A sound source identification method and system based on a nonlinear harmonic PCD phase conjugation method

Abstract

This invention discloses a sound source identification method and system based on the nonlinear harmonic phase conjugation method (PCD). The method involves acquiring the sound pressure gradient time-domain signal of the target sound source using a pre-constructed planar microphone array. After performing a fast Fourier transform on the sound pressure gradient time-domain signal to obtain the sound pressure gradient frequency-domain signal, a sound pressure gradient frequency-domain signal that meets the resolution requirements for reconstructing the sound field is selected as the higher harmonic sound pressure gradient signal. The sound field of the target sound source is reconstructed by establishing the phase conjugation method and the higher harmonic sound pressure gradient signal using dipole source emission based on the sound pressure gradient time-domain signal. This allows personnel to identify the target sound source through the reconstructed sound field. This method improves the resolution of sound field reconstruction by using the nonlinear harmonic phase conjugation method for sound source identification and is not limited by the near-field limitation of evanescent waves.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sound field reconstruction technology, and particularly relates to a sound source identification method and system based on a nonlinear harmonic PCD phase conjugation method. BACKGROUND

[0002] Sound source identification is of great significance in noise control and acoustic fault diagnosis. The commonly used sound source identification methods include beamforming, near-field acoustic holography and time reversal / phase conjugation methods.

[0003] The effectiveness of the above methods has been verified in the research and application of sound source identification, and they are widely used in various engineering fields and are currently the more mature methods in sound source identification. However, they still have some problems: the beamforming method is greatly affected by the array aperture, and when it is used to identify low-frequency sound sources, a large-aperture microphone array is often needed, which is not realistic in terms of economy and practicability, that is, the beamforming method is only suitable for the identification of medium and high frequency sound sources; the near-field acoustic holography method requires array measurement at a near-field position, i.e., the distance d between the holographic surface and the source surface is less than λ (λ is the wavelength), and its sound field reconstruction resolution cannot break through λ / 2, and the method is only suitable for the identification of medium and low frequency sound sources; the traditional time reversal / phase conjugation method can only break through the diffraction limit λ / 2 when using near-field sound pressure gradient measurement and using a dipole phase conjugation (PCD) method or when the sound source information is known and a sound sink opposite to the sound source is introduced at the sound source position, which is obviously a great limitation in actual sound source identification. SUMMARY

[0004] The present application provides a sound source identification method and system based on a nonlinear harmonic PCD phase conjugation method, which identifies sound sources by using a nonlinear harmonic phase conjugation method, improves the resolution of sound field reconstruction, and is not limited by the near field of evanescent waves.

[0005] A first aspect of the embodiment of the present application provides a sound source identification method based on a nonlinear harmonic PCD phase conjugation method, which comprises:

[0006] Obtaining a sound pressure gradient time domain signal, wherein the sound pressure gradient time domain signal is obtained by collecting a target sound source using a constructed planar microphone array;

[0007] The sound pressure gradient time domain signal is subjected to fast Fourier transform to obtain a sound pressure gradient frequency domain signal, and the sound pressure gradient frequency domain signal meeting the requirement of sound field reconstruction resolution is selected as the high-order harmonic sound pressure gradient signal;

[0008] The phase conjugation method and the high-order harmonic sound pressure gradient signal are used for sound field reconstruction of the target sound source, so that the target sound source can be identified by a person through the reconstructed sound source sound field.

[0009] In the embodiment, the sound pressure gradient time domain signal is obtained by collecting the target sound source by using the constructed planar microphone array, the sound pressure gradient time domain signal is subjected to fast Fourier transform to obtain a sound pressure gradient frequency domain signal, the sound pressure gradient frequency domain signal meeting the requirement of sound field reconstruction resolution is selected as the high-order harmonic sound pressure gradient signal, the phase conjugation method is obtained by using dipole source emission according to the sound pressure gradient time domain signal, and the high-order harmonic sound pressure gradient signal is used for sound field reconstruction of the target sound source, so that the target sound source can be identified by a person through the reconstructed sound source sound field. The sound source is identified by using the nonlinear harmonic phase conjugation method, the resolution of the sound field reconstruction is improved, and the near field limitation of the evanescent wave is avoided.

[0010] In a possible implementation of the first aspect, when the target sound source is collected by using the constructed planar microphone array, the spatial sampling wave number is greater than a preset multiple of the highest wave number in the sound field.

