Sound field construction system and method with vortex sound beam super-radiation low frequency enhancement function

Abstract

The present application relates to a kind of sound field construction system and method with vortex acoustic beam super-radiation low frequency enhancement function, belong to sound field construction technical field.Sound field construction system includes the microphone matrix, microphone preamplifier, sound card, power amplifier and loudspeaker matrix connected in turn, and the computer connected with sound card.The system also includes vortex acoustic beam super-radiation amplification system consisting of motor, microphone circular array and impeller type sound absorber.Through microphone matrix, the sound pressure spectrum of environmental sound field is collected, as sound field construction target, and sound is emitted through loudspeaker matrix to reproduce target sound field;While monitoring loudspeaker construction sound field, through adjusting loudspeaker input signal, reduce its 1 / 3 octaves spectrum error with target sound field.The present application can be constructed vortex acoustic beam to realize super-radiation low frequency amplification function by least square equalization feedback method, without using loudspeaker circular array and subwoofer, reduce the size of loudspeaker array, while reducing the cost of loudspeaker.

Description

Technical Field

[0001] This invention belongs to the field of sound field construction technology, and relates to a sound field construction system and method with vortex sound beam super-radiation low-frequency enhancement function. Background Technology

[0002] The sound insulation performance of an aircraft directly affects the comfort of its passengers, and excessive cabin noise can even harm their health. Therefore, sound insulation performance tests are conducted during aircraft design. Generally, sound insulation performance tests simulate the ambient noise of aircraft operation using speaker arrays. However, existing speaker arrays have weak low-frequency sound power, resulting in low sound pressure levels in the ambient sound field. To obtain a sound field with higher low-frequency power, low-frequency speakers such as subwoofers are needed. These speakers are not only expensive but also large, making them unsuitable for building a sound field system. If the principle of vortex beam superradiation can be applied to improve the low-frequency sound power of speaker arrays, it holds promise for use in acoustic fatigue testing of ambient sound field sound pressure levels often exceeding 135 dB.

[0003] To enable the sound field construction system to have superradiative low-frequency amplification capabilities, a multi-channel sound source system must first be used to construct an incident vortex sound beam carrying OAM (Optical Amplification), that is, to generate a beam with a phase relationship of... The sound field, where i is the imaginary unit and l is the topological series of the vortex beam. For phase. The traditional method is to use N s A circular loudspeaker array composed of equally spaced sound sources ensures that each loudspeaker has a relative frequency to the previous sound source. The phase delay is used to generate a vortex sound beam by a speaker array that emits sound according to this phase relationship. Then, a motor drives the sound absorber to rotate, applying the superradiative amplification principle of the vortex sound beam to improve the low-frequency sound power of the speaker. However, speaker arrays constructed in this way require a fixed structure, and the accuracy of the emitted sound beam depends on the manufacturing precision, installation, and dimensional accuracy of the speaker. The sound beam cannot be improved through feedback control. In addition, the size of the speaker array is often very large, for example, requiring 32 speakers to form a circular array, resulting in a poor user experience in practical applications.

[0004] Therefore, to address the above problems, there is a need for a sound field construction system and method that is not limited to circular loudspeaker arrays to achieve super-radiative amplification of vortex sound beams. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a sound field construction system and method with vortex sound beam superradiation low frequency enhancement function, which generates vortex sound beam by least square equalization feedback method, without the need for circular loudspeaker array, reducing the structural size of loudspeaker array, and using superradiation amplification to enhance its low frequency sound power.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] Option 1: A sound field construction system with vortex beam super-radiation low-frequency enhancement function, comprising a microphone matrix, a microphone preamplifier, a sound card, a power amplifier, and a speaker matrix connected in sequence, and a computer connected to the sound card. The microphone matrix is ​​used to collect the sound pressure spectrum of the ambient sound field as the target for sound field construction; the computer is used to control the input and output signals of the sound card; and the speaker matrix is ​​used to generate the target sound field. The microphone matrix is ​​a rectangular array composed of multiple microphones; the speaker matrix is ​​a rectangular array composed of multiple speakers.

