Sound field reproduction device and program

Abstract

To reduce the amount of calculation required for deriving a drive signal for a speaker when reproducing a desired sound field in a reproduction sound field by a spectral division method.SOLUTION: A moving speed calculation unit 10 of a sound field reproduction device 1 inputs the position (xn, yn) of a primary sound source 101 at a time Tn, and calculates the moving speed (vx, vy). A drive function calculation unit 11 calculates the angular spectrum D(kx,ω) of a drive function of a secondary sound source 102 by using the following formula on the basis of the moving speed (vx, vy), the input signal s(τ) from a time Tn-1 to a time Tn, and the position (xn-1, yn-1)=(xs0, ys0), and the preset sound speed c and the y value yr of a reference position. F(ω) can be obtained by Fourier-transforming f(τ).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to technology related to object acoustics in games, AR (Augmented Reality), VR (Virtual Reality), etc., and in particular to a sound field reproduction device and program that uses a spectral division method to model, describe, and reproduce sound sources that serve as objects. [Background technology]

[0002] BACKGROUND ART Conventionally, a sound field reproduction and synthesis method is known for reproducing and synthesizing a desired sound field in a sound reproduction field (a field in which sound is reproduced) using a plurality of speakers.

[0003] Figure 5 is a diagram explaining the sound field reproduction and synthesis method. A sound field formed by radiating sound waves from a certain sound source (hereinafter referred to as "primary sound source 101") is called a "desired sound field." Also, another location where the desired sound field is reproduced and synthesized using a speaker array (hereinafter referred to as "secondary sound source 102") consisting of speakers arranged in a line is called a "reproduced sound field."

[0004] The left side of Fig. 5 shows a desired sound field formed by sound waves emitted from a bell, which is a primary sound source 101. The secondary sound source 102 shown on the left side of Fig. 5 shows a case where a speaker placed in a reproduction sound field is reflected in the desired sound field, rather than a speaker placed in the desired sound field. The right side of Fig. 5 shows a reproduction sound field in which the desired sound field is reproduced and synthesized by driving the secondary sound source 102 when the desired sound field is formed by reproduction of the primary sound source 101.

[0005] Since it is usually difficult to completely match the entire sound field between the desired sound field and the reproduced sound field, a linear reference position is determined in advance as shown in Fig. 5. At this reference position, a drive signal for the secondary sound source is determined so that the sound (sound pressure) radiated from primary sound source 101 matches the sound radiated from secondary sound source 102. If secondary sound source 102 is a linear speaker array, the reference position is also linear at a position parallel to and a certain distance away from the speaker array.

[0006] As a result, the desired sound field is reproduced at the reference position of the reproduced sound field. As the distance from the reference position increases, the error gradually increases and the reproducibility decreases, but it is known that even if the reproducibility decreases to a certain extent, it does not cause a major problem to the ear.

[0007] In order to match the sounds of the desired sound field and the reproduced sound field at the reference position, it is necessary to compare the sound pressure at the reference position due to the propagation of sound from the primary sound source 101 with the sound pressure at the reference position due to the propagation of sound from the secondary sound source 102, and calculate a drive signal for the secondary sound source 102 that will match them.

[0008] In general, sound propagation is represented by an impulse response in the time domain, and is represented by a transfer function in the time-frequency domain, which is obtained by subjecting the time-domain impulse response to a time Fourier transform.

[0009] In this case, if the sound pressure (transfer function) in the sound field in the desired sound field is P, the transfer function from the secondary sound source 102 to each point in the sound field in the reproduction sound field is G, and the drive function (transfer function) of the secondary sound source 102 in the reproduction sound field is D, then it can be expressed by the following equation.

number

[0010] Furthermore, if the results in the spatiotemporal frequency domain (wavenumber domain) obtained by spatial Fourier transforming P, G, and D in space are P￣, G￣, and D￣ (hereinafter referred to as "angular spectrum"), respectively, the convolution operation becomes a product operation, and the relationship is expressed by the following equation.

number

[0011] That is, the angular spectrum D of the driving function of the secondary sound source 102 is calculated so that the signal obtained by multiplying the angular spectrum D of the driving function of the secondary sound source 102 by the angular spectrum G of the transfer function from the secondary sound source 102 to each point in the sound field matches the angular spectrum P of the sound pressure in the desired sound field.