[0011] In a possible implementation of the first aspect, the sound pressure gradient time domain signal is obtained by collecting the target sound source by using the constructed planar microphone array, and specifically:

[0012] The first radiation sound pressure autospectrum value of the target sound source at the microphone in a preset time period is measured by using the planar microphone array;

[0013] After the planar microphone array is moved by a preset distance in a preset direction, the second radiation sound pressure autospectrum value of the target sound source at the microphone in a preset time period is measured;

[0014] The sound pressure gradient is obtained according to the second radiation sound pressure autospectrum value and the first radiation sound pressure autospectrum value in the preset time period, and the sound pressure gradient is subjected to variable conversion to obtain the sound pressure gradient time domain signal.

[0015] In a possible implementation of the first aspect, the phase conjugation method is obtained by using dipole source emission according to the sound pressure gradient time domain signal, and specifically:

[0016] The Helmholtz-Kirchhoff integral formula is used to calculate a sound pressure gradient time domain signal to obtain a first phase conjugate sound field of the sound pressure gradient time domain signal, wherein the first phase conjugate sound field is:

[0017]

[0018] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R = |r-r'|, and n is a normal unit vector;

[0019] According to the first phase conjugate sound field, a phase conjugate sound field of a finite discrete array of a plurality of plane microphone arrays is calculated to obtain a second phase conjugate sound field, wherein the second phase conjugate sound field is:

[0020]

[0021] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R = |r-r'|, and n is a normal unit vector;

[0022] According to the second phase conjugate sound field, a dipole source is used to time reverse the sound pressure gradient time domain signal to obtain a final phase conjugate sound field of the sound pressure gradient time domain signal, wherein the final phase conjugate sound field is:

[0023]

[0024] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function.

[0025] In a possible implementation manner of the first aspect, a phase conjugate method and a high-order harmonic sound pressure gradient signal are used to reconstruct a sound field of a target sound source, specifically:

[0026] According to the high-order harmonic sound pressure gradient signal, a high-order harmonic sound pressure gradient value is obtained, wherein the high-order harmonic sound pressure gradient is:

[0027]

[0028] wherein r s is a source point position, r is a field point position, and n is a normal unit vector;

[0029] The high-order harmonic sound pressure gradient value is substituted into the final phase conjugate sound field to obtain a sound field amplitude of the target sound source, and the sound field reconstruction is completed according to the sound field amplitude.

[0030] The second aspect of the embodiment of the present application provides a sound source identification system based on a nonlinear harmonic PCD phase conjugation method, the system comprising:

[0031] An acquisition module is configured to acquire a sound pressure gradient time domain signal, wherein the sound pressure gradient time domain signal is obtained by collecting the target sound source using the constructed planar microphone array;

[0032] A transformation module is configured to perform fast Fourier transform on the sound pressure gradient time domain signal to obtain a sound pressure gradient frequency domain signal, and select the sound pressure gradient frequency domain signal meeting the requirement of the resolution of the reconstructed sound field as a high-order harmonic sound pressure gradient signal;

[0033] A reconstruction module is configured to use a phase conjugation method and the high-order harmonic sound pressure gradient signal to reconstruct the sound field of the target sound source, so that the target sound source can be identified by a person through the reconstructed sound field of the sound source, wherein the phase conjugation method is obtained by using a dipole source emission according to the sound pressure gradient time domain signal.

[0034] In a possible implementation manner of the second aspect, the acquisition module comprises a first acquisition unit, a second acquisition unit and a calculation unit,

[0035] The first acquisition unit is configured to measure a first radiated sound pressure autospectrum value of the target sound source at the microphone in a preset time period using the planar microphone array;

[0036] The second acquisition unit is configured to measure a second radiated sound pressure autospectrum value of the target sound source at the microphone in the preset time period after moving the planar microphone array measurement to a preset direction by a preset distance;

[0037] The calculation unit is configured to obtain the sound pressure gradient according to the second radiated sound pressure autospectrum value and the first radiated sound pressure autospectrum value in the preset time period, and perform variable conversion on the sound pressure gradient to obtain the sound pressure gradient time domain signal.

[0038] In a possible implementation manner of the second aspect, the reconstruction module comprises a first calculation unit, a second calculation unit and a third calculation unit,

[0039] The first calculation unit is configured to calculate the sound pressure gradient time domain signal using a Helmholtz-Kirchhoff integral formula to obtain a first phase conjugate sound field of the sound pressure gradient time domain signal, wherein the first phase conjugate sound field is:

[0040]

[0041] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R = |r―r'|, and n is a normal unit vector.

