 150 is connected with the sound sensor 120, the output end is connected with the loudspeaker 110, and the signal processing circuit 150 can obtain the pickup signal y from the sound sensor 120 when working, perform a preset signal processing procedure on the pickup signal y to obtain the driving signal u, and send the driving signal u to the loudspeaker 110.

[0054] In some embodiments, the signal processing circuit 150 can include a plurality of hardware circuits having a connection relationship, each hardware circuit including one or more electrical elements, each electrical element implementing one or more functional units, so that the plurality of hardware circuits work together to implement the signal processing procedure.

[0055] In some embodiments, the signal processing circuit 150 can include a hardware device having a data information processing function and a program necessary for driving the hardware device to work, which implements the signal processing procedure by executing the program. For example, the signal processing circuit 150 can include at least one storage medium and at least one processor. The storage medium can include a data storage device. The data storage device can be a non-transitory storage medium or a transitory storage medium. For example, the data storage device can include one or more of a magnetic disk, a read-only memory (ROM), or a random access memory (RAM). The storage medium further includes at least one instruction set stored in the data storage device. The instructions are computer program codes, which can include programs, routines, objects, components, data structures, processes, modules, etc. that perform the signal processing methods provided in the present specification.

[0056] The at least one processor can be communicatively connected to the at least one storage medium. The at least one processor is used to execute the at least one instruction set. When the acoustic system is running, the at least one processor reads the at least one instruction set and executes the signal processing procedure according to the instructions of the at least one instruction set. The processor can 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 physics 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.

[0057] Continuing to refer to Figure 2 , in order to reduce or eliminate the feedback component, the signal processing circuit 150 can include an acoustic feedback cancellation unit 170. The input of the acoustic feedback cancellation unit 170 includes the driving signal u and the pickup signal y. The acoustic feedback cancellation unit 170 can reduce the signal component corresponding to the first sound in the pickup signal y based on the driving signal u, thereby obtaining the target signal e.

[0058] In combination with Figure 2To be specific, the acoustic feedback cancellation unit 170 can solve and adaptively update a time-varying transfer function F' to fit the transfer function F corresponding to the feedback path. For the sake of distinction, the transfer function F' is referred to as a predicted transfer function F' hereinafter, and the transfer function F corresponding to the feedback path is referred to as a true transfer function F. The acoustic feedback cancellation unit 170 performs an adaptive filtering operation on the driving signal u using the predicted transfer function F' to obtain a signal x', i.e., x' = u * F'. The signal x' can be regarded as a predicted value of the feedback component (i.e., the signal component in the pickup signal y corresponding to the first sound) in the pickup signal y. Further, the acoustic feedback cancellation unit 170 can subtract the signal x' from the pickup signal y to obtain a target signal e, i.e., e = y - x'. The target signal e thus obtained does not contain or contains less components of the feedback sound.

[0059] It should be noted that the acoustic feedback cancellation unit 170 can be implemented by using various adaptive filtering algorithms when solving the predicted transfer function F', for example, one or more of the least mean square (LMS), normalized least mean square (NLMS), recursive least squares (RLS), other adaptive filtering algorithms, and any derivative algorithm of the above-mentioned algorithms, which are not limited in the present application. In addition, the adaptive filtering algorithm can be adaptive filtering in the time domain, frequency domain or other transform domain.

[0060] According to the theory of the adaptive filtering algorithm, the update of the predicted transfer function F' can be achieved by minimizing the expectation of the mean square function of the target signal e, i.e.:

[0061] min F′ E[e 2 ]=min F′ E[(y-u*F′) 2 ] Formula (1-1)

[0062] For example, taking the LMS algorithm used by the acoustic feedback cancellation unit 170 as an example, based on the gradient descent optimization method, the above formula (1-1) can be derived to obtain the update formula of the predicted transfer function F' as follows:

[0063] F' <- F' + μ * e * u Formula (2-1)

[0064] Wherein, μ is the iteration step.

[0065] It should be understood that when the acoustic feedback cancellation unit 170 employs an algorithm such as NLMS, RLS, etc., the update formula of the predicted transfer function F' can be derived in a similar way, which will not be exemplified one by one in the present specification.

[0066] It can be seen from the above, Figure 2 The acoustic system shown can reduce or eliminate the feedback sound by employing the AFC technology, thereby avoiding a series of problems caused by the feedback sound.

[0067] According to the signal processing theory, Figure 2 The closed-loop gain A of the acoustic system shown can be expressed as follows:

[0068]

[0069] According to the Nyquist stability criterion, the requirement for the acoustic system to cancel the feedback sound is that the predicted transfer function F' obtained is exactly equal to the real transfer function F, i.e. F' = F. When the above requirement is met, the acoustic system will always be stable, no howling will be produced, and the acoustic system can achieve infinite gain at this time, i.e. when the forward gain G→∞, A = G→∞.

[0070] However, in an actual acoustic system, since the real transfer function F can be time-varying, and the convergence process of the iterative solution can oscillate, it is difficult for the iterative process of F' to reach the ideal condition F' = F. That is, there is a certain deviation between the predicted transfer function F' obtained by actual iteration and the real transfer function F. At this time, in order to keep the acoustic system stable, the forward gain G provided by the gain amplification unit 130 cannot be infinite. The maximum forward gain that the acoustic system can achieve is:

[0071]

[0072] As can be seen from formula (4), the deviation between the predicted transfer function F' and the real transfer function F can be used to measure the convergence performance of the adaptive filtering algorithm, and further measure the cancellation effect of the acoustic system on the feedback sound. Specifically, the smaller the deviation between the predicted transfer function F' and the real transfer function F, the better the convergence performance of the adaptive filtering algorithm, and the better the cancellation effect of the acoustic system on the feedback sound. The greater the deviation between the predicted transfer function F' and the real transfer function F, the worse the convergence performance of the adaptive filtering algorithm, and the worse the cancellation effect of the acoustic system on the feedback sound.

[0073] In some embodiments, misalignment (MIS) can also be used to measure the convergence performance of the adaptive filtering algorithm. The misalignment MIS can be expressed by the following formula:

[0074]

[0075] The unit of offset MIS is decibel (dB). When the predicted transfer function F′ is initially zero, the offset MIS is 0 dB. The smaller the offset MIS, and the closer it is to negative infinity, the smaller the deviation between the predicted transfer function F′ and the true transfer function F, indicating better convergence performance of the adaptive filtering algorithm, and thus a better cancellation effect of the acoustic system on feedback sounds. Conversely, the larger the offset MIS, and the closer it is to positive infinity, the larger the deviation between the predicted transfer function F′ and the true transfer function F, indicating worse convergence performance of the adaptive filtering algorithm, and thus a worse cancellation effect of the acoustic system on feedback sounds.

[0076] It should be noted that the convergence performance of the adaptive filtering algorithm in this application includes, but is not limited to, convergence speed and convergence error. Convergence speed can refer to the fitting speed of the predicted transfer function F′ to the true transfer function F, and convergence error can refer to the deviation between the predicted transfer function F′ and the true transfer function F when the convergence condition is met.

[0077] exist Figure 2 In the acoustic system shown, the reason why an adaptive filtering algorithm can be used to solve a time-varying predictive transfer function F′ to fit the transfer function F corresponding to the feedback path is based on the following ideal assumption: the feedback path is entirely linear.

[0078] However, real-world acoustic systems typically fail to meet these ideal assumptions. This is because real acoustic systems contain various devices along the feedback path, which may exhibit nonlinear responses. For example, the interaction between the diaphragm and magnet of speaker 110 causes hysteresis and saturation distortion, thus the response of speaker 110 includes nonlinear components. Furthermore, power amplifiers, operational amplifiers, and other devices are usually present between signal processing circuit 150 and speaker 110. Power amplifiers and operational amplifiers typically contain limiting effects, therefore their responses also contain nonlinear components. Similarly, other devices between signal processing circuit 150 and speaker 110 may also exhibit nonlinear response components.

[0079] Since the acoustic feedback cancellation unit 170 acquires the driving signal u before the output port of the signal processing circuit 150 and adaptively filters the driving signal u using the predictive transfer function F′, the nonlinear responses of devices such as the loudspeaker 110, power amplifier, and operational amplifier are inevitably introduced into the iterative solution of the predictive transfer function F′. This results in low convergence performance of the adaptive filtering algorithm; for example, the predictive transfer function F′ may fail to converge, converge slowly, or have a large convergence error. This deteriorates the misalignment index (MIS) of the acoustic system, thus affecting the acoustic system's ability to cancel feedback sound.