[0012] Therefore, the angular spectrum D of the driving function of the secondary sound source 102 is expressed by a division formula as follows:

number

[0013] This method of calculating the driving function by dividing the angular spectrum is called the "spectral division method." The signal (driving signal) for driving the speaker array, which is the secondary sound source 102, is obtained as a time signal by performing an inverse Fourier transform on the angular spectrum D of the driving function of the secondary sound source 102 in equation (3).

[0014] Fig. 6 is a diagram for explaining the arrangement of a sound source in a Cartesian coordinate system. When a stationary sound source is at the origin in the free space of the Cartesian coordinate system shown in Fig. 6, the impulse response between the coordinates (x, y, z) is expressed by the following equation:

number

[0015] The transfer function obtained by subjecting the impulse response of the above-mentioned equation (4) to a time Fourier transform on the time axis is expressed by the following equation.

number

[0016] The angular spectrum obtained by spatial Fourier transforming the transfer function of the above equation (5) in the x-axis direction is expressed by the following equation.

number

[0017] On the other hand, when the sound source moves, the sound pressure at the position of coordinates (x, y, z) is expressed as follows: the input signal (the driving signal of the primary sound source 101, the sound source signal) at time τ is expressed as s(τ), and the position of the primary sound source 101 is expressed as the sound source position r s (τ)=(x s (τ),y s (τ),z s (τ)), it can be expressed by the following equation.

number

[0018] The angular spectrum obtained by subjecting the sound pressure of the above equation (7) to a time Fourier transform on the time axis and then a spatial Fourier transform in the x-axis direction is expressed by the following equation (see Non-Patent Documents 1 and 2).

number

[0019] [Non-Patent Document 1] Firtha Gergely and Fiala Peter, “Sound Field Synthesis of Uniformly Moving Virtual Monopoles”, JAES Volume 63 Issue 1 / 2 pp. 46-53, January 2015 [Non-patent document 2] Sasaki, Matsui, Nakayama, "Reproduction of sound fields formed by moving sound sources using SDM," Acoustical Society of Japan 2021 Spring Meeting, Sound Lectures (Spring), 2-1P-5, 2021 Summary of the Invention [Problem to be solved by the invention]

[0020] As shown in Fig. 6, the angular spectrum G from the speaker array, which is the secondary sound source 102 arranged linearly on the x-axis (the angular spectrum of the transfer function from the secondary sound source 102 to each point in the reproduction sound field) is expressed by the above formula (6). Also, the angular spectrum P of the sound pressure formed by the propagation of sound from the moving primary sound source 101 (the angular spectrum of the sound pressure in the desired sound field) is expressed by the above formula (8).

[0021] By substituting the equations (6) and (8) into the equation (3), the angular spectrum of the driving function (the angular spectrum of the driving function of the secondary sound source 102) D is expressed by the following equation.

number

[0022] As shown in Figure 6, the linear reference position is (x, y r ,z r ), the above formula (9) can be expressed as follows:

number

[0023] When the primary sound source 101 moves, in order to synthesize its trajectory (movement locus) in the playback sound field, it is necessary to integrate the input signal s(τ) and the angular spectrum representing the trajectory along the time axis, as shown in equation (10). This integration process increases the amount of calculation required to derive the angular spectrum D of the driving function shown in equation (10).