[0042] The second calculation unit is configured to calculate a phase conjugate sound field of a finite discrete array of a plurality of planar microphone arrays according to the first phase conjugate sound field, to obtain a second phase conjugate sound field, wherein the second phase conjugate sound field is:

[0043]

[0044] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R = |r-r'|, and n is a normal unit vector;

[0045] The third calculation unit is configured to use a dipole source to time-reverse a sound pressure gradient time-domain signal according to the second phase conjugate sound field, to obtain a final phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the final phase conjugate sound field is:

[0046]

[0047] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function.

[0048] To solve the same technical problem, an embodiment of the present application further provides a terminal device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the sound source identification method based on the nonlinear harmonic PCD phase conjugation method shown in the embodiment of the present application when executing the program.

[0049] To solve the same technical problem, an embodiment of the present application further provides a computer readable storage medium, which stores a computer executable program, and the computer executable program is used to make a computer execute the steps of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method shown in the embodiment of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 a flowchart of an embodiment of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application;

[0051] Figure 2 a sound source sound field reconstruction flowchart of an embodiment of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application;

[0052] Figure 3The simulation model schematic diagram of the nonlinear propagation of the sound source in the air according to the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 1.

[0053] Figure 4 The schematic diagram of the sound field reconstruction result of the field point 0-2λ0 (x=y=0) when the array center is 0.1λ away from the sound source according to the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 2.

[0054] Figure 5 The schematic diagram of the sound field reconstruction result of the field point 0-2λ0 (x=y=0) when the array center is 0.2λ away from the sound source according to the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 3.

[0055] Figure 6 The schematic diagram of the sound field reconstruction result of the field point 0-2λ0 (x=y=0) when the array center is 2λ away from the sound source according to the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 4.

[0056] Figure 7 The schematic diagram of the system structure of another embodiment of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 5. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0058] Embodiment one

[0059] Please refer to Figure 1 , Figure 1 The schematic diagram of the flow of one embodiment of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method provided by the present application is shown in FIG. 1, which includes steps S11-S13. The steps are specifically as follows.

[0060] S11, obtaining the sound pressure gradient time domain signal, wherein the sound pressure gradient time domain signal is obtained by collecting the target sound source by using the constructed planar microphone array.

[0061] In the preferred embodiment, the spatial sampling wave number when collecting the target sound source by using the constructed planar microphone array is greater than the preset multiple of the highest wave number in the sound field.

[0062] In the preferred embodiment, the sound pressure gradient time domain signal is obtained by using the constructed planar microphone array to collect the target sound source, specifically:

[0063] The first radiation sound pressure autospectrum value of the target sound source at the microphone in the preset time period is measured using the planar microphone array;

[0064] After moving the planar microphone array measurement to the preset direction by a preset distance, the second radiation sound pressure autospectrum value of the target sound source at the microphone in the preset time period is measured;

[0065] The sound pressure gradient is obtained according to the second radiation sound pressure autospectrum value and the first radiation sound pressure autospectrum value in the preset time period, and the sound pressure gradient is converted by variable to obtain the sound pressure gradient time domain signal.

[0066] In this embodiment, the planar microphone array is constructed to obtain the nonlinear sound field data of the vibration source. The planar microphone array is constructed by fixing the microphones on the prepared square plane support, and the sound pressure gradient time domain signal of each microphone of the array is obtained. The sound pressure gradient time domain signal can be expressed as: In order to avoid aliasing in the frequency domain, the spatial sampling interval of the planar microphone array should satisfy the Nyquist sampling theorem, that is, the spatial sampling wave number must be greater than 2 times the highest wave number existing in the sound field:

[0067]

[0068] In the formula, Δ is the spatial sampling interval, 2π / Δ is the spatial sampling wave number, k max = 2π / λ min ; The area size of the planar array has little effect on the conjugate sound field. Research shows that as long as the array side length a ≥ 1.4λ, that is, the array side length is greater than or equal to 1.4 times the wavelength.

[0069] It should be noted that because the sound pressure gradient time domain signal is obtained by numerical simulation, in the embodiment, only the field point sound pressure gradient corresponding to the calculation step of the above microphone construction position needs to be calculated in the field point sound pressure gradient simulation.

