WO2024239318A1 - 声学系统 - Google Patents

声学系统 Download PDF

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Publication number
WO2024239318A1
WO2024239318A1 PCT/CN2023/096286 CN2023096286W WO2024239318A1 WO 2024239318 A1 WO2024239318 A1 WO 2024239318A1 CN 2023096286 W CN2023096286 W CN 2023096286W WO 2024239318 A1 WO2024239318 A1 WO 2024239318A1
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WO
WIPO (PCT)
Prior art keywords
sound
signal
sound sensor
speaker
acoustic
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2023/096286
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English (en)
French (fr)
Inventor
李伯诚
吴晨阳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Shokz Co Ltd
Original Assignee
Shenzhen Shokz Co Ltd
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Filing date
Publication date
Application filed by Shenzhen Shokz Co Ltd filed Critical Shenzhen Shokz Co Ltd
Priority to CN202380075696.1A priority Critical patent/CN120130085A/zh
Priority to PCT/CN2023/096286 priority patent/WO2024239318A1/zh
Priority to EP23937991.0A priority patent/EP4561106A4/en
Publication of WO2024239318A1 publication Critical patent/WO2024239318A1/zh
Priority to US19/055,460 priority patent/US20250193596A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers
    • H04R3/02—Circuits for transducers for preventing acoustic reaction, i.e. acoustic oscillatory feedback
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers
    • H04R3/04—Circuits for transducers for correcting frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
    • H04R1/025—Arrangements for fixing loudspeaker transducers, e.g. in a box, furniture
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
    • H04R1/406—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R29/00—Monitoring arrangements; Testing arrangements
    • H04R29/001—Monitoring arrangements; Testing arrangements for loudspeakers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers
    • H04R3/005—Circuits for transducers for combining the signals of two or more microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
    • H04R1/1058—Manufacture or assembly
    • H04R1/1075—Mountings of transducers in earphones or headphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/326—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only for microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
    • H04R2430/01—Aspects of volume control, not necessarily automatic, in sound systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R2460/00—Details of hearing devices, i.e. of ear- or headphones covered by H04R1/10 or H04R5/033 but not provided for in any of their subgroups, or of hearing aids covered by H04R25/00 but not provided for in any of its subgroups
    • H04R2460/13—Hearing devices using bone conduction transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Electric hearing aids
    • H04R25/40—Arrangements for obtaining a desired directivity characteristic
    • H04R25/405—Arrangements for obtaining a desired directivity characteristic by combining a plurality of transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Electric hearing aids
    • H04R25/45—Prevention of acoustic reaction, i.e. acoustic oscillatory feedback
    • H04R25/453—Prevention of acoustic reaction, i.e. acoustic oscillatory feedback electronically

Definitions

  • the present specification relates to the field of acoustic technology, and in particular to an acoustic system.
  • Some acoustic systems include both a speaker and a sound sensor. These acoustic systems usually have the problem of acoustic feedback. Among them, acoustic feedback means that the sound signal collected by the sound sensor is played through the speaker after a certain processing, and the sound emitted by the speaker is re-collected by the sound sensor, so that the acoustic system forms a closed loop of "speaker->sound sensor->speaker". In the above acoustic system, the sound of the speaker picked up by the sound sensor can be called feedback sound. The existence of feedback sound causes some problems in the acoustic system. For example, it causes problems such as howling in the acoustic system, and may also limit the maximum forward gain that the acoustic system can achieve. Therefore, it is necessary to provide an acoustic system that can reduce or eliminate feedback sound.
  • the present specification provides an acoustic system that can reduce or eliminate feedback sound, thereby avoiding problems such as howling caused by the feedback sound and improving the maximum forward gain that the acoustic system can achieve.
  • the present specification provides an acoustic system, comprising: a speaker, a first sound sensor, a second sound sensor and a signal processing circuit, wherein the speaker receives a driving signal and converts it into a first sound when in operation, the first sound sensor collects ambient sound and generates a first signal when in operation, the ambient sound includes the first sound and a second sound from a target sound source, the target sound source includes other sound sources except the speaker, the second sound sensor collects the ambient sound and generates a second signal when in operation, wherein the first signal and the second signal satisfy k 2 ⁇ 2k 1 , wherein k 1 is a ratio of a signal energy corresponding to the first sound in the first signal to a signal energy corresponding to the second sound, and k 2 is a ratio of a signal energy corresponding to the first sound in the second signal to a signal energy corresponding to the second sound, the signal processing circuit is connected to the first sound sensor and the second sound sensor respectively, and when in operation, based on the second
  • the first signal and the second signal satisfy at least one of the following conditions: a ratio of a signal energy in the second signal corresponding to the first sound to a signal energy in the second signal corresponding to the second sound is greater than or equal to 2; a ratio of a signal energy in the second signal corresponding to the first sound to a signal energy in the first signal corresponding to the first sound is greater than or equal to 2; and a ratio of a signal energy in the first signal corresponding to the second sound to a signal energy in the first signal corresponding to the first sound is greater than or equal to 2.
  • the positional relationship between the first sound sensor, the second sound sensor, and the speaker meets a preset condition, so that the first signal and the second signal satisfy k 2 ⁇ 2k 1 .
  • the preset condition includes: L 1 ⁇ 2L 2 , where L 2 is the distance between the second sound sensor and the speaker, and L 1 is the distance between the first sound sensor and the speaker.
  • the acoustic system further includes a shell, a partial area of the shell forms an acoustic cavity, the speaker and the second sound sensor are both located inside the acoustic cavity, and the first sound sensor is located outside the acoustic cavity.
  • the sound-emitting component of the speaker divides the acoustic cavity into a first acoustic cavity and a second acoustic cavity, and the sound-emitting surface of the sound-emitting component faces the first acoustic cavity, wherein the second sound sensor is located inside the first acoustic cavity, or the second sound sensor is located inside the second acoustic cavity.
  • the second sound sensor is coupled to a sound emitting component of the speaker.
  • the acoustic system further includes a shell, 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 shell, and the second sound sensor is closer to the speaker than the first sound sensor.
  • the acoustic system also includes a shell, a partial area of which forms a first acoustic cavity and a second acoustic cavity, the speaker 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 speaker than the first sound sensor.
  • the acoustic system further comprises a shell, the pickup surface of the first sound sensor is located in a free space outside the shell, the pickup surface of the second sound sensor is located in an internal space of the shell, and the second sound sensor is closer to the speaker than the first sound sensor.
  • the acoustic system further comprises a first shell and a second shell, wherein:
  • the second shell is located inside the first shell, and the second shell forms an acoustic cavity, and the speaker and the second sound sensor are located inside the acoustic cavity.
  • the acoustic system further includes a baffle, the second sound sensor and the speaker are located on a first side of the baffle, and the first sound sensor is located on a second side of the baffle.
  • the sound pickup directivities of the first sound sensor and the second sound sensor meet a preset condition, so that the first signal and the second signal satisfy k 2 ⁇ 2k 1 .
  • the sound pickup directivities of the first sound sensor and the second sound sensor satisfy at least one of the following conditions: the sound pickup sensitivity of the first sound sensor in a first direction is greater than the sound pickup sensitivity in a second direction; and the sound pickup sensitivity of the second sound sensor in the first direction is less than the sound pickup sensitivity in the second direction, wherein the first direction points to the target sound source and the second direction points to the speaker.
  • the first sound sensor is located at a first position within the target area
  • 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 position is less than the sound energy from the speaker at other positions within the target area except the first position; and the sound energy from the speaker at the second position is greater than the sound energy from the speaker at other positions within the target area except the second position.
  • the signal processing circuit in order to obtain the target signal, 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.
  • the signal processing circuit further: updates a filtering parameter corresponding to the adaptive filtering operation based on at least one of the second signal and the target signal.
  • the signal processing circuit in order to obtain the target signal, performs a first preprocessing operation on the first signal to obtain a first intermediate signal; performs a second preprocessing operation on the second signal to obtain a second intermediate signal; and based on the second intermediate signal, reduces the signal component corresponding to the first sound in the first intermediate signal to obtain the target signal.
  • the first preprocessing operation includes at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation; and the second preprocessing operation includes at least one of a gain amplification operation, a filtering operation, a frequency response compensation operation, and a phase modification operation.
  • the signal processing circuit is also connected to the speaker.
  • the signal processing circuit When executing the target operation, the signal processing circuit: performs gain amplification on the target signal, and sends the gain-amplified signal to the speaker to drive the speaker to produce sound.
  • the acoustic system includes: a speaker, a first sound sensor, a second sound sensor and a signal processing circuit.
  • the speaker when the speaker 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, and the environmental sound includes the first sound and the second sound from the target sound source; when the second sound sensor is working, it collects environmental sound and generates a second signal, and the first signal and the second signal satisfy k 2 ⁇ 2k 1 , wherein k 1 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, and k 2 is the ratio of the signal energy corresponding to the first sound in the second signal to the signal energy corresponding to the second sound; the signal processing circuit is connected to the first sound sensor and the second sound sensor respectively, and when working, the signal component corresponding to the first sound in the first signal is reduced based
  • FIG1 is a schematic diagram showing an application scenario provided according to an embodiment of this specification.
  • FIG2 shows a schematic diagram of a design of an acoustic system provided according to an embodiment of this specification
  • FIG3 shows another schematic diagram of a design of an acoustic system provided according to an embodiment of this specification
  • FIG4 shows another schematic diagram of a design of an acoustic system provided according to an embodiment of this specification
  • FIG5 shows another schematic diagram of a design of an acoustic system provided according to an embodiment of this specification
  • 6A to 6F show several structural schematic diagrams of acoustic systems provided according to embodiments of this specification.
  • FIG. 7A to 7G show several other structural schematic diagrams of acoustic systems provided according to embodiments of this specification.
  • FIG. 8A to 8F show several structural schematic diagrams of acoustic systems provided according to embodiments of this specification.
  • FIG9 shows a schematic diagram of the sound pickup direction of an acoustic system provided according to an embodiment of this specification.
  • FIG10A is 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 the present specification
  • FIG10B is a schematic diagram showing feedback sound energy corresponding to various positions within the target area of the acoustic system.
  • FIG. 1 shows a schematic diagram of an application scenario provided according to an embodiment of the present specification.
  • application scenario 001 may be a sound amplification scenario, an auxiliary listening scenario, a hearing aid scenario, etc.
  • the sound sensor 120 collects ambient sound when working.
  • the speaker 110 is also playing sound synchronously, the sound played by the speaker 110 will also be collected by the sound sensor 120.
  • the ambient sound collected by the sound sensor 120 includes both the sound from the target sound source 160 and the sound from the speaker 110.
  • the sound pickup signal collected by the sound sensor 120 is input to the speaker 110 after forward gain amplification (G), thereby driving the speaker 110 to make a sound.
  • G forward gain amplification
  • FIG. 1 is only part of the multiple application scenarios applicable to the present application.
  • the acoustic system provided by the present application can also be applied to other similar scenarios, which are not listed one by one in the specification.
  • Those skilled in the art should understand that the application of the acoustic system provided by the present application to other usage scenarios is also within the protection scope of the present application.
  • the presence of feedback sound can cause a series of problems in the acoustic system, including but not limited to: generating howling, limiting the maximum forward gain that the acoustic system can achieve, etc.
  • the present application provides an acoustic system that reduces or eliminates feedback sound, thereby avoiding the above series of problems.
  • the acoustic system provided in this application can use acoustic feedback cancellation (AFC) technology to reduce or eliminate feedback sound.
  • AFC acoustic feedback cancellation
  • FIG2 shows a schematic diagram of a design of an acoustic system provided according to an embodiment of the present specification.
  • the acoustic system 10 may be a hearing aid/auxiliary listening system or a sound amplification system.
  • the acoustic system 10 may utilize AFC technology to reduce or eliminate feedback components (i.e., signal components corresponding to feedback sounds).
  • the acoustic system 10 may include a speaker 110, a sound sensor 120, and a signal processing circuit 150.
  • the speaker 110 is a device for converting an electrical signal into sound, and may also be referred to as an electroacoustic converter.
  • the speaker 110 may be a speaker.
  • the speaker 110 may be a device that makes sound based on at least one conduction method among gas, liquid, and solid.
  • the speaker 110 may be connected to the signal processing circuit 150, and when working, receives the electrical signal from the signal processing circuit 150 and converts it into sound to play out.
  • the acoustic system 10 may further include a first peripheral circuit (not shown in FIG. 2 ).
  • the first peripheral circuit is connected between the signal processing circuit 150 and the speaker 110.
  • the first peripheral circuit may include all or part of the circuits between the output end of the signal processing circuit 150 and the speaker 110.
  • the first peripheral circuit may perform some processing on the electrical signal output by the signal processing circuit 150, so that the processed electrical signal is suitable for playing by the speaker 110.
  • the first peripheral circuit may 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.
  • the sound sensor 120 is a device for picking up sound and converting it into an electrical signal, and may also be called an acoustic-electrical converter.
  • the sound sensor 120 may be a microphone (MIC).
  • the sound sensor 120 may be a gas, liquid, or solid
  • the acoustic system 10 may further include a second peripheral circuit (not shown in FIG. 2 ).
  • the second peripheral circuit is connected between the sound sensor 120 and the signal processing circuit 150.
  • the second peripheral circuit may include all or part of the circuits between the sound sensor 120 and the input end of the signal processing circuit 150.
  • the second peripheral circuit may perform some processing on the electrical signal picked up by the sound sensor 120 so as to convert it into a signal suitable for processing by the signal processing circuit 150.
  • the second peripheral circuit may 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.
  • the sound sensor 120 collects environmental sound to generate a sound pickup signal y, and inputs the sound pickup signal y to the signal processing circuit 150.
  • the environmental sound includes at least a second sound emitted by the target sound source 160.
  • the target sound source 160 refers to a sound source other than the speaker 110.
  • the target sound source 160 may include an electronic device with a sound playback function (such as a television, a speaker, a mobile phone, etc.); for another example, the target sound source 160 may also include a human throat.
  • the above-mentioned sound 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 sound pickup signal y to obtain a drive signal u, and sends the drive signal u to the speaker 110.
  • the above-mentioned drive signal u can be used as an output signal of the signal processing circuit 150.
  • the speaker 110 receives the drive 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, so the first sound can also be referred to as a feedback sound.
  • the ambient sound collected by the sound sensor 120 includes not only the second sound from the target sound source 160, but also the first sound from the speaker 110.
  • the sound pickup signal y includes both the signal component x corresponding to the first sound (i.e., the feedback sound) and the signal component v corresponding to the second sound.
  • the signal processing circuit 150 may be a circuit with certain signal processing capabilities.
  • the input end of the signal processing circuit 150 is connected to the sound sensor 120, and the output end is connected to the speaker 110.
  • the signal processing circuit 150 can obtain the sound pickup signal y from the sound sensor 120, and obtain the driving signal u after performing a preset signal processing process on the sound pickup signal y, and send the driving signal u to the speaker 110.
  • the signal processing circuit 150 may include multiple hardware circuits with a connection relationship, each hardware circuit includes one or more electrical components, and each electrical component implements one or more functional units, so that the above-mentioned multiple hardware circuits cooperate with each other when working to implement the signal processing process.
  • the signal processing circuit 150 may include a hardware device with a data information processing function and a necessary program to drive the hardware device to work, and the hardware device implements the signal processing flow by executing the program.
  • the signal processing circuit 150 may include at least one storage medium and at least one processor.
  • the storage medium may include a data storage device.
  • the data storage device may be a non-temporary storage medium or a temporary storage medium.
  • the data storage device may include one or more of a disk, a read-only storage medium (ROM), or a random access storage medium (RAM).
  • the storage medium also includes at least one instruction set stored in the data storage device.
  • the instruction is a computer program code, and the computer program code may include a program, a routine, an object, a component, a data structure, a process, a module, etc. for executing the signal processing method provided in this specification.
  • the at least one processor may be in communication with the at least one storage medium.
  • the at least one processor is configured to execute the at least one instruction set.
  • the at least one processor reads the at least one instruction set and executes the at least one instruction set according to the instructions.
  • the signal processing flow is executed according to the instructions of the at least one instruction set.
