Spatial sound field playback method and system based on directivity compensation of sound field playback equipment

Abstract

The present invention discloses a method and system for spatial sound field reproduction based on directivity compensation of sound field reproduction equipment. The method comprises: using a microphone array to collect speaker directivity in a discrete hemisphere centered on a speaker; converting the position of the microphone array in a global coordinate system into a position in a local coordinate system based on each speaker; interpolating the directivity of the microphone position points after the coordinate system conversion based on the directivity of the collected spatial discrete points; solving the driving weight of the compensated speaker array by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the expected sound pressure; and driving each speaker based on the obtained driving weight to achieve sound field reproduction. The present invention solves the problem of low sound field reproduction accuracy caused by the large difference between the actual directivity and theoretical directivity of the speaker caused by the manufacturing and processing level in actual use.

Description

Technical Field

[0001] The present invention relates to the technical field of spatial sound field playback, and in particular to a spatial sound field playback method and system based on directivity compensation of sound field playback equipment. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the widespread adoption of intelligent devices, people are increasingly demanding the quality of the acoustic environments they create. This is particularly true for cinematic environments and home theater surround sound systems, where a more realistic and immersive experience is desired. Spatial sound field reproduction technology is a method that enables this immersive spatial stereo experience through sound field reproduction devices, namely speakers.

[0004] When using sound field playback equipment to reproduce spatial sound fields, the directional characteristics of the acoustic characteristics of the sound field playback equipment have a great influence on the accuracy of the sound field playback. The difference in directional acoustic characteristics is caused by differences in process during the manufacturing and processing of the speakers, which will affect the accuracy of the sound field reproduction, so the speaker system needs to be equalized and corrected. In addition, there are speakers on the market with good acoustic characteristics, but their unit price is high. When the frequency and range of the reproduced sound field are large, the number of speakers required for accurate playback will increase sharply, which will lead to a significant increase in the cost of the intelligent playback system. The poor acoustic characteristics of spatial sound field playback equipment will make users have a poor functional experience of the sound field playback system, which is not conducive to product promotion. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a spatial sound field playback method and system based on the directivity compensation of the sound field playback device, which can compensate for the directivity of the spatial observation point by using the methods of coordinate transformation and cubic spline interpolation, and obtain the appropriate driving weight of the playback speaker through the sound pressure matching method to accurately playback the desired sound field, thereby improving the immersive experience of smart devices.

[0006] In some embodiments, the following technical solutions are adopted:

[0007] A spatial sound field playback method based on directivity compensation of a sound field playback device, comprising:

[0008] The speaker directivity is collected using a microphone array in a discrete hemisphere centered on the speaker, with the location of each microphone as a discrete point in space.

[0009] Convert the position of the microphone array in the global coordinate system to the position in the local coordinate system based on each loudspeaker;

[0010] Interpolation compensates for the directivity of the microphone position point after the coordinate system transformation based on the directivity of the collected spatial discrete points;

[0011] The driving weight of the compensated loudspeaker array is solved by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the desired sound pressure;

[0012] Each speaker is driven based on the obtained driving weight to achieve sound field reproduction.

[0013] In other embodiments, the following technical solutions are adopted:

[0014] A spatial sound field playback system based on directivity compensation of a sound field playback device, comprising:

[0015] The loudspeaker directivity acquisition module is used to collect loudspeaker directivity in a discrete hemisphere centered on the loudspeaker using a microphone array, with the location of each microphone being considered as a spatial discrete point.

[0016] A coordinate conversion module, configured to convert the position of the microphone array in the global coordinate system into a position in the local coordinate system based on each loudspeaker;

[0017] A directivity compensation module is used to interpolate and compensate the directivity of the microphone position point after the coordinate system is transformed based on the directivity of the collected spatial discrete points;

[0018] The sound field reproduction module is used to solve the driving weight of the compensated speaker array by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the desired sound pressure; and drive each speaker based on the obtained driving weight to achieve sound field reproduction.

[0019] In other embodiments, the following technical solutions are adopted:

[0020] A terminal device includes a processor and a memory, wherein the processor is used to implement instructions; the memory is used to store multiple instructions, and the instructions are suitable for being loaded by the processor and executing the above-mentioned spatial sound field playback method based on the directivity compensation of the sound field playback device.