[0070] The point sound source sound field simulation calculation method is done under the condition of Matlab simulation. In actual application, the sound pressure and sound pressure gradient are obtained by measuring the radiation sound pressure autospectrum value p1 of the sound source at the measurement microphone using the planar microphone array. Then, the measurement array is moved forward or backward by 1 cm, and the radiation sound pressure autospectrum value p2 of the sound source at the measurement microphone is measured. In the phase conjugation algorithm, the sound pressure can be replaced by the arithmetic mean of the two measured sound pressure values, that is, p = (p1 + p2) / 2. The sound pressure gradient is: Δd = 1 cm

[0071] In the formula, p1 represents the first measured radiation sound pressure autospectrum value, and p2 represents the measured radiation sound pressure autospectrum value after the array is moved.

[0072] S12, after the sound pressure gradient time domain signal is subjected to fast Fourier transform to obtain a sound pressure gradient frequency domain signal, a sound pressure gradient frequency domain signal meeting the requirement of the resolution of the reconstructed sound field is selected as a high-order harmonic sound pressure gradient signal.

[0073] In the embodiment, the sound pressure gradient time domain signal is subjected to fast Fourier transform (FFT) to obtain a sound pressure gradient frequency domain signal and a high-order harmonic sound pressure gradient signal of a suitable order is selected according to the requirement of the resolution of the reconstructed sound field

[0074] S13, the sound field of the target sound source is reconstructed using the phase conjugation method and the high-order harmonic sound pressure gradient signal, so that the target sound source can be identified by the personnel through the reconstructed sound source sound field, wherein the phase conjugation method is established by using dipole source emission according to the sound pressure gradient time domain signal.

[0075] In the preferred embodiment, the phase conjugation method is established by using dipole source emission according to the sound pressure gradient time domain signal, specifically:

[0076] The Helmholtz-Kirchhoff integral formula is used to calculate the sound pressure gradient time domain signal to obtain a first phase conjugate sound field of the sound pressure gradient time domain signal, wherein the first phase conjugate sound field is:

[0077]

[0078] wherein r s is the source point position, r is the field point position, S' represents the array surface, is the free field Green function, R = |r-r'|, and n is a normal unit vector;

[0079] According to the first phase conjugate sound field, a phase conjugate sound field of a finite discrete array of a plurality of plane microphone arrays is calculated to obtain a second phase conjugate sound field, wherein the second phase conjugate sound field is:

[0080]

[0081] wherein r s is the source point position, r is the field point position, S' represents the array surface, is the free field Green function, R = |r-r'|, and n is a normal unit vector;

[0082] According to the second phase conjugate sound field, the sound pressure gradient time domain signal is time reversed using a dipole source to obtain a final phase conjugate sound field of the sound pressure gradient time domain signal, wherein the final phase conjugate sound field is:

[0083]

[0084] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function.

[0085] In the embodiment, the time reversal method can realize the reverse propagation and adaptive focusing of the sound wave because p(r,t) and p(r,―t) are both solutions of the wave equation, and the time reversal in the time domain is equivalent to the phase conjugation in the frequency domain, that is, p(r,t) and p(r,―t) are equivalent to p(r,ω) and p * (r,ω), wherein p * (r,ω) is the complex conjugate of p(r,ω).

[0086] Based on the above analysis, according to the Helmholtz-Kirchhoff integral formula, after the sound pressure and the sound pressure gradient are measured by the planar array, the phase conjugate sound field is:

[0087]

[0088] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R=|r―r'|, and n is a normal unit vector.

[0089] The actual array is discrete, and for a finite discrete array containing N microphone array elements, the phase conjugate sound field is:

[0090]

[0091] And based on the measured sound pressure gradient, the phase conjugate sound field using a dipole source for time reversal is:

[0092]

[0093] wherein r s is a source point position, r is a field point position, S' represents an array surface, is a free field Green function, R=|r―r'|, and n is a normal unit vector.

[0094] In the preferred embodiment, the phase conjugation method and the high-order harmonic sound pressure gradient signal are used to reconstruct the sound field of the target sound source, specifically:

[0095] According to the high-order harmonic sound pressure gradient signal, a high-order harmonic sound pressure gradient value is obtained, wherein the high-order harmonic sound pressure gradient is:

[0096]

[0097] wherein r s is a source point position, r is a field point position, and n is a normal unit vector;

[0098] The high-order harmonic sound pressure gradient value is substituted into the final phase conjugate sound field to obtain a sound field amplitude of the target sound source, and sound field reconstruction is completed according to the sound field amplitude.