  • the processor may include one or more hardware processors, such as a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application-specific integrated circuit (ASIC), an application-specific instruction set processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physical processing unit (PPU), a microcontroller unit, a digital signal processor (DSP), a field programmable gate array (FPGA), an advanced RISC machine (ARM), a programmable logic device (PLD), any circuit or processor capable of performing one or more functions, etc., or any combination thereof.
  • RISC reduced instruction set computer
  • ASIC application-specific integrated circuit
  • ASIP application-specific instruction set processor
  • CPU central processing unit
  • GPU graphics processing unit
  • PPU physical processing unit
  • DSP digital signal processor
  • FPGA field programmable gate array
  • ARM advanced RISC machine
  • PLD programmable logic device
  • the signal processing circuit 150 may include an acoustic feedback cancellation unit 170.
  • the input of the acoustic feedback cancellation unit 170 includes: a driving signal u and a pickup signal y.
  • the acoustic feedback cancellation unit 170 may reduce the signal component corresponding to the first sound in the pickup signal y based on the driving signal u, thereby obtaining a target signal e.
  • 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.
  • the transfer function F' will be referred to as the predicted transfer function F' and the transfer function F corresponding to the feedback path will be referred to as the real transfer function F.
  • the signal x' can be regarded as the predicted value of the feedback component in the picked-up signal y (that is, the signal component in the picked-up signal y corresponding to the first sound).
  • the target signal e obtained in this way does not contain or contains less feedback sound components.
  • the acoustic feedback cancellation unit 170 can be implemented using a variety of adaptive filtering algorithms when solving the predicted transfer function F', for example, the least mean square (Least Mean Square, LMS), normalized least mean square (Normalized Least Mean Square, NLMS), recursive least squares (Recursive least squares, RLS), other adaptive filtering algorithms, and any derivative algorithms of the above-mentioned algorithms.
  • LMS least mean square
  • NLMS normalized Least Mean Square
  • RLS recursive least squares
  • the adaptive filtering algorithm can be adaptive filtering in the time domain, frequency domain or other transform domains.
  • the above formula (1-1) is derived based on the gradient descent optimization method, and the update formula of the predicted transfer function F' can be obtained as follows: F′ ⁇ F′+ ⁇ *e*u formula (2-1)
  • ⁇ is the iteration step size.
  • acoustic feedback cancellation unit 170 adopts algorithms such as NLMS, RLS, etc.
  • a similar method can be used to derive an update formula for the predicted transfer function F', which will not be described one by one in this specification.
  • the acoustic system shown in FIG. 2 can reduce or eliminate feedback sound by adopting the AFC technology, thereby avoiding a series of problems caused by the feedback sound.
  • the closed-loop gain A of the acoustic system shown in Figure 2 can be expressed as follows:
  • the acoustic system will always be stable and will not produce howling.
  • the deviation between the predicted transfer function F′ and the true transfer function F can be used to measure the convergence performance of the adaptive filtering algorithm, and further measure the acoustic system's effect of canceling feedback sound. Specifically, if the deviation between the predicted transfer function F′ and the true transfer function F is smaller, it means that the convergence performance of the adaptive filtering algorithm is better, and thus the acoustic system's effect of canceling feedback sound is better. If the deviation between the predicted transfer function F′ and the true transfer function F is larger, it means that the convergence performance of the adaptive filtering algorithm is worse, and thus the acoustic system's effect of canceling feedback sound is worse.
  • misalignment (MIS) to measure the convergence performance of the adaptive filtering algorithm.
  • MIS misalignment
  • the misalignment MIS can be expressed by the following formula:
  • the unit of the offset MIS is decibel (dB).
  • the offset MIS is 0dB.
  • the offset MIS is smaller and approaches negative infinity, the deviation between the predicted transfer function F′ and the true transfer function F is smaller, indicating that the convergence performance of the adaptive filtering algorithm is better, and thus the acoustic system has a better effect of canceling feedback sound.
  • the offset MIS is larger and approaches positive infinity, the deviation between the predicted transfer function F′ and the true transfer function F is larger, indicating that the convergence performance of the adaptive filtering algorithm is worse, and thus the acoustic system has a worse effect of canceling feedback sound.
  • the convergence performance of the adaptive filtering algorithm in the present application includes but is not limited to: convergence speed, convergence error, etc.
  • the convergence speed may refer to the fitting speed of the predicted transfer function F′ to the true transfer function F
  • the convergence error may refer to the deviation between the predicted transfer function F′ and the true transfer function F when the convergence condition is reached.
  • the actual acoustic system usually cannot meet the above ideal assumptions. Because in the actual acoustic system, there are many devices in the feedback path, and these devices may have nonlinear responses. For example, the interaction between the diaphragm and the magnet of the speaker 110 leads to hysteresis effect and saturation distortion, so the response of the speaker 110 contains nonlinear response components.
  • power amplifiers, operational amplifiers and other devices between the signal processing circuit 150 and the speaker 110 there are usually power amplifiers, operational amplifiers and other devices between the signal processing circuit 150 and the speaker 110. Power amplifiers and operational amplifiers usually have limited The amplitude effect is caused by the two components, so the responses of the two components also contain nonlinear response components. Similarly, other components between the signal processing circuit 150 and the speaker 110 may also contain nonlinear response components.
  • the acoustic feedback cancellation unit 170 may be independent of other units in the signal processing circuit 150, and the design architecture of the acoustic system limits the access rights or communication capabilities between different units. Therefore, the acoustic feedback cancellation unit 170 may not be able to obtain the driving signal u from other units. As a result, such an acoustic system cannot use the AFC technology to reduce or eliminate feedback sound.
  • Fig. 3 shows another schematic diagram of an acoustic system according to an embodiment of the present specification.
  • the acoustic system 20 may include: a speaker 110 , a first sound sensor 120 - 1 , a second sound sensor 120 - 2 , and a signal processing circuit 150 .
  • the acoustic system 20 shown in FIG3 can be regarded as a further improvement on the acoustic system 10 shown in FIG2.
  • the first sound sensor 120-1 in the acoustic system 20 shown in FIG3 can correspond to the sound sensor 120 in the acoustic system 10 shown in FIG2.
  • the acoustic system 20 shown in FIG3 is equivalent to adding a second sound sensor 120-2 on the basis of the acoustic system 10 shown in FIG2.
  • the structure of the second sound sensor 120-2 can be the same as or different from that of the first sound sensor 120-1, and this application does not limit this.
  • the working process of the acoustic system 20 shown in FIG3 is as follows: when the speaker 110 is working, it receives the driving signal u from the signal processing circuit 150 and converts the driving signal u into the first sound. When the first sound sensor 120-1 is working, it collects the environmental sound and generates the first signal y 1. When the second sound sensor 120-2 is working, it collects the environmental sound and generates the second signal y 2. The environmental sound includes the first sound from the speaker 110 and the second sound from the external sound source 160.
  • the first signal y 1 includes a signal component x 1 corresponding to the first sound and a signal component v 1 corresponding to the second sound
  • the second signal y 2 includes a signal component x 2 corresponding to the first sound and a signal component v 2 corresponding to the second sound.
  • the external sound source 160 includes other sound sources in the environment except the speaker 110, for example, a person's throat, an electronic device with a sound playing function, other speakers, etc.
  • the first sound emitted by the speaker 110 can be transmitted through one or more media among gas, liquid and solid, and then picked up by the first sound sensor 120-1 and the second sound sensor 120-2.
  • the second sound emitted by the target sound source 160 can be transmitted through one or more media among gas, liquid and solid, and then picked up by the first sound sensor 120-1 and the second sound sensor 120-2.
  • this specification does not limit the carrying method of the first signal y 1 , the second signal y 2 , and the driving signal u, and all three can be signals carried by any carrier.
  • the first signal y 1 , the second signal y 2 , and the driving signal u can all be electrical signals, optical signals, digital carrier signals, or signals of other carrier types.
  • the first sound sensor 120 - 1 and the second sound sensor 120 - 2 have different sound pickup emphases.
  • the first sound sensor 120-1 focuses on picking up the sound from the target sound source 160
  • the second sound sensor 120-2 focuses on picking up the sound from the speaker 110.
  • 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: k 2 ⁇ 2k 1 Formula (6)
  • k1 is the ratio of the signal energy
  • k2 is the ratio of the signal energy
  • the value of N can be a real number greater than or equal to 2.
  • the value of N can be within the interval specified by any two of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, ..., ⁇ .
  • the second sound sensor 120-2 is closer to picking up only the sound of the speaker 110
  • the first sound sensor 120-1 is closer to picking up only the sound of the target sound source 160.
  • the closed-loop gain A of the acoustic system can be expressed as follows:
  • the first signal y 1 and the second signal y 2 may satisfy one or more of the following conditions:
  • 2 corresponding to the second sound in the second signal y 2 is greater than or equal to 2, that is:
  • the above condition can also be expressed as: the signal energy
  • the above condition can also be expressed as: the signal energy
  • the above condition can also be expressed as: the signal energy
  • the signal processing circuit 150 may be connected to the first sound sensor 120-1 and the second sound sensor 120-2, respectively.
  • the signal processing circuit 150 may obtain the first signal y 1 from the first sound sensor 120-1 and obtain the second signal y 2 from the second sound sensor 120-2. Furthermore, the signal processing circuit 150 may reduce the signal component corresponding to the first sound in the first signal y 1 based on the second signal y 2 , thereby obtaining the target signal e. In this way, the target signal e does not contain or contains less feedback sound components.
  • the acoustic system shown in FIG. 3 can also reduce or eliminate the feedback component in the target signal based on the AFC technology.
  • the signal processing circuit 150 may include an acoustic feedback cancellation unit 170, and the interior of the acoustic feedback cancellation unit 170 may solve and adaptively update a time-varying predicted transfer function F′ to fit the real transfer function F corresponding to the feedback path.
  • the input of the acoustic feedback cancellation unit 170 includes: a first signal y 1 and a second signal y 2 .
  • the third signal x′ can be regarded as a predicted value of the feedback component in the first signal y 1 (that is, the signal component corresponding to the first sound in the first signal y 1 ).
  • the target signal e obtained in this way contains no or less feedback sound components.
  • 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.
  • the above formula (1-2) is derived based on the gradient descent optimization method, and the update formula of the predicted transfer function F′ can be obtained as follows: F′ ⁇ F′+ ⁇ *e*y 2 formula (2-2)
  • ⁇ is the iteration step size.
  • the signal processing circuit 150 can perform a target operation on the target signal e.
  • the signal processing circuit 150 can also include a gain amplifier unit 130 (the gain amplifier unit is marked as G in FIG3 ).
  • the gain amplifier unit performs gain amplification on the target signal e, and sends the gain-amplified signal to the speaker 110 as the driving signal u at the next moment, thereby driving the speaker 110 to make a sound. Since the feedback component in the target signal e is reduced or eliminated, the acoustic system 10 can be prevented from generating howling or suppressed, and it also helps to improve the maximum forward gain that the acoustic system 10 can achieve.
  • the acoustic system 20 shown in FIG3 uses the newly added second sound sensor 120-2 to focus on picking up the first sound to obtain the second signal y2 . 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. Compared with the acoustic system 10 shown in FIG2, the acoustic system 20 shown in FIG3 is obtained from the signal path behind the speaker 110.
  • the feedback cancellation unit 170 when solving the predicted transfer function F', only needs to fit the transfer function of the feedback path after the speaker 110, thereby avoiding 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.
  • 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 authority between the feedback cancellation unit 170 and other units, it does not affect the application of the AFC technology in the acoustic system 20, thereby reducing the requirements of the AFC technology on the design architecture of the acoustic system and improving the application flexibility and breadth of the AFC technology.
  • the feedback cancellation unit 170 originally has system access rights to the first sound sensor 120-1, and the rights required to access the second sound sensor 120-2 are the same as the rights required to access the first sound sensor 120-1, after the second sound sensor 120-2 is added to the acoustic system shown in FIG. 3, the feedback cancellation unit 170 does not need to add new system access rights to access the data of the second sound sensor 120-2.
  • the acoustic system shown in FIG3 adds the second sound sensor 120-2, 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 predicted transfer function F′ and the calculation formula of the feedback sound cancellation, but only to replace the input signal u of the acoustic feedback cancellation unit 170 with y2 .
  • the acoustic system shown in FIG3 can be applied, adapted, and compatible with the existing acoustic feedback cancellation unit 170, regardless of what kind of adaptive filtering algorithm these existing acoustic feedback cancellation units 170 use (including but not limited to the aforementioned LMS, NLMS, RLS or other adaptive filtering algorithms). Therefore, the difficulty of modifying the acoustic system is relatively low and has wide applicability.
  • F1 represents the acoustic transfer function between the speaker 110 and the first sound sensor 120-1
  • F2 represents the acoustic transfer function between the speaker 110 and the second sound sensor 120-2.
  • the requirement for the acoustic system 20 to offset the feedback sound is that the predicted transfer function F′ to be solved satisfies the following conditions:
  • the prediction transfer function F′ needs to satisfy:
  • the acoustic transfer function F 2 ⁇ 1 from the speaker 110 to the second sound sensor 120 - 2 , and the first signal y 1 and the second signal y 2 satisfy the following conditions:
  • 2 in the second signal y 2 corresponding to the first sound is much greater than the signal energy
  • the acoustic system shown in FIG3 can be simplified to the acoustic system shown in FIG4.
  • the second sound sensor 120-2 almost only picks up the sound from the speaker 110.
  • the second signal y 2 ⁇ u. Therefore, the update formula of the prediction transfer function F′ can be updated as: F′ ⁇ F′+ ⁇ ey 2 ⁇ F′+ ⁇ eu Formula (2-3)
  • the closed-loop gain A of the acoustic system 30 can be expressed as:
  • FIG5 shows another design schematic diagram of an acoustic system provided according to an embodiment of the present specification.
  • the signal processing circuit 150 may further include a preprocessing unit 180. After obtaining the first signal y1 and the second signal y2 , the signal processing circuit 150 may preprocess the first signal y1 and the second signal y2 respectively through the preprocessing unit 180. Specifically, the signal processing circuit 150 performs a first preprocessing operation H1 on the first signal y1 through the preprocessing unit 180 to obtain a first intermediate signal y1 ′, and performs a second preprocessing operation H2 on the second signal y2 to obtain a second intermediate signal y2 ′.
  • 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 a 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.
  • the first preprocessing operation H1 may 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 preprocessing operation H2 may 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 first preprocessing operation H1 and the second preprocessing operation H2 may be designed based on the requirements of different application scenarios. For example, in some cases, there is a difference in the frequency response of the first sound sensor 120-1 and the second sound sensor 120-2.
  • a suitable first preprocessing operation H1 and a second preprocessing operation H2 may 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. It can be seen that the signal processing circuit 150 can meet the processing requirements of different application scenarios by performing preprocessing operations on the first signal y1 and the second signal y2 .
  • the above-mentioned Figures 3 to 5 are illustrated by taking the acoustic system 20 including a speaker 110 as an example.
  • the number of speakers 110 in the acoustic system 20 may be M, where M is an integer greater than 1.
  • the number of second sound sensors 120-2 may also be M.
  • the M second sound sensors 120-2 correspond one-to-one to the M speakers 110.
  • the i-th second sound sensor 120-2 focuses on picking up the sound emitted by the i-th speaker 110.
  • the i-th second sound sensor 120-2 collects environmental sound and generates a second signal y 2i when in operation.
  • the first signal y 1 and the second signal y 2i satisfy k 2i ⁇ 2k 1
  • k 2i is the ratio of the signal energy corresponding to the sound emitted by the i-th speaker 110 in the second signal y 2i to the signal energy corresponding to the sound emitted by the target sound source.
  • the target sound source includes other sound sources in the environment except the i-th speaker.
  • the signal processing circuit 150 can reduce the feedback component in the first signal y 1 based on the second signal y 2i to obtain the target signal e i .
  • the signal processing circuit obtains the target signal e by superimposing the target signal e 1 to the target signal e M , and then performs the target operation on the target signal e.
  • the acoustic system 20 may include M second sound sensors 120-2.