[0080] Furthermore, in some acoustic system designs, the acoustic feedback cancellation unit 170 may be independent of other units in the signal processing circuit 150, and the acoustic system's design architecture may limit access permissions or communication capabilities between different units. Therefore, the acoustic feedback cancellation unit 170 may not be able to obtain a drive signal u from other units. Consequently, such an acoustic system cannot employ AFC technology to reduce or eliminate feedback sound.

[0081] Figure 3 A schematic diagram of another design for an acoustic system provided according to an embodiment of this specification is shown. For example... Figure 3 As shown, the acoustic system 20 may include: a loudspeaker 110, a first sound sensor 120-1, a second sound sensor 120-2, and a signal processing circuit 150.

[0082] Figure 3 The acoustic system 20 shown can be considered as being in Figure 2 Further improvements based on the acoustic system 10 shown. Comparison. Figure 2 and Figure 3 visible, Figure 3 The first sound sensor 120-1 in the acoustic system 20 shown can correspond to Figure 2 The acoustic sensor 120 in the acoustic system 10 shown, thus, Figure 3 The acoustic system 20 shown is equivalent to in Figure 2 A second sound sensor 120-2 is added to the acoustic system 10 shown. The structure of the second sound sensor 120-2 may be the same as or different from that of the first sound sensor 120-1, and this application does not limit it.

[0083] Figure 3The working process of the acoustic system 20 is as follows: the loudspeaker 110 receives the driving signal u from the signal processing circuit 150 when working, and converts the driving signal u into the first sound. The first sound sensor 120-1 collects the environmental sound when working and generates the first signal y1. The second sound sensor 120-2 collects the environmental sound when working and generates the second signal y2. The environmental sound includes the first sound from the loudspeaker 110 and the second sound from the external sound source 160. In this way, the first signal y1 includes a signal component x1 corresponding to the first sound and a signal component v1 corresponding to the second sound, and the second signal y2 includes a signal component x2 corresponding to the first sound and a signal component v2 corresponding to the second sound. The external sound source 160 includes other sound sources in the environment except the loudspeaker 110, for example, the throat of a person, an electronic device with a sound playing function, other loudspeakers, etc.

[0084] It should be noted that the first sound emitted by the loudspeaker 110 can be picked up by the first sound sensor 120-1 and the second sound sensor 120-2 after being conducted through one or more media of gas, liquid and solid. The second sound emitted by the target sound source 160 can be picked up by the first sound sensor 120-1 and the second sound sensor 120-2 after being conducted through one or more media of gas, liquid and solid. In addition, the present specification does not limit the carrying manner of the first signal y1, the second signal y2 and the driving signal u, and all of them can be signals carried by any carrier. For example, the first signal y1, the second signal y2 and the driving signal u can all be electrical signals, optical signals, digital carrier signals or signals of other carrier types.

[0085] In Figure 3 In the acoustic system 20, the pickup sides of the first sound sensor 120-1 and the second sound sensor 120-2 are different. The first sound sensor 120-1 mainly picks up the sound from the target sound source 160, and the second sound sensor 120-2 mainly picks up the sound from the loudspeaker 110. Specifically, the first signal y1 picked up by the first sound sensor 120-1 and the second signal y2 picked up by the second sound sensor 120-2 satisfy the following relationship:

[0086] k2≥2k1 Formula (6)

[0087] Wherein, k1 is the ratio of the signal energy |x1| corresponding to the first sound in the first signal y1 to the signal energy |v1| corresponding to the second sound, and k2 is the ratio of the signal energy |x2| corresponding to the first sound in the second signal y2 to the signal energy |v2| corresponding to the second sound. 2 2 2 corresponding to the second sound.​​2 The ratio of k2 to k1, i.e.,

[0088]

[0089]

[0090] In other words, let the ratio of k2 to k1 be N, i.e., N = k2 / k1, then N can be a real number greater than or equal to 2. For example, N can be within any interval defined by any two of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, …, ∞. When N is greater, and approaches to ∞, the second sound sensor 120-2 approaches to only pick up the sound of the loudspeaker 110, and the first sound sensor 120-1 approaches to only pick up the sound of the target sound source 160. In addition, when the ratio of k2 to k1 is N, the closed loop gain A of the acoustic system can be expressed as follows:

[0091]

[0092] It should be noted that the derivation of the above formula (20) can refer to the derivation process of formula (19) in the following, which will not be described in detail here. As can be seen from the above formula (20), when the value of N gradually increases, the closed loop gain A gradually approaches the forward gain G, that is, the energy loss of the system gradually decreases. When the value of N is ∞, the closed loop gain A reaches the ideal forward gain G.

[0093] In order to make the above condition k2≥2k1 satisfied, the first signal y1 and the second signal y2 can satisfy one or more of the following conditions:

[0094] (1) The ratio of the signal energy corresponding to the first sound in the second signal y2 |x2| to the signal energy corresponding to the second sound in the second signal y2 |v2| is greater than or equal to 2, i.e., 2 2

[0095]

[0096] The above condition can also be expressed as: the signal energy corresponding to the first sound in the second signal y2 |x2| is much greater than the signal energy corresponding to the second sound in the second signal y2 |v2| 2 2 It can be understood that when |x2| is much greater than |v2| 2 2 ​​​​When k2 is maximized, the second sound sensor 120-2 picks up the first sound much more than the second sound. When k2 approaches infinity, the second sound sensor 120-2 picks up almost only the first sound and not the second sound.

[0097] (2) The signal energy |v1| in the first signal y1 corresponding to the second sound 2 The signal energy |x1| corresponding to the first sound in the first signal y1 2 The ratio is greater than or equal to 2, that is:

[0098]

[0099] The above condition can also be expressed as: the signal energy |v1| in the first signal y1 corresponding to the second sound. 2 Much greater than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 I can understand that when |v1| 2 Much greater than |x1| 2 When k1 is as small as possible, the first sound sensor 120-1 picks up the second sound much more than the first sound. When k1 approaches zero, the first sound sensor 120-2 picks up almost only the second sound and not the first sound.

[0100] (3) The signal energy |x2| in the second signal y2 corresponding to the first sound 2 The signal energy |x1| corresponding to the first sound in the first signal y1 2 The ratio is greater than or equal to 2, that is:

[0101]

[0102] The above condition can also be expressed as: the signal energy |x2| in the second signal y2 corresponding to the first sound. 2 Much greater than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 I can understand that when |x2| 2 Much greater than |x1| 2 At that time, the second sound sensor 120-2 picks up the first sound much more than the first sound sensor 120-1 picks up the first sound. For example, the second sound sensor 120-2 picks up almost all of the first sound, while the first sound sensor 120-2 picks up almost none of the first sound.

[0103] The signal processing circuit 150 can be connected to the first sound sensor 120-1 and the second sound sensor 120-2, respectively. The signal processing circuit 150 can obtain a first signal y1 from the first sound sensor 120-1 and a second signal y2 from the second sound sensor 120-2. Furthermore, based on the second signal y2, the signal processing circuit 150 can reduce the signal component in the first signal y1 corresponding to the first sound to obtain the target signal e. Thus, the target signal e contains little or no feedback sound component.

[0104] and Figure 2 similar, Figure 3 The acoustic system shown can also be based on AFC technology to reduce or eliminate feedback components in the target signal. See also Figure 3 The signal processing circuit 150 may include an acoustic feedback cancellation unit 170. Internally, the acoustic feedback cancellation unit 170 can solve for and adaptively update a time-varying prediction transfer function F′ to fit the true transfer function F corresponding to the feedback path. The inputs of the acoustic feedback cancellation unit 170 include a first signal y1 and a second signal y2. Based on the second signal y2, the acoustic feedback cancellation unit 170 can reduce the signal component in the first signal y1 corresponding to the first sound to obtain the target signal e. Specifically, the acoustic feedback cancellation unit 170 uses the prediction transfer function F′ to perform an adaptive filtering operation on the second signal y2 to obtain a third signal x′, i.e., x′ = y2 * F′. The third signal x′ can be regarded as the predicted value of the feedback component in the first signal y1 (i.e., the signal component in the first signal y1 corresponding to the first sound). Furthermore, the acoustic feedback cancellation unit 170 can subtract the third signal x′ from the first signal y1 to obtain the target signal e, i.e., e = y1 - x′ = y1 - y2 * F′. The resulting target signal e contains little or no feedback sound component.