[0099] In this embodiment, the high-order harmonic sound pressure gradient value is substituted into the final phase conjugate sound field calculation formula, and the high-order harmonic sound pressure gradient here is The sound source sound field is reconstructed, and the reconstruction result is a sound pressure amplitude.

[0100] In addition, the reconstruction resolution refers to the distance between the maximum wave peak point of the sound pressure of the reconstructed sound field and its adjacent trough point.

[0101] As an example of this embodiment, under the condition of Matlab simulation, a point source is used for sound source identification by using this method.

[0102] This embodiment uses a small radius r0pulsating spherical source to replace the point source to simulate the nonlinear propagation of spherical waves in air, and the nonlinear Burges equation solution of the finite amplitude cylindrical wave / spherical wave is:

[0103]

[0104] In the formula, m = 1 is a spherical wave, m = 2 is a cylindrical wave, J n (·) is a Bessel function, and σ is the shock wave formation distance, p0is the sound pressure amplitude, and p0= ρ0c0v0, τ = t-(r-r0) / c0is the relaxation time, n takes the highest order of the high-order harmonic concerned, and n = 10 in this embodiment.

[0105] The sound pressure gradient is obtained by calculating the radiation sound field of the dipole source. Specifically, according to linear acoustic theory, the sound pressure gradient of the point source is the radiation sound field of the dipole source, so this embodiment approximates the sound pressure gradient of the point source under the consideration of nonlinearity by superimposing the time domain sound fields of two small radius pulsating spherical sources with equal intensity, opposite phase and very close (distance d0).

[0106] The simulation model of the nonlinear propagation of sound generated by the point source in the air is shown in Figure 3 The specific simulation parameters are as follows:

[0107] Point source (small radius pulsating sphere source) parameters: sound source frequency f0=100 Hz, pulsating sphere source radius r0=0.01 m, normal vibration velocity of the pulsating sphere source v=v0sin(2pft), ω=2pft, t=0.0005:0.0005:1 s;

[0108] Medium parameters: the simulation calculation medium is air, density p0=1.16 kg / m 3 , nonlinear coefficient B / A=0.4, sound velocity c0=350 m / s, wavelength l0=c0 / f0=3.5 m;

[0109] Microphone array parameters: the array shape is a square, the side length is a=10 m, and it contains 121 array elements, the array element spacing is D=1 m< l0 / 2.

[0110] This embodiment uses the phase conjugation method (PCD) based on the sound pressure gradient using the dipole source emission to calculate the sound field amplitude of the fundamental frequency f0and the multiple frequency nf0(n=10) wave between the field point 0:2l0(x=y=0) (taking 101 discrete points) when the distance between the planar array and the point sound source is d=0.1l0, d=0.2l0and d=2l0.

[0111] Figure 4 The figure is the sound field reconstruction result of the field point 0:2l0(x=y=0) when the array center is 0.1l0away from the sound source, wherein Figure 4 (a) and Figure 4 (b) respectively represent the sound pressure reconstruction results of the field point using the sound pressure gradient of the fundamental frequency f=100 Hz and the sound pressure gradient of the multiple frequency f=1000 Hz. It can be seen from the figure that the sound field reconstruction resolution using the sound pressure gradient of the multiple frequency is 0.14 m and the sound field reconstruction resolution using the sound pressure gradient of the fundamental frequency is 0.8 m, which shows that the sound source recognition method based on the nonlinear harmonic phase conjugation proposed in the present application has higher resolution in the near-field sound source recognition.

[0112] Figure 5 The figure is the sound field reconstruction result of the field point 0:2l0(x=y=0) when the array center is 0.2l0away from the sound source, wherein Figure 5 (a) and Figure 5 (b) respectively represent the sound pressure reconstruction results of the field point using the sound pressure gradient of the fundamental frequency f=100 Hz and the sound pressure gradient of the multiple frequency f=1000 Hz. It can be seen from the figure that the sound field reconstruction resolution using the sound pressure gradient of the multiple frequency is 0.14 m and the sound field reconstruction resolution using the sound pressure gradient of the fundamental frequency is 2.5 m, which shows that the sound source recognition method based on the nonlinear harmonic phase conjugation proposed in the present application has higher resolution in the far-field sound source recognition.