  • the i-th sound sensor 120-2 focuses on picking up the sound of the i-th speaker and is used for the adaptive filtering process of AFC. In this way, it is equivalent to superimposing M AFC-based adaptive filtering processes in the acoustic system 20.
  • each adaptive filtering process is consistent with the description of Figures 3 to 5 above, and will not be repeated here.
  • the use of AFC technology can effectively reduce or eliminate feedback sound, and can avoid or reduce the nonlinear response to the adaptive The impact of the filtering algorithm on its convergence performance.
  • the acoustic system may be designed from a structural dimension so that the positional relationship among the first sound sensor 120 - 1 , the second sound sensor 120 - 2 , and the speaker 110 satisfies a preset condition, thereby making the first signal y 1 and the second signal y 2 satisfy the condition k 2 ⁇ 2k 1 .
  • the first sound sensor 120 - 1 , the second sound sensor 120 - 2 , and the speaker 110 satisfy a preset distance condition.
  • the distance condition may include: 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 to the first sound sensor 120-1. Assuming that the distance between the first sound sensor 120-1 and the speaker 110 is recorded as L 1 , and the distance between the second sound sensor 120-2 and the speaker 110 is recorded as L 2 , then L 1 and L 2 satisfy the distance condition: L 1 ⁇ 2L 2.
  • the above distance condition can also be expressed as the ratio of L 1 to L 2 is greater than or equal to a preset value. The above preset value can be located in an interval specified by any two of 2, 3, 4, 5, 6, 7, 8, 9, 10, ... ⁇ .
  • the acoustic system 20 can be in the form of a true wireless headset, an earmuff form, a glasses form, a rear-hanging form, a behind-the-ear form, an in-ear form, or any other possible form.
  • Figures 6A to 6F are only used as examples for illustration of several possible product forms.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 may be as shown in FIG6A.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 may be as shown in FIG6B.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 may be as shown in FIG6C.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 may be as shown in FIG6D.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 may be as shown in FIG6E.
  • the behind-the-ear form includes but is not limited to BTE (Behind-The-Ear) and RIC (Receiver-In-Canal) in hearing aids.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be as shown in FIG6F.
  • the in-the-ear form includes but is not limited to ITE (In-The-Ear), ITC (In-The-Canal), CIC (Completely-In-the-Canal) in hearing aids.
  • ITE In-The-Ear
  • ITC In-The-Canal
  • CIC Completely-In-the-Canal
  • the second sound sensor 120-2 can pick up a stronger first sound than the first sound sensor 120-1 . is much larger than the signal energy
  • Figures 6A to 6F show some examples of acoustic systems that meet the distance condition L 1 ⁇ 2L 2
  • some acoustic systems may not meet the distance condition L 1 ⁇ 2L 2 due to the influence of product form or specific requirements. That is to say, the values of L 1 and L 2 are relatively close.
  • Figures 7A to 7G respectively show the structural schematic diagrams of the acoustic system when the values of L 1 and L 2 are relatively close.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be shown in Figure 7A.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be shown in Figure 7B.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be shown in Figure 7C.
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be as shown in FIG. 7D (when the distances between the two sound sensors and the speaker are both far), or as shown in FIG. 7E (when the distances between the two sound sensors and the speaker are both close).
  • the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be as shown in FIG. 7F.
  • the behind-the-ear form includes but is not limited to forms such as BTE (Behind-The-Ear) and RIC (Receiver-In-Canal) in hearing aids.
  • the acoustic system 20 adopts an in-ear form the positional relationship between the first sound sensor 120-1, the second sound sensor 120-2 and the speaker 110 can be as shown in FIG. 7G.
  • the in-ear type includes but is not limited to: ITE (In-The-Ear), ITC (In-The-Canal), CIC (Completely-In-the-Canal) and other types in hearing aids.
  • the acoustic system can be designed using the subsequent schemes so that the first signal y 1 and the second signal y 2 satisfy the condition k 2 ⁇ 2k 1 . It should be noted that when the acoustic system adopts the design scheme shown in FIGS. 6A to 6F , it can also be combined with one or more of the subsequent schemes.
  • the first sound sensor 120-1, the second sound sensor 120-2, and the speaker 110 meet preset structural conditions.
  • the structural conditions met by the acoustic system are described below in conjunction with Figures 8A to 8F. It should be noted that Figures 8A to 8F only show a partial structure of the acoustic system.
  • the acoustic system 20 may adopt an acoustic cavity design.
  • the acoustic system 20 may include a shell 21, and an acoustic cavity 22 is formed in a partial area of the shell 21. It should be noted that the present application does not limit the specific form of the acoustic cavity 22.
  • the speaker 110 is located inside the acoustic cavity 22. The sound-emitting component of the speaker 110 can separate the acoustic cavity 22 into a first acoustic cavity 22-1 and a second acoustic cavity 22-2.
  • the above-mentioned sound-emitting component may refer to a component that generates vibration in the speaker 110, for example, a vibrating membrane, 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 speaker 110 before it enters the external free space.
  • the second acoustic cavity 22-2 refers to the acoustic resonance cavity where the component of the first sound emitted by the speaker 110 is not directly propagated to the external free space.
  • the sound-emitting component of the speaker 110 divides the acoustic cavity 22 into two sub-cavities, of which the sub-cavity facing the sound-emitting surface of the sound-emitting component is the first acoustic cavity 22-1, and the sub-cavity facing away from the sound-emitting surface of the sound-emitting component is the second acoustic cavity 22-2.
  • the first acoustic cavity 22-1 can also be referred to as The front cavity
  • the second acoustic cavity 22 - 2 may also be referred to as the rear cavity.
  • the second sound sensor 120-2 may be located inside the acoustic cavity 22, and the first sound sensor 120-2 may be located outside the acoustic cavity 22. It can be understood that since the speaker 110 is located inside the acoustic cavity 22, the second sound sensor 120-2 is arranged inside the acoustic cavity 22, and the first sound sensor 120-1 is arranged outside the acoustic cavity 22, so that the second sound sensor 120-2 can pick up a stronger sound of the speaker 110 than the first sound sensor 120-1.
  • 2 corresponding to the first sound in the second signal y2 is much greater than the signal energy
  • the second sound sensor 120-2 can be located inside the first acoustic cavity 22-1.
  • the second sound sensor 120-2 can capture a stronger first sound than the first sound sensor 120-1, thereby helping to achieve the following condition: the signal energy
  • the second sound sensor 120-2 may be located inside the second acoustic cavity 22-2.
  • This approach can achieve the following two effects: First, the second sound sensor 120-2 can capture a stronger first sound at least in a partial frequency band compared to the first sound sensor 120-1, thereby helping to achieve the following condition: the signal energy
  • the speaker 110 will have a certain blocking effect on the second sound emitted by the target sound source 160, thereby helping to achieve the following condition: the signal energy
  • the combined effect of the above two aspects enables the condition k 2 ⁇ 2k 1 to be achieved .
  • the second sound sensor 120-2 can be coupled with the sound-generating component of the speaker 110.
  • the second sound sensor 120-2 can be a bone conduction MIC with a relatively light mass
  • the speaker 110 can be an air conduction speaker
  • the bone conduction MIC can be fitted on the diaphragm of the air conduction speaker. In this way, since the bone conduction MIC picks up the bone vibration signal, the air vibration will not interfere with the sound pickup of the bone conduction MIC, thereby ensuring the accuracy of the second signal y2 picked up by the bone conduction MIC.
  • the acoustic system 20 can reduce the influence of the bone conduction MIC on the vibration of the speaker diaphragm, thereby avoiding the introduction of additional distortion. It should be noted that this coupling method is applicable to various types of sound sensors and speakers, and the above-mentioned coupling method of the bone conduction MIC and the air conduction speaker is only a possible example.
  • the second sound sensor 120-2 since the second sound sensor 120-2 is coupled with the sound-emitting component of the speaker 110, the second sound sensor 120-2 can directly pick up the sound emitted by the speaker 110, and therefore, the second sound sensor 120-2 can capture a stronger first sound than the first sound sensor 120-1.
  • 2 corresponding to the first sound in the second signal y2 is much greater than the signal energy
  • FIGS. 8A to 8C above do not limit the specific position of the first sound sensor 120-1. It only needs to be located outside the acoustic cavity 22 and can conveniently pick up the sound of the target sound source 160.
  • the first sound sensor 120-1 can be located inside the housing 21, and the sound pickup surface is set on the surface of the housing 21 at a position away from the acoustic cavity 22.
  • Figures 8A to 8C do not illustrate the position of the first sound sensor 120-1.
  • 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 the free space outside the housing 21, and 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.
  • the free space refers to a space where sound is not affected by reflection, refraction, or diffraction and is mainly propagated in the form of spherical waves or plane waves.
  • the second sound sensor 120-2 can be set in the free space outside the housing 21 without being physically connected to the housing 21.
  • the second sound sensor 120-2 can be a wired or wireless MIC, and after the second signal y2 is picked up in the free space, the second signal y2 can be sent to the signal processing circuit 150 in a wired or wireless manner.
  • an acoustic cavity 22 and an acoustic cavity 23 may be formed in a partial area of the housing 21 of the acoustic system.
  • the speaker 110 is located in the acoustic cavity 22, the second sound sensor 120-2 is located in the acoustic cavity 23, and the second sound sensor 120-2 is closer to the speaker 110 than the first sound sensor 120-1.
  • the acoustic cavity 23 can protect the second sound sensor 120-2 from wind, and may also be referred to as a windproof cavity.
  • the second sound sensor 120-2 can still pick up sound signals in the free space in the acoustic cavity 23.
  • Figures 8D to 8E do not limit the specific position of the first sound sensor 120-1, as long as the sound pickup surface of the first sound sensor 120-1 is located in the free space and can conveniently pick up the sound of the target sound source 160 in the free space.
  • the first sound sensor 120-1 can be located inside the housing 21, and the sound pickup surface is set on the surface of the housing 21 away from the acoustic cavity 22.
  • Figures 8D and 8E do not illustrate the position of the first sound sensor 120-1.
  • the second sound sensor 120-2 since 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.
  • 2 corresponding to the first sound in the second signal y2 is much greater than the signal energy
  • the second sound sensor 120-2 since the second sound sensor 120-2 is located in the free space outside the housing 21, there is no need to modify the housing 21 structure and the acoustic cavity 22, and the implementation difficulty is relatively low.
  • the second sound sensor 120-2 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 relatively low.
  • the sound pickup surface of the first sound sensor 120-1 can be set in the free space outside the shell 21, and the sound pickup surface of the second sound sensor 120-2 can be set in the internal space of the shell 21, and 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.
  • the second sound sensor 120-2 can be located in an area inside the shell 21 close to the second acoustic cavity 22-2 (or the back cavity), and the sound pickup surface of the second sound sensor 120-2 faces the second acoustic cavity 22-2. It should be noted that the present application does not limit the specific position of the first sound sensor 120-1, as long as it can conveniently pick up the sound of the target sound source 160.
  • the first sound sensor 120-1 can be located inside the shell 21, and the sound pickup surface is set on the surface of the shell 21 away from the speaker 110 (or away from the acoustic cavity 22).
  • the position of the first sound sensor 120 - 1 is not shown in FIG8F .
  • the second sound sensor 120-2 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 pick up the first sound propagated in a solid medium. Further, since 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. Thus, the signal energy
  • the housing 21 since the first sound sensor 120-1 is hidden inside the housing 21, the housing 21 has a certain blocking effect on the sound of the target sound source 160, so that the signal energy
  • the above two aspects work together to make the first signal y 1 and the second signal y 2 satisfy the condition k 2 ⁇ 2k 1 .
  • the above solution does not require modification of the acoustic cavity 22 and is relatively easy to implement.
  • the first sound sensor 120-1 and the speaker 110 can also be coupled to different shells respectively.
  • the acoustic system 20 can also include a first shell and a second shell.
  • the first shell can be regarded as the device housing of the acoustic system 20.
  • the first sound sensor 120-1 can be located inside the first shell, and the sound pickup surface is arranged on the surface of the first shell and faces the free space outside the first shell.
  • the second shell can also be located inside the first shell, and the second shell is formed with an acoustic cavity, and the speaker 110 and the second sound sensor 120-2 are located inside the acoustic cavity.
  • the sound-emitting device of the speaker 110 can separate 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 inside the second acoustic cavity, and can also be coupled with the sound-emitting component of the speaker 110.
  • the first sound sensor 120-1 picks up sound in the free space outside the first shell
  • 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 second sound sensor 120-2 will reduce the sound pickup of the target sound source 160, and on the other hand, the first sound sensor 120-1 will reduce the sound pickup of the speaker 110.
  • 2 corresponding to the first sound in the second signal y 2 is much greater than the signal energy
  • 2 corresponding to the second sound in the second signal y 2 is much smaller than the signal energy
  • the acoustic system 20 may further include a barrier.
  • the barrier acts as a barrier to sound. It should be noted that the present application does not limit the form of the barrier, for example, it may be a barrier plate, or a barrier cover, etc.
  • the second sound sensor 120-2 and the speaker 110 are located on the first side of the barrier, and the first sound sensor 120-1 is located on the second side of the barrier. In this way, since the barrier acts as a barrier to the first sound, the first sound sensor 120-1 picks up less of the first sound than the second sound sensor 120-2, that is, the second sound sensor 120-2 can capture a stronger first sound than the first sound sensor 120-1.
  • 2 corresponding to the first sound in the second signal y 2 is much greater than the signal energy
  • the acoustic system 20 may be designed from the sound pickup directivity dimension so that the sound pickup directivities of the first sound sensor 120-1 and the second sound sensor 120-2 meet a preset condition, thereby making the first signal y1 and the second signal y2 meet the condition k2 ⁇ 2k1 .
  • the sound pickup directivity of the sound sensor may refer to the different degrees of directivity in different directions due to the different sound pickup sensitivities of the sound sensor in different directions.
  • the sound pickup sensitivity in a certain direction may refer to the ability of the sound sensor to pick up the sound from that direction.
  • the sound pickup sensitivity in a certain direction is higher, it means that the sound sensor has a stronger ability to pick up the sound in that direction, that is, the more signal components corresponding to the sound in that direction in the sound pickup signal picked up by the sound sensor, so that the directivity of the sound sensor in that direction is stronger.
  • the sound pickup sensitivity in a certain direction When the sound pickup sensitivity in a certain direction is lower, it means that the sound sensor has a weaker ability to pick up the sound in that direction, that is, the fewer signal components corresponding to the sound in that direction in the sound pickup signal picked up by the sound sensor, so that the directivity of the sound sensor in that direction is weaker.
  • the sound pickup sensitivity in a certain direction is zero, it means that the sound sensor does not pick up the sound in that direction, and this direction can also be called the zero-point pickup direction.
  • Fig. 9 shows a schematic diagram of the sound pickup direction of the acoustic system provided according to an embodiment of the present specification. As shown in Fig. 9, the sound pickup direction of the first sound sensor 120-1 and the second sound sensor 120-2 can meet at least one of the following conditions:
  • 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.
  • the first direction points to the target sound source 160, and the second direction points to the speaker 110. It can be understood that when the above condition (1) is met, the first sound sensor 120-1 can focus on picking up the sound of the target sound source 160.
  • the direction in which the first sound sensor 120-1 has a higher sound pickup sensitivity can be directed toward the target sound source 160, and/or the direction in which the first sound sensor 120-1 has a lower sound pickup sensitivity can be directed toward the speaker 110.
  • the direction in which the first sound sensor 120-1 has the highest sound pickup sensitivity can be directed toward the target sound source 160, and/or the direction in which the first sound sensor 120-1 has the lowest sound pickup sensitivity can be directed toward the speaker 110.
  • the sound pickup sensitivity of the second sound sensor 120-2 in the first direction is lower than the sound pickup sensitivity in the second direction.
  • the second sound sensor 120-2 can focus on picking up the sound of the speaker 110.
  • the direction of the second sound sensor 120-2 with a higher sound pickup sensitivity can be directed toward the speaker 110, and/or the direction of the second sound sensor 120-2 with a lower sound pickup sensitivity can be directed toward the target sound source 160.
  • the direction of the second sound sensor 120-2 with the highest sound pickup sensitivity can be directed toward the speaker 110, and/or the direction of the second sound sensor 120-2 with the lowest sound pickup sensitivity can be directed toward the target sound source 160.