[0105] After obtaining the target signal e, the signal processing circuit 150 can also update the filtering parameters of the adaptive filtering operation F′ based on at least one of the second signal y2 and the target signal e. Specifically, according to the theory of adaptive filtering algorithms, the update of the prediction transfer function F′ can be achieved by minimizing the expectation of the mean square function of the target signal e, that is:

[0106] min F′ E[e 2 ] = min F′ E[(y1-y2*F′) 2 ] Formula (1-2)

[0107] Still taking the LMS algorithm as an example, based on the gradient descent optimization method, the above formula (1-2) can be derived to obtain the update formula of the prediction transfer function F' as follows:

[0108] F' <- F' + μ * e * y2 Formula (2-2)

[0109] Wherein, μ is the iteration step.

[0110] It should be understood that when the acoustic feedback cancellation unit 170 adopts algorithms such as NLMS, RLS, etc., the update formula of the prediction transfer function F' can be derived in a similar manner, and this specification will not be exemplified one by one.

[0111] Figure 3 After obtaining the target signal e, the signal processing circuit 150 can perform a target operation on the target signal e. Continuing to refer to Figure 3 , the signal processing circuit 150 can further include a gain amplification unit 130 ( Figure 3 annotated as G in the figure). The gain amplification unit performs gain amplification on the target signal e, and sends the gain-amplified signal as the driving signal u of the next moment to the loudspeaker 110, so as to drive the loudspeaker 110 to produce sound. Since the feedback component in the target signal e is reduced or eliminated, it can avoid or suppress the acoustic system 10 from producing howling, and also helps to improve the maximum forward gain that the acoustic system 10 can achieve.

[0112] Figure 3 The acoustic system 20 shown in the figure focuses on picking up the first sound by adding a second sound sensor 120-2 to obtain a second signal y2, and then the signal processing circuit 150 can use the AFC technology to reduce the feedback component in the first signal y1 based on the second signal y2, so that the feedback component is reduced or eliminated. Figure 3 The acoustic system 20 shown in the figure is compared with Figure 2In the acoustic system 10 shown, since the second signal y2 is obtained from the signal path behind the speaker 110, the feedback cancellation unit 170 only needs to fit the transfer function of the feedback path after the speaker 110 when solving the predicted transfer function F′. This avoids the influence of the nonlinear response of the speaker 110 and the devices before the speaker 110 (such as operational amplifiers, power amplifiers, etc.) on the convergence performance of the adaptive filtering algorithm, thereby improving the cancellation effect of the feedback sound. In addition, since the second signal y2 required by the feedback cancellation unit 170 is picked up by the second sound sensor 120-2, even if the acoustic system 20 restricts the interaction between the feedback cancellation unit 170 and other units, it does not affect the application of AFC technology in the acoustic system 20. This reduces the requirements of AFC technology on the design architecture of the acoustic system and improves the application flexibility and versatility of AFC technology.

[0113] Furthermore, since the feedback cancellation unit 170 originally had system access permissions to the first sound sensor 120-1, and the permissions required to access the second sound sensor 120-2 are the same type of permissions required to access the first sound sensor 120-1, therefore, Figure 3 After the addition of the second sound sensor 120-2, the feedback cancellation unit 170 can access the data of the second sound sensor 120-2 without having to add new system access permissions.

[0114] Furthermore, Figure 3 After adding the second sound sensor 120-2 to the acoustic system shown, it is not necessary to change the internal implementation of the acoustic feedback cancellation unit 170. That is, it is not necessary to change the update formula of the prediction transfer function F′ or the calculation formula of feedback sound cancellation. Only the input signal u of the acoustic feedback cancellation unit 170 needs to be replaced with y2. Therefore, it can be seen that... Figure 3 The acoustic system shown can be applied, adapted, and compatible with existing acoustic feedback cancellation units 170, regardless of the adaptive filtering algorithm used by these existing acoustic feedback cancellation units 170 (including but not limited to LMS, NLMS, RLS, or other adaptive filtering algorithms mentioned above). Therefore, the modification of the acoustic system is relatively simple and has wide applicability.

[0115] The following is about Figure 3 The system stability of the acoustic system 20 shown was verified.

[0116] According to signal processing theory, Figure 3 The closed-loop gain A of the acoustic system shown can be expressed as follows:

[0117]

[0118] wherein F1 represents an acoustic transfer function between the loudspeaker 110 and the first sound sensor 120-1, and F2 represents an acoustic transfer function between the loudspeaker 110 and the second sound sensor 120-2.

[0119] According to the Nyquist stability criterion, it can be known that the requirement for the acoustic system 20 to be able to cancel the feedback sound is that the solved prediction transfer function F' satisfies the following condition:

[0120]

[0121] That is, the prediction transfer function F' needs to satisfy:

[0122]

[0123] When the prediction transfer function F' satisfies the above formula (14), the formula (3-2) can be transformed into:

[0124]

[0125] Since the first signal y1 and the second signal y2 satisfy the following condition: k2≥2k1, that is:

[0126]

[0127] Substituting x1 and x2 in the formula (16), the following formula is obtained:

[0128]

[0129] Simplifying the formula (17), the following formula is obtained:

[0130] |v1F2| 2 ≥2·|v2F1| 2 Formula (18)

[0131] Substituting the above formula (18) into the formula (15), the following formula is obtained:

[0132]

[0133] As can be seen from the formula (19), when the current gain G→∞, the closed-loop gain A→∞. Therefore, Figure 3 The acoustic system shown in the formula (20) is still stable when the prediction transfer function F' reaches the convergence condition. Thus, the correctness of the scheme of the present application is verified.

[0134] Based on Figure 3In the acoustic system 20 shown, under certain conditions, when the second sound sensor 120-2 is in a strong feedback environment, the acoustic transfer function F2≈1 between the loudspeaker 110 and the second sound sensor 120-2, and the first signal y1 and the second signal y2 satisfy the following conditions:

[0135] The signal energy |x2| corresponding to the first sound in the second signal y2 2 Much greater than the signal energy |v2| corresponding to the second sound in the second signal y2. 2 That is: |x2| 2 >>|v2| 2 .

[0136] In this case, Figure 4 The acoustic system shown can be simplified to Figure 4 The acoustic system shown. In Figure 4 In the acoustic system shown, the second sound sensor 120-2 picks up almost only the sound from the speaker 110. In this case, the second signal y2≈u. Therefore, the update formula for the prediction transfer function F′ can be updated as follows:

[0137] F′←F′+μey2≈F′+μeu Formula (2-3)

[0138] Accordingly, the closed-loop gain A of the acoustic system 30 can be expressed as:

[0139]

[0140] Therefore, it can be seen that when the second sound sensor 120-2 is in a strong feedback scenario, Figure 2 The AFC mathematical expression in the acoustic system shown is... Figure 5 The AFC mathematical expression based on the ideal assumption is exactly the same in the acoustic system shown. This further confirms the correctness of the scheme in this application.

[0141] Figure 5 A schematic diagram of yet another design of an acoustic system provided according to an embodiment of this specification is shown. For example... Figures 3 to 5As shown, the signal processing circuit 150 can further include a pre-processing unit 180. After obtaining the first signal y1 and the second signal y2, the signal processing circuit 150 can pre-process the first signal y1 and the second signal y2 respectively through the pre-processing unit 180. Specifically, the signal processing circuit 150 performs a first pre-processing operation H1 on the first signal y1 through the pre-processing unit 180 to obtain a first intermediate signal y1', and performs a second pre-processing operation H2 on the second signal y2 to obtain a second intermediate signal y2'. Further, the first intermediate signal y1' and the second intermediate signal y2' are input to the acoustic feedback cancellation unit 170. The acoustic feedback cancellation unit 170 reduces the signal component corresponding to the first sound in the first intermediate signal y1' based on the second intermediate signal y2' to obtain the target signal e. It should be understood that the internal processing process of the acoustic feedback cancellation unit 170 has been described above and will not be repeated here.