[0113] Figure 6The sound field reconstruction result of the field point 0:2λ0(x=y=0) when the array center distance is 2λ from the sound source, wherein Figure 6 (a) and Figure 6 (b) respectively represent the sound pressure results of the field point reconstructed by using the sound pressure gradient of the fundamental frequency f=100Hz and the sound pressure gradient of the multiple frequency f=1000Hz. As can be seen from the figure, the sound field reconstruction resolution using the sound pressure gradient of the multiple frequency is 0.3m, while the sound field reconstruction using the sound pressure gradient of the fundamental frequency directly fails. The results show that the sound source recognition method based on the nonlinear harmonic phase conjugation proposed in the application can still break through the diffraction limit under the far field condition, so that the reconstructed sound field has very high resolution.

[0114] In summary, the sound source recognition method based on the nonlinear harmonic phase conjugation proposed in the application can break through the diffraction limit in the reconstructed sound field constructed under the far field and near field conditions, and has higher recognition resolution for the point source recognition in the embodiment. From the results of the embodiment, the method breaks through the near field limitation and the diffraction limit limitation existing in the existing sound source recognition method.

[0115] The application obtains the sound pressure gradient time domain signal by using the constructed planar microphone array to collect the target sound source, performs fast Fourier transform on the sound pressure gradient time domain signal to obtain the sound pressure gradient frequency domain signal, selects the sound pressure gradient frequency domain signal meeting the requirement of the resolution of the reconstructed sound field as the high-order harmonic sound pressure gradient signal, and performs sound field reconstruction of the target sound source by using the phase conjugation method and the high-order harmonic sound pressure gradient signal obtained by using the dipole source emission according to the sound pressure gradient time domain signal, so that the target sound source can be recognized by the reconstructed sound field of the sound source. The method recognizes the sound source by using the nonlinear harmonic PCD phase conjugation method, improves the resolution of the sound field reconstruction, and is not limited by the evanescent wave near field.

[0116] Embodiment two

[0117] Correspondingly, referring to Figure 7 , Figure 7 A sound source recognition system based on the nonlinear harmonic PCD phase conjugation method provided by the application, as shown in the figure, comprises:

[0118] The acquisition module 701 is configured to acquire a sound pressure gradient time domain signal, wherein the sound pressure gradient time domain signal is obtained by using a constructed planar microphone array to collect a target sound source.

[0119] The transformation module 702 is configured to perform fast Fourier transform on the sound pressure gradient time domain signal to obtain a sound pressure gradient frequency domain signal, and select a sound pressure gradient frequency domain signal meeting the requirement of the resolution of the reconstructed sound field as a high-order harmonic sound pressure gradient signal.

[0120] The reconstruction module 703 is configured to perform sound field reconstruction of the target sound source using a phase conjugation method and the high-order harmonic sound pressure gradient signal, so that the target sound source can be identified by a person through the reconstructed sound source sound field, and the phase conjugation method is established by using dipole source emission according to the sound pressure gradient time domain signal.

[0121] In the preferred embodiment, the acquisition module 701 is further configured to use the constructed planar microphone array to collect the target sound source, and the spatial sampling wave number is greater than a preset multiple of the highest wave number in the sound field.

[0122] In the preferred embodiment, the acquisition module 701 includes a first acquisition unit 7011, a second acquisition unit 7012, and a calculation unit 7013.

[0123] The first acquisition unit 7011 is configured to measure the first radiated sound pressure autospectrum value of the target sound source at the microphone in a preset time period using the planar microphone array.

[0124] The second acquisition unit 7012 is configured to measure the second radiated sound pressure autospectrum value of the target sound source at the microphone in a preset time period after moving the planar microphone array measurement to a preset direction by a preset distance.

[0125] The calculation unit 7013 is configured to obtain the sound pressure gradient according to the second radiated sound pressure autospectrum value and the first radiated sound pressure autospectrum value in the preset time period, and perform variable conversion on the sound pressure gradient to obtain the sound pressure gradient time domain signal.

[0126] In the preferred embodiment, the reconstruction module 703 includes a first calculation unit 7031, a second calculation unit 7032, and a third calculation unit 7033.