[0008] The system also includes a vortex beam superradiative amplification system, comprising a motor, a circular array of microphones, and an impeller-type sound absorber. The motor drives the impeller-type sound absorber to rotate; the circular array of microphones is used to monitor the target sound pressure and phase of the vortex beam during vortex beam superradiative amplification; and the impeller-type sound absorber is used to enhance the low-frequency sound power of the loudspeaker matrix.

[0009] Optionally, the sound card is a multi-channel input / output sound card.

[0010] Option 2: A sound field construction method with low-frequency sound enhancement function for the sound field construction system, comprising the following steps:

[0011] S1. Acquire the sound pressure spectrum of the ambient sound field through a microphone matrix, and use it as the target for sound field construction;

[0012] S2. The computer-controlled sound card outputs signals to the speaker matrix, driving the speaker matrix to produce sound and create a sound field.

[0013] S3. Use the least squares equalization feedback method to control the input signal of the loudspeaker matrix until the 1 / 3 octave band spectral error between the constructed sound field and the target sound field is less than the set value. At this time, the optimal input signal of the loudspeaker matrix is ​​obtained.

[0014] S4. The loudspeaker matrix emits sound based on the input signal obtained in step S3. The sound pressure level of the sound field generated by the loudspeaker matrix is ​​monitored by the microphone matrix. If the sound pressure level is at a low-frequency center frequency f in a certain 1 / 3 octave band spectrum... m When the sound pressure level at a certain location is lower than that of the target sound field, the least squares equalization feedback method is used to generate a vortex sound beam. The principle of superradiative amplification of the vortex sound beam is used to increase the low-frequency sound power of the loudspeaker, thereby increasing the sound pressure level.

[0015] S5. Drive the speaker matrix to produce sound based on the obtained optimal input signal and enhance the low-frequency sound power of the speaker matrix in the manner described in S4 to reproduce the target sound field.

[0016] Furthermore, in step S3, the least squares equalization feedback method specifically involves: [The text abruptly shifts to a different topic] ...the target sound field P acquired by the microphone matrix... t Input equalizer filter In the process, the time-domain and frequency-domain output signals of the sound card are obtained as S and s, respectively. Signal s is output from the DAC terminal of the sound card to the power amplifier to drive the speaker matrix to generate and construct the sound field P. r ; will construct sound field P r With the target sound field P t The difference is used to obtain the error vector. Error vector The target sound field is corrected in the input feedback equalizer (EQ) to obtain the sound field. And then fed back into the equalization filter In the middle, the optimal input signal for the speaker matrix is ​​obtained through cyclic feedback control.

[0017] Furthermore, in step S4, the sound pressure level of the sound field constructed by the loudspeaker matrix is ​​monitored through the microphone matrix. If the low-frequency center frequency f of a certain 1 / 3 octave band spectrum is... m When the sound pressure level at a certain location is lower than the target sound field, first keep all speakers operating at the low-frequency point f. m The input signal at frequencies other than f remains unchanged, and then the frequency of some loudspeakers is adjusted based on the least squares equalization feedback method. m The input signal is used to generate a vortex sound beam, and while keeping the input signal of this part of the loudspeakers constant, the impeller-type sound absorber is driven to rotate to activate the super-radiative amplification function, thereby increasing the low-frequency sound power of the loudspeakers; in addition, the input signals of the remaining loudspeakers are adjusted until the constructed sound field is within f m The sound pressure level at that location reaches the target sound field.

[0018] Furthermore, when generating a vortex sound beam through a loudspeaker, using a circular array of microphones as the monitoring point for the vortex sound beam, the target sound pressure and phase of the vortex sound beam generated by the loudspeaker at the monitoring point have the following characteristics:

[0019]

[0020] In the formula, N r ′ represents the total number of microphones in the circular microphone array, and n represents 0 to N. r The microphone serial number is ′-1, P t ′ represents the ideal value of the vortex sound beam at the monitoring point, and P0 represents the arbitrary single-frequency sound pressure amplitude that the loudspeaker matrix can achieve after emitting sound.