  • condition (1) the first sound sensor 120-1 focuses on picking up the sound from the target sound source 160
  • condition (2) the second sound sensor 120-2 focuses on picking up the sound from the speaker 110. Both cases help to make the first signal y 1 and the second signal y 2 meet the condition k 2 ⁇ 2k 1 .
  • the first sound sensor 120-1 can pick up a stronger sound from the target sound source 160 than the second sound sensor 120-2
  • the second sound sensor 120-2 can pick up a stronger sound from the speaker 110 than the first sound sensor 120-1.
  • 2 corresponding to the first sound in the second signal y2 is much greater than the signal energy
  • 2 corresponding to the second sound in the second signal y2 is much smaller than the signal energy
  • the sound pickup directivity of the first sound sensor 120-1 and the sound pickup directivity of the second sound sensor 120-2 can be achieved by using a single sound pickup device with a certain directivity, or by using a plurality of sound pickup devices to form a preset array, which is not limited in this application.
  • the present application does not specifically limit the sound pickup direction patterns corresponding to the first sound sensor 120-1 and the second sound sensor 120-2, and the two can use the same sound pickup direction pattern or different sound pickup direction patterns.
  • the sound 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 directional patterns.
  • the sound pickup direction pattern of the first sound sensor 120-1 is a gun-shaped pattern and the stronger sound pickup direction points to the target sound source 160
  • the sound pickup direction pattern of the second sound sensor 120-2 is a heart-shaped pattern and the stronger sound pickup direction points to the speaker 110.
  • Solution 2 designs the acoustic system from the perspective of sound pickup directivity, that is, it is necessary to design the sound pickup directivity of the first sound sensor 120-1 and/or the second sound sensor 120-2, and no requirement or reduced requirement may be made for the positional relationship of each component in the acoustic system. It can be seen that Solution 2 can be applied to scenarios where it is inconvenient to change the structure of the acoustic system 20. In some embodiments, Solution 2 can also be combined with one or more designs in the aforementioned Solution 1.
  • the positions of the first sound sensor 120 - 1 and the second sound sensor 120 - 2 may be designed based on the feedback sound energy at each position in the target area, so that the first signal y 1 and the second signal y 2 satisfy the condition k 2 ⁇ 2k 1 .
  • the first sound sensor 120-1 is located at a first position within the target area
  • the second sound sensor 120-2 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 110 at the first position is smaller than the sound energy from the speaker 110 at other positions in the target area except the first position.
  • the first sound sensor 120-1 is set at a position in the target area where the corresponding feedback sound energy (ie, the sound energy from the speaker 110) is the smallest.
  • condition (1) the first sound sensor 120-1 cannot pick up the sound of the speaker 110 or picks up a weak sound.
  • the sound energy from the speaker 110 at the second position is greater than the sound energy from the speaker 110 at other positions in the target area except the second position.
  • the second sound sensor 120-2 is set at the position in the target area where the corresponding feedback sound energy (ie, the sound energy from the speaker 110) is the largest.
  • condition (2) the second sound sensor 120-2 can pick up the stronger sound of the speaker 110.
  • 2 corresponding to the first sound in the second signal y2 is much greater than the signal energy
  • FIG10A shows a schematic diagram of the positions of the first sound sensor and the second sound sensor in the target area in the acoustic system provided according to an embodiment of the present specification.
  • arrows are marked at different positions in the target area 190, and the length of the arrow represents the size of the feedback sound energy (i.e., the sound energy from the speaker 110) corresponding to the position.
  • the larger the arrow length the larger the feedback sound energy
  • the smaller the arrow length the smaller the feedback sound energy.
  • the feedback sound energy corresponding to the position of the first sound sensor 120-1 is the smallest
  • the feedback sound energy corresponding to the position of the second sound sensor 120-2 is the largest.
  • the acoustic system 20 can be designed in the following manner: 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, the feedback sound energy distribution corresponding to each position on the target area 190 is obtained through simulation calculation or field measurement. For example, FIG10B shows a schematic diagram of the feedback sound energy corresponding to each position in the target area of an acoustic system.
  • the larger the gray value of a certain position in the target area 190 black when the gray value is 0, and white when the gray value is 255
  • 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.
  • the position with the strongest feedback sound energy in the target area 190 is taken as the second position 192
  • the second sound sensor 120-2 is set at the second position 192
  • the position with the weakest feedback sound energy in the target area 190 is taken as the first position 191
  • the first sound sensor 120-1 is set at the first position 191.
  • the present application does not limit the shape of the target area 190.
  • a rectangle is used as an example for illustration in FIG10A and FIG10B.
  • the target area 190 may be any other shape, such as a circle, a triangle, a pentagon, a hexagon, a ring, a hollow shape, etc. It may also be any other irregular shape, or it may be an area enclosed by a three-dimensional space.
  • Scheme 3 designs the positions of the first sound sensor 120-1 and the second sound sensor 120-2 based on the feedback sound energy at each position in the target area 190, that is, the first sound sensor 120-1 is set at the position where the corresponding feedback sound energy is the smallest in the target area 190, and the second sound sensor 120-2 is set at the position where the corresponding feedback sound energy is the largest in the target area 190, therefore, Scheme 3 does not have high requirements for the positional relationship between the components in the acoustic system 20 (for example, it is not required that the first sound sensor 120-1 must be far away from the speaker 110, and the second sound sensor 120-2 must be close to the speaker 110, etc.).
  • Scheme 3 can be applicable to scenarios where the positions of the components are not pre-specified, and allows the selection and determination of the positions of the components in a certain candidate area. In some embodiments, Scheme 3 can also be combined with one or more designs in Scheme 1 and Scheme 2 described above.
  • FIG11 shows a schematic diagram of the test results of the acoustic system provided according to the embodiment of the present specification in terms of adaptive filtering performance.
  • the speaker 110 in the acoustic system 20 has a limiting characteristic
  • the adaptive filtering scheme based on AFC shown in FIG2 when the adaptive filtering scheme based on AFC shown in FIG2 is adopted, the calculated misalignment (MIS) is shown in Curve A.
  • the calculated misalignment (MIS) is shown in Curve B.
  • Curve B decreases faster than Curve A in the initial period (about 0.2 seconds ago), and maintains a faster average downward trend in the period after the turning point (about 0.2 seconds later).
  • the acoustic system 20 includes: a speaker 110, a first sound sensor 120-1, a second sound sensor 120-2 and a signal processing circuit 150.
  • the speaker 110 receives a driving signal and converts it into a first sound when it is working;
  • the first sound sensor 120-1 collects ambient sound and generates a first signal when it is working, and the ambient sound includes the first sound and the second sound from the target sound source;