[0127] The first calculation unit 7031 is configured to calculate the sound pressure gradient time domain signal using the Helmholtz-Kirchhoff integral formula to obtain a first phase conjugate sound field of the sound pressure gradient time domain signal, and the first phase conjugate sound field is:

[0128]

[0129] wherein r s is the source point position, r is the field point position, S' represents the array surface, is the free field Green function, R = |r―r'|, and n is the normal unit vector;

[0130] The second calculation unit 7032 is configured to calculate a plurality of phase conjugate sound fields of the finite discrete array of the planar microphone array according to the first phase conjugate sound field to obtain a second phase conjugate sound field, and the second phase conjugate sound field is:

[0131]

[0132] Where, r s Let r be the source point location, r be the field point location, and S′ represent the array surface. Let R be the free field Green's function, R = |r―r′|, and n be the normal unit vector;

[0133] The third calculation unit 7033 is used to perform time reversal on the sound pressure gradient time-domain signal using a dipole source based on the second phase conjugate sound field, to obtain the final phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the final phase conjugate sound field is:

[0134]

[0135] Where, r s Let r be the source point location, r be the field point location, and S′ represent the array surface. For the free field Green's function.

[0136] In a preferred embodiment, the reconstruction module 703 is further configured to obtain the higher harmonic sound pressure gradient value based on the higher harmonic sound pressure gradient signal, wherein the higher harmonic sound pressure gradient is:

[0137]

[0138] Where, r s r is the source point position, r is the field point position, and n is the normal unit vector;

[0139] Substituting the higher harmonic sound pressure gradient values ​​into the final phase conjugate sound field yields the sound field amplitude of the target sound source, and the sound field reconstruction is completed based on the sound field amplitude.

[0140] In a preferred embodiment, the invention provides a terminal device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the sound source identification method based on the nonlinear harmonic PCD phase conjugation method as shown in Embodiment 1 of the present invention.

[0141] As a preferred embodiment, the present invention provides a computer-readable storage medium storing a computer-executable program, which is used to cause a computer to perform the steps of the sound source identification method based on the nonlinear harmonic PCD phase conjugation method as shown in Embodiment 1 of the present invention.

[0142] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0143] The sound pressure gradient time domain signal is obtained by collecting a target sound source by using the constructed planar microphone array, the sound pressure gradient time domain signal is subjected to fast Fourier transform to obtain a sound pressure gradient frequency domain signal, the sound pressure gradient frequency domain signal meeting the requirements of the sound field resolution is selected as a high-order harmonic sound pressure gradient signal, the phase conjugation method is established by using a dipole source emission according to the sound pressure gradient time domain signal, the target sound source is reconstructed by using the high-order harmonic sound pressure gradient signal, so that the target sound source can be identified by the reconstructed sound source sound field, the sound source is identified by using the nonlinear harmonic PCD phase conjugation method, the resolution of the sound field reconstruction is improved, and the near field limitation of the evanescent wave is avoided.

[0144] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.

Claims

1. A sound source identification method based on the nonlinear harmonic PCD phase conjugation method, characterized in that, include: Acquire the sound pressure gradient time-domain signal, wherein the sound pressure gradient time-domain signal is obtained by acquiring the target sound source using a pre-constructed planar microphone array; After performing a fast Fourier transform on the sound pressure gradient time-domain signal to obtain the sound pressure gradient frequency-domain signal, the sound pressure gradient frequency-domain signal that meets the requirements of the reconstructed sound field resolution is selected as the higher harmonic sound pressure gradient signal. The sound field of the target sound source is reconstructed using the phase conjugation method and the higher harmonic sound pressure gradient signal, so that personnel can identify the target sound source through the reconstructed sound field. The phase conjugation method is established by using dipole source emission based on the sound pressure gradient time-domain signal.

2. The sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in claim 1, characterized in that, When using the constructed planar microphone array to collect data from the target sound source, the spatial sampling wavenumber is greater than a preset multiple of the highest wavenumber in the sound field.

3. The sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in claim 1, characterized in that, The sound pressure gradient time-domain signal is obtained by acquiring the target sound source using a pre-constructed planar microphone array, specifically: The first radiated sound pressure spectrum value of the target sound source at the microphone is measured using a planar microphone array during a preset time period. After moving the planar microphone array a preset distance in a preset direction, the second radiated sound pressure spectrum value of the target sound source at the microphone is measured during a preset time period. The sound pressure gradient is obtained based on the second radiated sound pressure autospectral value and the first radiated sound pressure autospectral value within the preset time period, and the sound pressure gradient is transformed to obtain the sound pressure gradient time domain signal.

