Directional spiral microphone array and beam forming method thereof

Abstract

The invention provides a directional spiral microphone array and a beam forming method thereof, and relates to the technical field of acoustics, the microphone array comprises a plurality of directional array elements, and the directional array elements are distributed on an Archimedes spiral at equal azimuth angles. According to the directional spiral microphone array and the beam forming method thereof provided by the invention, the beam direction can be adjusted more flexibly, so that the problem that the beam direction adjusting capability of a traditional microphone array is limited is solved, the null phenomenon can be effectively avoided, the amplification effect on white noise can be reduced, the signal acquisition quality can be improved, and the signal quality can be improved. According to the microphone array, the receiving sensitivity of an expected pointing direction can be enhanced, uniform sampling in space can be ensured, and the audio signal acquisition reliability is improved, so that the audio signal acquisition quality and reliability of the microphone array can be improved under the condition that the number of array elements in the microphone array and the space distribution area are not increased; and the performance and the frequency invariant characteristic of the microphone array at high frequency can be improved.

Description

Technical Field

[0001] The present invention relates to the field of acoustic technology, and in particular to a directional spiral microphone array and a beam forming method thereof. Background Art

[0002] With the development of audio devices such as smart speakers, voice recognition systems, and teleconferencing systems, improving the quality of audio signal acquisition has become one of the key technologies. In a noisy environment, a single microphone is often difficult to accurately capture the audio signal of the target sound source. Microphone array technology can effectively enhance the audio signal of the target sound source and suppress background noise through the coordination of multiple microphones, thereby improving the quality of audio signal acquisition and has been widely used in the field of audio processing.

[0003] Traditional microphone arrays in the related technology mainly include cascade microphone arrays, linear microphone arrays based on zero-point constraint method, frequency-invariant circular microphone arrays based on Jacobi expansion method, traditional circular and concentric circle microphone arrays, and frequency-invariant concentric circle microphone arrays based on circular harmonic decomposition method.

[0004] However, the above-mentioned traditional microphone arrays have defects such as limited beam steering capability, prone to nulling problems, white noise amplification, and high equipment costs, which seriously affect the quality and reliability of the collected audio signals. Therefore, how to improve the quality and reliability of audio signal collection at high frequencies by microphone arrays without increasing the number of array elements in the microphone array and without increasing the spatial distribution area of ​​the microphone array is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present invention provides a directional spiral microphone array and a beam forming method thereof, which are used to solve the defects of the above-mentioned traditional microphone array in the prior art, such as limited beam steering capability, easy occurrence of nulling problem, white noise amplification and high equipment cost, and improve the audio signal acquisition quality and reliability of the microphone array at high frequency without increasing the number of array elements in the microphone array and without increasing the spatial distribution area of ​​the microphone array.

[0006] The invention provides a directional spiral microphone array, comprising: a plurality of directional array elements, each of which is distributed on an Archimedean spiral at an equal azimuth angle.

[0007] According to a directional spiral microphone array provided by the present invention, the number of each directional array element is determined based on the order of an ideal beam pattern, and the ideal beam pattern is used to form a beam corresponding to the directional spiral microphone array.

[0008] According to a directional spiral microphone array provided by the present invention, the number of each directional array element satisfy , represents the order of the ideal beam pattern.

[0009] The present invention also provides a beamforming method applied to any of the above-mentioned directional spiral microphone arrays, comprising: Measuring the audio signal of the target sound source by using the directional spiral microphone array; After performing circular harmonic decomposition on the steering vector of the directional spiral microphone array to obtain the original beam pattern corresponding to the directional spiral microphone array, the front of the original beam pattern is taken. , as the target beam pattern corresponding to the directional spiral microphone array, represents a positive integer greater than zero; The target beam pattern is set equal to the ideal beam pattern, and after the target beam pattern is set to be unconstrained and distorted in the desired pointing direction, the minimum norm solution of the filter coefficients is calculated based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The directional angle of the ideal beam pattern and the beam forming coefficient for controlling the beam shape are predefined, and the desired directional direction is the direction in which the center point of the directional spiral microphone array points to the target sound source; The minimum norm solution of the filter coefficients is multiplied by the steering vector of the directional spiral microphone array to obtain a beam corresponding to the directional spiral microphone array.

[0010] According to a beam forming method provided by the present invention, after obtaining the beam corresponding to the directional spiral microphone array, the method further includes: Obtaining a white noise gain evaluation index and a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array; Based on a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array, an evaluation result of the beam corresponding to the directional spiral microphone array is obtained.