  • the second sound sensor 120-2 collects ambient sound and generates a second signal when it is working, and the first signal and the second signal satisfy k 2 ⁇ 2k 1 , wherein k 1 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, and k 2 is the ratio of the signal energy corresponding to the first sound in the second signal to the signal energy corresponding to the second sound;
  • the signal processing circuit 150 is connected to the first sound sensor 120-1 and the second sound sensor 120-2 respectively, and when working, the signal component corresponding to the first sound in the first

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Abstract

本说明书的实施例提供一种声学系统，包括：扬声器、第一声音传感器、第二声音传感器和信号处理电路。第一声音传感器工作时采集环境声音并生成第一信号，所述环境声音包括来自扬声器的第一声音和来自目标声源的第二声音；第二声音传感器工作时采集环境声音并生成第二信号，其中，第一信号和第二信号满足k2≥2k1，k1为第一信号中的对应于第一声音的信号能量与对应于第二声音的信号能量之比，k2为第二信号中的对应于第一声音的信号能量与对应于第二声音的信号能量之比；信号处理电路工作时基于第二信号对第一信号中的对应于第一声音的信号成分进行削减得到目标信号，并对目标信号执行目标操作。该声学系统能够减少或消除目标信号中反馈成分。

Description

声学系统 技术领域
本说明书涉及声学技术领域，尤其涉及一种声学系统。
背景技术
一些声学系统同时包括扬声器和声音传感器。这些声学系统中通常存在声反馈的问题。其中，声反馈是指：声音传感器采集到的声音信号经过一定处理后通过扬声器播放，而扬声器发出的声音又被声音传感器重新采集，从而使得声学系统形成“扬声器->声音传感器->扬声器”的闭环回路。在上述声学系统中，声音传感器所拾取到的扬声器的声音可以称为反馈声音。反馈声音的存在导致声学系统存在一些问题。例如，导致声学系统产生啸叫等问题，还可能制约声学系统能够取得的最大前向增益。因此，需要提供一种能够减少或者消除反馈声音的声学系统。
发明内容
本说明书提供一种声学系统，能够减少或者消除反馈声音，从而避免由于反馈声音导致的啸叫等问题，并提升声学系统能够取得的最大前向增益。
第一方面，本说明书提供一种声学系统，包括：扬声器、第一声音传感器、第二声音传感器和信号处理电路，其中，所述扬声器工作时接收驱动信号并转换为第一声音，所述第一声音传感器工作时采集环境声音并生成第一信号，所述环境声音包括所述第一声音和来自目标声源的第二声音，所述目标声源包括除所述扬声器之外的其他声源，所述第二声音传感器工作时采集所述环境声音并生成第二信号，其中，所述第一信号和所述第二信号满足k2≥2k1，其中k1为所述第一信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比，k2为所述第二信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比，所述信号处理电路与所述第一声音传感器和所述第二声音传感器分别连接，工作时基于所述第二信号，对所述第一信号中的对应于所述第一声音的信号成分进行削减，得到目标信号，以及对所述目标信号执行目标操作。
在一些实施例中，为了满足k2≥2k1，所述第一信号和所述第二信号满足下面条件中的至少一个：所述第二信号中的对应于所述第一声音的信号能量与所述第二信号中的对应于所述第二声音的信号能量之比大于或等于2；所述第二信号中对应于所述第一声音的信号能量与所述第一信号中对应于所述第一声音的信号能量之比大于或等于2；以及所述第一信号中对应于所述第二声音的信号能量与所述第一信号中对应于所述第一声音的信号能量之比大于或等于2。
在一些实施例中，所述第一声音传感器、所述第二声音传感器、以及所述扬声器之间的位置关系满足预设条件，使得所述第一信号和所述第二信号满足k2≥2k1。
在一些实施例中，所述预设条件包括：L1≥2L2，其中，L2为所述第二声音传感器与所述扬声器之间的距离，L1为所述第一声音传感器与所述扬声器之间的距离。
在一些实施例中，所述声学系统还包括壳体，所述壳体的部分区域形成有声学腔体，所述扬声器和所述第二声音传感器均位于所述声学腔体的内部，所述第一声音传感器位于所述声学腔体的外部。
在一些实施例中，所述扬声器的发声部件将所述声学腔体分隔为第一声学腔体和第二声学腔体，所述发声部件的出音面朝向所述第一声学腔体，其中，所述第二声音传感器位于所述第一声学腔体的内部，或者所述第二声音传感器位于所述第二声学腔体的内部。
在一些实施例中，所述第二声音传感器与所述扬声器的发声部件耦合。
在一些实施例中，所述声学系统还包括壳体，所述第二声音传感器的拾音面和所述第一声音传感器的拾音面均位于所述壳体外部的自由空间中，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
在一些实施例中，所述声学系统还包括壳体，所述壳体的部分区域形成有第一声学腔体和第二声学腔体，所述扬声器位于所述第一声学腔体内，所述第二声音传感器位于所述第二声学腔体内，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
在一些实施例中，所述声学系统还包括壳体，所述第一声音传感器的拾音面位于所述壳体外部的自由空间中，所述第二声音传感器的拾音面位于所述壳体的内部空间中，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
在一些实施例中，所述声学系统还包括第一壳体和第二壳体，其中，
所述第二壳体位于所述第一壳体的内部，且所述第二壳体形成有声学腔体，所述扬声器和所述第二声音传感器位于所述声学腔体的内部。
在一些实施例中，所述声学系统还包括隔挡件，所述第二声音传感器和所述扬声器位于所述隔挡件的第一侧，所述第一声音传感器位于所述隔挡件的第二侧。
在一些实施例中，所述第一声音传感器和所述第二声音传感器的拾音指向性满足预设条件，使得所述第一信号和所述第二信号满足k2≥2k1。
在一些实施例中，所述第一声音传感器和所述第二声音传感器的拾音指向性满足下面条件中的至少一个：所述第一声音传感器在第一方向的拾音灵敏度大于在第二方向的拾音灵敏度；以及所述第二声音传感器在所述第一方向的拾音灵敏度小于在所述第二方向的拾音灵敏度，其中，所述第一方向指向所述目标声源，所述第二方向指向所述扬声器。
在一些实施例中，所述第一声音传感器位于目标区域内的第一位置，所述第二声音传感器位于所述目标区域内的第二位置，其中，所述第一位置和所述第二位置满足下面条件中的至少一个：所述第一位置处的来自所述扬声器的声音能量小于所述目标区域内除所述第一位置之外的其他位置处 的来自所述扬声器的声音能量；以及所述第二位置处的来自所述扬声器的声音能量大于所述目标区域内除所述第二位置之外的其他位置处的来自所述扬声器的声音能量。
在一些实施例中，为了得到所述目标信号，所述信号处理电路：对所述第二信号执行自适应滤波操作得到第三信号，并从所述第一信号中减去所述第三信号得到所述目标信号。
在一些实施例中，所述信号处理电路还：基于所述第二信号和所述目标信号中的至少一个更新所述自适应滤波操作对应的滤波参数。
在一些实施例中，为了得到所述目标信号，所述信号处理电路：对所述第一信号执行第一预处理操作得到第一中间信号；对所述第二信号执行第二预处理操作得到第二中间信号；以及基于所述第二中间信号，对所述第一中间信号中的对应于所述第一声音的信号成分进行削减，得到所述目标信号。
在一些实施例中，所述第一预处理操作包括增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项；以及所述第二预处理操作包括增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项。
在一些实施例中，所述信号处理电路还与所述扬声器连接，在执行所述目标操作时，所述信号处理电路：对所述目标信号进行增益放大，以及向所述扬声器发送所述增益放大后的信号，以驱动所述扬声器发声。
由以上技术方案可知，本说明书提供的声学系统包括：扬声器、第一声音传感器、第二声音传感器和信号处理电路。其中，扬声器工作时接收驱动信号并转换为第一声音；第一声音传感器工作时采集环境声音并生成第一信号，所述环境声音包括第一声音和来自目标声源的第二声音；第二声音传感器工作时采集环境声音并生成第二信号，所述第一信号和所述第二信号满足k2≥2k1，其中k1为所述第一信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比，k2为所述第二信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比；信号处理电路与第一声音传感器和第二声音传感器分别连接，工作时基于所述第二信号对所述第一信号中的对应于所述第一声音的信号成分进行削减得到目标信号，并对目标信号执行目标操作。由此可见，本说明书提供的声学系统能够减少或消除目标信号中反馈成分，从而避免由于反馈声音导致的啸叫等问题，还能够提升声学系统所能达到的最大前向增益。
本说明书提供的声学系统的其他功能将在以下说明中部分列出。本说明书提供的声学系统的创造性方面可以通过实践或使用下面详细示例中所述的方法、装置和组合得到充分解释。
附图说明
为了更清楚地说明本说明书实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本说明书的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1示出了根据本说明书的实施例提供的一种应用场景的示意图；
图2示出了根据本说明书的实施例提供的声学系统的一种设计示意图；
图3示出了根据本说明书的实施例提供的声学系统的另一种设计示意图；
图4示出了根据本说明书的实施例提供的声学系统的又一种设计示意图；
图5示出了根据本说明书的实施例提供的声学系统的又一种设计示意图；
图6A至图6F示出了根据本说明书的实施例提供的声学系统的几种结构示意图；
图7A至图7G示出了根据本说明书的实施例提供的声学系统的另外几种结构示意图；
图8A至图8F示出了根据本说明书的实施例提供的声学系统的又几种结构示意图；
图9示出了根据本说明书的实施例提供的声学系统的拾音指向示意图；
图10A示出了根据本说明书的实施例提供的声学系统中第一声音传感器和第二声音传感器在目标区域内的位置示意图；
图10B示出了声学系统的目标区域内各位置对应的反馈声音能量的示意图；以及
图11示出了根据本说明书的实施例提供的声学系统在自适应滤波性能方面的测试结果示意图。
具体实施方式
以下描述提供了本说明书的特定应用场景和要求，目的是使本领域技术人员能够制造和使用本说明书中的内容。对于本领域技术人员来说，对所公开的实施例的各种局部修改是显而易见的，并且在不脱离本说明书的精神和范围的情况下，可以将这里定义的一般原理应用于其他实施例和应用。因此，本说明书不限于所示的实施例，而是与权利要求一致的最宽范围。
这里使用的术语仅用于描述特定示例实施例的目的，而不是限制性的。比如，除非上下文另有明确说明，这里所使用的，单数形式“一”，“一个”和“该”也可以包括复数形式。当在本说明书中使用时，术语“包括”、“包含”和/或“含有”意思是指所关联的整数，步骤、操作、元素和/或组件存在，但不排除一个或多个其他特征、整数、步骤、操作、元素、组件和/或组的存在或在该系统/方法中可以添加其他特征、整数、步骤、操作、元素、组件和/或组。
考虑到以下描述，本说明书的这些特征和其他特征、以及结构的相关元件的操作和功能、以及部件的组合和制造的经济性可以得到明显提高。参考附图，所有这些形成本说明书的一部分。然而，应该清楚地理解，附图仅用于说明和描述的目的，并不旨在限制本说明书的范围。还应理解，附图未按比例绘制。
本说明书中使用的流程图示出了根据本说明书中的一些实施例的系统实现的操作。应该清楚地理解，流程图的操作可以不按顺序实现。相反，操作可以以反转顺序或同时实现。此外，可以向流程图添加一个或多个其他操作。可以从流程图中移除一个或多个操作。
在对本说明书具体实施例说明之前，先对本说明书的应用场景进行如下介绍。本说明书提供的声学系统可被应用于需要减少或者消除反馈声音的场景。下面结合图1进行举例说明。
图1示出了根据本说明书的实施例提供的一种应用场景的示意图。如图1所示，应用场景001可以是扩音场景、辅听场景、助听场景等。该场景中，声音传感器120工作时采集环境声音。在此过程中如果扬声器110也在同步播放声音，则扬声器110播放的声音也会被声音传感器120采集。这样声音传感器120采集到的环境声音中既包括来自目标声源160的声音还包括来自扬声器110的声音。进而，声音传感器120采集得到的拾音信号经过前向增益放大(G)后，被输入至扬声器110，从而驱动扬声器110发声。这样在所述声学系统中形成了“扬声器->声音传感器->扬声器”的闭环回路。该情况下，当某些频率的声音信号发生自激振荡时就会产生啸叫现象。这样的啸叫会使用户感到不适，当所述啸叫严重时可能还会对声学系统中的器件造成损坏。另外，所述啸叫的存在也对声学系统的前向增益放大倍数带来了局限性，从而制约了声学系统能够达到的最大前向增益。
需要说明的是，上述图1所示的应用场景只是本申请适用的多个应用场景中的部分场景，本申请提供的声学系统还可以应用于其他类似的场景，不说明书对此不作一一列举说明。本领域技术人员应当明白，本申请提供的声学系统应用于其他使用场景也在本申请的保护范围内。
综上可见，反馈声音的存在会导致声学系统存在一系列的问题，包括但不限于：产生啸叫、制约声学系统能够取得的最大前向增益等。为此，本申请提供一种具有减少或者消除反馈声音的声学系统，从而避免上述一系列问题。
本申请提供的声学系统，可以采用声反馈消除(Acoustic Feedback Cancellation，AFC)技术来减少或者消除反馈声音。为了方便后续描述，下面先结合图2对AFC技术的原理进行介绍。
图2示出了根据本说明书的实施例提供的声学系统的一种设计示意图。该声学系统10可以为助听/辅听系统、扩音系统中的一种。该声学系统10可以利用AFC技术减少或消除反馈成分(即对应于反馈声音的信号成分)。如图2所示，声学系统10可以包括扬声器110、声音传感器120和信号处理电路150。
扬声器110是用于将电信号转换为声音的器件，也可以称为电声转换器。例如扬声器110可以为喇叭(speaker)。扬声器110可以为基于气体、液体、固体中的至少一种传导方式进行发声的器件。扬声器110可以与信号处理电路150连接，工作时从信号处理电路150接收所述电信号并将之转换为声音播放出来。在一些实施例中，声学系统10还可以包括第一外围电路(图2中未示出)。第一外围电路连接在信号处理电路150和扬声器110之间。第一外围电路可以包括信号处理电路150的输出端到扬声器110之间的所有电路或者部分电路。第一外围电路可以对信号处理电路150输出的电信号进行一些处理，使得处理后的电信号适合扬声器110播放。第一外围电路可以包括但不限于运算放大器件、功率放大器件、数模转换器件、电容、电感、电阻等器件中的至少一种。
声音传感器120是用于拾取声音并将声音转换为电信号的器件，也可以称为声电转换器。例如声音传感器120可以为麦克风(Microphone，MIC)。声音传感器120可以为基于气体、液体、固体 中的至少一种传导方式进行拾音的器件。声音传感器120可以与信号处理电路150连接，工作时采集环境声音并将环境声音转换为电信号，进而将所述电信号发送至信号处理电路150。在一些实施例中，声学系统10还可以包括第二外围电路(图2中未示出)。第二外围电路连接在声音传感器120和信号处理电路150之间。第二外围电路可以包括声音传感器120到信号处理电路150的输入端之间的所有电路或者部分电路。第二外围电路可以对声音传感器120拾取的电信号进行一些处理，以便转换为适合信号处理电路150处理的信号。第二外围电路可以包括但不限于功率放大器件、运算放大器件、模数转换器件、电容、电感、电阻等器件中的至少一种。
继续参见图2，声音传感器120采集环境声音生成拾音信号y，并将拾音信号y输入至信号处理电路150。所述环境声音至少包括目标声源160发出的第二声音。目标声源160是指除所述扬声器110之外的其他声源。例如，目标声源160可以包括具有声音播放功能的电子设备(例如电视、音箱、手机等)；又例如，目标声源160还可以包括人的喉咙。上述拾音信号y可以称为信号处理电路150的输入信号。信号处理电路150对拾音信号y进行一系列处理后得到驱动信号u，并将驱动信号u发送至扬声器110。上述驱动信号u可以作为信号处理电路150的输出信号。扬声器110接收驱动信号u并将之转换为第一声音。所述第一声音经过反馈路径的传递后被声音传感器120重新采集，因此，所述第一声音也可以称为反馈声音。由此可见，声音传感器120采集到的环境声音不仅包括来自目标声源160的第二声音，还包括来自扬声器110的第一声音。也就是说，拾音信号y中同时包括对应于所述第一声音(即反馈声音)的信号成分x、以及对应于所述第二声音的信号成分v。
信号处理电路150可以是具有一定信号处理能力的电路。信号处理电路150的输入端与声音传感器120连接，输出端与扬声器110连接，工作时可以从声音传感器120获得拾音信号y，并对拾音信号y执行预设的信号处理流程之后得到驱动信号u，并将驱动信号u发送至扬声器110。
在一些实施例中，信号处理电路150可以包括具有连接关系的多个硬件电路，每个硬件电路包括一个或多个电器元件，每个电器元件实现一个或多个功能单元，从而上述多个硬件电路工作时相互配合实现所述信号处理流程。
在一些实施例中，信号处理电路150可以包括具有数据信息处理功能的硬件设备和驱动该硬件设备工作所需必要的程序，所述硬件设备通过执行所述程序来实现所述信号处理流程。例如，信号处理电路150可以包括至少一个存储介质和至少一个处理器。其中，所述存储介质可以包括数据存储装置。所述数据存储装置可以是非暂时性存储介质，也可以是暂时性存储介质。比如，所述数据存储装置可以包括磁盘、只读存储介质(ROM)或随机存取存储介质(RAM)中的一种或多种。存储介质还包括存储在所述数据存储装置中的至少一个指令集。所述指令是计算机程序代码，所述计算机程序代码可以包括执行本说明书提供的信号处理方法的程序、例程、对象、组件、数据结构、过程、模块等等。
所述至少一个处理器可以同所述至少一个存储介质通信连接。所述至少一个处理器用以执行上述至少一个指令集。当声学系统运行时，所述至少一个处理器读取所述至少一个指令集，并且根据 所述至少一个指令集的指示，执行所述信号处理流程。处理器可以包括一个或多个硬件处理器，例如微控制器，微处理器，精简指令集计算机(RISC)，专用集成电路(ASIC)，特定于应用的指令集处理器(ASIP)，中心处理单元(CPU)，图形处理单元(GPU)，物理处理单元(PPU)，微控制器单元，数字信号处理器(DSP)，现场可编程门阵列(FPGA)，高级RISC机器(ARM)，可编程逻辑器件(PLD)，能够执行一个或多个功能的任何电路或处理器等，或其任何组合。