[0021] The steps for constructing a vortex acoustic beam using the least squares equalization feedback method are as follows:

[0022] 1) The ideal vortex sound beam P t Input equalizer filter The frequency domain and time domain output signals S′ and s′ of the sound card are obtained as follows:

[0023]

[0024] s′=iFFT(S′)

[0025] Where iFFT represents the inverse Fourier transform function;

[0026] 2) The sound field P is generated by driving this part of the loudspeaker with the time-domain signal s′. r ′;

[0027] 3) The sound field P r The sound pressure level in decibels and phase at each monitoring point minus P t The value of ′ is used to obtain a vector containing sound pressure error and phase error.

[0028] 4) Convert the error vector Introducing a feedback equalizer (EQ) to the sound field P t After making corrections, we get And input the equalization filter again. Perform cyclic feedback control until the error (especially phase error) of the vortex beam constructed by this part of the loudspeaker is reduced to a minimum.

[0029] The beneficial effects of this invention are as follows: This invention enables the loudspeaker matrix to generate vortex sound beams through the least squares equalization feedback method, eliminating the need for traditional circular loudspeaker arrays and making the loudspeaker array structure more flexible; at the same time, this invention also enhances the low-frequency sound power of the loudspeaker through the super-radiative amplification principle, which not only achieves miniaturization in the structural size of the loudspeaker matrix, but also allows the use of ordinary loudspeakers to obtain a low-frequency sound field with high sound power, saving the expensive cost of loudspeakers.

[0030] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is a schematic diagram of the super-radiation amplification system.

[0033] Figure 2 Hardware connection diagram for building a sound field system;

[0034] Figure 3 This is a schematic diagram of the least squares equilibrium feedback method.

[0035] Figure 4 It is an impeller-type sound absorber;

[0036] Figure 5 This represents the relationship between the power amplification factor of the vortex sound beam and the rotational frequency of the impeller-type sound absorber. Detailed Implementation

[0037] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0038] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0039] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0040] like Figure 2The image shows a sound field construction system with vortex beam super-radiation low-frequency enhancement function. The system includes a microphone matrix, microphone preamplifiers, a sound card, a power amplifier, and a speaker matrix, as well as a computer connected to the sound card. The microphone matrix contains slightly more microphones than the speaker matrix. The microphone matrix collects the sound pressure spectrum of an environmental sound field as the target for sound field construction, which is then reproduced in an experimental chamber. The sound field signal collected by the microphone matrix is ​​input to the computer through the ADC terminal of the multi-channel input / output sound card. The computer then controls the sound card to drive the speaker matrix to emit sound through its DAC terminal. Simultaneously, a vortex beam super-radiation amplification system is set at the sound emission point of the speaker matrix, such as... Figure 1 As shown, the system includes an impeller-type sound absorber, a motor, and a circular array of microphones. The impeller-type sound absorber is located at the sound outlet of the loudspeaker matrix, and the circular array of microphones is attached behind the impeller-type sound absorber as a monitoring point for the vortex sound beam. The motor is used to drive the impeller-type sound absorber to rotate, thereby achieving super-radiative amplification and increasing the low-frequency sound power of the loudspeaker matrix.

[0041] The target sound pressure and phase characteristics of an ideal vortex acoustic beam at each monitoring point are as follows:

[0042]

[0043] In the formula, N r ′ represents the total number of microphones in the circular microphone array, and n represents 0 to N. r The microphone serial number is ′-1, P t ′ represents the ideal vortex sound beam at the monitoring point, and P0 represents the arbitrary single-frequency sound pressure amplitude that can be achieved after the loudspeaker matrix emits sound.

[0044] The method for constructing a sound field according to the present invention is as follows:

[0045] S1. Acquire the sound pressure spectrum of the ambient sound field through a microphone matrix, and use it as the target for sound field construction;

[0046] S2. The computer-controlled sound card outputs signals to the speaker matrix, driving the speaker matrix to produce sound and construct a sound field.