[0011] According to a beam forming method provided by the present invention, after obtaining the beam corresponding to the directional spiral microphone array, the method further includes: Obtaining a white noise gain evaluation index and a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array; Based on a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array, an evaluation result of the beam corresponding to the directional spiral microphone array is obtained.

[0012] According to a beamforming method provided by the present invention, the relationship between the pointing direction of the ideal beam pattern and the beamforming coefficient satisfies: ; in, represents the maximum response direction of the beam, and the maximum response direction is the direction where the point of the corresponding maximum value on the beam diagram is located; Represents the incident direction of the audio signal of the target sound source; An expression representing the beam pattern; represents the beamforming coefficient; represents an imaginary unit; represents the sum function; Represents the parameters of the sum function, ranging from - N to N ; The directional spiral microphone array Ring The polar diameter of the directional array element The mathematical expression is as follows: ; in, represents the initial polar diameter of the directional spiral microphone array; represents the first Ring The azimuth angle of the directional array element, ; represents the rate of change of the spiral polar diameter with the polar angle in the directional spiral microphone array; The directional spiral microphone array Ring The directional pattern of the directional array elements The mathematical expression is as follows: ; in, represents the first Ring The weight factor corresponding to the directional array element is In the case of Ring The directional array elements are omnidirectional; In the case of Ring The directional array element has directivity, and the first directional array element in the directional spiral microphone array Ring The directional pattern of each directional element is determined by the weight factor Determine: In the directional spiral microphone array When the directional patterns of the directional array elements in the ring are the same, the first The weight factor of any directional array element in the ring is express.

[0013] According to a beam forming method provided by the present invention, the steering vector of the directional spiral microphone array The mathematical expression is: ; ; in, Indicates transpose calculation; represents the first Ring a directional pattern of a directional array element, wherein the directional pattern is used to define the shape of the beam pattern; represents an imaginary unit; , is the speed of sound in air, The frequency of the audio signal representing the target sound source; represents the first Ring The polar diameter of a directional array element; represents the first Ring The azimuth of the directional array element; , , represents the first The number of directional elements in the ring, represents the total number of rings in the directional spiral microphone array, and are all positive integers; The steering vector of the directional spiral microphone array The mathematical expression for circular harmonic decomposition is as follows: ; in, The quantity is of Bessel function of the first kind; express The first derivative of .

[0014] According to a beamforming method provided by the present invention, the mathematical expression of the target beam pattern corresponding to the directional spiral microphone array is as follows: ; in, represents conjugate calculation; The vector form of the filter coefficients is The mathematical representation of is as follows: ; in: ; The mathematical expression of the target beam pattern without constraint distortion in the desired pointing direction is as follows: ; in, represents the conjugate transpose calculation; Based on the target beam diagram and the ideal beam diagram, the minimum norm solution of the filter coefficients is calculated The calculation formula is as follows: ; in, ; ; ; ; ; ; .

[0015] According to a beamforming method provided by the present invention, a white noise gain evaluation index of a beam corresponding to the directional spiral microphone array is obtained. The calculation formula is as follows: ; in, Represents the conjugate transpose computation.

[0016] According to a beam forming method provided by the present invention, a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array is obtained. The calculation formula is as follows: ; in, yes The number of discrete points within the range.

[0017] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the beamforming method described above is implemented.

[0018] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the beamforming method described in any one of the above is implemented.

[0019] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the beamforming methods described above.

[0020] The present invention provides a directional spiral microphone array and a beam forming method thereof. The directional spiral microphone array includes a plurality of directional array elements distributed on an Archimedean spiral at equal azimuth angles. The beam direction can be adjusted more flexibly based on the special geometric shape and arrangement of the directional spiral microphone array, thereby solving the problem of limited beam steering capability of the traditional microphone array. By optimizing the phase relationship between the array elements and the signal processing technology, the occurrence of the nulling phenomenon can be effectively avoided, the amplification effect on white noise can be reduced, and the quality of signal acquisition can be improved. The directional array elements arranged along the Archimedean spiral can form a narrower beam width, thereby enhancing the receiving sensitivity to the desired pointing direction, helping to reduce the influence of background noise and interference signals, improving the quality of audio signal acquisition, ensuring uniform sampling in space, and improving the reliability of audio signal acquisition. Therefore, the quality and reliability of audio signal acquisition by the microphone array can be improved without increasing the number of array elements in the microphone array and the spatial distribution area of ​​the microphone array, and the performance of the microphone array at high frequencies and the frequency invariant characteristics can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the structure of the directional spiral microphone array provided by the present invention.