[0021] In other embodiments, the following technical solutions are adopted:

[0022] A computer-readable storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor of a terminal device and executing the above-mentioned spatial sound field playback method based on directivity compensation of a sound field playback device.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention uses coordinate transformation and cubic spline interpolation methods to compensate for the spatial directivity of the sound field playback device (i.e., the loudspeaker), and obtains the driving weight suitable for the loudspeaker playback through the sound pressure matching method to accurately playback the desired sound field; it solves the problem that the actual directivity of the loudspeaker is greatly different from the theoretical directivity due to the manufacturing and processing level in actual use, resulting in low sound field playback accuracy and poor user immersive experience.

[0025] Other features and advantages of additional aspects of the present invention will be given in part in the following description and in part will become obvious from the following description or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flowchart of a method for spatial sound field playback based on directivity compensation of a sound field playback device in an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the positional relationship between the microphone array and the loudspeaker in an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the positions of microphones and loudspeakers for controlling the playback of the sound field in the playback area during spatial directivity compensation in the playback area according to an embodiment of the present invention;

[0029] Figure 4 A simulated cloud diagram of the real part sound pressure of the spatial sound field to be reproduced on the horizontal plane in an embodiment of the present invention;

[0030] Figure 5 A simulated cloud diagram of the real part sound pressure of the reproduced spatial sound field on the horizontal plane in an embodiment of the present invention;

[0031] Figure 6 A simulation diagram of the relative error between the reproduced spatial sound field and the to-be-reproduced spatial sound field on the horizontal plane in an embodiment of the present invention;

[0032] Figure 7 3D is a graph showing relative errors between playback with directivity compensation and playback without directivity compensation, obtained in a specific experiment at 400-1000 Hz in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] Example 1

[0036] In one or more embodiments, a spatial sound field playback method based on directivity compensation of a sound field playback device is disclosed, combined with Figure 1 , specifically including:

[0037] S101: Using a microphone array, collect loudspeaker directivity in a discrete hemisphere centered on the loudspeaker, with the location of each microphone being considered as a spatial discrete point;

[0038] In this embodiment, combined with Figure 2 , using a semicircular microphone array with a radius of 1 meter, the microphones of the array are in the horizontal plane The speakers are evenly spaced at 5° intervals within the semicircular microphone array. A sweep frequency signal of unit intensity is used to drive the speakers, and the microphone array with a sampling rate of 44.1 kHz collects the sound pressure of the speakers on the semicircular surface.

[0039] Then, with the point on the central axis of the loudspeaker as the origin, the circular microphone array is rotated to measure the sound pressure driven by a swept frequency signal of unit intensity at an angular interval of 5°, forming a directional collection process of a discrete hemisphere in space.

[0040] The sound pressure model obtained by a single microphone in one acquisition can be written as:

[0041]

[0042] Among them, the center position of the speaker The equivalent point source position of the sound radiation is also regarded as the center of the local coordinate system of the playback system in this embodiment. The local coordinate system is represented by the superscript s.

[0043] On the speaker The equivalent intensity at q i When the sound source is The sound pressure generated at the point is p j .

[0044] Considering the acoustic characteristics of the actual directivity of the loudspeaker, the i-th loudspeaker in the playback system To microphone No. j The radiation sound pressure p j (f) With directional The point source model description is: is the Green's function of the free field. Where k is the wave number, k=2πf / c. ji Expressed as distance, is the distance vector, Respectively represent speakers and spatial location

[0045] In the local coordinate system, is the distance vector The pitch and azimuth angles in spherical coordinates are, Distance r ji is a scalar quantity that is the same in both the local and global coordinate systems.

[0046] It should be noted that the spherical coordinate system takes the center of the speaker as the origin. The X-axis and Y-axis are established on the surface of the speaker according to the right-hand rule. The Z-axis is perpendicular to the speaker surface and upward. The position of the microphone in space can be calculated by Indicates that r is the distance from the origin to the microphone point, the pitch angle θ is the angle between the line connecting the origin to the microphone point and the positive Z axis, and the azimuth angle It is the angle between the projection line of the line from the origin to the microphone point on the XY plane and the positive X-axis.