[0142] The first pre-processing operation H1 can include, but is not limited to, at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation. The second pre-processing operation H2 can include, but is not limited to, at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation. When designing the acoustic system, the first pre-processing operation H1 and the second pre-processing operation H2 can be designed based on the requirements of different application scenarios. For example, in some cases, the frequency responses of the first sound sensor 120-1 and the second sound sensor 120-2 are different, and therefore appropriate first pre-processing operation H1 and second pre-processing operation H2 can be designed to compensate for the difference, so that the frequency responses of the first signal y1 and the second signal y2 match each other and meet the calculation requirements of the AFC algorithm. As can be seen, by performing pre-processing operations on the first signal y1 and the second signal y2, the signal processing circuit 150 can meet the processing requirements of different application scenarios.

[0143] The above Figures 3 to 5 The above is an example of taking an acoustic system 20 including one loudspeaker 110 as an example. In some scenarios, the number of loudspeakers 110 in the acoustic system 20 can be M, where M is an integer greater than 1. In this case, the number of second sound sensors 120-2 can also be M. The M second sound sensors 120-2 correspond one-to-one to the M loudspeakers 110. Among them, the i-th second sound sensor 120-2 mainly picks up the sound emitted by the i-th loudspeaker 110.

[0144] Specifically, for any i-th second sound sensor in the M second sound sensors 120-2, the i-th second sound sensor 120-2 collects environmental sound and generates a second signal y 2i when working. The first signal y1 and the second signal y 2i satisfy k2i ≥ 2k1, k 2i is a second signal y 2i The ratio of the signal energy corresponding to the sound emitted by the i-th loudspeaker 110 and the signal energy corresponding to the sound emitted by the target sound source in the first signal y1. The target sound source includes other sound sources in the environment in addition to the i-th loudspeaker. Further, the signal processing circuit 150 can subtract the feedback component in the first signal y1 based on the second signal y 2i to obtain a target signal e i The signal processing circuit obtains the target signal e by superimposing the target signal e1 to the target signal e M , and then performs a target operation on the target signal e.

[0145] As can be seen, when the acoustic system 20 includes M loudspeakers 110, the acoustic system 20 can include M second sound sensors 120-2. Among them, the i-th sound sensor 120-2 focuses on the sound of the i-th loudspeaker, and is used for the adaptive filtering process of AFC. In this way, M AFC-based adaptive filtering processes are added to the acoustic system 20. Among them, each adaptive filtering process is consistent with the description of the foregoing Figures 3 to 5 , which will not be repeated here.

[0146] As can be seen, based on the acoustic system shown in Figures 6A to 6F , when the first signal y1 and the second signal y2 satisfy the condition k2≥2k1, the AFC technology can effectively reduce or eliminate feedback sound, and can avoid or reduce the influence of nonlinear response on the convergence performance of the adaptive filtering algorithm.

[0147] The following will explain in detail how to design the acoustic system so that the first signal y1 and the second signal y2 satisfy the condition k2≥2k1. It should be noted that there can be multiple schemes for designing the acoustic system, and the following will only take a few possible schemes as examples for illustration. The different schemes listed below can be combined with each other.

[0148] Scheme 1: The acoustic system can be designed from the structural dimension, so that the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 satisfies the preset condition, so that the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0149] In some embodiments, the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 satisfy the preset distance condition.

[0150] For example, the distance condition can include that the distance between the second sound sensor 120-2 and the speaker 110 is much smaller than the distance between the first sound sensor 120-1 and the speaker 110. That is, the second sound sensor 120-2 is as close to the speaker 110 as possible compared with the first sound sensor 120-1. Assuming that the distance between the first sound sensor 120-1 and the speaker 110 is denoted as L1, and the distance between the second sound sensor 120-2 and the speaker 110 is denoted as L2, then L1 and L2 satisfy the distance condition: L1≥2L2. The above distance condition can also be expressed as that the ratio of L1 to L2 is greater than or equal to a preset value. The above preset value can be located in any interval defined by any two of 2, 3, 4, 5, 6, 7, 8, 9, 10, … ∞.

[0151] The possible structures of the acoustic system will be illustrated below Figures 6A to 6F , respectively. It should be noted that the product form of the acoustic system 20 is not limited in the present specification, for example, the acoustic system 20 can adopt a truly wireless earphone form, an ear muff form, a glasses form, a behind-the-ear form, an ear-in-the-ear form, or any other possible form. Figure 6A Only a few possible product forms are taken as examples for illustration.

[0152] For example, when the acoustic system 20 adopts a truly wireless earphone form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1A. Figure 6B When the acoustic system 20 adopts an ear muff form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1B. Figure 6C When the acoustic system 20 adopts a glasses form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1C. Figure 6D When the acoustic system 20 adopts a behind-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1D. Figure 6E When the acoustic system 20 adopts an ear-in-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1E. Figure 6F Among them, the ear-in-the-ear form includes but is not limited to the BTE (Behind-The-Ear) form, the RIC (Receiver-In-Canal) form, etc. in a hearing aid. When the acoustic system 20 adopts an ear-in-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 can be as shown in FIG. 1E. Figures 6A to 6FThe ear-in type forms include, but are not limited to, ITE (In-The-Ear), ITC (In-The-Canal), CIC (Completely-In-the-Canal), etc. in a hearing aid. Figures 6A to 6F The acoustic system structures shown all satisfy the distance condition L1≥2L2.

[0153] It should be understood that when the acoustic system satisfies the distance condition L1≥2L2, the second sound sensor 120-2 can pick up stronger signals of the first sound relative to the first sound sensor 120-1. Therefore, the signal energy |x2| 2 in the second signal y2 corresponding to the first sound is much larger than the signal energy |x1| 2 in the first signal y1 corresponding to the first sound, thereby helping to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0154] It can be understood that although the above Figures 7A to 7G Some examples of acoustic systems satisfying the distance condition L1≥2L2 are shown, but in some cases, some acoustic systems may not satisfy the distance condition L1≥2L2 due to product forms or specific requirements. That is, the values of L1 and L2 are relatively close. For example, Figure 7A The structural schematic diagrams of acoustic systems in the case where the values of L1 and L2 are relatively close are shown respectively. Specifically, when the acoustic system 20 adopts a true wireless earphone form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7B When the acoustic system 20 adopts an ear cover form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7C When the acoustic system 20 adopts a glasses form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7D When the acoustic system 20 adopts a behind-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7E When the acoustic system 20 adopts a behind-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7F When the acoustic system 20 adopts a behind-the-ear form, the positional relationship among the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 can be as shown in Figure 7GAs shown. Among them, the behind-the-ear mode includes but is not limited to BTE (Behind-The-Ear), RIC (Receiver-In-Canal), etc. in the hearing aid. When the acoustic system 20 adopts the in-ear mode, the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the loudspeaker 110 can be as shown. Figures 7A to 7G As shown. Among them, the behind-the-ear mode includes but is not limited to BTE (Behind-The-Ear), RIC (Receiver-In-Canal), etc. in the hearing aid. When the acoustic system 20 adopts the in-ear mode, the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the loudspeaker 110 can be as shown.

[0155] In the case that the acoustic system cannot meet the distance condition L1≥2L2(e.g. Figures 6A to 6F As shown), the subsequent scheme can be used to design the acoustic system, so that the first signal y1 and the second signal y2 meet the condition k2≥2k1. It should be noted that the acoustic system can also be combined with one or more of the subsequent schemes when the design scheme shown in Figures 8A to 8F As shown.

[0156] In some embodiments, the first sound sensor 120-1, the second sound sensor 120-2, and the loudspeaker 110 satisfy a preset structural condition. The structural condition satisfied by the acoustic system will be described below. Figures 8A to 8F It should be noted that, Figures 8A to 8C Only the local structure of the acoustic system is shown.