[0047] S3. The constructed sound field is monitored by the microphone matrix, and the input signal of the loudspeaker matrix is ​​controlled by the least square equalization feedback method until the 1 / 3 octave band spectrum error between the constructed sound field and the target sound field is less than the set value. At this time, the optimal input signal of the loudspeaker matrix is ​​obtained.

[0048] S4. The loudspeaker matrix emits sound based on the input signal obtained in step S3. The sound pressure level of the sound field generated by the loudspeaker matrix is ​​monitored by the microphone matrix. If the sound pressure level is at a low-frequency center frequency f in a certain 1 / 3 octave band spectrum... mWhen the sound pressure level at a certain location is lower than that of the target sound field, the least squares equalization feedback method is used to generate a vortex sound beam. The principle of superradiative amplification of the vortex sound beam is used to increase the low-frequency sound power of the loudspeaker, thereby increasing the sound pressure level.

[0049] S5. Drive the speaker matrix to produce sound according to the optimal input signal, and increase the low-frequency sound power of the speaker matrix through step S4 to reproduce the target sound field.

[0050] The least squares equilibrium feedback method is as follows: Figure 3 As shown, the details are as follows:

[0051] In the initial stage, the feedback equalizer (EQ) is not working, and the target sound field P acquired by the microphone matrix is... t Direct input to the equalizer filter added before the sound card (by N) s ×N r The complex matrix representation of N, where N s N represents the total number of speakers in the speaker matrix. r (representing the total number of microphones in the microphone matrix), the frequency domain and time domain output signals S and s of the sound card are obtained as follows:

[0052]

[0053] s = iFFT(S)

[0054] Where iFFT represents the inverse Fourier transform function. The signal s is output to a power amplifier to drive the speaker matrix to generate the sound field P. r .

[0055] Figure 3 In this context, G represents the entire physical transmission path consisting of the sound card output, power amplifier, speakers, and environment. To make the constructed sound field approximate the target sound field P... t ,but The equilibrium system composed of G and We should try our best to meet the following requirements:

[0056]

[0057] In the formula, I is the identity matrix, Δ is the delay of the hardware system, and ω is the angular frequency. Therefore The ideal value of is the inverse matrix of G, but the sound card output signal S obtained from the inverse matrix may exceed the dynamic range of the sound card itself. Therefore, the least squares method is used, and the Tikhonov regularization parameter λ is introduced to calculate S as follows:

[0058]

[0059] The solution to the above equation is:

[0060]

[0061]

[0062] In the formula, the superscript H denotes the transpose of the matrix. For N r ×N s The complex matrix represents the measured value of G. Its elements are the frequency response functions between each microphone and loudspeaker in the microphone matrix and loudspeaker matrix, which can be measured by the logarithmic sine sweep method.

[0063] The constructed sound field P r With the target sound field P t The difference is used to obtain the error vector. Error Introduced into the equalizer (EQ) for the sound field P t After making corrections, the result is Entered again Perform cyclic feedback control until the spectral error of the constructed sound field and the target sound field is less than 1 / 3 octave band less than the set value.

[0064] Specifically, since the loudspeaker used in this invention is a common loudspeaker, its low-frequency sound power is relatively small, which may result in the sound pressure level at the low-frequency point not reaching the target sound field. Therefore, this invention monitors the sound pressure level of the sound field generated by the loudspeaker matrix through a microphone matrix (at this time, the loudspeaker matrix emits sound according to the input signal obtained in step S3). If it is repeatedly adjusted by the least squares equalization feedback method, the low-frequency center frequency f at a certain 1 / 3 octave band spectrum is achieved. m When the sound pressure level at f is still lower than that of the target sound field (where, when f m When the frequency is ≤250Hz (all frequencies are low), the least squares equalization feedback method is used to generate a vortex sound beam. The principle of superradiative amplification of the vortex sound beam is used to increase the low-frequency sound power of the loudspeaker, thereby increasing the sound pressure level.