[0023] Figure 2 It is a flow chart of the beamforming method provided by the present invention.

[0024] Figure 3 The cardioid beam directivity diagram of the double-loop helical directional spiral microphone array provided by the present invention.

[0025] Figure 4 This is one of the graphs showing the variation of white noise gain and directivity factor of the double-loop spiral directional spiral microphone array provided by the present invention with frequency.

[0026] Figure 5 This is the second graph of the variation of white noise gain and directivity factor of the double-loop helical directional spiral microphone array with frequency provided by the present invention.

[0027] Figure 6 It is a grayscale image of the traditional concentric microphone array beam pattern changing with pointing angle and frequency.

[0028] Figure 7 The present invention provides a grayscale diagram of the double-loop helical directional spiral microphone array beam pattern changing with the directional angle and frequency.

[0029] Figure 8 It is a structural schematic diagram of the beamforming device provided by the present invention.

[0030] Fig. 9 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the description of the present application, the terms "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are usually a class, and the number of objects is not limited. For example, the first object can be one or more. In addition, in the description of the present application, "and / or" represents at least one of the connected objects, and the character " / " generally represents that the front and back associated objects are in an "or" relationship.

[0034] It should be noted that the traditional cascade microphone array uses the time difference between the sound waves reaching the adjacent microphones in the microphone array to obtain the sound pressure gradient by subtracting them, thereby forming a directional beam pattern. However, the traditional cascade microphone array has a serious white noise amplification problem, is very sensitive to the self-noise of the microphone, and has a fixed structure, making it difficult to solve the problem of the robustness of the microphone array.

[0035] The traditional linear microphone array based on the zero-point constraint method can improve the white noise gain by increasing the number of microphones in the microphone array, thereby solving the serious white noise amplification problem in the traditional cascade microphone array. However, in the traditional linear microphone array based on the zero-point constraint method, the beam steering capability is only in the end-fire direction within the plane where the microphone array is located, and only limited beam steering options can be provided.

[0036] In the traditional frequency-invariant circular microphone array based on the Jacobi expansion method, the beam can be adjusted to any azimuth within the plane where the microphone array is located. However, at certain specific frequencies, the denominator of the filter coefficient approaches infinity due to the influence of the zero value of the Bessel function, and the white noise gain and directivity factor will have a zero-sink problem, resulting in serious distortion of the beam pattern. Although the frequency-invariant circular microphone array designed based on the Jacobi expansion method can solve the zero-sink problem in most cases, it will still have a zero-sink problem in some special cases. In addition, there are many microphones in the traditional frequency-invariant circular microphone array based on the Jacobi expansion method, resulting in a high equipment cost for the traditional frequency-invariant circular microphone array based on the Jacobi expansion method.

[0037] Traditional circular and concentric microphone arrays are mostly implemented with omnidirectional microphones. The traditional frequency-invariant concentric microphone array based on the circular harmonic decomposition method uses a first-order directional microphone instead of an omnidirectional microphone, which can completely avoid the null problem. In addition, the use of a first-order directional microphone can improve the white noise amplification problem at low frequencies in traditional circular and concentric microphone arrays. When the order of the desired beam pattern is 1, the white noise amplification problem at low frequencies can be completely avoided. However, at high frequencies, the white noise gain of the traditional frequency-invariant concentric microphone array based on the circular harmonic decomposition method using a first-order directional microphone will deteriorate, and the frequency-invariant characteristic of the array cannot be maintained in the high frequency band.

[0038] Therefore, the above-mentioned traditional microphone array has defects such as limited beam steering capability, prone to nulling problems and white noise amplification, which seriously affects the quality and reliability of audio signal collection by the above-mentioned traditional microphone array. Therefore, how to improve the quality and reliability of audio signal collection by microphone array is a technical problem to be solved urgently in this field.

[0039] Combine the following Figure 1 The directional spiral microphone array provided by the present invention is described.

[0040] Figure 1 Schematic diagram of the structure of the directional spiral microphone array provided by the present invention. Figure 1 The directional spiral microphone array provided by the present invention is described. Figure 1 As shown, the directional spiral microphone array 101 includes: a plurality of directional array elements 102, and each directional array element 102 is distributed on the Archimedean spiral at an equal azimuth angle.

[0041] As an optional embodiment, the number of each directional array element 102 is determined based on the order of an ideal beam pattern, and the ideal beam pattern is used to form a beam corresponding to the directional spiral microphone array 101 .

[0042] As an optional embodiment, the number of each directional array element 102 is satisfy , Represents the order of the ideal beam pattern.

