Directional spiral microphone array and beamforming method thereof

Abstract

The present invention provides a directional spiral microphone array and a beamforming method thereof, relating to the field of acoustic technology. The microphone array comprises: a plurality of directional array elements, each of the directional array elements being equiazimuthally distributed on an Archimedean spiral. The present invention provides a directional spiral microphone array and a beamforming method thereof, which can more flexibly adjust the beam direction, thereby resolving the problem of limited beam steering capability of traditional microphone arrays, effectively avoiding the occurrence of nulling, reducing the amplification effect on white noise, improving the quality of signal acquisition, enhancing the receiving sensitivity in the desired pointing direction, ensuring uniform sampling in space, and improving the reliability of audio signal acquisition. Furthermore, 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 or the spatial distribution area, and the performance of the microphone array at high frequencies and the frequency-invariant characteristics can be enhanced.

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 beamforming 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 a key technology. In noisy environments, a single microphone often struggles to accurately capture the audio signal of a target sound source. However, microphone array technology, through the collaboration of multiple microphones, can effectively enhance the audio signal of the target sound source and suppress background noise, thereby improving audio signal acquisition quality. This technology has been widely used in the field of audio processing.

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

[0004] However, these traditional microphone arrays suffer from limitations such as limited beam steering capabilities, susceptibility to nulling, white noise amplification, and high equipment costs, which severely impact the quality and reliability of collected audio signals. Therefore, improving the quality and reliability of high-frequency audio signal acquisition using microphone arrays without increasing the number of elements in the array or the spatial distribution area of ​​the microphone array remains a pressing technical challenge in this field. Summary of the Invention

[0005] The present invention provides a directional spiral microphone array and a beamforming method thereof, which are used to overcome the defects of the above-mentioned traditional microphone arrays in the prior art, such as limited beam steering capability, susceptibility to nulling problems, white noise amplification, and high equipment costs. The invention improves the audio signal acquisition quality and reliability of the microphone array at high frequencies without increasing the number of array elements in the microphone array or the spatial distribution area of ​​the microphone array.

[0006] The present invention provides a directional spiral microphone array, comprising: a plurality of directional array elements, wherein the directional array elements are distributed on an Archimedean spiral at equal azimuth angles.

[0007] According to a directional spiral microphone array provided by the present invention, the number 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.

[0008] According to a directional spiral microphone array provided by the present invention, the number of each directional array element is 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:

[0010] Measuring the audio signal of the target sound source using the directional spiral microphone array;

[0011] 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. order, as the target beam pattern corresponding to the directional spiral microphone array, represents a positive integer greater than zero;

[0012] The target beam pattern is set equal to the ideal beam pattern, and after the target beam pattern is distorted in the desired pointing direction without constraints, 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 beamforming 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;

[0013] 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.

[0014] According to a beamforming method provided by the present invention, after obtaining the beam corresponding to the directional spiral microphone array, the method further includes:

[0015] Obtaining a white noise gain evaluation index and a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array;

[0016] An evaluation result of the beam corresponding to the directional spiral microphone array is obtained based on a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array.

[0017] According to a beamforming method provided by the present invention, after obtaining the beam corresponding to the directional spiral microphone array, the method further includes:

[0018] Obtaining a white noise gain evaluation index and a directivity factor evaluation index of a beam corresponding to the directional spiral microphone array;

[0019] An evaluation result of the beam corresponding to the directional spiral microphone array is obtained based on a white noise gain evaluation index and a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array.

[0020] 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:

[0021] ;

[0022] in, Indicates the maximum response direction of the beam, which is the direction of the point with the corresponding maximum value on the beam pattern; The incident direction of the audio signal representing the target sound source; An expression representing the beam pattern; represents the beamforming coefficient; represents an imaginary unit; represents the summation function; The parameter of the sum function is - N to N ;

[0023] The first Ring The polar diameter of a directional array element The mathematical expression is as follows:

[0024] ;

[0025] in, represents the initial polar diameter of the directional spiral microphone array; Indicates 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;

[0026] The first Ring The directional pattern of the directional array elements The mathematical expression is as follows:

[0027] ;

[0028] in, Indicates 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 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 expressed as express.