继续参见图2，为了减少或消除反馈成分，信号处理电路150可以包括声反馈抵消单元170。声反馈抵消单元170的输入包括：驱动信号u和拾音信号y。声反馈抵消单元170可以基于驱动信号u，对拾音信号y中的对应于所述第一声音的信号成分进行削减，从而得到目标信号e。
结合图2进行具体说明，声反馈抵消单元170的内部可以求解并自适应更新一个时变的传递函数F'，来拟合反馈路径对应的传递函数F。为了以示区分，后文将传递函数F'称为预测传递函数F'，将反馈路径对应的传递函数F称为真实传递函数F。声反馈抵消单元170利用预测传递函数F'对驱动信号u执行自适应滤波操作得到信号x'，即x'＝u*F'。信号x'可以视为拾音信号y中的反馈成分(即拾音信号y中对应于所述第一声音的信号成分)的预测值。进而，声反馈抵消单元170可以从拾音信号y中减去信号x'得到目标信号e，即e＝y-x'。这样得到的目标信号e中不包含或者较少包含反馈声音的成分。
需要说明的是，上述声反馈抵消单元170在求解预测传递函数F'时可以采用多种自适应滤波算法实现，例如可以采用最小均方(Least Mean Square，LMS)、归一化最小均方(Normalized Least Mean Square，NLMS)、递归最小二乘(Recursive least squares，RLS)、其他自适应滤波算法、以及上述提及算法的任意衍生算法中的一种或者多种，本申请对此不做限定。另外，所述自适应滤波算法可以是在时域、频域或者其他变换域进行自适应滤波。
按照自适应滤波算法的理论，预测传递函数F'的更新方式可以通过最小化目标信号e的均方函数的期望实现，即：
minF′E[22]＝minF′E[(y-u*F′)2]     公式(1-1)
例如，以声反馈抵消单元170采用LMS算法为例，基于梯度下降的最优化方法对上述公式(1-1)进行推导，可以得到预测传递函数F'的更新公式如下：
F′←F′+μ*e*u      公式(2-1)
其中，μ为迭代步长。
应理解，当声反馈抵消单元170采用诸如NLMS、RLS等算法时，可以采用类似的方式推导得到预测传递函数F'的更新公式，本说明书对此不作一一举例说明。
由此可见，图2所示的声学系统通过采用AFC技术，能够减少或者消除反馈声音，从而避免由于反馈声音导致的一系列问题。
根据信号处理理论，图2所示的声学系统的闭环增益A可以表示如下：
根据奈奎斯特稳定判据(Nyquist stability criterion)可知，声学系统能够抵消反馈声音的要求是：所求解的预测传递函数F′完全等于真实传递函数F，即F′＝F。当满足上述要求时，声学系统将总是稳定的，不会产生啸叫，并且，此时的声学系统能够取得无穷增益，即，当前向增益G→∞时，A＝G→∞。
然而，在实际的声学系统中，由于真实传递函数F可能是时变的，以及迭代求解的收敛过程可能会振荡，因此，F′的迭代过程很难达到理想条件F′＝F。也就是说，实际迭代得到的预测传递函数F′与真实传递函数F之间存在一定的偏差。此时，为了让声学系统保持稳定，增益放大单元130提供的前向增益G自然是不能取得无穷大的。声学系统能够取得的最大前向增益为:
由公式(4)可见，预测传递函数F′与真实传递函数F之间的偏差情况可用于衡量自适应滤波算法的收敛性能，并进而衡量声学系统对反馈声音的抵消效果。具体而言，若预测传递函数F′与真实传递函数F之间偏差越小，则说明自适应滤波算法的收敛性能越好，从而声学系统对反馈声音的抵消效果越佳。若预测传递函数F′与真实传递函数F之间偏差越大，则说明自适应滤波算法的收敛性能越差，从而声学系统对反馈声音的抵消效果越差。
在一些实施例中，我们还可以采用失调量(misalignment,MIS)来衡量自适应滤波算法的收敛性能。其中，失调量MIS可以采用如下公式表示：
失调量MIS的单位是分贝(dB)。当预测传递函数F′为初始值零时，失调量MIS为0dB。当失调量MIS越小、越趋于负无穷时，预测传递函数F′与真实传递函数F之间的偏差越小，说明自适应滤波算法的收敛性能越好，从而声学系统对反馈声音的抵消效果越佳。当失调量MIS越大、越趋于正无穷时，预测传递函数F′与真实传递函数F之间的偏差越大，说明自适应滤波算法的收敛性能越差，从而声学系统对反馈声音的抵消效果越差。
需要说明的是，本申请中自适应滤波算法的收敛性能包括但不限于：收敛速度、收敛误差等。其中，收敛速度可以是指预测传递函数F′对真实传递函数F的拟合速度，收敛误差可以是指在达到收敛条件时预测传递函数F′与真实传递函数F之间的偏差。
在图2所示的声学系统中，之所以能够通过自适应滤波算法求解一个时变的预测传递函数F′来拟合反馈路径对应的传递函数F，是因为基于如下理想假设：反馈路径全部为线性传递。
然而，实际的声学系统通常无法满足上述理想假设。因为在实际的声学系统中，反馈路径上存在多种器件，这些器件可能存在非线性响应。例如，扬声器110的振膜及磁铁相互作用导致迟滞效应和饱和失真等，因此扬声器110的响应是包含非线性响应的成分。另外，在信号处理电路150和扬声器110之间通常还存在功率放大器、运算放大器等器件。功率放大器和运算放大器通常含有限 幅效应，因此二者的响应也包含非线性响应的成分。类似的，在信号处理电路150和扬声器110之间存在的其他器件也可能存在非线性响应的成分。
由于声反馈抵消单元170是在信号处理电路150的输出端口之前的位置获取驱动信号u，并利用预测传递函数F′对驱动信号u进行自适应滤波，因此，扬声器110、功率放大器、运算放大器等器件的非线性响应不可避免的被引入到预测传递函数F′的迭代求解中，从而，导致自适应滤波算法的收敛性能较低，例如，导致预测传递函数F′不能收敛、收敛缓慢、或者收敛误差较大等。这样使得声学系统的失调量指标MIS变差，进而影响声学系统对反馈声音的抵消效果。
另外，在一些声学系统的设计架构中，声反馈抵消单元170可能与信号处理电路150中的其他单元相互独立，并且声学系统的设计架构限制了不同单元间的访问权限或通信能力。因此，声反馈抵消单元170可能无法从其他单元获得驱动信号u。从而，这样的声学系统无法采用AFC技术来减少或者消除反馈声音。
图3示出了根据本说明书的实施例提供的声学系统的另一种设计示意图。如图3所示，声学系统20可以包括：扬声器110、第一声音传感器120-1、第二声音传感器120-2和信号处理电路150。
图3所示的声学系统20可以视为在图2所示声学系统10基础上的进一步改进。对比图2和图3可见，图3所示声学系统20中的第一声音传感器120-1可以对应图2所示声学系统10中的声音传感器120，这样，图3所示声学系统20相当于在图2所示声学系统10的基础上增加了第二声音传感器120-2。其中，第二声音传感器120-2与第一声音传感器120-1的结构可以相同也可以不同，本申请对此不做限定。
图3所示声学系统20的工作过程如下：扬声器110工作时从信号处理电路150接收驱动信号u，并将驱动信号u转换为第一声音。第一声音传感器120-1工作时采集环境声音并生成第一信号y1。第二声音传感器120-2工作时采集环境声音并生成第二信号y2。其中，环境声音包括来自扬声器110的第一声音和来自外部声源160的第二声音。这样，第一信号y1包括对应于所述第一声音的信号成分x1和对应于所述第二声音的信号成分v1，第二信号y2包括对应于所述第一声音的信号成分x2和对应于所述第二声音的信号成分v2。其中，外部声源160包括环境中除扬声器110之外的其他声源，例如，人的喉咙、具有声音播放功能的电子设备、其他扬声器等。
需要说明的是，扬声器110发出的所述第一声音可以通过气体、液体和固体中的一种或多种介质传导之后，被第一声音传感器120-1和第二声音传感器120-2拾取。目标声源160发出的所述第二声音可以通过气体、液体和固体中的一种或多种介质传导之后，被第一声音传感器120-1和第二声音传感器120-2拾取。另外，本说明书对于第一信号y1、第二信号y2、以及驱动信号u的承载方式不做限定，三者均可以是由任意载体承载的信号。例如，第一信号y1、第二信号y2、以及驱动信号u均可以是电信号、光信号、数字载波信号或者其他载体类型的信号。
在图3所示的声学系统20中，第一声音传感器120-1与第二声音传感器120-2的拾音侧重有所 不同。第一声音传感器120-1重点拾取来自目标声源160的声音，第二声音传感器120-2重点拾取来自扬声器110的声音。具体而言，第一声音传感器120-1拾取得到的第一信号y1和第二声音传感器120-2拾取得到的第二信号y2满足如下关系：
k2≥2k1      公式(6)
其中，k1为第一信号y1中的对应于所述第一声音的信号能量|x1|2与对应于所述第二声音的信号能量|v1|2之比，k2为第二信号y2中的对应于所述第一声音的信号能量|x2|2与对应于所述第二声音的信号能量|v2|2之比，即：

换言之，将k2与k1之比记为N，即：N＝k2/k1，那么N的取值可以为大于或等于2的实数。例如，N的取值可以位于2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、…、∞中的任意两个所规定的区间内。当N的取值越大，越趋近于∞时，第二声音传感器120-2越趋近于只拾取扬声器110的声音，第一声音传感器120-1越趋近于只拾取目标声源160的声音。另外，当k2与k1之间的比值为N时，声学系统的闭环增益A可以表示为如下：
需要说明的是，上述公式(20)的推导方式可以参见后文对公式(19)的推导过程，此处不做详述。由上述公式(20)可见，当N的取值逐渐增大时，闭环增益A与前向增益G逐渐接近，也就是说，系统的能量损失逐渐减少。当N的取值为∞时，闭环增益A达到理想的前向增益G。
为了使得上述条件k2≥2k1满足，第一信号y1和第二信号y2可以满足下述条件中的一项或者多项：
(1)第二信号y2中的对应于所述第一声音的信号能量|x2|2与第二信号y2中对应于所述第二声音的信号能量|v2|2之比大于或等于2，即：
上述条件还可以表述为：第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第二信号y2中的对应于所述第二声音的信号能量|v2|2。能够理解，当|x2|2远大于|v2|2时，能够使得k2尽可能地大，从而第二声音传感器120-2对所述第一声音的拾取远大于对所述第二声音的拾取。当k2趋近于无穷大时，第二声音传感器120-2几乎只拾取所述第一声音，而不拾取所述第二声音。
(2)第一信号y1中的对应于所述第二声音的信号能量|v1|2与第一信号y1中的对应于所述第一声音的信号能量|x1|2之比大于或等于2，即：
上述条件还可以表述为：第一信号y1中的对应于所述第二声音的信号能量|v1|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2。能够理解，当|v1|2远大于|x1|2时，能够使得k1尽可能地小，从而第一声音传感器120-1对所述第二声音的拾取远大于对所述第一声音的拾取。当k1趋近于零时，第一声音传感器120-2几乎只拾取所述第二声音，而不拾取所述第一声音。
(3)第二信号y2中的对应于所述第一声音的信号能量|x2|2与第一信号y1中的对应于所述第一声音的信号能量|x1|2之比大于或等于2，即：
上述条件还可以表述为：第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2。能够理解，当|x2|2远大于|x1|2时，第二声音传感器120-2对所述第一声音的拾取远大于第一声音传感器120-1对所述第一声音的拾取，例如，第二声音传感器120-2几乎拾取所述第一声音的全部，而第一声音传感器120-2几乎不拾取所述第一声音。
信号处理电路150可以与第一声音传感器120-1和第二声音传感器120-2分别连接。信号处理电路150可以从第一声音传感器120-1获得第一信号y1，并从第二声音传感器120-2获得第二信号y2。进而，信号处理电路150可以基于第二信号y2，对第一信号y1中的对应于所述第一声音的信号成分进行削减，从而得到目标信号e。这样，目标信号e中不包含或者较少包含反馈声音的成分。
与图2类似，图3所示的声学系统也可以基于AFC技术来减少或消除目标信号中的反馈成分。继续参见图3，信号处理电路150可以包括声反馈抵消单元170，声反馈抵消单元170的内部可以求解并自适应更新一个时变的预测传递函数F′，来拟合反馈路径对应的真实传递函数F。声反馈抵消单元170的输入包括：第一信号y1和第二信号y2。声反馈抵消单元170可以基于第二信号y2，对第一信号y1中的对应于所述第一声音的信号成分进行削减，从而得到目标信号e。具体而言，声反馈抵消单元170利用预测传递函数F′对第二信号y2执行自适应滤波操作得到第三信号x′，即x′＝y2*F′。第三信号x'可以视为第一信号y1中的反馈成分(即第一信号y1中对应于所述第一声音的信号成分)的预测值。进而，声反馈抵消单元170可以从第一信号y1中减去第三信号x'得到目标信号e，即e＝y1-x′＝y1-y2*F′。这样得到的目标信号e中不包含或者较少包含反馈声音的成分。
在得到目标信号e之后，信号处理电路150还可以基于第二信号y2和目标信号e中的至少一项更新自适应滤波操作F′的滤波参数。具体而言，按照自适应滤波算法的理论，预测传递函数F′的更新方式可以通过最小化目标信号e的均方函数的期望实现，即：
minF′E[e2]＝minF′E[(y1-y2*F′)2]     公式(1-2)
仍然以声反馈抵消单元170采用LMS算法为例，基于梯度下降的最优化方法对上述公式(1-2)进行推导，可以得到预测传递函数F′的更新公式如下：
F′←F′+μ*e*y2      公式(2-2)
其中，μ为迭代步长。
应理解，当声反馈抵消单元170采用诸如NLMS、RLS等算法时，可以采用类似的方式推导得到预测传递函数F′的更新公式，本说明书对此不作一一举例说明。
图3所示的声学系统在得到目标信号e之后，信号处理电路150可以对目标信号e执行目标操作。继续参见图3，信号处理电路150还可以包括增益放大单元130(图3中将增益放大单元标注为G)。增益放大单元对目标信号e进行增益放大，并将增益放大后的信号作为下一时刻的驱动信号u发送至扬声器110，从而驱动扬声器110发声。由于目标信号e中的反馈成分得到减少或消除，因此能够避免或抑制声学系统10产生啸叫，并且，还有助于提升声学系统10能够取得的最大前向增益。
图3所示的声学系统20通过新增的第二声音传感器120-2重点拾取所述第一声音得到第二信号y2，进而，信号处理电路150可以采用AFC技术基于第二信号y2对第一信号y1中的反馈成分进行削减，从而使得反馈成分得到减少或消除。图3所示的声学系统20相较于图2所示的声学系统10，由于第二信号y2是从扬声器110后面的信号路径中获得的，因此，反馈抵消单元170在求解预测传递函数F′时，只需要拟合扬声器110之后的反馈路径的传递函数，从而能够避免扬声器110以及扬声器110之前的器件(例如运算放大器、功率放大器等)的非线性响应对自适应滤波算法的收敛性能的影响，进而提高反馈声音的抵消效果。另外，由于反馈抵消单元170所需的第二信号y2是通过第二声音传感器120-2拾取得到，因此，即使声学系统20对反馈抵消单元170与其他单元之间的交互权限有所限制，也不影响AFC技术在声学系统20中的应用，降低了AFC技术对声学系统的设计架构的要求，提高了AFC技术的应用灵活性和广泛性。
另外，因为反馈抵消单元170原本具有对第一声音传感器120-1的系统访问权限，而访问第二声音传感器120-2所需的权限与访问第一声音传感器120-1所需的权限属于同一种权限，因此，图3所示的声学系统在增加第二声音传感器120-2之后，反馈抵消单元170不必额外增加新的系统访问权限，即可实现对第二声音传感器120-2的数据的访问。
进一步的，图3所示的声学系统增加第二声音传感器120-2之后，并不需要改变声反馈抵消单元170的内部实现，即不需要改变预测传递函数F′的更新公式以及反馈声音抵消的计算式，而只需要把声反馈抵消单元170的输入信号u替换为y2即可。由此可见，图3所示的声学系统能够应用、适配、兼容已有的声反馈抵消单元170，而无论这些已有的声反馈抵消单元170采用的是何种自适应滤波算法(包括但不限于前文提到的LMS、NLMS、RLS或者其他的自适应滤波算法)。因此，对声学系统的改造难度较低，具有广泛适用性。
下面对图3所示的声学系统20的系统稳定性进行验证。
根据信号处理的理论，图3所示的声学系统的闭环增益A可以表示如下：
其中，F1表示扬声器110到第一声音传感器120-1之间的声学传递函数，F2表示扬声器110到第二声音传感器120-2之间的声学传递函数。
根据奈奎斯特稳定判据，可知该声学系统20能够抵消反馈声音的要求是：所求解的预测传递函数F′满足如下条件：
也就是说，预测传递函数F′需要满足：
当预测传递函数F′满足上述公式(14)时，公式(3-2)可以变形为：
由于第一信号y1和第二信号y2满足如下条件：k2≥2k1，即：
对公式(16)中的x1和x2进行替换，得到：
对公式(17)进行化简得到：
|v1F2|2≥2·|v2F1|2      公式(18)
将上述公式(18)代入到公式(15)中，得到：
由公式(19)可见，当前向增益G→∞时，闭环增益A→∞。因此，图3所示的声学系统在预测传递函数F′达到收敛条件时仍然是稳定的。从而证实了本申请方案的正确性。
基于图3所示的声学系统20，在一些情况下，当第二声音传感器120-2处于强反馈环境时，从扬声器110到第二声音传感器120-2之间的声学传递函数F2≈1，并且，第一信号y1和第二信号y2满足如下条件：
第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第二信号y2中的对应于所述第二声音的信号能量|v2|2，即：|x2|2＞＞|v2|2。
该情况下，图3所示的声学系统可以简化为图4所示的声学系统。在图4所示的声学系统中，第二声音传感器120-2几乎只拾取来自扬声器110的声音。该情况下，第二信号y2≈u。因此，预测传递函数F′的更新公式可以更新为：
F′←F′+μey2≈F′+μeu      公式(2-3)
相应的，声学系统30的闭环增益A可以表示为：
由此可见，当第二声音传感器120-2位于强反馈场景时，图4所示声学系统中AFC数学表达式与图2所示声学系统中基于理想假设的AFC数学表达式完全相同。从而进一步证实了本申请方案的 正确性。
图5示出了根据本说明书的实施例提供的声学系统的又一种设计示意图。如图5所示，信号处理电路150还可以包括预处理单元180。信号处理电路150在得到第一信号y1和第二信号y2之后，可以通过预处理单元180分别对第一信号y1和第二信号y2进行预处理。具体的，信号处理电路150通过预处理单元180对第一信号y1执行第一预处理操作H1得到第一中间信号y1′，并对第二信号y2执行第二预处理操作H2得到第二中间信号y2′。进而，第一中间信号y1′和第二中间信号y2′被输入至声反馈抵消单元170。声反馈抵消单元170基于第二中间信号y2′，对第一中间信号y1′中的对应于所述第一声音的信号成分进行削减，得到目标信号e。应理解，声反馈抵消单元170的内部处理过程已在前文描述，此处不做赘述。
其中，上述第一预处理操作H1可以包括但不限于增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项。上述第二预处理操作H2可以包括但不限于增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项。在对声学系统进行设计时，可以基于不同应用场景的需求来对第一预处理操作H1和第二预处理操作H2进行设计。例如，在一些情况下，第一声音传感器120-1和第二声音传感器120-2的频响存在差异，因此，可以设计合适的第一预处理操作H1和第二预处理操作H2来补偿所述差异，从而使得第一信号y1和第二信号y2的频响相互匹配，满足AFC算法的计算要求。由此可见，信号处理电路150通过对第一信号y1和第二信号y2执行预处理操作，能够满足不同应用场景的处理需求。