[0043] Specifically, the directional spiral microphone array 101 in the embodiment of the present invention is composed of The directional array elements 102 are distributed on the Archimedean spiral at equal azimuth angles to form a directional spiral microphone array 101 with an Archimedean spiral structure.

[0044] It should be noted that an array element refers to a single receiver or sensor that makes up an array. An array element can be an antenna, a microphone, an underwater acoustic sensor, etc., which is used to receive signals from a signal source. Each array element has its own receiving directivity and response characteristics, that is, the sensitivity and phase characteristics of the received signal. The directivity of an array refers to a characteristic in which the amplitude of its transmitted or received signal changes with the azimuth. For a transmitting array, directivity is usually manifested as an increase or decrease in the radiation intensity of sound waves or electromagnetic waves in a specific direction; for a receiving array, directivity is manifested as a difference in receiving sensitivity to waves from different directions. Directivity is the basis for realizing functions such as signal source positioning, beamforming, and interference suppression in array signal processing. The directional array element 102 in the embodiment of the present invention refers to an array element with clear directivity.

[0045] Optionally, the directional array element 102 in the embodiment of the present invention may be a differential microphone.

[0046] It should be noted that the number of directional array elements 102 in the directional spiral microphone array 101 is satisfy , the distance between any two directional array elements 102 is less than half of the minimum wavelength of the received sound wave, and the azimuth difference between any two adjacent directional array elements 102 is .

[0047] The microphone array in the embodiment of the present invention includes a plurality of directional array elements distributed on the Archimedean spiral at equal azimuth angles. The beam direction can be adjusted more flexibly based on the special geometric shape and arrangement of the microphone array, thereby solving the problem of limited beam steering capability. The phase relationship between the array elements and the signal processing technology can be optimized to effectively avoid the occurrence of the null phenomenon, reduce the amplification effect on white noise, and improve the quality of signal acquisition. The directional array elements arranged along the Archimedean spiral can form a narrower beam width, thereby enhancing the receiving sensitivity to the desired pointing direction, helping to reduce the influence of background noise and interference signals, and improving the quality of audio signal acquisition. It can ensure uniform sampling in space, thereby improving the reliability of audio signal acquisition, and further, without increasing the number of array elements in the microphone array and the spatial distribution area of ​​the microphone array, the quality and reliability of audio signal acquisition by the microphone array can be improved, and the performance of the microphone array at high frequencies and the frequency-invariant characteristics can be improved.

[0048] Figure 2 1 is a flow chart of the beamforming method provided by the present invention. The beamforming method provided by the present invention is implemented based on the directional spiral microphone array 101. Figure 2 As shown, the method comprises the following steps: Step 201 , using the directional spiral microphone array 101 to measure the audio signal of the target sound source.

[0049] Step 202: perform circular harmonic decomposition on the steering vector of the directional spiral microphone array 101 to obtain the original beam pattern corresponding to the directional spiral microphone array 101, and then take the front of the original beam pattern. , as the target beam pattern corresponding to the directional spiral microphone array 101, Represents a positive integer greater than zero.

[0050] Step 203: Make the target beam pattern equal to the ideal beam pattern, make the target beam pattern unconstrained and distorted in the desired pointing direction, and then calculate the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The order, the directional angle of the ideal beam pattern and the beamforming coefficients for controlling the beam shape are predefined, and the expected directional direction is the direction in which the center point of the directional spiral microphone array 101 points to the target sound source.

[0051] Step 204 : multiply the minimum norm solution of the filter coefficients by the steering vector of the directional spiral microphone array 101 to obtain a beam corresponding to the directional spiral microphone array 101 .

[0052] It should be noted that the embodiment of the present invention is performed by a beamforming device. The beamforming device may be configured in an electronic device such as a computer or a server.

[0053] As an optional embodiment, the relationship between the pointing direction of the ideal beam pattern and the beamforming coefficient satisfies: in, Indicates the maximum response direction of the beam, which is the direction where the point of the corresponding maximum value on the beam diagram is located; The incident direction of the audio signal representing the target sound source; An expression representing the beam pattern; Represents the beamforming coefficient. Different values ​​of the beamforming coefficient can form beam patterns with different directivities. represents an imaginary unit; represents the sum function; Represents the parameters of the sum function, the range is - N to N .

[0054] Directional spiral microphone array 101 Ring The polar diameter of the directional array element 102 The mathematical expression is as follows: ; in, represents the initial polar diameter of the directional spiral microphone array 101; The directional spiral microphone array 101 represents Ring The azimuth angle of the directional array element 102, ; It represents the rate of change of the spiral polar diameter with the polar angle in the directional spiral microphone array 101.