4. The sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in claim 1, characterized in that, The phase conjugation method is established by using dipole source emission based on the sound pressure gradient time-domain signal, specifically as follows: The sound pressure gradient time-domain signal is calculated using the Helmholtz-Kirchhoff integral formula to obtain the first phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the first phase conjugate sound field is: in, For the source point location, For the location of the venue, Indicates the array surface. For the free field Green's function, , It is the normal unit vector; Based on the first phase conjugate sound field, the phase conjugate sound field of a finite discrete array of multiple planar microphone arrays is calculated, resulting in a second phase conjugate sound field, wherein the second phase conjugate sound field is: in, For the source point location, For the location of the venue, This represents the array surface of the nth planar microphone array. For the free field Green's function, , It is the normal unit vector; Based on the second phase conjugate sound field, the sound pressure gradient time-domain signal is time-reversed using a dipole source to obtain the final phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the final phase conjugate sound field is: in, For the source point location, For the location of the venue, This represents the array surface of the nth planar microphone array. For the free field Green's function, , It is the normal unit vector.

5. The sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in claim 1, characterized in that, The process of reconstructing the sound field of the target sound source using the phase conjugation method and the higher harmonic sound pressure gradient signal specifically involves: Based on the higher harmonic sound pressure gradient signal, the higher harmonic sound pressure gradient value is obtained, wherein the higher harmonic sound pressure gradient is: in, For the source point location, For the location of the venue, It is the normal unit vector; Substituting the higher harmonic sound pressure gradient value into the final phase conjugate sound field, the sound field amplitude of the target sound source is obtained, and the sound field reconstruction is completed based on the sound field amplitude.

6. A sound source identification system based on the nonlinear harmonic PCD phase conjugate method, characterized in that, include: The acquisition module is used to acquire the sound pressure gradient time-domain signal, wherein the sound pressure gradient time-domain signal is obtained by acquiring the target sound source using a pre-constructed planar microphone array; The transformation module is used to perform a fast Fourier transform on the sound pressure gradient time domain signal to obtain the sound pressure gradient frequency domain signal, and then select the sound pressure gradient frequency domain signal that meets the requirements of the reconstructed sound field resolution as the higher harmonic sound pressure gradient signal. The reconstruction module is used to reconstruct the sound field of the target sound source using a phase conjugation method and the higher harmonic sound pressure gradient signal, so that personnel can identify the target sound source through the reconstructed sound source sound field. The phase conjugation method is established by using dipole source emission based on the sound pressure gradient time-domain signal.

7. The sound source identification system based on the nonlinear harmonic PCD phase conjugate method as described in claim 6, characterized in that, The acquisition module includes a first acquisition unit, a second acquisition unit, and a calculation unit. The first acquisition unit is used to measure the first radiated sound pressure self-spectrum value of the target sound source at the microphone during a preset time period using a planar microphone array; The second acquisition unit is used to move the planar microphone array measurement a preset distance in a preset direction and then measure the second radiated sound pressure spectrum value of the target sound source at the microphone during a preset time period. The calculation unit is used to obtain the sound pressure gradient based on the second radiated sound pressure autospectral value and the first radiated sound pressure autospectral value within the preset time period, and to perform variable transformation on the sound pressure gradient to obtain the sound pressure gradient time domain signal.

8. The sound source identification system based on the nonlinear harmonic PCD phase conjugate method as described in claim 6, characterized in that, The reconstruction module includes a first computing unit, a second computing unit, and a third computing unit. The first calculation unit is used to calculate the sound pressure gradient time-domain signal using the Helmholtz-Kirchhoff integral formula to obtain the first phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the first phase conjugate sound field is: in, For the source point location, For the location of the venue, Indicates the array surface. For the free field Green's function, , It is the normal unit vector; The second calculation unit is used to calculate the phase conjugate sound field of a finite discrete array of multiple planar microphone arrays based on the first phase conjugate sound field, and to obtain the second phase conjugate sound field, wherein the second phase conjugate sound field is: in, For the source point location, For the location of the venue, This represents the array surface of the nth planar microphone array. For the free field Green's function, , It is the normal unit vector; The third calculation unit is used to perform time reversal on the sound pressure gradient time-domain signal using a dipole source based on the second phase conjugate sound field, to obtain the final phase conjugate sound field of the sound pressure gradient time-domain signal, wherein the final phase conjugate sound field is: in, For the source point location, For the location of the venue, This represents the array surface of the nth planar microphone array. For the free field Green's function, , It is the normal unit vector.

9. A terminal device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in any one of claims 1 to 5 when executing the computer program.

10. A storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the sound source identification method based on the nonlinear harmonic PCD phase conjugate method as described in any one of claims 1 to 5.

Images