[0029] According to a beam forming method provided by the present invention, the steering vector of the directional spiral microphone array The mathematical expression is:

[0030] ;

[0031] ;

[0032] in, Indicates transpose calculation; Indicates 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; , represents the speed of sound in air, The frequency of the audio signal representing the target sound source; Indicates the first Ring The polar diameter of a directional array element; Indicates the first Ring The azimuth angle of the directional array element; , , Indicates 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;

[0033] The steering vector of the directional spiral microphone array The mathematical expression for circular harmonic decomposition is as follows:

[0034] ;

[0035] in, The quantity is of Bessel function of the first kind; express The first derivative of .

[0036] 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:

[0037] ;

[0038] in, represents conjugate calculation;

[0039] The vector form of the filter coefficients The mathematical representation of is as follows:

[0040] ;

[0041] in:

[0042] ;

[0043] The mathematical expression of the target beam pattern with no constraint distortion in the desired pointing direction is as follows:

[0044] ;

[0045] in, Indicates conjugate transpose calculation;

[0046] 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:

[0047] ;

[0048] in,

[0049] ;

[0050] ;

[0051] ;

[0052] ;

[0053] ;

[0054] ;

[0055] .

[0056] According to a beamforming method provided by the present invention, a white noise gain evaluation index of the beam corresponding to the directional spiral microphone array is obtained. The calculation formula is as follows:

[0057] ;

[0058] in, Represents the conjugate transpose computation.

[0059] According to a beamforming method provided by the present invention, a directivity factor evaluation index of the beam corresponding to the directional spiral microphone array is obtained. The calculation formula is as follows:

[0060] ;

[0061] in, yes The number of discrete points in the range.

[0062] 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 the processor implements any of the above-described beamforming methods when executing the computer program.

[0063] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which implements any of the beamforming methods described above when executed by a processor.

[0064] 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 one of the beamforming methods described above.

[0065] The present invention provides a directional spiral microphone array and a beamforming method thereof. The directional spiral microphone array includes multiple directional array elements distributed at equal azimuth angles on an Archimedean spiral. Based on the special geometric shape and arrangement of the directional spiral microphone array, the beam direction can be more flexibly adjusted, thereby solving the problem of limited beam steering capability of traditional microphone arrays. By optimizing the phase relationship between array elements and signal processing technology, the occurrence of nulling 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 in the desired direction, helping to reduce the influence of background noise and interference signals, and improving the quality of audio signal acquisition. It can ensure spatially uniform sampling and improve 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 or the spatial distribution area of ​​the microphone array. The performance of the microphone array at high frequencies and the frequency-invariant characteristics can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to 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 any creative work.

[0067] Figure 1 It is a structural schematic diagram of the directional spiral microphone array provided by the present invention.

[0068] Figure 2 It is a flowchart of the beamforming method provided by the present invention.

[0069] Figure 3 This is the cardioid beam directivity diagram of the double-loop helical directional spiral microphone array provided by the present invention.

[0070] Figure 4 This is one of the graphs showing how the white noise gain and directivity factor of the double-loop helical directional spiral microphone array provided by the present invention vary with frequency.

[0071] 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.

[0072] Figure 6 It is a grayscale image of the traditional concentric microphone array beam pattern changing with pointing angle and frequency.

[0073] Figure 7The present invention provides a grayscale diagram of the double-loop helical directional spiral microphone array beam pattern changing with the pointing angle and frequency.

[0074] Figure 8 It is a structural schematic diagram of the beamforming device provided by the present invention.

[0075] Figure 9 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0076] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0077] In the description of the invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0078] In the description of this 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 where appropriate, so that the embodiments of this application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, in the description of this application, "and / or" represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0079] It should be noted that traditional cascaded microphone arrays use the time difference between sound waves reaching adjacent microphones in the array to generate a sound pressure gradient through subtraction, thereby forming a directional beam pattern. However, traditional cascaded microphone arrays suffer from severe white noise amplification issues, are highly sensitive to microphone self-noise, and have a rigid structure, making it difficult to ensure robustness of the microphone array.

[0080] Traditional linear microphone arrays based on zero-point constraints can improve white noise gain by increasing the number of microphones in the array, thereby addressing the severe white noise amplification problem in traditional cascaded microphone arrays. However, these linear microphone arrays based on zero-point constraints only offer limited beam steering options within the plane of the array, with beam steering capabilities limited to the end-fire direction.