[0055] Directional spiral microphone array 101 Ring The directional pattern of the directional array element 102 The mathematical expression is as follows: ; in, The directional spiral microphone array 101 represents Ring The weight factor corresponding to the directional array element 102 is In the case of Ring The directional array element 102 is omnidirectional; In the case of Ring The directional array element 102 has directivity, and the first directional spiral microphone array 101 has directivity. Ring The directional pattern of the directional array element 102 is determined by the weight factor Determine; in the directional spiral microphone array 101 When the directional array elements 102 in the ring have the same directional pattern, the first The weight factor of any directional array element 102 in the ring is express.

[0056] It should be noted that the desired pointing angle of the frequency-invariant beam pattern can point to any azimuth angle in the two-dimensional plane.

[0057] As an optional embodiment, the steering vector of the directional spiral microphone array 101 The mathematical expression is: in, Indicates transpose calculation; represents the first microphone in the directional spiral microphone array 101 Ring A directional pattern of a directional array element 102, the directional pattern is used to define the shape of the beam pattern; represents an imaginary unit; , is the speed of sound in air, The frequency of the audio signal representing the target sound source; represents the first microphone in the directional spiral microphone array 101 Ring The polar diameter of a directional array element 102; represents the first microphone in the directional spiral microphone array 101 Ring An azimuth angle of a directional array element 102; , , represents the first microphone in the directional spiral microphone array 101 The number of directional array elements 102 in the ring, represents the total number of rings in the directional spiral microphone array 101, and All are positive integers.

[0058] Steering vector of directional spiral microphone array 101 The mathematical expression for circular harmonic decomposition is as follows: in, The quantity is of Bessel function of the first kind; express The first derivative of .

[0059] As an optional embodiment, the mathematical expression of the target beam pattern corresponding to the directional spiral microphone array 101 is as follows: in, Represents a conjugate calculation.

[0060] Vector form of filter coefficients The mathematical representation of is as follows: in: The mathematical expression of the target beam pattern with no constraint distortion in the desired pointing direction is as follows: in, Represents the conjugate transpose computation.

[0061] Based on the target beam pattern and the ideal beam pattern, the minimum norm solution of the filter coefficients is calculated The calculation formula is as follows: ; in, ; ; ; ; ; ; ; in, Represents the filter coefficients.

[0062] As an optional embodiment, after obtaining the beam corresponding to the directional spiral microphone array 101 , the method further includes: obtaining a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array 101 .

[0063] Based on the white noise gain evaluation index and the directivity factor evaluation index of the beam corresponding to the directional spiral microphone array 101, an evaluation result of the beam corresponding to the directional spiral microphone array 101 is obtained.

[0064] As an optional embodiment, the white noise gain evaluation index of the beam corresponding to the directional spiral microphone array 101 is obtained: The calculation formula is as follows: in, Represents the conjugate transpose computation.

[0065] As an optional embodiment, obtaining the directivity factor evaluation index of the beam corresponding to the directional spiral microphone array 101 The calculation formula is as follows: ; in, yes The number of discrete points within the range.

[0066] To facilitate understanding of the directional spiral microphone array 101 and the beamforming method based on the directional spiral microphone array 101 provided by the present invention, the directional spiral microphone array 101 and the beamforming method based on the directional spiral microphone array 101 provided by the present invention are described below by using an example.

[0067] like Figure 1 The number of directional array elements 102 in the directional spiral microphone array 101 shown is 10, where M 1 = M 2 =5.

[0068] Setting the initial polar diameter of the directional spiral microphone array 101 , the polar diameter of the fifth directional array element 102 in the second ring of the directional spiral microphone array 101 , the speed of sound in air , the maximum response direction of the beam Directional spiral microphone array 101 The directional array elements 102 in the ring have the same directional pattern. The weight factor of any directional array element 102 in the ring In the case of Any directional array element 102 in the ring is an omnidirectional array element. The weight factor of any directional array element 102 in the ring In the case of Any directional array element 102 in the ring is a cardioid directional array element.

[0069] The ideal beam pattern is a first-order cardioid, and the first-order beam coefficient vector is ; In contrast, the number of elements in the traditional concentric circle microphone array is M 1 = M 2 =5, a total of 10. In the traditional concentric circle microphone array, the inner radius of the concentric circle , the outer ring radius Set the frequency range of the audio signal of the target sound source to between 0 and 8 kHz.