[0157] For example, the acoustic system 20 can adopt the design of an acoustic cavity. Referring to Figure 8A, the acoustic system 20 can include a housing 21, and a partial region of the housing 21 is formed with an acoustic cavity 22. It should be noted that the present application does not limit the specific form of the acoustic cavity 22. The loudspeaker 110 is located inside the acoustic cavity 22. The sound generating component of the loudspeaker 110 can separate the acoustic cavity 22 into a first acoustic cavity 22-1 and a second acoustic cavity 22-2. Among them, the above-mentioned sound generating component can refer to the component that generates vibration in the loudspeaker 110, for example, it can be a vibrating diaphragm, a vibrating beam, a vibrating rod, a vibrating block, etc. The first acoustic cavity 22-1 refers to the acoustic resonance cavity of the first sound emitted by the loudspeaker 110 before entering the external free space. The second acoustic cavity 22-2 refers to the acoustic resonance cavity in which the component of the first sound emitted by the loudspeaker 110 does not directly propagate to the external free space. In other words, the sound generating component of the loudspeaker 110 separates the acoustic cavity 22 into two sub-cavities, in which the sub-cavity towards which the sound emitting surface of the sound generating component faces as the first acoustic cavity 22-1, and the sub-cavity away from which the sound emitting surface of the sound generating component faces as the second acoustic cavity 22-2. The first acoustic cavity 22-1 can also be referred to as the front cavity, and the second acoustic cavity 22-2 can also be referred to as the rear cavity.

[0158] Based on the above design of the acoustic cavity, in some embodiments, the second sound sensor 120-2 can be located inside the acoustic cavity 22, and the first sound sensor 120-2 can be located outside the acoustic cavity 22. It can be understood that since the loudspeaker 110 is located inside the acoustic cavity 22, by setting the second sound sensor 120-2 inside the acoustic cavity 22 and the first sound sensor 120-1 outside the acoustic cavity 22, the second sound sensor 120-2 can pick up stronger sound of the loudspeaker 110 relative to the first sound sensor 120-1. That is, the signal energy |x2| corresponding to the first sound in the second signal y2 is much larger than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 2 , thereby helping to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0159] Among them, the specific position of the second sound sensor 120-2 inside the acoustic cavity 22 can have multiple cases. For example, referring to Figure 8B , the second sound sensor 120-2 can be located inside the first acoustic cavity 22-1. In this way, the second sound sensor 120-2 can capture stronger first sound than the first sound sensor 120-1, thereby helping to achieve the condition that the signal energy |x2| corresponding to the first sound in the second signal y2 is much larger than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 2 ​​. Further, it is helpful to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0160] For another example, referring to Figure 8C , the second sound sensor 120-2 can be located inside the second acoustic cavity 22-2. In this way, two effects can be achieved. First, the second sound sensor 120-2 can capture stronger first sound in at least some frequency bands compared to the first sound sensor 120-1, thereby helping to achieve the condition that the signal energy |x2| corresponding to the first sound in the second signal y2 is much larger than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 2 Second, the loudspeaker 110 can block the second sound emitted by the target sound source 160 to some extent, thereby helping to achieve the condition that the signal energy |v2| corresponding to the second sound in the second signal y2 is much smaller than the signal energy |v1| corresponding to the second sound in the first signal y1. 2 2 The joint effect of the above two aspects makes it possible to achieve the condition k2≥2k1.

[0161] For another example, referring to Figure 8C , the second sound sensor 120-2 can be coupled with the sound emitting component of the loudspeaker 110. For example, the second sound sensor 120-2 can be a bone conduction MIC with light mass, and the loudspeaker 110 can be an air conduction loudspeaker. The bone conduction MIC can be attached to the diaphragm of the air conduction loudspeaker. In this way, since the bone conduction MIC picks up bone vibration signals, air vibration will not interfere with the pickup of the bone conduction MIC, thereby ensuring the accuracy of the second signal y2 picked up by the bone conduction MIC. In addition, by using a bone conduction MIC with light mass, the acoustic system 20 can reduce the impact of the bone conduction MIC on the vibration of the loudspeaker diaphragm, thereby avoiding introducing additional distortion. It should be noted that this coupling method is applicable to various types of sound sensors and loudspeakers. The above-mentioned coupling of the bone conduction MIC and the air conduction loudspeaker is only one possible example.

[0162] Figures 8A to 8C In the illustrated acoustic system, since the second sound sensor 120-2 is coupled with the sound emitting component of the loudspeaker 110, the second sound sensor 120-2 can most directly pick up the sound emitted by the loudspeaker 110. Therefore, the second sound sensor 120-2 can capture stronger first sound compared to the first sound sensor 120-1. Thus, the signal energy |x2| corresponding to the first sound in the second signal y2 is much larger than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 2 ​​​, which helps the first signal y1 and the second signal y2 to satisfy the condition k2≥2k1.

[0163] It should be noted that the above Figures 8A to 8C The design of the first sound sensor 120-1 is not limited to a specific position, as long as it is located outside the acoustic cavity 22 and can easily pick up the sound of the target sound source 160. For example, the first sound sensor 120-1 can be located inside the shell 21, and the sound pickup surface is arranged on the surface of the shell 21 away from the acoustic cavity 22. Figure 8E The position of the first sound sensor 120-1 is not shown.

[0164] In some embodiments, the sound pickup surface of the first sound sensor 120-1 and the sound pickup surface of the second sound sensor 120-2 can both be located in a free space outside the shell 21, and the second sound sensor 120-2 is closer to the loudspeaker 110 (or closer to the acoustic cavity 22) relative to the first sound sensor 120-1. Wherein, the free space refers to a space in which sound is not affected by reflection, refraction, and diffraction, and mainly propagates in the form of spherical waves or plane waves. For example, see Figure 8D The second sound sensor 120-2 can be arranged in a free space outside the shell 21 without being physically connected to the shell 21. In this case, the second sound sensor 120-2 can be a wired or wireless MIC, and after picking up the second signal y2 in the free space, it can send the second signal y2 to the signal processing circuit 150 in a wired or wireless manner.

[0165] In some embodiments, referring to Figures 8D to 8E The acoustic cavity 22 and the acoustic cavity 23 can be formed in a part of the shell 21 of the acoustic system. Wherein, the loudspeaker 110 is located in the acoustic cavity 22, and the second sound sensor 120-2 is located in the acoustic cavity 23, and the second sound sensor 120-2 is closer to the loudspeaker 110 relative to the first sound sensor 120-1. The acoustic cavity 23 can act as a wind shield for the second sound sensor 120-2, which can also be referred to as a wind shield cavity. The second sound sensor 120-2 can still pick up sound signals in the free space in the acoustic cavity 23.

[0166] It should be noted that the above Figure 8D The design of the first sound sensor 120-1 is not limited to a specific position, as long as the sound pickup surface of the first sound sensor 120-1 is located in the free space and can easily pick up the sound of the target sound source 160. For example, the first sound sensor 120-1 can be located inside the shell 21, and the sound pickup surface is arranged on the surface of the shell 21 away from the acoustic cavity 22. Figure 8E and Figure 8DThe location of the first sound sensor 120-1 is not shown.

[0167] Figure 8E and Figure 8E In the design shown, because the second sound sensor 120-2 is closer to the speaker 110 than the first sound sensor 120-1, the second sound sensor 120-2 can capture a stronger first sound than the first sound sensor 120-1. Therefore, the signal energy |x2| corresponding to the first sound in the second signal y2... 2 Much greater than the signal energy |x1| corresponding to the first sound in the first signal y1. 2 This helps ensure that the first signal y1 and the second signal y2 satisfy the condition k2≥2k1. Additionally, Figure 8D In the design, since the second sound sensor 120-2 is located in the free space outside the housing 21, there is no need to modify the structure of the housing 21 or the acoustic cavity 22, making the implementation relatively easy. Figure 8F In the design, since the second sound sensor 120-2 is located in other acoustic cavities outside the acoustic cavity 22, there is no need to modify the acoustic cavity 22, and the implementation difficulty is also relatively low.

[0168] In some embodiments, the pickup surface of the first sound sensor 120-1 can be disposed in the free space outside the housing 21, and the pickup surface of the second sound sensor 120-2 can be disposed in the internal space of the housing 21. Furthermore, the second sound sensor 120-2 is closer to the speaker 110 (or closer to the acoustic cavity 22) than the first sound sensor 120-1. See, for example... Figure 8F The second sound sensor 120-2 can be located inside the housing 21 near the second acoustic cavity 22-2 (or the rear cavity), and the pickup surface of the second sound sensor 120-2 faces the second acoustic cavity 22-2. It should be noted that this application does not limit the specific location of the first sound sensor 120-1, as long as it can conveniently pick up the sound from the target sound source 160. For example, the first sound sensor 120-1 can be located inside the housing 21, and the pickup surface can be positioned on the surface of the housing 21 away from the speaker 110 (or away from the acoustic cavity 22). Figure 8F The location of the first sound sensor 120-1 is not shown in the diagram.