[0081] In traditional frequency-invariant circular microphone arrays based on the Jacobi expansion method, the beam can be steered to any azimuth within the plane of the microphone array. However, at certain 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 experience nulling, resulting in severe distortion of the beam pattern. Although the frequency-invariant circular microphone array designed based on the Jacobi expansion method can solve the nulling problem in most cases, it still occurs in some special cases. In addition, the traditional frequency-invariant circular microphone array based on the Jacobi expansion method has a large number of microphones, resulting in a high equipment cost for the traditional frequency-invariant circular microphone array based on the Jacobi expansion method.

[0082] 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 characteristics of the array cannot be maintained in the high frequency band.

[0083] Therefore, these traditional microphone arrays suffer from limitations such as limited beam steering capabilities, susceptibility to nulling, and white noise amplification, which severely impact the quality and reliability of audio signals collected by these traditional microphone arrays. Therefore, improving the quality and reliability of audio signal collection using microphone arrays is a pressing technical issue in this field.

[0084] The following combination Figure 1 The directional spiral microphone array provided by the present invention is described.

[0085] Figure 1 This is a 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 1As 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.

[0086] As an optional embodiment, the number of directional array elements 102 is determined based on the order of an ideal beam pattern, which is used to form a beam corresponding to the directional spiral microphone array 101 .

[0087] As an optional embodiment, the number of each directional array element 102 is satisfy , Indicates the order of the ideal beam pattern.

[0088] 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.

[0089] 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, microphone, underwater acoustic sensor, etc., and is used to receive signals from a signal source. Each array element has its own receiving directivity and response characteristics, namely, the sensitivity and phase characteristics of the received signal. The directivity of an array refers to the characteristic that the amplitude of its transmitted or received signal varies with the azimuth angle. For a transmitting array, directivity is generally 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 implementing functions such as signal source positioning, beamforming, and interference suppression in array signal processing. The directional array element 102 in this embodiment of the present invention refers to an array element with clear directivity.

[0090] Optionally, the directional array element 102 in the embodiment of the present invention may be a differential microphone.

[0091] 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 angle difference between any two adjacent directional array elements 102 is .

[0092] The microphone array in an embodiment of the present invention includes a plurality of directional array elements distributed at equal azimuth angles on an Archimedean spiral. Based on the special geometric shape and arrangement of the above-mentioned microphone array, the beam direction can be adjusted more flexibly, thereby solving the problem of limited beam steering capability. By optimizing the phase relationship between the array elements and signal processing technology, the occurrence of nulling 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 in 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 thus can improve the quality and reliability of audio signal acquisition by the microphone array without increasing the number of array elements in the microphone array or the spatial distribution area of ​​the microphone array. It can also improve the performance of the microphone array at high frequencies and the frequency-invariant characteristics.

[0093] Figure 2 : 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 above-mentioned directional spiral microphone array 101. Figure 2 As shown, the method includes the following steps: Step 201 , using the directional spiral microphone array 101 to measure the audio signal of the target sound source.

[0094] 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. order, as the target beam pattern corresponding to the directional spiral microphone array 101, Represents a positive integer greater than zero.

[0095] Step 203: The target beam pattern is set equal to the ideal beam pattern. After the target beam pattern is distorted in the desired pointing direction without constraints, 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 order, the pointing angle of the ideal beam pattern and the beamforming coefficient for controlling the beam shape are predefined, and the expected pointing direction is the direction in which the center point of the directional spiral microphone array 101 points to the target sound source.

[0096] 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 .

[0097] It should be noted that the embodiment of the present invention is performed by a beamforming device, which can be configured in electronic devices such as computers or servers.

[0098] As an optional embodiment, the relationship between the pointing direction of the ideal beam pattern and the beamforming coefficient satisfies:

[0099]

[0100] in, Indicates the maximum response direction of the beam, which is the direction of the point with the corresponding maximum value on the beam pattern; 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 summation function; Indicates the parameters of the sum function, the range is - N to N .

[0101] The first directional spiral microphone array 101 Ring The polar diameter of the directional array element 102 The mathematical expression is as follows:

[0102] ;

[0103] in, represents the initial polar diameter of the directional spiral microphone array 101; represents the first directional spiral microphone array 101 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.

[0104] The first directional spiral microphone array 101 Ring The directional pattern of the directional array element 102 The mathematical expression is as follows:

[0105] ;

[0106] in, represents the first directional spiral microphone array 101 Ring The weight factors corresponding to the directional array elements 102 are In the case of Ring The directional array elements 102 are 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 directional array element 102 in the directional spiral microphone array 101 The weight factor of any directional array element 102 in the ring is express.