上述图3至图5是以声学系统20包括一个扬声器110为例进行举例说明。在一些场景中，声学系统20中扬声器110的数量可以为M，所述M为大于1的整数。该情况下，第二声音传感器120-2的数量也可以为M。M个第二声音传感器120-2与M个扬声器110一一对应。其中，第i个第二声音传感器120-2重点拾取第i个扬声器110发出的声音。
具体而言，针对M个第二声音传感器120-2中的任意第i个第二声音传感器，第i个第二声音传感器120-2工作时采集环境声音并生成第二信号y2i。其中，第一信号y1和第二信号y2i满足k2i≥2k1，k2i为第二信号y2i中的对应于第i个扬声器110发出声音的信号能量与对应于目标声源发出的声音的信号能量之比。所述目标声源包括环境中除第i个扬声器之外的其他声源。进一步的，信号处理电路150可以基于第二信号y2i对第一信号y1中的反馈成分进行削减，得到目标信号ei。信号处理电路通过对目标信号e1至目标信号eM进行叠加得到目标信号e，进而对目标信号e执行目标操作。
由此可见，当声学系统20包括M个扬声器110的情况下，声学系统20中可以包括M个第二声音传感器120-2。其中，第i个声音传感器120-2重点拾取第i个扬声器的声音，并用于AFC的自适应滤波过程。这样，相当于声学系统20中叠加了M个基于AFC自适应滤波过程。其中，每个自适应滤波过程与前面图3至图5的描述一致，此处不做赘述。
综上可知，基于图3至图5所示的声学系统，在第一信号y1和第二信号y2满足条件k2≥2k1的情况下，采用AFC技术能够有效减少或者消除反馈声音，并且能够避免或者减少非线性响应对自适 应滤波算法的收敛性能的影响。
下面详细说明如何对声学系统进行设计能够使得第一信号y1和第二信号y2满足条件k2≥2k1。需要说明的是，对声学系统进行设计的方案可以存在多种，下面仅以几种可能的方案为例进行举例说明。下面所列举的不同方案之间可以相互结合。
方案1：可以从结构维度对声学系统进行设计，使得第一声音传感器120-1、第二声音传感器120-2、以及扬声器110之间的位置关系满足预设条件，从而使得第一信号y1和第二信号y2满足条件k2≥2k1。
在一些实施例中，第一声音传感器120-1、第二声音传感器120-2、以及扬声器110之间满足预设的距离条件。
例如，所述距离条件可以包括：第二声音传感器120-2与扬声器110之间的距离远小于第一声音传感器120-1与扬声器110之间的距离。也就是说，第二声音传感器120-2相较于第一声音传感器120-1尽可能的靠近扬声器110。假设第一声音传感器120-1与扬声器110之间的距离记为L1，第二声音传感器120-2与扬声器110之间的距离记为L2，则L1和L2满足距离条件：L1≥2L2。上述距离条件也可以表述为L1与L2的比值大于或等于预设值。上述预设值可以位于2、3、4、5、6、7、8、9、10、…∞中的任意两个所规定的区间。
下面结合图6A至图6F，分别对声学系统的可能的结构进行举例说明。需要说明的是，本说明书对于声学系统20的产品形态不做限定，例如，声学系统20可以采用真无线耳机形态、耳罩式形态、眼镜式形态、后挂式形态、耳后式形态、耳内式形态或者其他任意可能的形态。图6A至图6F仅以几种可能的产品形态为例进行举例说明。
例如，当声学系统20采用真无线耳机形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6A所示。当声学系统20采用耳罩式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6B所示。当声学系统20采用眼镜式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6C所示。当声学系统20采用后挂式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6D所示。当声学系统20采用耳后式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6E所示。其中，所述耳后式形态包括但不限于助听器中的BTE(Behind-The-Ear)、RIC(Receiver-In-Canal)等形态。当声学系统20采用耳内式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图6F所示。其中，所述耳内式形态包括但不限于：助听器中的ITE(In-The-Ear)、ITC(In-The-Canal)、CIC(Completely-In-the-Canal)等形态。图6A至图6F示出的声学系统结构均满足距离条件L1≥2L2。
应理解，当声学系统满足距离条件L1≥2L2时，第二声音传感器120-2相对于第一声音传感器120-1能够拾取到更强的所述第一声音。因此，第二信号y2中的对应于所述第一声音的信号能量|x2|2 远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，从而有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
能够理解的是，尽管上述图6A至图6F示出了满足距离条件L1≥2L2的声学系统的一些举例，但是，在一些情况下，有些声学系统受到产品形态或者特定需求的影响可能无法满足距离条件L1≥2L2。也就是说，L1和L2的取值较为接近。例如，图7A至图7G分别示出L1和L2的取值较为接近情况下的声学系统的结构示意图。具体而言，当声学系统20采用真无线耳机形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7A所示。当声学系统20采用耳罩式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7B所示。当声学系统20采用眼镜式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7C所示。当声学系统20采用后挂式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7D所示(两个声音传感器与扬声器之间的距离均较远的情况)，还可以如图7E所示(两个声音传感器与扬声器之间的距离均较近的情况)。当声学系统20采用耳后式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7F所示。其中，所述耳后式形态包括但不限于助听器中的BTE(Behind-The-Ear)、RIC(Receiver-In-Canal)等形态。当声学系统20采用耳内式形态时，第一声音传感器120-1、第二声音传感器120-2和扬声器110之间的位置关系可以如图7G所示。其中，所述耳内式形态包括但不限于：助听器中的ITE(In-The-Ear)、ITC(In-The-Canal)、CIC(Completely-In-the-Canal)等形态。
在声学系统无法满足距离条件L1≥2L2的情况下(例如图7A至图7G所示的情况)，可以采用后续的方案对声学系统进行设计，以使得第一信号y1和第二信号y2满足条件k2≥2k1。需要说明的是，声学系统在采用图6A至图6F所示的设计方案时，也可以与后续的方案中的一种或多种进行结合。
在一些实施例中，第一声音传感器120-1、第二声音传感器120-2、以及扬声器110之间满足预设的结构条件。下面结合图8A至图8F对声学系统满足的结构条件进行说明。需要说明的是，图8A至图8F仅示出了声学系统的局部结构。
例如，声学系统20可以采用声学腔体的设计。参见图8A至图8C，声学系统20可以包括壳体21，壳体21的部分区域形成有声学腔体22。需要说明的是，本申请对于声学腔体22的具体形态不做限定。扬声器110位于声学腔体22的内部。扬声器110的发声部件可以将声学腔体22分隔为第一声学腔体22-1和第二声学腔体22-2。其中，上述发声部件可以是指扬声器110中产生振动的部件，例如，可以是振动膜、振动梁、振动杆、振动块等。第一声学腔体22-1是指扬声器110发出的第一声音在进入外部自由空间之前的声学共振腔。第二声学腔体22-2是指扬声器110发出的第一声音不会直接传播到外部自由空间的分量所处的声学共振腔。换言之，扬声器110的发声部件将声学腔体22分隔为两个子腔体，在这两个子腔体中，所述发声部件的出音面朝向的子腔体作为第一声学腔体22-1，所述发声部件的出音面背向的子腔体作为第二声学腔体22-2。第一声学腔体22-1也可以称为 前腔，第二声学腔体22-2也可以称为后腔。
基于上述声学腔体的设计，在一些实施例中，第二声音传感器120-2可以位于声学腔体22的内部，第一声音传感器120-2可以位于声学腔体22的外部。能够理解，由于扬声器110位于声学腔体22的内部，因此，将第二声音传感器120-2设置在声学腔体22的内部，并将第一声音传感器120-1设置在声学腔体22的外部，能够使得第二声音传感器120-2相对于第一声音传感器120-1拾取到更强的扬声器110的声音。也就是说，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，从而有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
其中，第二声音传感器120-2在声学腔体22内部的具体位置可以有多种情况。例如，参见图8A，第二声音传感器120-2可以位于第一声学腔体22-1的内部。这种方式下，第二声音传感器120-2相较于第一声音传感器120-1能够捕捉较强的所述第一声音，从而有助于实现下述条件：第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2。进而有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
再例如，参见图8B，第二声音传感器120-2可以位于第二声学腔体22-2的内部。这种方式能够达到如下两方面的效果：第一方面，第二声音传感器120-2相较于第一声音传感器120-1至少在部分频段上能够捕捉到较强的所述第一声音，从而有助于实现下述条件：第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2。第二方面，扬声器110会对目标声源160发出的第二声音起到一定的阻挡作用，从而有助于实现下述条件：第二信号y2对应于所述第二声音的信号能量|v2|2远小于第一信号y1中对应于所述第二声音的信号能量|v1|2。上述两方面的共同作用使得条件k2≥2k1能够实现。
又例如，参见图8C，第二声音传感器120-2可以与扬声器110的发声部件耦合。比如，第二声音传感器120-2可以为质量较轻的骨传导MIC，扬声器110可以为气传导扬声器，骨传导MIC可以贴合设置在气导扬声器的振膜上。这样，由于骨传导MIC拾取的是骨振动信号，空气振动不会对骨传导MIC的拾音造成干扰，从而保证骨传导MIC拾取的第二信号y2的准确性。另外，声学系统20通过采用质量较轻的骨传导MIC，能够减少骨传导MIC对扬声器振膜振动的影响，从而避免引入额外失真。需要说明的是，这种耦合的方式对于各种类型的声音传感器和扬声器都是适用的，上述骨传导MIC和气传导扬声器耦合的方式仅为一种可能的示例。
图8C所示的声学系统中，由于第二声音传感器120-2与扬声器110的发声部件耦合，第二声音传感器120-2能够最直接的拾取扬声器110发出的声音，因此，第二声音传感器120-2相较于第一声音传感器120-1能够捕捉到较强的第一声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
需要说明的是，上述图8A至图8C的设计对于第一声音传感器120-1的具体位置不做限定，只 要是位于声学腔体22外部且能够方便拾取目标声源160的声音即可。例如，第一声音传感器120-1可以位于壳体21的内部，并且拾音面设置在壳体21的表面上远离声学腔体22的位置。图8A至图8C未对第一声音传感器120-1的位置进行示意。
在一些实施例中，第一声音传感器120-1的拾音面和第二声音传感器120-2的拾音面可以均位于壳体21外部的自由空间中，并且第二声音传感器120-2相对于第一声音传感器120-1更靠近扬声器110(或者说更靠近声学腔体22)。其中，所述自由空间指声音不受反射、折射、衍射的影响，主要以球面波或平面波的方式传播的空间。例如，参见图8E，第二声音传感器120-2可以设置在壳体21外部的自由空间，而不与壳体21物理连接。该情况下，第二声音传感器120-2可以为有线或无线MIC，在所述自由空间拾取得到第二信号y2之后，可以通过有线或无线方式向信号处理电路150发送第二信号y2。
在一些实施例中，参见图8D，声学系统的壳体21的部分区域内可以形成有声学腔体22和声学腔体23。其中，扬声器110位于声学腔体22内，第二声音传感器120-2位于声学腔体23内，并且，第二声音传感器120-2相对于第一声音传感器120-1更靠近扬声器110。声学腔体23对第二声音传感器120-2可以起到防风作用，也可以称为防风腔体。第二声音传感器120-2在声学腔体23内依然可以拾取到自由空间中的声音信号。
需要说明的是，上述图8D至图8E的设计对于第一声音传感器120-1的具体位置不做限定，只要第一声音传感器120-1的拾音面位于所述自由空间，且能够方便地在所述自由空间拾取目标声源160的声音即可。例如，第一声音传感器120-1可以位于壳体21的内部，且拾音面设置在壳体21的表面上远离声学腔体22的位置。图8D和图8E未对第一声音传感器120-1的位置进行示意。
图8D和图8E所示的设计中，由于第二声音传感器120-2相对于第一声音传感器120-1更靠近扬声器110，因此，第二声音传感器120-2相较于第一声音传感器120-1能够捕捉到更强的第一声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。另外，图8E的设计中，由于第二声音传感器120-2位于壳体21外部的自由空间中，不需要对壳体21结构以及声学腔体22进行改造，实现难度较低。图8D的设计中，由于第二声音传感器120-2位于声学腔体22之外的其他声学腔体中，不需要对声学腔体22进行改造，实现难度也较低。
在一些实施例中，第一声音传感器120-1的拾音面可以设置在壳体21外部的自由空间中，第二声音传感器120-2的拾音面可以设置在壳体21的内部空间中，并且，第二声音传感器120-2相对于第一声音传感器120-1更靠近扬声器110(或者说更靠近声学腔体22)。例如，参见图8F，第二声音传感器120-2可以位于壳体21内部靠近第二声学腔体22-2(或者后腔)的区域，且第二声音传感器120-2的拾音面朝向第二声学腔体22-2。需要说明的是，本申请对于第一声音传感器120-1的具体位置不做限定，只要是能够方便拾取目标声源160的声音即可。例如，第一声音传感器120-1可以位于壳体21的内部，且拾音面设置在壳体21的表面上远离扬声器110(或者说远离声学腔体22)的 位置。图8F中未对第一声音传感器120-1的位置进行示意。
图8F所示的设计中，由于第二声音传感器120-2靠近后腔(即第二声学腔体22-2)，因此，第二声音传感器120-2可以拾取到从后腔中泄露出来的第一声音，或者拾取到以固体介质传播的第一声音。进一步的，由于第二声音传感器120-2相对于第一声音传感器120-1更靠近扬声器110，因此，第二声音传感器120-2相较于第一声音传感器120-1能够捕捉到更强的第一声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2。另外，由于第一声音传感器120-1被隐藏在壳体21的内部，壳体21对目标声源160的声音起到一定阻挡作用，从而，第二信号y2中的对应于所述第二声音的信号能量|v2|2远小于第一信号y1中的对应于所述第二声音的信号能量|v1|2。上述两方面共同作用有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。另外，上述方案不需要对声学腔体22进行改造，实现难度较低。
在一些实施例中，第一声音传感器120-1和扬声器110还可以分别耦合于不同壳体上。例如，声学系统20还可以包括第一壳体和第二壳体。第一壳体可以视为声学系统20的装置外壳。第一声音传感器120-1可以位于所述第一壳体的内部，且拾音面设置在第一壳体的表面，并朝向第一壳体外部的自由空间。第二壳体也可以位于所述第一壳体的内部，并且所述第二壳体形成有声学腔体，扬声器110和第二声音传感器120-2位于所述声学腔体的内部。其中，与图8A至图8C类似，扬声器110的发声器件可以将声学腔体分隔为第一声学腔体(前腔)和第二声学腔体(后腔)，第二声音传感器120-2可以位于第一声学腔体的内部，也可以位于第二声学腔体的内部，还可以与扬声器110的发声部件耦合。
基于上述设计，第一声音传感器120-1在第一壳体外部的自由空间内拾取声音，第二声音传感器120-2在第一壳体内部的声学腔体内拾取声音。由于第一壳体对声音的阻挡作用，一方面会降低第二声音传感器120-2对目标声源160的声音的拾取，另一方面会降低第一声音传感器120-1对扬声器110的声音的拾取。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，并且，第二信号y2中的对应于所述第二声音的信号能量|v2|2远小于第一信号y1中的对应于所述第二声音的信号能量|v1|2。进而有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
在一些实施例中，声学系统20还可以包括隔挡件。隔挡件件对声音起到隔挡作用。需要说明的是，本申请对于隔挡件的形态不做限定，例如可以为隔挡板、也可以为隔挡罩等。第二声音传感器120-2和扬声器110位于所述隔挡件的第一侧，第一声音传感器120-1位于所述隔挡件的第二侧。这样，由于所述隔挡件对所述第一声音起到阻挡作用，第一声音传感器120-1相对于第二声音传感器120-2拾取到的所述第一声音更少，也就是说，第二声音传感器120-2相较于第一声音传感器120-1能够捕捉到更强的第一声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
方案2：可以从拾音指向性维度对声学系统20进行设计，使得第一声音传感器120-1和第二声音传感器120-2的拾音指向性满足预设条件，从而使得第一信号y1和第二信号y2满足条件k2≥2k1。
其中，声音传感器的拾音指向性可以是指，由于声音传感器对不同方向的拾音灵敏度不同而对不同方向具有不同程度的指向性。其中，某个方向的拾音灵敏度可以是指声音传感器对来自该方向的声音的拾取能力。当某个方向的拾音灵敏度越高时，说明声音传感器对该方向的声音的拾取能力越强，即该声音传感器拾取得到的拾音信号中对应于该方向声音的信号成分越多，从而声音传感器对该方向的指向性越强。当某个方向的拾音灵敏度越低时，说明声音传感器对该方向的声音的拾取能力越弱，即声音传感器拾取得到的拾音信号中对应于该方向声音的信号成分越少，从而声音传感器对该方向的指向性越弱。当某个方向的拾音灵敏度为零时，说明声音传感器对该方向的声音不拾取，该方向也可以称为零点拾音方向。