[0047] When the observation point j is located on the central axis of the loudspeaker, the expression of its polar coordinates is:

[0048] The corresponding directivity coefficient

[0049] S102: Converting the position of the microphone array in the global coordinate system into a position in the local coordinate system based on each loudspeaker;

[0050] In this embodiment, the directivity of the playback device (i.e., the directivity of the loudspeaker) is described relative to the loudspeaker in the local coordinate system; while the position of the playback area and the position of the playback device are given in the global coordinate system, so the directivity in the local coordinate system needs to be compensated.

[0051] This embodiment converts the position of the microphone in the global coordinate system into a position in the local coordinate system based on each speaker; then, based on the directivity of existing spatial discrete points, interpolation is performed to compensate for the directivity of the microphone position point after coordinate conversion.

[0052] Specifically, the microphone's position in the global coordinate system is converted to a position in the local coordinate system for each loudspeaker. Microphone and loudspeaker placement is typically given in global coordinates. Directivity compensation for the reproduction area is performed on a per-loudspeaker basis and exists in the local coordinate system, necessitating a coordinate conversion. The center of the global coordinate system is the center of the spherical loudspeaker array, and the global coordinate system is denoted by the superscript w.

[0053] The position of the microphone in the global coordinate system Transformed to the position of the local coordinate system of the i-th speaker

[0054]

[0055] Among them, R z is the global coordinate system around Z w The rotation matrix for axis rotation, R y is the global coordinate system around Y w The rotation matrix for axis rotations, Is the coordinate of the global coordinate origin in the i-th local coordinate system. When converting from the global coordinate system to the i-th speaker's local coordinate system, you need to rotate around Z w , Y w Axis rotation and Then pan and are the horizontal angle and elevation angle of the loudspeaker in the global coordinate system.

[0056] Point in the global coordinate system The position of the i-th speaker The conversion formula is as follows:

[0057]

[0058] S103: interpolating and compensating the directivity of the microphone position point after the coordinate system transformation based on the directivity of the collected spatial discrete points;

[0059] In this embodiment, the directivity of the microphone position is interpolated and compensated based on the directivity of the existing spatially discrete points. To achieve sound field reproduction within the playback area, the playback area needs to be discretized at certain spatial intervals to form spatially discrete points. The sound pressure at these points in the playback area is then controlled to achieve regional sound field reproduction.

[0060] Figure 3A schematic diagram of the positions of microphones and loudspeakers for controlling the regional sound field playback when compensating for the spatial directivity of the playback area is given. In the playback module, multiple loudspeakers need to be driven for control to accurately playback the sound field. If the number of loudspeakers is small, the regional sound field cannot be accurately played back. The microphones in the playback module represent the control points required for sound field playback based on sound pressure matching.

[0061] When performing directivity interpolation compensation, it is necessary to discuss the relationship between the directivity of the position to be determined and the directivity of the known position, which can be divided into the following situations:

[0062] (1) When there is a discrete point with known directivity at the microphone location point with the required directivity, the directivity of the discrete point is directly used as the directivity of the microphone location point;

[0063] (2) When there is no discrete point with known directivity at the microphone location point with the required directivity, the directivity of the microphone location point needs to be obtained by interpolation using discrete points with known directivity;

[0064] The discrete points of the measured spatial directivity are in a grid format and are located at the grid nodes. When there are no discrete points of known directivity at the microphone position point with the required directivity, there may be two situations:

[0065] ① The microphone position point that needs directivity is located on the grid line, that is, the angle of the microphone position point that needs directivity Two angles θ at discrete points of known directivity s or When the axis is one of the two, the directivity of the adjacent four discrete points collected is taken for cubic spline interpolation to obtain the directivity of the microphone position point, that is, the directivity of the observation point to be determined Directivity of 4 adjacent discrete points Interpolation is performed to obtain. Among them, θ s or are the elevation and azimuth angles of the discrete points with known directivity in the local coordinate system; is the angle of the microphone position point after coordinate system transformation.

[0066] ② The microphone position point that needs directivity is not located on the grid line, but is located in the grid, that is, the angle of the microphone position point that needs directivity The two angles θ that are not at the known directivity discrete points s and When the directionality of the microphone is on the axis, the directivity of the 16 adjacent discrete points collected is performed on a two-dimensional cubic spline interpolation to obtain the directivity of the microphone position point; that is, By 16 adjacent points Get, where lie in Between four points.