[0070] Figure 3 : is the cardioid beam directivity diagram of the double-loop helical microphone array provided by the present invention. Figure 3 As shown, in , In this case, the cardioid beam directivity diagram of the dual-loop helical directional spiral microphone array 101 provided by the present invention is well consistent with the corresponding ideal beam diagram, with only a slight deviation from the ideal beam diagram at the zero point.

[0071] Figure 4 This is one of the graphs of white noise gain and directivity factor of the dual-loop helical microphone array provided by the present invention as a function of frequency. Figure 4 As shown, in In the case of FIG. 1 , compared with the traditional concentric circle microphone array using the cardioid directional array element 102, since the spacing of the directional array elements 102 in the dual-loop helical directional spiral microphone array 101 provided by the present invention is gradually changed, its small spacing can alleviate the influence of high-frequency time-space aliasing, and after 2000Hz, the white noise gain of the dual-loop helical directional spiral microphone array 101 provided by the present invention is 0~2.3dB higher than that of the circular array, indicating that the dual-loop helical directional spiral microphone array 101 provided by the present invention has better robustness in the frequency band of 0~8kHz; since the spacing between adjacent directional array elements 102 in the dual-loop helical directional spiral microphone array 101 provided by the present invention is small and gradually changed, the directivity factor of the dual-loop helical directional spiral microphone array 101 provided by the present invention is not affected, while the directivity factor of the traditional concentric circle microphone array begins to decrease at 6000Hz.

[0072] Figure 5 This is the second graph of the variation of white noise gain and directivity factor of the dual-loop helical microphone array with frequency provided by the present invention. Figure 5 As shown, in , Under the circumstances, the white noise gain of the dual-loop helical directional spiral microphone array 101 provided by the present invention and the traditional concentric circle microphone array intersect at 3700 Hz. After 3700 Hz, the white noise gain of the dual-loop helical directional spiral microphone array 101 provided by the present invention is 0~8.7dB higher than that of the traditional concentric circle microphone array, indicating that the dual-loop helical directional spiral microphone array 101 provided by the present invention is better in the frequency band of 0~8kHz.

[0073] Figure 5 The white noise gain of the traditional concentric circle microphone array has large fluctuations, while the dual-loop spiral directional spiral microphone array 101 provided by the present invention does not have large fluctuations. This is because the inner ring of the traditional concentric circle microphone array uses omnidirectional microphone elements, and the filter coefficient is affected by the zero value of the Bessel function, which causes the white noise gain to fluctuate. The dual-loop spiral directional spiral microphone array 101 provided by the present invention can alleviate the influence of the zero value of the Bessel function, so the white noise gain of the dual-loop spiral directional spiral microphone array 101 provided by the present invention will not fluctuate. On the whole, the dual-loop spiral directional spiral microphone array 101 provided by the present invention has better robustness.

[0074] Figure 6 It is a grayscale image of the traditional concentric microphone array beam pattern changing with pointing angle and frequency. Figure 7 The present invention provides a grayscale diagram of the beam pattern of the double-loop helical directional spiral microphone array 101 as the directional angle and frequency change. Figure 6 and Figure 7 As shown, in , In this case, the conventional concentric circle microphone array will have side lobes in the beam pattern after 6000 Hz and the beam pattern maximum value is not at 0° due to the distortion of the beam pattern. However, the dual-loop helical directional spiral microphone array 101 provided by the present invention does not have side lobes and the beam pattern is not distorted in the 0~8kHz frequency band, indicating that the dual-loop helical directional spiral microphone array 101 provided by the present invention has better frequency invariant characteristics.

[0075] The beamforming method based on microphone array provided by the present invention can accurately obtain the beam pattern corresponding to the microphone array by performing circular harmonic decomposition on the steering vector of the microphone array, and obtain the beam pattern corresponding to the microphone array by taking the foreground of the original beam pattern. N The order is used as the target beam pattern and matched with the ideal beam pattern to ensure that the formed beam has the expected directivity and shape. By making the target beam pattern unconstrainedly distorted in the desired pointing direction of the target direction and calculating the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern, the optimal filtering can be obtained, thereby maximizing the retention of the signal of the target sound source while minimizing interference from other directions. By multiplying the minimum norm solution of the filter coefficients with the steering vector of the microphone array, the beam corresponding to the microphone array can be obtained. The above beam has high directivity and anti-interference capabilities, which can significantly improve the quality of the received audio signal.