[0169] Figures 8A to 8CIn the illustrated design, since the second sound sensor 120-2 is close to the back cavity (i.e., the second acoustic cavity 22-2), the second sound sensor 120-2 can pick up the first sound leaked from the back cavity or the first sound propagating in the solid medium. Further, since the second sound sensor 120-2 is closer to the loudspeaker 110 than the first sound sensor 120-1, the second sound sensor 120-2 can capture stronger first sound than the first sound sensor 120-1. Thus, the signal energy corresponding to the first sound in the second signal y2 |x2| 2 is much larger than the signal energy corresponding to the first sound in the first signal y1 |x1| 2 . In addition, since the first sound sensor 120-1 is hidden inside the housing 21, the housing 21 blocks the sound from the target sound source 160 to a certain extent, so that the signal energy corresponding to the second sound in the second signal y2 |v2| 2 is much smaller than the signal energy corresponding to the second sound in the first signal y1 |v1| 2 The above two aspects work together to help the first signal y1 and the second signal y2 satisfy the condition k2≥2k1. In addition, the above scheme does not require modification of the acoustic cavity 22, and the implementation difficulty is low.

[0170] In some embodiments, the first sound sensor 120-1 and the loudspeaker 110 can also be coupled to different housings, respectively. For example, the acoustic system 20 can further include a first housing and a second housing. The first housing can be regarded as the device housing of the acoustic system 20. The first sound sensor 120-1 can be located inside the first housing, and the sound pickup surface is arranged on the surface of the first housing and faces the free space outside the first housing. The second housing can also be located inside the first housing, and the second housing forms an acoustic cavity, and the loudspeaker 110 and the second sound sensor 120-2 are located inside the acoustic cavity. Among them, the sound pickup surface of the first sound sensor 120-1 is arranged on the surface of the first housing and faces the free space outside the first housing. Figure 9 Similarly, the sound generating device of the loudspeaker 110 can divide the acoustic cavity into a first acoustic cavity (front cavity) and a second acoustic cavity (back cavity), and the second sound sensor 120-2 can be located inside the first acoustic cavity or the second acoustic cavity, and can also be coupled with the sound generating component of the loudspeaker 110.

[0171] Based on the above design, the first sound sensor 120-1 picks up sound in the free space outside the first shell, and the second sound sensor 120-2 picks up sound in the acoustic cavity inside the first shell. Due to the blocking effect of the first shell on sound, on the one hand, the pickup of the second sound sensor 120-2 to the sound of the target sound source 160 is reduced, and on the other hand, the pickup of the first sound sensor 120-1 to the sound of the loudspeaker 110 is reduced. Therefore, the signal energy corresponding to the first sound in the second signal y2 |x2| 2 is much larger than the signal energy corresponding to the first sound in the first signal y1 |x1| 2 , and the signal energy corresponding to the second sound in the second signal y2 |v2| 2 is much smaller than the signal energy corresponding to the second sound in the first signal y1 |v1| 2 . Further, it helps to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0172] In some embodiments, the acoustic system 20 can further include a barrier. The barrier has a blocking effect on sound. It should be noted that the application does not limit the form of the barrier, which can be a barrier plate or a barrier cover, etc. The second sound sensor 120-2 and the loudspeaker 110 are located on a first side of the barrier, and the first sound sensor 120-1 is located on a second side of the barrier. In this way, due to the blocking effect of the barrier on the first sound, the first sound sensor 120-1 picks up less of the first sound relative to the second sound sensor 120-2, that is, the second sound sensor 120-2 can capture stronger first sound than the first sound sensor 120-1. Therefore, the signal energy corresponding to the first sound in the second signal y2 |x2| 2 is much larger than the signal energy corresponding to the first sound in the first signal y1 |x1| 2 , which helps to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0173] Scheme 2: The acoustic system 20 can be designed from the sound pickup directivity dimension, so that the sound pickup directivity of the first sound sensor 120-1 and the second sound sensor 120-2 satisfies a predetermined condition, thereby making the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0174] The sound sensor can have different degrees of directivity to different directions due to different sound pickup sensitivities of the sound sensor to different directions. The sound pickup sensitivity of a certain direction can refer to the sound pickup capability of the sound sensor to sound from the direction. The higher the sound pickup sensitivity of a certain direction, the stronger the sound pickup capability of the sound sensor to sound from the direction, that is, the more signal components corresponding to sound from the direction in the sound pickup signal picked up by the sound sensor, and thus the stronger the directivity of the sound sensor to the direction. The lower the sound pickup sensitivity of a certain direction, the weaker the sound pickup capability of the sound sensor to sound from the direction, that is, the fewer signal components corresponding to sound from the direction in the sound pickup signal picked up by the sound sensor, and thus the weaker the directivity of the sound sensor to the direction. When the sound pickup sensitivity of a certain direction is zero, the sound sensor does not pick up sound from the direction, and the direction can also be referred to as a zero-point sound pickup direction.

[0175] Figure 9 A sound pickup directivity diagram of an acoustic system provided by an embodiment of the present specification is shown. As shown in Figure 9 The sound pickup directivity of the first sound sensor 120-1 and the second sound sensor 120-2 can satisfy at least one of the following conditions:

[0176] (1) The sound pickup sensitivity of the first sound sensor 120-1 in the first direction is greater than the sound pickup sensitivity in the second direction.

[0177] The first direction points to the target sound source 160, and the second direction points to the loudspeaker 110. It can be understood that when the above condition (1) is satisfied, the first sound sensor 120-1 can mainly pick up sound of the target sound source 160. When designing the acoustic system 20, in order to satisfy the above condition (1), the direction with higher sound pickup sensitivity of the first sound sensor 120-1 can be directed towards the target sound source 160, and / or the direction with lower sound pickup sensitivity of the first sound sensor 120-1 can be directed towards the loudspeaker 110. For example, the direction with the highest sound pickup sensitivity of the first sound sensor 120-1 is directed towards the target sound source 160, and / or the direction with the lowest sound pickup sensitivity of the first sound sensor 120-1 is directed towards the loudspeaker 110.

[0178] (2) The sound pickup sensitivity of the second sound sensor 120-2 in the first direction is less than the sound pickup sensitivity in the second direction.

[0179] When the above condition (2) is satisfied, the second sound sensor 120-2 can mainly pick up the sound of the loudspeaker 110. In designing the acoustic system 20, in order to satisfy the above condition (2), the direction with higher pickup sensitivity of the second sound sensor 120-2 can be directed towards the loudspeaker 110, and / or the direction with lower pickup sensitivity of the second sound sensor 120-2 can be directed towards the target sound source 160. For example, the direction with the highest pickup sensitivity of the second sound sensor 120-2 can be directed towards the loudspeaker 110, and / or the direction with the lowest pickup sensitivity of the second sound sensor 120-2 can be directed towards the target sound source 160.

[0180] It should be noted that the above conditions (1) and (2) only need to satisfy one of them. When condition (1) is satisfied, the first sound sensor 120-1 mainly picks up the sound from the target sound source 160, and when condition (2) is satisfied, the second sound sensor 120-2 mainly picks up the sound from the loudspeaker 110, both of which help to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1. Further, when the above conditions (1) and (2) are both satisfied, the first sound sensor 120-1 can pick up stronger sound of the target sound source 160 relative to the second sound sensor 120-2, and the second sound sensor 120-2 can pick up stronger sound of the loudspeaker 110 relative to the first sound sensor 120-1. Thus, the signal energy corresponding to the first sound in the second signal y2 |x2| 2 is much larger than the signal energy corresponding to the first sound in the first signal y1 |x1| 2 , the signal energy corresponding to the second sound in the second signal y2 |v2| 2 is much smaller than the signal energy corresponding to the second sound in the first signal y1 |v1| 2 , which is more helpful to make the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0181] It should be noted that the pickup directivity of the first sound sensor 120-1 and the pickup directivity of the second sound sensor 120-2 can be realized by using a single pickup device with a certain directivity, or can be realized by using multiple pickup devices to form a preset array, which is not limited in the present application. In addition, the present application does not specifically limit the pickup direction patterns corresponding to the first sound sensor 120-1 and the second sound sensor 120-2, respectively, and both of them can use the same pickup direction pattern or different pickup direction patterns. For example, the pickup direction patterns corresponding to the first sound sensor 120-1 and the second sound sensor 120-2 can be any one of an omnidirectional pattern, a heart-shaped pattern, a super heart-shaped pattern, an 8-shaped pattern, a gun-shaped pattern or other directivity patterns. For example,Figure 10A The pickup directivity pattern of the first sound sensor 120-1 is gun-shaped, and the strong pickup direction is directed to the target sound source 160. The pickup directivity pattern of the second sound sensor 120-2 is heart-shaped, and the strong pickup direction is directed to the loudspeaker 110.