[0067] S104: Calculating the driving weight of the compensated loudspeaker array by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the desired sound pressure;

[0068] In this embodiment, when the sound field is reproduced in the spatial region, the desired sound pressure vectors at J discrete points in the spatial region can be expressed as When the loudspeaker system is used for playback, the sound pressure generated by the loudspeaker playback system at the J microphones is p(f) = (p1(f), p2(f), ..., p J (f)) T The present invention adopts a sound pressure matching method to solve the driving weight of the loudspeaker system by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the desired sound pressure.

[0069] The cost function of the sound pressure matching method can be expressed as:

[0070]

[0071] The symbol ‖·‖2 represents the calculation method of the l2 norm, the symbol ⊙ represents the Hadamard product of the matrix, that is, the multiplication of the elements at corresponding positions in the matrix, D′ represents the directivity function matrix after the loudspeaker directivity compensation, and G is the transfer function matrix.

[0072] S105: driving each loudspeaker based on the obtained driving weight to achieve sound field reproduction.

[0073] Figure 4-Figure 7 The simulation diagram of this embodiment is given. It can be seen that when the playback frequency is 1000Hz, the real part sound pressure simulation cloud diagram of the spatial sound field after the spatial directivity compensation of the playback device on the horizontal plane is shown in FIG. Figure 5 ) and the real part sound pressure simulation cloud diagram of the spatial sound field to be reproduced on the horizontal plane (such as Figure 4 ) is basically similar in the playback area with a radius of 0.15 meters, and the maximum absolute error does not exceed 1% (such as Figure 6 ), and the relative error is 0.79%. Based on the measured loudspeaker directivity compensation playback simulation (such as Figure 7 ), the relative error in three-dimensional space was reduced by an average of 22.37% when directivity compensation was performed at 400-1000 Hz compared to playback without directivity compensation. The results show that this embodiment can effectively improve the effect of spatial sound field playback.

[0074] Example 2

[0075] In one or more embodiments, a spatial sound field playback system based on directivity compensation of a sound field playback device is disclosed, specifically comprising:

[0076] The loudspeaker directivity acquisition module is used to collect loudspeaker directivity in a discrete hemisphere centered on the loudspeaker using a microphone array, with the location of each microphone being considered as a spatial discrete point.

[0077] A coordinate conversion module, configured to convert the position of the microphone array in the global coordinate system into a position in the local coordinate system based on each loudspeaker;

[0078] A directivity compensation module is used to interpolate and compensate the directivity of the microphone position point after the coordinate system is transformed based on the directivity of the collected spatial discrete points;

[0079] The sound field reproduction module is used to solve the driving weight of the compensated speaker array by minimizing the mean square error between the reproduced sound pressure at the control point of the target area and the desired sound pressure; and drive each speaker based on the obtained driving weight to achieve sound field reproduction.

[0080] It should be noted that the specific implementation of each of the above modules has been described in detail in Example 1 and will not be described in detail here.

[0081] Example 3

[0082] In one or more embodiments, a terminal device is disclosed, including a server. The server includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for spatial sound field playback based on directivity compensation of a sound field playback device in Example 1 is implemented. For the sake of brevity, this description is omitted here.

[0083] It should be understood that in this embodiment, the processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), off-the-shelf field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0084] The memory may include a read-only memory and a random access memory, and provides instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0085] During implementation, each step of the above method may be completed by an integrated logic circuit of hardware in a processor or by instructions in the form of software.

[0086] Example 4

[0087] In one or more embodiments, a computer-readable storage medium is disclosed, which stores a plurality of instructions suitable for being loaded by a processor of a terminal device and executing the spatial sound field playback method based on directivity compensation of a sound field playback device described in Example 1.