图9示出了根据本说明书的实施例提供的声学系统的拾音指向示意图。如图9所示，第一声音传感器120-1和第二声音传感器120-2的拾音指向性可以满足下述条件中的至少一个：
(1)第一声音传感器120-1在第一方向的拾音灵敏度大于在第二方向的拾音灵敏度。
其中，所述第一方向指向目标声源160，所述第二方向指向扬声器110。能够理解，当满足上述条件(1)时，第一声音传感器120-1可以重点拾取目标声源160的声音。在对声学系统20进行设计时，为了满足上述条件(1)，可以将第一声音传感器120-1的拾音灵敏度较高的方向朝向目标声源160，和/或，将第一声音传感器120-1的拾音灵敏度较低的方向朝向扬声器110。例如，将第一声音传感器120-1的拾音灵敏度最高的方向朝向目标声源160，和/或，将第一声音传感器120-1的拾音灵敏度最低的方向朝向扬声器110。
(2)第二声音传感器120-2在所述第一方向的拾音灵敏度小于在所述第二方向的拾音灵敏度。
当满足上述条件(2)时，第二声音传感器120-2可以重点拾取扬声器110的声音。在对声学系统20进行设计时，为了满足上述条件(2)，可以将第二声音传感器120-2的拾音灵敏度较高的方向朝向扬声器110，和/或，将第二声音传感器120-2的拾音灵敏度较低的方向朝向目标声源160。例如，将第二声音传感器120-2的拾音灵敏度最高的方向朝向扬声器110，和/或，将第二声音传感器120-2的拾音灵敏度最低的方向朝向目标声源160。
需要说明的是，上述条件(1)和(2)只需要满足其中一项即可。当条件(1)满足时，第一声音传感器120-1重点拾取来自目标声源160的声音，当条件(2)满足时，第二声音传感器120-2重点拾取来自扬声器110的声音，两种情况下均有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。进一步的，当上述条件(1)和(2)同时满足时，第一声音传感器120-1相对于第二声音传感器120-2能够拾取到更强的目标声源160的声音，并且，第二声音传感器120-2相对于第一声音传感器120-1能够拾取到更强的扬声器110的声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，第二信号y2中的对应于所述第二声音的信号能量|v2|2远小于第一信号y1中对应于所述第二声音的信号能量|v1|2，更加有助于使得第一信号 y1和第二信号y2满足条件k2≥2k1。
需要说明的是，第一声音传感器120-1的拾音指向性、以及第二声音传感器120-2的拾音指向性均可以通过采用具有一定指向性的单个拾音器件实现，还可以通过采用多个拾音器件形成预设阵列来实现，本申请对此不做限定。另外，本申请对于第一声音传感器120-1和第二声音传感器120-2各自对应的拾音方向图案不做具体限定，二者可以采用相同的拾音方向图案，也可以采用不同的拾音方向图案。例如，第一声音传感器120-1和第二声音传感器120-2对应的拾音方向图案均可以为全向图案、心型图案、超心型图案、8字型图案、枪型图案或其他指向性图案中的任意一种。例如，图9中第一声音传感器120-1的拾音方向图案为枪型且较强拾音方向指向目标声源160，而第二声音传感器120-2的拾音方向图案为心型且较强拾音方向指向扬声器110。
由于方案2是从拾音指向性维度对声学系统进行设计，即，需要对第一声音传感器120-1和/或第二声音传感器120-2的拾音指向性进行设计，而对于声学系统中各器件的位置关系可以不做要求或者降低要求。可见，方案2可以适用于不便对声学系统20的结构做出改变的场景。在一些实施例中，方案2也可以与前述方案1中一种或多种设计相互结合。
方案3：可以基于目标区域内各位置处的反馈声音能量来设计第一声音传感器120-1和第二声音传感器120-2的位置，从而使得第一信号y1和第二信号y2满足条件k2≥2k1。
例如，第一声音传感器120-1位于目标区域内的第一位置，第二声音传感器120-2位于所述目标区域内的第二位置，其中，所述第一位置和所述第二位置满足下述条件中的至少一个：
(1)所述第一位置处的来自扬声器110的声音能量小于所述目标区域内除所述第一位置之外的其他位置处的来自扬声器110的声音能量。
也就是说，第一声音传感器120-1设置在目标区域内对应的反馈声音能量(即来自扬声器110的声音能量)最小的位置。当条件(1)满足时，第一声音传感器120-1拾取不到或者拾取到较弱的扬声器110的声音。
(2)所述第二位置处的来自扬声器110的声音能量大于所述目标区域内除所述第二位置之外的其他位置处的来自扬声器110的声音能量。
也就是说，第二声音传感器120-2设置在目标区域内对应的反馈声音能量(即来自扬声器110的声音能量)最大的位置。当条件(2)满足时，第二声音传感器120-2能够拾取到较强的扬声器110的声音。
需要说明的是，上述条件(1)和(2)只需要满足其中一项即可，在任意一项满足时均有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。进一步的，当上述条件(1)和条件(2)同时满足时，第一声音传感器120-1拾取不到或者拾取到较弱的扬声器110的声音，并且，第二声音传感器120-2能够拾取到较强的扬声器110的声音。从而，第二信号y2中的对应于所述第一声音的信号能量|x2|2远大于第一信号y1中的对应于所述第一声音的信号能量|x1|2，更加有助于使得第一信号y1和第二信号y2满足条件k2≥2k1。
图10A示出了根据本说明书的实施例提供的声学系统中第一声音传感器和第二声音传感器在目标区域内的位置示意图。如图10A所示，目标区域190内的不同位置处标注有箭头，箭头的长度表征该位置对应的反馈声音能量(即来自扬声器110的声音能量)的大小。其中，箭头长度越大表示反馈声音能量越大，箭头长度越小表示反馈声音能量越小。继续参见图10A，在目标区域190中，第一声音传感器120-1所在位置对应的反馈声音能量最小，第二声音传感器120-2所在位置对应的反馈声音能量最大。
为了满足上述条件(1)和条件(2)，可以采用如下方式对声学系统20进行设计：先在声学系统20的装置内确定出拟放置第一声音传感器120-1和第二声音传感器120-2的目标区域190。然后，通过仿真计算或者实地测量，得到目标区域190上各位置对应的反馈声音能量分布。例如，图10B示出了一种声学系统的目标区域内各位置对应的反馈声音能量的示意图。其中，目标区域190内某个位置的灰度值越大(灰度值为0时呈现为黑色，灰度值为255时呈现为白色)，则说明该位置对应的反馈声音能量越大，目标区域内某个位置的灰度值越小，则说明该位置对应的反馈声音能量越小。进而，将目标区域190内对应的反馈声音能量最强的位置作为第二位置192，并将第二声音传感器120-2设置在第二位置192处；将目标区域190内对应的反馈声音能量最弱的位置作为第一位置191，并将第一声音传感器120-1设置在第一位置191处。
需要说明的是，本申请对于目标区域190的形状不做限定，图10A和图10B中以矩形为例进行示意。实际应用中，目标区域190可以是其他的任意形状，例如，圆形、三角形、五边形、六边形、环形、镂空形等，还可以是其他不规则的任意形状，还可以是一块三维空间所围区域。
由于方案3是基于目标区域190内各位置的反馈声音能量，来对第一声音传感器120-1和第二声音传感器120-2的位置进行设计，即，将第一声音传感器120-1设置在目标区域190内对应的反馈声音能量最小的位置，将第二声音传感器120-2设置在目标区域190内对应的反馈声音能量最大的位置，因此，方案3对于声学系统20中各器件之间位置关系的要求不高(例如不要求第一声音传感器120-1必须远离扬声器110，第二声音传感器120-2必须靠近扬声器110等)。方案3可以适用于未预先指定各部件的位置，并允许在一定的候选区域选择确定各部件位置的场景。在一些实施例中，方案3也可以与前述方案1、方案2中一种或多种设计相互结合。
图11示出了根据本说明书的实施例提供的声学系统在自适应滤波性能方面的测试结果示意图。参见图11，在声学系统20中扬声器110具有限幅特性的情况下，当采用图2所示的基于AFC的自适应滤波方案时，计算得到的失调量(MIS)如曲线A所示。当采用图4所示的基于AFC的自适应滤波方案时，计算得到的失调量(MIS)如曲线B所示。在图11中，曲线B相对于曲线A在最初期(约0.2秒前)下降更快，且在转折后的时期(约0.2秒后)一直保持着较快的平均下降趋势。也就是说，曲线B在全部示出的时间段内都位于曲线A的下方。因而图4方案的失调量MIS一直低于图2方案，亦即图4方案在自适应滤波算法的收敛程度和收敛速度上优于图2方案。由图11可见，采用图4所示方案在自适应滤波算法的收敛程度和收敛速度上均有明显提升。
综上所述，本说明书提供的声学系统20包括：扬声器110、第一声音传感器120-1、第二声音传感器120-2和信号处理电路150。其中，扬声器110工作时接收驱动信号并转换为第一声音；第一声音传感器120-1工作时采集环境声音并生成第一信号，所述环境声音包括第一声音和来自目标声源的第二声音；第二声音传感器120-2工作时采集环境声音并生成第二信号，所述第一信号和所述第二信号满足k2≥2k1，其中k1为所述第一信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比，k2为所述第二信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比；信号处理电路150与第一声音传感器120-1和第二声音传感器120-2分别连接，工作时基于所述第二信号对所述第一信号中的对应于所述第一声音的信号成分进行削减，得到目标信号，并对目标信号执行目标操作。由此可见，本说明书提供的声学系统20能够减少或消除目标信号中反馈成分，从而避免由于反馈声音导致的啸叫等问题，还能够提升声学系统20所能达到的最大前向增益。
上述对本说明书特定实施例进行了描述。其他实施例在所附权利要求书的范围内。在一些情况下，在权利要求书中记载的动作或步骤可以按照不同于实施例中的顺序来执行并且仍然可以实现期望的结果。另外，在附图中描绘的过程不一定要求示出特定顺序或者连续顺序才能实现期望的结果。在某些实施方式中，多任务处理和并行处理也是可以的或者是可能有利的。
综上所述，在阅读本详细公开内容之后，本领域技术人员可以明白，前述详细公开内容可以仅以示例的方式呈现，并且可以不是限制性的。尽管这里没有明确说明，本领域技术人员可以理解本说明书需求囊括对实施例的各种合理改变，改进和修改。这些改变，改进和修改旨在由本说明书提出，并且在本说明书的示例性实施例的精神和范围内。
此外，本说明书中的某些术语已被用于描述本说明书的实施例。例如，“一个实施例”，“实施例”和/或“一些实施例”意味着结合该实施例描述的特定特征，结构或特性可以包括在本说明书的至少一个实施例中。因此，可以强调并且应当理解，在本说明书的各个部分中对“实施例”或“一个实施例”或“替代实施例”的两个或更多个引用不一定都指代相同的实施例。此外，特定特征，结构或特性可以在本说明书的一个或多个实施例中适当地组合。
应当理解，在本说明书的实施例的前述描述中，为了帮助理解一个特征，出于简化本说明书的目的，本说明书将各种特征组合在单个实施例、附图或其描述中。然而，这并不是说这些特征的组合是必须的，本领域技术人员在阅读本说明书的时候完全有可能将其中一部分设备标注出来作为单独的实施例来理解。也就是说，本说明书中的实施例也可以理解为多个次级实施例的整合。而每个次级实施例的内容在于少于单个前述公开实施例的所有特征的时候也是成立的。
本文引用的每个专利，专利申请，专利申请的出版物和其他材料，例如文章，书籍，说明书，出版物，文件，物品等，除了与其相关的任何历史起诉文件、可能与本文件不一致或相冲突的任何相同的、或者任何可能对权利要求的最宽范围具有限制性影响的任何相同的历史起诉文件，均可以通过引用结合于此，并用于现在或以后与本文件相关联的所有目的。此外，如果在与任何所包含的 材料相关联的术语的描述、定义和/或使用与本文档相关的术语、描述、定义和/或之间存在任何不一致或冲突时，使用本文件中的术语为准。
最后，应理解，本文公开的申请的实施方案是对本说明书的实施方案的原理的说明。其他修改后的实施例也在本说明书的范围内。因此，本说明书披露的实施例仅仅作为示例而非限制。本领域技术人员可以根据本说明书中的实施例采取替代配置来实现本说明书中的申请。因此，本说明书的实施例不限于申请中被精确地描述过的实施例。

Claims (20)

  1. 一种声学系统，其特征在于，包括：
    扬声器，工作时接收驱动信号并转换为第一声音；
    第一声音传感器，工作时采集环境声音并生成第一信号，所述环境声音包括所述第一声音和来自目标声源的第二声音，所述目标声源包括除所述扬声器之外的其他声源；
    第二声音传感器，工作时采集所述环境声音并生成第二信号，其中，所述第一信号和所述第二信号满足k2≥2k1，其中k1为所述第一信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比，k2为所述第二信号中的对应于所述第一声音的信号能量与对应于所述第二声音的信号能量之比；以及
    信号处理电路，与所述第一声音传感器和所述第二声音传感器分别连接，工作时：
    基于所述第二信号，对所述第一信号中的对应于所述第一声音的信号成分进行削减，得到目标信号，以及
    对所述目标信号执行目标操作。
  2. 根据权利要求1所述的声学系统，其特征在于，为了满足k2≥2k1，所述第一信号和所述第二信号满足下面条件中的至少一个：
    所述第二信号中的对应于所述第一声音的信号能量与所述第二信号中的对应于所述第二声音的信号能量之比大于或等于2；
    所述第二信号中对应于所述第一声音的信号能量与所述第一信号中对应于所述第一声音的信号能量之比大于或等于2；以及
    所述第一信号中对应于所述第二声音的信号能量与所述第一信号中对应于所述第一声音的信号能量之比大于或等于2。
  3. 根据权利要求1所述的声学系统，其特征在于，所述第一声音传感器、所述第二声音传感器、以及所述扬声器之间的位置关系满足预设条件，使得所述第一信号和所述第二信号满足k2≥2k1。
  4. 根据权利要求3所述的声学系统，其特征在于，所述预设条件包括：L1≥2L2，其中，L2为所述第二声音传感器与所述扬声器之间的距离，L1为所述第一声音传感器与所述扬声器之间的距离。
  5. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括壳体，所述壳体的部分区域形成有声学腔体，所述扬声器和所述第二声音传感器均位于所述声学腔体的内部，所述第一声音传感器位于所述声学腔体的外部。
  6. 根据权利要求5所述的声学系统，其特征在于，所述扬声器的发声部件将所述声学腔体分隔为第一声学腔体和第二声学腔体，所述发声部件的出音面朝向所述第一声学腔体，其中
    所述第二声音传感器位于所述第一声学腔体的内部，或者
    所述第二声音传感器位于所述第二声学腔体的内部。
  7. 根据权利要求5所述的声学系统，其特征在于，所述第二声音传感器与所述扬声器的发声部件耦合。
  8. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括壳体，所述第二声音传感器的拾音面和所述第一声音传感器的拾音面均位于所述壳体外部的自由空间中，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
  9. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括壳体，所述壳体的部分区域形成有第一声学腔体和第二声学腔体，所述扬声器位于所述第一声学腔体内，所述第二声音传感器位于所述第二声学腔体内，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
  10. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括壳体，所述第一声音传感器的拾音面位于所述壳体外部的自由空间中，所述第二声音传感器的拾音面位于所述壳体的内部空间中，所述第二声音传感器相对于所述第一声音传感器更靠近所述扬声器。
  11. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括第一壳体和第二壳体，其中，
    所述第二壳体位于所述第一壳体的内部，且所述第二壳体形成有声学腔体，所述扬声器和所述第二声音传感器位于所述声学腔体的内部。
  12. 根据权利要求3所述的声学系统，其特征在于，所述声学系统还包括隔挡件，所述第二声音传感器和所述扬声器位于所述隔挡件的第一侧，所述第一声音传感器位于所述隔挡件的第二侧。
  13. 根据权利要求1所述的声学系统，其特征在于，所述第一声音传感器和所述第二声音传感器的拾音指向性满足预设条件，使得所述第一信号和所述第二信号满足k2≥2k1。
  14. 根据权利要求13所述的声学系统，其特征在于，所述第一声音传感器和所述第二声音传感器的拾音指向性满足下面条件中的至少一个：
    所述第一声音传感器在第一方向的拾音灵敏度大于在第二方向的拾音灵敏度；以及
    所述第二声音传感器在所述第一方向的拾音灵敏度小于在所述第二方向的拾音灵敏度，其中
    所述第一方向指向所述目标声源，所述第二方向指向所述扬声器。
  15. 根据权利要求1所述的声学系统，其特征在于，所述第一声音传感器位于目标区域内的第一位置，所述第二声音传感器位于所述目标区域内的第二位置，其中，所述第一位置和所述第二位置满足下面条件中的至少一个：
    所述第一位置处的来自所述扬声器的声音能量小于所述目标区域内除所述第一位置之外的其他位置处的来自所述扬声器的声音能量；以及
    所述第二位置处的来自所述扬声器的声音能量大于所述目标区域内除所述第二位置之外的其他位置处的来自所述扬声器的声音能量。
  16. 根据权利要求1所述的声学系统，其特征在于，为了得到所述目标信号，所述信号处理电路：
    对所述第二信号执行自适应滤波操作得到第三信号，并从所述第一信号中减去所述第三信号得到所述目标信号。
  17. 根据权利要求16所述的声学系统，其特征在于，所述信号处理电路还：
    基于所述第二信号和所述目标信号中的至少一个更新所述自适应滤波操作对应的滤波参数。
  18. 根据权利要求1所述的声学系统，其特征在于，为了得到所述目标信号，所述信号处理电路：
    对所述第一信号执行第一预处理操作得到第一中间信号；
    对所述第二信号执行第二预处理操作得到第二中间信号；以及
    基于所述第二中间信号，对所述第一中间信号中的对应于所述第一声音的信号成分进行削减，得到所述目标信号。
  19. 根据权利要求18所述的声学系统，其特征在于，所述第一预处理操作包括增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项；以及
    所述第二预处理操作包括增益放大操作、滤波操作、频响补偿操作、相位修改操作中的至少一项。
  20. 根据权利要求1所述的声学系统，其特征在于，所述信号处理电路还与所述扬声器连接，在执行所述目标操作时，所述信号处理电路：
    对所述目标信号进行增益放大，以及
    向所述扬声器发送所述增益放大后的信号，以驱动所述扬声器发声。
PCT/CN2023/096286 2023-05-25 2023-05-25 声学系统 Ceased WO2024239318A1 (zh)

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