[0182] Since the scheme 2 is designed from the dimension of pickup directivity, i.e., the pickup directivity of the first sound sensor 120-1 and / or the second sound sensor 120-2 needs to be designed, the positional relationship of the devices in the acoustic system can not be required or the requirement can be reduced. It can be seen that the scheme 2 can be applied to the scene where it is inconvenient to change the structure of the acoustic system 20. In some embodiments, the scheme 2 can also be combined with one or more designs in the foregoing scheme 1.

[0183] Scheme 3: The positions of the first sound sensor 120-1 and the second sound sensor 120-2 can be designed based on the feedback sound energy at each position in the target area, so that the first signal y1 and the second signal y2 satisfy the condition k2≥2k1.

[0184] For example, the first sound sensor 120-1 is located at a first position in the target area, and the second sound sensor 120-2 is located at a second position in the target area, wherein the first position and the second position satisfy at least one of the following conditions:

[0185] (1) The sound energy from the loudspeaker 110 at the first position is less than the sound energy from the loudspeaker 110 at other positions in the target area except the first position.

[0186] That is, the first sound sensor 120-1 is arranged at the position in the target area corresponding to the minimum feedback sound energy (i.e., the sound energy from the loudspeaker 110). When condition (1) is satisfied, the first sound sensor 120-1 cannot pick up or can pick up weak sound of the loudspeaker 110.

[0187] (2) The sound energy from the loudspeaker 110 at the second position is greater than the sound energy from the loudspeaker 110 at other positions in the target area except the second position.

[0188] That is, the second sound sensor 120-2 is arranged at the position in the target area corresponding to the maximum feedback sound energy (i.e., the sound energy from the loudspeaker 110). When condition (2) is satisfied, the second sound sensor 120-2 can pick up strong sound of the loudspeaker 110.

[0189] It should be noted that the above conditions (1) and (2) only need to meet one of them, when any one of them is met, it is helpful to make the first signal y1 and the second signal y2 meet the condition k2≥2k1. Further, when the above conditions (1) and (2) are met at the same time, the first sound sensor 120-1 cannot pick up or pick up weaker sound of the loudspeaker 110, and the second sound sensor 120-2 can pick up the sound of the loudspeaker 110. Thus, the signal energy corresponding to the first sound in the second signal y2 is much larger than the signal energy corresponding to the first sound in the first signal y1. 2 2 , which is more helpful to make the first signal y1 and the second signal y2 meet the condition k2≥2k1.

[0190] Figure 10A The position of the first sound sensor and the second sound sensor in the target area in the acoustic system provided by the embodiment of the present specification is shown. As shown in Figure 10A , different positions in the target area 190 are marked with arrows, and the length of the arrow represents the size of the feedback sound energy (i.e. the sound energy from the loudspeaker 110) corresponding to the position. Among them, the larger the length of the arrow, the larger the feedback sound energy, and the smaller the length of the arrow, the smaller the feedback sound energy. Continue to refer to Figure 10B , in the target area 190, the position corresponding to the feedback sound energy of the first sound sensor 120-1 is the smallest, and the position corresponding to the feedback sound energy of the second sound sensor 120-2 is the largest.

[0191] In order to meet the above conditions (1) and (2), the acoustic system 20 can be designed in the following way: first, determine the target area 190 where the first sound sensor 120-1 and the second sound sensor 120-2 are to be placed in the device of the acoustic system 20. Then, through simulation calculation or field measurement, the feedback sound energy distribution corresponding to each position on the target area 190 is obtained. For example, Figure 10A A schematic diagram of the feedback sound energy corresponding to each position in the target area of an acoustic system is shown. Among them, the larger the gray value of a certain position in the target area 190 (the gray value is 0, which is black; the gray value is 255, which is white), the larger the feedback sound energy corresponding to the position, and the smaller the gray value of a certain position in the target area, the smaller the feedback sound energy corresponding to the position. Further, the position corresponding to the strongest feedback sound energy in the target area 190 is taken as the second position 192, and the second sound sensor 120-2 is set at the second position 192; the position corresponding to the weakest feedback sound energy in the target area 190 is taken as the first position 191, and the first sound sensor 120-1 is set at the first position 191. ​

[0192] It should be noted that the shape of the target region 190 is not limited in the present application, Figure 10B and Figure 11 The rectangular shape is taken as an example in Scheme 3. In practical applications, the target region 190 can be of any other shape, such as a circular shape, a triangular shape, a pentagonal shape, a hexagonal shape, a ring shape, a hollow shape, etc., or any other irregular shape, or a region surrounded by a three-dimensional space.

[0193] Since Scheme 3 is based on the feedback sound energy at each position in the target region 190 to design the positions of the first sound sensor 120-1 and the second sound sensor 120-2, i.e., the first sound sensor 120-1 is arranged at a position in the target region 190 corresponding to the minimum feedback sound energy, and the second sound sensor 120-2 is arranged at a position in the target region 190 corresponding to the maximum feedback sound energy, Scheme 3 has a low requirement for the positional relationship between the devices in the acoustic system 20 (e.g., it does not require that the first sound sensor 120-1 must be far away from the loudspeaker 110, and the second sound sensor 120-2 must be close to the loudspeaker 110, etc.). Scheme 3 can be applied to a scenario where the positions of the components are not pre-specified and are allowed to be determined in a certain candidate region. In some embodiments, Scheme 3 can also be combined with one or more of the aforementioned Scheme 1 and Scheme 2.

[0194] Figure 11 A schematic diagram of test results of the adaptive filtering performance of the acoustic system provided according to an embodiment of the present specification is shown. Referring to Figure 2 , in the case where the loudspeaker 110 in the acoustic system 20 has a limited amplitude characteristic, when the AFC-based adaptive filtering scheme shown in Figure 4 is adopted, the calculated misadjustment (MIS) is as shown in curve A. When the AFC-based adaptive filtering scheme shown in Figure 11 is adopted, the calculated misadjustment (MIS) is as shown in curve B. In Figure 4 , curve B decreases faster than curve A in the initial period (before about 0.2 seconds) and maintains a faster average downward trend after the turning point (after about 0.2 seconds). That is, curve B is below curve A in the entire time period shown. Thus Figure 2 the misadjustment MIS of Scheme 3 is always lower than that of Scheme 1, i.e., Figure 4 Scheme 1, and the convergence degree and convergence speed of the adaptive filtering algorithm of Figure 2 Scheme 3 are superior to those of Figure 11 Scheme 1. As can be seen from Figure 4 , the convergence degree and convergence speed of the adaptive filtering algorithm are both significantly improved by adopting the scheme shown in ​ .

[0195] In summary, the acoustic system 20 provided in the specification comprises a loudspeaker 110, a first sound sensor 120-1, a second sound sensor 120-2, and a signal processing circuit 150. The loudspeaker 110 receives a driving signal and converts it into a first sound when in operation. The first sound sensor 120-1 collects ambient sound and generates a first signal when in operation, the ambient sound including the first sound and a second sound from a target sound source. The second sound sensor 120-2 collects ambient sound and generates a second signal when in operation, the first signal and the second signal satisfying k2≥2k1, where k1 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the first signal, and k2 is a ratio of signal energy corresponding to the first sound to signal energy corresponding to the second sound in the second signal. The signal processing circuit 150 is connected with the first sound sensor 120-1 and the second sound sensor 120-2 respectively, and performs, when in operation, subtraction of signal components corresponding to the first sound in the first signal based on the second signal to obtain a target signal, and performs a target operation on the target signal. As can be seen, the acoustic system 20 provided in the specification can reduce or eliminate feedback components in the target signal, thereby avoiding problems such as howling caused by feedback sound, and can also improve the maximum forward gain that can be achieved by the acoustic system 20.