[0088] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A spatial sound field playback method based on directivity compensation of a sound field playback device, characterized in that: include: The speaker directivity is collected using a microphone array in a discrete hemisphere centered on the speaker, with the location of each microphone as a discrete point in space. Convert the position of the microphone array in the global coordinate system to the position in the local coordinate system based on each speaker; specifically: in, is the position of the j-th microphone in the global coordinate system, To position the microphone in the global coordinate system Convert to The position of each loudspeaker in the local coordinate system; When converting from the global coordinate system to the local coordinate system of the i-th speaker, the coordinates of the global coordinate system must be converted to the local coordinate system of the i-th speaker. Axis and Axis rotation and Then pan , , ;in, and are the horizontal angle and elevation angle of the loudspeaker in the global coordinate system, , , The origin of the global coordinates is Coordinates in a local coordinate system; Based on the directivity of the collected spatial discrete points, the directivity of the microphone position point after the coordinate system conversion is interpolated and compensated. Specifically, according to the relationship between the directivity of the position to be determined and the directivity of the known position, it is divided into the following cases: When there is a discrete point with known directivity at the microphone location point with required directivity, the directivity of the discrete point is directly adopted as the directivity of the microphone location point; When there is no discrete point with known directivity at the microphone location point with the required directivity, the directivity of the microphone location point needs to be obtained by interpolation using discrete points with known directivity: If the angle of the microphone position point with the required directivity is Two angles at discrete points of known directivity or When the axis is one of the axes, the directivity of the four adjacent discrete points collected is taken for cubic spline interpolation to obtain the directivity of the microphone position point, where or are the elevation and azimuth angles of the discrete points with known directivity in the local coordinate system; If the angle of the microphone position point with the required directivity is Neither of the two angles of the known directivity discrete point and When the microphone is on the axis, the directivity of the 16 adjacent discrete points collected is performed with a two-dimensional cubic spline interpolation to obtain the directivity of the microphone position point; The driving weight of the compensated loudspeaker array is solved by minimizing the mean square error between the playback sound pressure and the desired sound pressure at the control point in the target area, specifically: The cost function of the sound pressure matching method is expressed as: in, Symbolic calculations norm, The symbol represents the Hadamard product of the matrix, that is, the elements at corresponding positions in the matrix are multiplied. Represents the directivity function matrix after the loudspeaker directivity compensation, is the transfer function matrix, in the spatial region The expected sound pressure vector at each discrete point Expressed as , the speaker playback system in The sound pressure generated at the microphone Expressed as , Drive weights for the desired loudspeaker; Find the vector that makes the derivative of the cost function with respect to 𝒒 equal to 0 , get the driving weight of the speaker: in, stands for conjugate transpose, is the regularization parameter, is the identity matrix; Each speaker is driven based on the obtained driving weight to achieve sound field reproduction.

2. The spatial sound field playback method based on directivity compensation of a sound field playback device according to claim 1, characterized in that: The microphone array is used to collect the loudspeaker directivity in a discrete hemisphere centered on the loudspeaker. Specifically: A semicircular microphone array is used, with the microphones of the microphone array being arranged in a horizontal plane. The speakers are evenly arranged at set angles within an angle; the speakers are placed at the center of the semicircular microphone array, a swept frequency signal of unit intensity is used to drive the speakers to sound, and the microphone array is used to collect the sound pressure of the speakers on the semicircle; With the point on the center axis of the loudspeaker as the origin, the circular microphone array is rotated to form a discrete hemisphere of directional collection in space.

3. A spatial sound field playback system based on directivity compensation of a sound field playback device, used to implement the spatial sound field playback method based on directivity compensation of a sound field playback device according to any one of claims 1 to 2, characterized in that: include: The loudspeaker directivity acquisition module is used to collect loudspeaker directivity in a discrete hemisphere centered on the loudspeaker using a microphone array, with the location of each microphone being considered as a spatial discrete point. A coordinate conversion module, configured to convert the position of the microphone array in the global coordinate system into a position in the local coordinate system based on each loudspeaker; A directivity compensation module is used to interpolate and compensate the directivity of the microphone position point after the coordinate system is transformed based on the directivity of the collected spatial discrete points; A sound field playback module, configured to solve the drive weight of the compensated loudspeaker array by minimizing the mean square error between the playback sound pressure at the control point of the target area and the desired sound pressure; Each speaker is driven based on the obtained driving weight to achieve sound field reproduction.

4. A terminal device comprising a processor and a memory, wherein the processor is used to implement instructions; the memory is used to store multiple instructions, characterized in that: The instructions are suitable for being loaded by a processor and executing the spatial sound field playback method based on directivity compensation of a sound field playback device according to any one of claims 1-2.

5. A computer-readable storage medium storing a plurality of instructions, characterized in that: The instructions are suitable for being loaded by a processor of a terminal device and executing the spatial sound field playback method based on directivity compensation of a sound field playback device according to any one of claims 1-2.

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