[0107] It should be noted that the desired pointing angle of the frequency-invariant beam pattern can point to any azimuth angle in a two-dimensional plane.

[0108] As an optional embodiment, the steering vector of the directional spiral microphone array 101 The mathematical expression is:

[0109]

[0110]

[0111] in, Indicates transpose calculation; represents the first directional spiral microphone array 101 Ring a directional pattern of a directional array element 102, the directional pattern being used to define the shape of the beam pattern; represents an imaginary unit; , is the speed of sound in air, Indicates the frequency of the audio signal of the target sound source; represents the first directional spiral microphone array 101 Ring The polar diameter of a directional array element 102; represents the first directional spiral microphone array 101 Ring The azimuth angle of the directional array element 102; , , represents the first directional spiral microphone array 101 The number of directional elements 102 in the ring, represents the total number of rings in the directional spiral microphone array 101, and All are positive integers.

[0112] Steering vector of directional spiral microphone array 101 The mathematical expression for circular harmonic decomposition is as follows:

[0113]

[0114] in, The quantity is of Bessel function of the first kind; express The first derivative of .

[0115] As an optional embodiment, the mathematical expression of the target beam pattern corresponding to the directional spiral microphone array 101 is as follows:

[0116]

[0117] in, Represents a conjugate calculation.

[0118] Vector form of filter coefficients The mathematical representation of is as follows:

[0119]

[0120] in:

[0121]

[0122] The mathematical expression for the target beam pattern with no constraint distortion in the desired pointing direction is as follows:

[0123]

[0124] in, Represents the conjugate transpose computation.

[0125] 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:

[0126] ;

[0127] in,

[0128] ;

[0129] ;

[0130] ;

[0131] ;

[0132] ;

[0133] ;

[0134] ;

[0135] in, Represents the filter coefficients.

[0136] 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 .

[0137] 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.

[0138] 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:

[0139]

[0140] in, Represents the conjugate transpose computation.

[0141] As an optional embodiment, the directivity factor evaluation index of the beam corresponding to the directional spiral microphone array 101 is obtained. The calculation formula is as follows:

[0142] ;

[0143] in, yes The number of discrete points in the range.

[0144] 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 through an example.

[0145] 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.

[0146] 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

[0147] The first 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.

[0148] The ideal beam pattern is a first-order cardioid, and the first-order beam coefficient vector is ; In comparison, the number of elements in a traditional concentric 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 is , outer ring radius Set the frequency range of the audio signal of the target sound source to between 0 and 8 kHz.

[0149] Figure 3 This is the cardioid beam directivity diagram of the dual-loop helical microphone array provided by the present invention. Figure 3 As shown, in , In this case, the cardioid beam directivity pattern of the dual-loop helical directional spiral microphone array 101 provided by the present invention is well consistent with the corresponding ideal beam pattern, with only a slight deviation from the ideal beam pattern at the zero point.

[0150] Figure 4 This is one of the graphs showing how the white noise gain and directivity factor of the dual-loop helical microphone array vary with frequency. Figure 4 As shown, in In this case, compared with the traditional concentric circle microphone array using cardioid directional array elements 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. After 2000 Hz, the white noise gain of the dual-loop helical directional spiral microphone array 101 provided by the present invention is 0-2.3 dB 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 0-8 kHz; 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 6000 Hz.

[0151] Figure 5 This is the second graph of the white noise gain and directivity factor of the dual-loop helical microphone array as a function of frequency. Figure 5 As shown, in , In this case, the white noise gain of the dual-loop helical directional spiral microphone array 101 provided by the present invention intersects with that of the traditional concentric circle microphone array 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 has better robustness in the frequency band of 0~8kHz.

[0152] Figure 5 The white noise gain of a traditional concentric circle microphone array fluctuates significantly, while the dual-loop helical directional spiral microphone array 101 provided by the present invention does not experience significant fluctuations. This is because the inner ring of the traditional concentric circle microphone array uses omnidirectional microphone elements, and the filter coefficients are affected by the zero value of the Bessel function, which causes the white noise gain to fluctuate. The dual-loop helical 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 helical directional spiral microphone array 101 provided by the present invention does not fluctuate. Overall, the dual-loop helical directional spiral microphone array 101 provided by the present invention has better robustness.