[0076] Figure 8 Schematic diagram of the structure of the beamforming device provided by the present invention. Figure 8 The beamforming device provided by the present invention is described. The beamforming device described below and the beamforming method provided by the present invention described above can be referred to each other. Figure 8 As shown, the device includes: a signal acquisition module 801, a circular harmonic decomposition module 802, a coefficient calculation module 803 and a beam forming module 804.

[0077] The signal acquisition module 801 is used to measure the audio signal of the target sound source using a microphone array.

[0078] The circular harmonic decomposition module 802 is used to perform circular harmonic decomposition on the steering vector of the microphone array, obtain the original beam pattern corresponding to the microphone array, and then take the front of the original beam pattern. order, as the target beam pattern corresponding to the microphone array, Represents a positive integer greater than zero.

[0079] The coefficient calculation module 803 is used to make the target beam pattern equal to the ideal beam pattern, and after making the target beam pattern unconstrained and distorted in the desired pointing direction, the minimum norm solution of the filter coefficient is calculated based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The order, the pointing angle of the ideal beam pattern and the beamforming coefficients for controlling the beam shape are predefined, and the expected pointing direction is the direction from the center point of the microphone array to the target sound source.

[0080] The beam forming module 804 multiplies the minimum norm solution of the filter coefficients by the steering vector of the microphone array to obtain a beam corresponding to the microphone array.

[0081] Specifically, the signal acquisition module 801, the circular harmonic decomposition module 802, the coefficient calculation module 803 and the beam forming module 804 are electrically connected.

[0082] Fig. 9 An example of a physical structure diagram of an electronic device is shown in FIG. Fig. 9 As shown, the electronic device may include: a processor 910, a communication interface 920, a memory 930 and a communication bus 940, wherein the processor 910, the communication interface 920 and the memory 930 communicate with each other through the communication bus 940. The processor 910 may call the logic instructions in the memory 930 to execute the beamforming method, which includes: measuring the audio signal of the target sound source using the microphone array; performing circular harmonic decomposition on the steering vector of the microphone array, obtaining the original beam pattern corresponding to the microphone array, and taking the front of the original beam pattern. order, as the target beam pattern corresponding to the microphone array, represents a positive integer greater than zero; let the target beam pattern be equal to the ideal beam pattern, let the target beam pattern be distorted in the desired pointing direction without constraints, and then calculate the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The order, the pointing angle of the ideal beam pattern and the beamforming coefficients that control the beam shape are predefined, and the expected pointing direction is the direction from the center point of the microphone array to the target sound source; the minimum norm solution of the filter coefficients is multiplied by the steering vector of the microphone array to obtain the beam corresponding to the microphone array.

[0083] In addition, the logic instructions in the above-mentioned memory 930 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0084] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the beamforming method provided by the above methods, which includes: using a microphone array to measure the audio signal of the target sound source; performing circular harmonic decomposition on the steering vector of the microphone array to obtain the original beam pattern corresponding to the microphone array, and then taking the front of the original beam pattern. order, as the target beam pattern corresponding to the microphone array, represents a positive integer greater than zero; let the target beam pattern be equal to the ideal beam pattern, let the target beam pattern be distorted in the desired pointing direction without constraints, and then calculate the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The order, the pointing angle of the ideal beam pattern and the beamforming coefficients that control the beam shape are predefined, and the expected pointing direction is the direction from the center point of the microphone array to the target sound source; the minimum norm solution of the filter coefficients is multiplied by the steering vector of the microphone array to obtain the beam corresponding to the microphone array.

[0085] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to execute the beamforming method provided by the above methods, the method comprising: measuring the audio signal of the target sound source using a microphone array; performing circular harmonic decomposition on the steering vector of the microphone array to obtain an original beam pattern corresponding to the microphone array, and then taking the foreground of the original beam pattern; order, as the target beam pattern corresponding to the microphone array, represents a positive integer greater than zero; let the target beam pattern be equal to the ideal beam pattern, let the target beam pattern be distorted in the desired pointing direction without constraints, and then calculate the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The order, the pointing angle of the ideal beam pattern and the beamforming coefficients that control the beam shape are predefined, and the expected pointing direction is the direction from the center point of the microphone array to the target sound source; the minimum norm solution of the filter coefficients is multiplied by the steering vector of the microphone array to obtain the beam corresponding to the microphone array.

[0086] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0087] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A directional spiral microphone array, characterized in that: include: A plurality of directional array elements are distributed on the Archimedean spiral at equal azimuth angles.

2. The directional spiral microphone array according to claim 1, characterized in that: The number of each of the directional array elements is determined based on the order of an ideal beam pattern, and the ideal beam pattern is used to form a beam corresponding to the directional spiral microphone array.