[0065] First, keep all speakers at the low frequency point f. m The input signal at frequencies other than f remains unchanged, and then the frequency of some loudspeakers is adjusted based on the least squares equalization feedback method. m The input signal is used to generate a vortex sound beam, and while keeping the input signal of this part of the loudspeakers constant, the impeller-type sound absorber is driven to rotate, activating the super-radiative amplification function to enhance the low-frequency sound power of the loudspeakers. Similarly, the input signal of the remaining loudspeakers is adjusted in the same way at f... m The input signal, until the sound field constructed by the speaker matrix is ​​at f m The sound pressure level at that location reaches the set value. This method can overcome the performance limitations of the speaker itself and achieve higher low-frequency sound power.

[0066] The process of constructing a vortex sound beam is as follows:

[0067] The feedback equalizer (EQ) is not working in the initial stage, thus preventing the ideal vortex sound beam P from being activated. t The input is directly added to the equalizer filter before the sound card. (by N) s ′×N r The complex matrix representation of ′, where N s ′ represents the number of speakers, N r ' represents the total number of microphones in the circular microphone array), and the frequency domain and time domain output signals S' and s' of the sound card are obtained as follows:

[0068]

[0069] s′=iFFT(S′)

[0070] Here, iFFT represents the inverse Fourier transform function. The output s′ is fed to a power amplifier to drive this part of the loudspeaker to generate the sound field P. r ′.

[0071] In order to make the constructed sound field approximate the sound field P t ',but The equilibrium system composed of G and G′ We should try our best to meet the following requirements:

[0072]

[0073] The ideal value is the inverse matrix of G′. However, the sound card output signal S′ obtained from the inverse matrix may exceed the dynamic range of the sound card itself. Therefore, the least squares method is used, and the Tikhonov regularization parameter λ′ is introduced to calculate S′ as follows:

[0074]

[0075] The solution to the above equation is:

[0076]

[0077]

[0078] In the formula, the superscript H denotes the transpose of the matrix. For N r ′×N s The complex matrix ' represents the measured value of G', whose elements are the frequency response functions between the microphone and the loudspeaker in the circular array of microphones and the loudspeaker that emits vortex beams. It can be measured by the logarithmic sine sweep method.

[0079] The constructed sound field P r The sound pressure level in decibels and phase at each monitoring point minus P tThe value of ′ is a vector containing sound pressure error and phase error. In order to precisely control the phase relationship of the sound waves emitted by each speaker, the error... Introduced into the equalization feedback (EQ) system for P t After making corrections, the result is... Entered again This continues until the constructed vortex beam error (especially the phase error) is minimized.

[0080] Once the vortex acoustic beam is constructed, it is driven by a motor. Figure 4 The impeller-type sound absorber shown rotates, utilizing the vortex sound beam superradiance amplification principle of the impeller-type sound absorber (this superradiance amplification principle is described in the article "Experimental study of acoustic superradiance from a rotating absorber, Journal of Applied Physics," and will not be specifically described in this embodiment), to achieve the effect of pressing f m (The sound field frequencies that need enhancement) The speaker matrix that produces sound is enhanced in low frequencies to increase the low-frequency sound power of the speakers, and the amplification effect is as follows: Figure 5 As shown.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for constructing a sound field with low-frequency sound enhancement function, characterized in that: The method includes the following steps: S1. Acquire the sound field signal of the ambient sound field through the microphone matrix, and transmit the acquired sound field signal to the computer through the microphone preamplifier and sound card to convert it into a sound pressure spectrum as the target for sound field construction. S2. The computer-controlled sound card outputs a signal to the speaker matrix through a power amplifier, driving the speaker matrix to produce sound and construct a sound field. S3. Use the least squares equalization feedback method to control the input signal of the loudspeaker matrix until the 1 / 3 octave band spectral error between the constructed sound field and the target sound field is less than the set value. At this time, the optimal input signal of the loudspeaker matrix is ​​obtained. S4. The loudspeaker matrix emits sound based on the input signal obtained in step S3. The sound pressure level of the sound field generated by the loudspeaker matrix is ​​monitored by the microphone matrix. If the sound pressure level is at a low-frequency center frequency of a certain 1 / 3 octave band spectrum... When the sound pressure level at a certain location is lower than the target sound field, the least squares equalization feedback method is used to generate vortex sound beams, which are then used as the loudspeaker matrix at a certain frequency. The input signal at the input point is simultaneously driven by a motor to rotate an impeller-type sound absorber. This utilizes the principle of vortex beam superradiative amplification to increase the low-frequency sound power of the loudspeaker, thereby increasing the sound pressure level. During this process, a circular array of microphones monitors the vortex beam, ensuring that the sound field constructed by the loudspeaker matrix... The sound pressure level at that location reached the set value; S5. Drive the speaker matrix to emit sound according to the optimal input signal and increase the low-frequency sound power of the speaker matrix through step S4 to reproduce the target sound field.