[0153] 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 image of the beam pattern of the double-loop spiral directional spiral microphone array 101 as it changes with the pointing angle and frequency. Figure 6 and Figure 7 As shown, in , In this case, the traditional concentric circle microphone array will have side lobes in the beam pattern after 6000 Hz, and the beam pattern maximum 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 frequency band of 0~8kHz, indicating that the dual-loop helical directional spiral microphone array 101 provided by the present invention has better frequency invariance characteristics.

[0154] 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. N Using the order as the target beam pattern and matching it with the ideal beam pattern ensures that the formed beam has the desired directivity and shape. By allowing the target beam pattern to be distorted unconstrained in the desired direction of the target, and calculating the minimum norm solution of the filter coefficients based on the target beam pattern and the ideal beam pattern, optimal filtering can be achieved, thereby maximizing the retention of the signal from 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. This beam has high directivity and anti-interference capabilities, which can significantly improve the quality of the received audio signal.

[0155] Figure 8 This is a 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 below. The beamforming device described below and the beamforming method provided by the present invention described above can be referred to in correspondence with 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.

[0156] The signal acquisition module 801 is used to measure the audio signal of the target sound source using a microphone array.

[0157] 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.

[0158] The coefficient calculation module 803 is used to make the target beam pattern equal to the ideal beam pattern, and after the target beam pattern is distorted in the desired pointing direction without constraints, 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 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.

[0159] 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.

[0160] Specifically, the signal acquisition module 801 , the circular harmonic decomposition module 802 , the coefficient calculation module 803 and the beamforming module 804 are electrically connected.

[0161] Figure 9 An example of a physical structure diagram of an electronic device is shown below. Figure 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 via the communication bus 940. The processor 910 may call the logic instructions in the memory 930 to execute a beamforming method, which includes: 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 the original beam pattern corresponding to the microphone array, and then taking the forward vector 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 coefficient 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. 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.

[0162] Furthermore, the logic instructions in the aforementioned memory 930 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product, stored in a storage medium, includes instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0163] On the other hand, the present invention also provides a computer program product, which includes a computer program that 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 coefficient 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. 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.

[0164] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the beamforming method provided by the above-mentioned 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 taking the forward vector 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 coefficient 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. 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.

[0165] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0166] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0167] 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 various embodiments of the present invention.

Claims

1. A beamforming method for a directional spiral microphone array, characterized in that: The directional spiral microphone array comprises: a plurality of directional array elements, each of the directional array elements being distributed on the Archimedean spiral at equal azimuth angles; The method comprises: Measuring the audio signal of the target sound source 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. order, 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 distorted in the desired pointing direction without constraints, 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 beamforming 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; multiplying the minimum norm solution of the filter coefficients by the steering vector of the directional spiral microphone array to obtain a beam corresponding to the directional spiral microphone array; 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; obtaining an evaluation result of the 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; 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 of the point with the corresponding maximum value on the beam pattern; The incident direction of the audio signal representing the target sound source; Expression representing the beam pattern; represents the beamforming coefficient; represents an imaginary unit; represents the summation function; The parameter of the summation function is - N to N ; The first Ring The polar diameter of a directional array element The mathematical expression is as follows: ； in, represents the initial polar diameter of the directional spiral microphone array; Indicates 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 first Ring The directional pattern of the directional array elements The mathematical expression is as follows: ； in, Indicates 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 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 expressed as express.

2. The beamforming method according to claim 1, wherein: The steering vector of the directional spiral microphone array The mathematical expression is: ； ； in, Indicates transpose calculation; Indicates 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; , represents the speed of sound in air, The frequency of the audio signal representing the target sound source; Indicates the first Ring The polar diameter of a directional array element; Indicates the first Ring The azimuth angle of the directional array element; , Indicates 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 .

3. The beamforming method according to claim 2, wherein: 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 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, Indicates conjugate transpose calculation; 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, ； ； ； ； ； ； 。 4. The beamforming method according to claim 3, wherein: 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.

5. The beamforming method according to claim 4, wherein: 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 in the range.

6. The beamforming method according to claim 1, wherein: The number of the directional array elements in the directional spiral microphone array 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.

7. The beamforming method according to claim 6, wherein: The number of directional array elements in the directional spiral microphone array ,satisfy , represents the order of the ideal beam pattern.

Images