3. The directional spiral microphone array according to claim 2, characterized in that: The number of each directional array element satisfy , represents the order of the ideal beam pattern.

4. A beam forming method applied to a directional spiral microphone array as claimed in any one of claims 1 to 3, characterized in that: include: Measuring the audio signal of the target sound source by using the directional spiral microphone array; After performing circular harmonic decomposition on the steering vector of the directional spiral microphone array to obtain the original beam pattern corresponding to the directional spiral microphone array, the front of the original beam pattern is taken. , as the target beam pattern corresponding to the directional spiral microphone array, represents a positive integer greater than zero; The target beam pattern is set equal to the ideal beam pattern, and after the target beam pattern is set to be unconstrained and distorted in the desired pointing direction, the minimum norm solution of the filter coefficients is calculated based on the target beam pattern and the ideal beam pattern. The order of the ideal beam pattern is The directional angle of the ideal beam pattern and the beam forming coefficient for controlling the beam shape are predefined, and the desired directional direction is the direction in which the center point of the directional spiral microphone array points to the target sound source; The minimum norm solution of the filter coefficients is multiplied by the steering vector of the directional spiral microphone array to obtain a beam corresponding to the directional spiral microphone array.

5. The beamforming method according to claim 4, characterized in that: After obtaining the beam corresponding to the directional spiral microphone array, the method further includes: Obtaining a white noise gain evaluation index and a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array; Based on a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array, an evaluation result of the beam corresponding to the directional spiral microphone array is obtained.

6. The beamforming method according to claim 5, characterized in that: The relationship between the pointing direction of the ideal beam pattern and the beamforming coefficient satisfies: ； in, represents the maximum response direction of the beam, where the maximum response direction is the direction where the point of the corresponding maximum value on the beam diagram is located; Represents the incident direction of the audio signal of the target sound source; Expressions representing beam patterns; represents the beamforming coefficient; represents an imaginary unit; represents the sum function; Represents the parameters of the sum function, ranging from - N to N ; The directional spiral microphone array Ring The polar diameter of the directional array element The mathematical expression is as follows: ； in, represents the initial polar diameter of the directional spiral microphone array; represents the first Ring The azimuth angle of the directional array element, ; represents the rate of change of the spiral polar diameter with the polar angle in the directional spiral microphone array; The directional spiral microphone array Ring The directional pattern of the directional array elements The mathematical expression is as follows: ； in, represents the first Ring The weight factor corresponding to the directional array element is In the case of Ring The directional array elements are omnidirectional; In the case of Ring The directional array element has directivity, and the first directional spiral microphone array Ring The directional pattern of each directional element is determined by the weight factor Determine: In the directional spiral microphone array When the directional patterns of the directional array elements in the ring are the same, the first The weight factor of any directional array element in the ring is express.

7. The beamforming method according to claim 6, characterized in that: The steering vector of the directional spiral microphone array The mathematical expression is: ； ； in, Indicates transpose calculation; represents the first Ring a directional pattern of a directional array element, wherein the directional pattern is used to define the shape of the beam pattern; represents an imaginary unit; , is the speed of sound in air, The frequency of the audio signal representing the target sound source; represents the first Ring The polar diameter of a directional array element; represents the first Ring The azimuth of the directional array element; , , represents the first The number of directional elements in the ring, represents the total number of rings in the directional spiral microphone array, and All are positive integers; The steering vector of the directional spiral microphone array The mathematical expression for circular harmonic decomposition is as follows: ； in, The quantity is of Bessel function of the first kind; express The first derivative of .

8. The beamforming method according to claim 7, characterized in that: The mathematical expression of the target beam pattern corresponding to the directional spiral microphone array is as follows: ； in, represents conjugate calculation; The vector form of the filter coefficients is The mathematical representation of is as follows: ； in: ； The mathematical expression of the target beam pattern without constraint distortion in the desired pointing direction is as follows: ； in, represents the conjugate transpose calculation; Based on the target beam diagram and the ideal beam diagram, the minimum norm solution of the filter coefficients is calculated The calculation formula is as follows: ； in, ； ； ； ； ； ； 。 9. The beamforming method according to claim 8, characterized in that: Obtaining the white noise gain evaluation index of the beam corresponding to the directional spiral microphone array The calculation formula is as follows: ； in, Represents the conjugate transpose computation.

10. The beamforming method according to claim 9, characterized in that: Obtaining the directivity factor evaluation index of the beam corresponding to the directional spiral microphone array The calculation formula is as follows: ； in, yes The number of discrete points within the range.

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