[0196] The foregoing description of specific embodiments of the specification has been presented. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve the desired results. In certain implementations, multitasking and parallel processing can be advantageous.

[0197] In summary, after reading the detailed disclosure, those skilled in the art can understand that the foregoing detailed disclosure can be presented only in an exemplary manner, and can not be limiting. Although not explicitly stated here, those skilled in the art can understand that the specification requires to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are intended to be presented by the specification, and are within the spirit and scope of the exemplary embodiments of the specification.

[0198] Furthermore, certain terminology has been used in this specification for the purpose of reference only. For example, "one embodiment", "an embodiment” and / or "some embodiments” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the specification. Thus, use of such terms in various places of the specification are not necessarily all referring to the same embodiment. Further, where a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the purview of one of ordinary skill in the art to effect such feature, structure, or characteristic in connection with a different embodiment.

[0199] It should be understood that in the foregoing description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description of a combination of features. This should not be understood as necessitating that these features are only together in that embodiment. In some embodiments, the application can be realized without one or more of the described features. Further, it is entirely possible that some of the features of one embodiment are used in another without the corresponding benefits being present. In other words, different embodiments of the application can be implemented to realize the benefits of some of the features without realizing the benefits of other features.

[0200] Each patent, patent application, publication of a patent application, and other material, for example articles, books, specifications, publications, documents, items, and the like, referenced herein are hereby incorporated herein by reference in their entirety for all purposes to the same extent as if each were specifically and individually indicated to be incorporated by reference herein. Furthermore, there may be instances where terminology used herein may differ from terminology used in the materials incorporated by reference. In such instances, that terminology used herein shall control. In case of inconsistencies or conflict between the terminology, description, definition, and / or use of terms associated with any of the incorporated materials and the terminology, description, definition, and / or use of terms in this document, the terms in this document shall control.

[0201] Finally, it should be understood that the embodiments of the application disclosed herein are illustrative of the principles of the present application. Other modifications that fall within the scope of the present application can be made by those skilled in the art upon the reading and understanding of this specification, disclosure and the examples. Accordingly, the application disclosed in the specification is intended to be illustrative only and not limiting of the scope of the application. The scope of the application is thus indicated by the appended claims, rather than the foregoing description, disclosure and examples.

Claims

1. An acoustic system, characterized in that, include: The loudspeaker receives drive signals and converts them into the first sound when it is working. The first sound sensor collects ambient sound and generates a first signal when it is working. The ambient sound includes the first sound and a second sound from a target sound source. The target sound source includes other sound sources besides the speaker. The second sound sensor, during operation, collects ambient sound and generates a second signal. The positional relationship between the first sound sensor, the second sound sensor, and the speaker satisfies a first preset condition, and / or the sound pickup directivity of the first and second sound sensors satisfies a second preset condition, such that the first signal and the second signal satisfy... ,in It is the ratio of the signal energy corresponding to the first sound in the first signal to the signal energy corresponding to the second sound. The ratio of the signal energy corresponding to the first sound in the second signal to the signal energy corresponding to the second sound; as well as The signal processing circuit is connected to the first sound sensor and the second sound sensor respectively, and operates as follows: Based on the second signal, the signal component in the first signal corresponding to the first sound is reduced to obtain the target signal, and Perform the target operation on the target signal.

2. The acoustic system according to claim 1, characterized in that, In order to satisfy The first signal and the second signal satisfy at least one of the following conditions: The ratio of the signal energy corresponding to the first sound in the second signal to the signal energy corresponding to the second sound in the second signal is greater than or equal to 2; The ratio of the signal energy corresponding to the first sound in the second signal to the signal energy corresponding to the first sound in the first signal is greater than or equal to 2; as well as The ratio of the signal energy corresponding to the second sound in the first signal to the signal energy corresponding to the first sound in the first signal is greater than or equal to 2.

3. The acoustic system according to claim 1, characterized in that, The first preset conditions include: ,in, The distance between the second sound sensor and the speaker. The distance between the first sound sensor and the speaker.

4. The acoustic system according to claim 1, characterized in that, The acoustic system also includes a housing, a portion of which forms an acoustic cavity. The loudspeaker and the second sound sensor are both located inside the acoustic cavity, while the first sound sensor is located outside the acoustic cavity.

5. The acoustic system according to claim 4, characterized in that, The speaker's sound-emitting component divides the acoustic cavity into a first acoustic cavity and a second acoustic cavity, with the sound-emitting surface of the sound-emitting component facing the first acoustic cavity. The second sound sensor is located inside the first acoustic cavity, or The second sound sensor is located inside the second acoustic cavity.

6. The acoustic system according to claim 4, characterized in that, The second sound sensor is coupled to the sound-emitting component of the speaker.

7. The acoustic system according to claim 1, characterized in that, The acoustic system also includes a housing, and the pickup surfaces of the second sound sensor and the first sound sensor are both located in the free space outside the housing, with the second sound sensor being closer to the speaker than the first sound sensor.

8. The acoustic system according to claim 1, characterized in that, The acoustic system also includes a housing, a portion of which forms a first acoustic cavity and a second acoustic cavity. The loudspeaker is located in the first acoustic cavity, and the second sound sensor is located in the second acoustic cavity, with the second sound sensor being closer to the loudspeaker than the first sound sensor.

9. The acoustic system according to claim 1, characterized in that, The acoustic system further includes a housing, the pickup surface of the first sound sensor is located in the free space outside the housing, the pickup surface of the second sound sensor is located in the internal space of the housing, and the second sound sensor is closer to the speaker than the first sound sensor.

10. The acoustic system according to claim 1, characterized in that, The acoustic system further includes a first housing and a second housing, wherein... The second housing is located inside the first housing, and the second housing forms an acoustic cavity, with the speaker and the second sound sensor located inside the acoustic cavity.

11. The acoustic system according to claim 1, characterized in that, The acoustic system also includes a partition, with the second sound sensor and the speaker located on a first side of the partition and the first sound sensor located on a second side of the partition.

12. The acoustic system according to claim 1, characterized in that, The sound pickup directivity of the first sound sensor and the second sound sensor satisfies at least one of the following conditions: The first sound sensor has a greater sound pickup sensitivity in the first direction than in the second direction; and The second sound sensor has a lower pickup sensitivity in the first direction than in the second direction, wherein The first direction points towards the target sound source, and the second direction points towards the loudspeaker.

13. The acoustic system according to claim 1, characterized in that, The first sound sensor is located at a first position within the target area, and the second sound sensor is located at a second position within the target area, wherein the first position and the second position satisfy at least one of the following conditions: The sound energy from the speaker at the first location is less than the sound energy from the speaker at other locations within the target area besides the first location; and The sound energy from the speaker at the second location is greater than the sound energy from the speaker at other locations within the target area besides the second location.

14. The acoustic system according to claim 1, characterized in that, To obtain the target signal, the signal processing circuit: An adaptive filtering operation is performed on the second signal to obtain a third signal, and the third signal is subtracted from the first signal to obtain the target signal.

15. The acoustic system according to claim 14, characterized in that, The signal processing circuit also includes: The filter parameters corresponding to the adaptive filtering operation are updated based on at least one of the second signal and the target signal.

16. The acoustic system according to claim 1, characterized in that, To obtain the target signal, the signal processing circuit: Perform a first preprocessing operation on the first signal to obtain a first intermediate signal; Perform a second preprocessing operation on the second signal to obtain a second intermediate signal; as well as Based on the second intermediate signal, the signal component corresponding to the first sound in the first intermediate signal is reduced to obtain the target signal.

17. The acoustic system according to claim 16, characterized in that, The first preprocessing operation includes at least one of gain amplification, filtering, frequency response compensation, and phase modification; and The second preprocessing operation includes at least one of the following: gain amplification operation, filtering operation, frequency response compensation operation, and phase modification operation.

18. The acoustic system according to claim 1, characterized in that, The signal processing circuit is also connected to the speaker, and during the execution of the target operation, the signal processing circuit: Gain amplification is applied to the target signal, and The amplified signal is sent to the speaker to drive the speaker to produce sound.

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