2. The sound field construction method according to claim 1, characterized in that: The microphone matrix is ​​a rectangular array composed of multiple microphones; the loudspeaker matrix is ​​a rectangular array composed of multiple loudspeakers.

3. The sound field construction method according to claim 1, characterized in that: The sound card is a multi-channel input / output sound card.

4. The sound field construction method according to claim 1, characterized in that: In step S3, the least squares equalization feedback method specifically involves: [The text abruptly shifts to a different topic] ...the target sound field acquired by the microphone matrix... Input equalizer filter In the process, the time-domain and frequency-domain output signals of the sound card are obtained as follows: S and s ,Signal s The sound card's DAC output is sent to a power amplifier to drive the speaker matrix, generating and constructing the sound field. ; will construct a sound field With the target sound field The difference is used to obtain the error vector. , the error vector The target sound field is corrected in the input feedback equalizer (EQ) to obtain the sound field. And then fed back into the equalization filter middle; The optimal input signal for the speaker matrix is ​​obtained through cyclic feedback control.

5. The sound field construction method according to claim 1, characterized in that: Step S4 specifically involves: first keeping all speakers at the same frequency. The input signal at frequencies other than those specified remains unchanged, and then the frequency distribution of some speakers is adjusted based on the least squares equalization feedback method. The input signal is used to generate a vortex sound beam, and the input signal of this part of the loudspeaker remains unchanged, driving the impeller-type sound absorber to rotate and activate the super-radiation amplification function, thereby increasing the low-frequency sound power of the loudspeaker. Then adjust the input signals of the remaining speakers until the constructed sound field is within range. The sound pressure level at that location reaches the target sound field.

6. The sound field construction method according to claim 5, characterized in that: Using a circular array of microphones as the monitoring point for the vortex sound beam, the target sound pressure and phase of the vortex sound beam generated by the loudspeaker at the monitoring point have the following characteristics: In the formula, This represents the total number of microphones in a circular microphone array. n Represents 0~ Microphone serial number, This represents the ideal value of the vortex acoustic beam at the monitoring point. This represents the arbitrary single-frequency sound pressure level that the loudspeaker matrix can achieve after it emits sound.

7. The sound field construction method according to claim 5, characterized in that: The steps for constructing a vortex acoustic beam using the least squares equalization feedback method include: 1) Ideal vortex sound beam Input equalizer filter The frequency and time domain output signals of the sound card are obtained. and They are respectively: Where iFFT represents the inverse Fourier transform function; 2) Through time-domain signals Drive the aforementioned speakers to generate a sound field ; 3) Sound field Subtract the sound pressure decibel value and phase at each monitoring point The value of is used to obtain a vector containing sound pressure error and phase error. ; 4) Convert the error vector Introducing a feedback equalizer (EQ) Make corrections to obtain And input the equalization filter again Circular feedback control is performed until the error of the vortex sound beam constructed by the partial loudspeaker is reduced to a minimum.

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