[0024] Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to provide a sound field reproduction device and program that can reduce the amount of calculation required to derive speaker drive signals when reproducing a desired sound field in a playback sound field using the spectral division method. [Means for solving the problem]

[0025] In order to solve the above problem, the sound field reproduction device of claim 1 is a sound field reproduction device that generates a drive signal for reproducing a sound field formed by a moving primary sound source using a speaker array of a secondary sound source, wherein s(τ) is a sound source signal of the primary sound source at time τ, and H0 (2) Let (·) be the 0th order Hankel function of the second kind, ω be the angular frequency, c be the speed of sound, and k x is the wave number in the x-axis direction, and y r ,z r Let be the y and z values ​​of the linear reference position, and (x s (τ),y s (τ),z s (τ)) is the position of the primary sound source at the time τ, and the angular spectrum D̂(k x ,ω) is the formula for the angular spectrum by the spectral division method: TIFF0007799501000011.tif26170, the primary sound source and the secondary sound source are arranged on the xy plane, and the description of the z axis is omitted. The nth (n is an integer of 1 or more) trajectory sampling time T n The position (x n ,y n ) and enter the time T n-1 ,T n The position (x n-1 ,y n-1 ),(x n ,y n ) based on time T n The moving speed of the primary sound source (v x ,v y ) and a moving speed calculation unit that calculates the time Tn-1 From time T n The signal s(τ) between n-1 The position (x n-1 ,y n-1 ) at the position (x s0 ,y s0 ), and the preset sound speed c and the y value y of the reference position r Based on the above, the Hankel function H0 (2) The equation expressed by approximating (·) with an exponential function and approximating the trajectory of the primary sound source with continuous uniform linear motion is: TIFF0007799501000012.tif17170(F(ω) is the formula: TIFF0007799501000013.tif16170 is used to obtain the spectrum obtained by Fourier transform. x , ω), and the angular spectrum D̂(k x and a drive signal calculation unit that calculates the drive signal in the time domain by performing an inverse Fourier transform on the drive signal.

[0026] The sound field reproduction device of claim 2 is the sound field reproduction device of claim 1, further comprising: a buffer in which the drive signal is stored; and a drive signal writing unit that writes the drive signal calculated by the drive signal calculation unit into the buffer, and the drive signal writing unit writes the drive signal calculated by the drive signal calculation unit at time T n-1 From time T n The time T calculated corresponding to the signal s(τ) between n-1 From time T n Time T n When the calculated drive signals (D1 and D2) for the period up to +a1 are written into the buffer, the time T n-1 From the time T n-1 Time T n-1 +a2, the drive signal (D0) is n-1From the time T n-1 +a2, the calculated drive signal (D1) is added and written, and the time T n-1 +a2 to the time T n The calculated drive signal (D2) up to +a1 is written as is.

[0027] Furthermore, the program of claim 3 is a program for causing a computer constituting a sound field reproduction device to generate a drive signal for reproducing a sound field formed by a moving primary sound source using a speaker array of a secondary sound source, by setting s(τ) as the sound source signal of the primary sound source at time τ, and (2) Let (·) be the 0th order Hankel function of the second kind, ω be the angular frequency, c be the speed of sound, and k x is the wave number in the x-axis direction, and y r ,z r Let be the y and z values ​​of the linear reference position, and (x s (τ),y s (τ),z s (τ)) is the position of the primary sound source at the time τ, and the angular spectrum D̂(k x ,ω) is the formula for the angular spectrum by the spectral division method: TIFF0007799501000014.tif26170, the primary sound source and the secondary sound source are arranged on the xy plane, and the description of the z axis is omitted. The nth (n is an integer of 1 or more) trajectory sampling time T n The position (x n ,y n ) and enter the time T n-1 ,T n The position (x n-1 ,y n-1 ),(x n ,y n ) based on time T n The moving speed of the primary sound source (v x ,v y ), the moving speed calculation unit calculates the time T n-1 From time T n The signal s(τ) between n-1The position (x n-1 ,y n-1 ) at the position (x s0 ,y s0 ), and the preset sound speed c and the y value y of the reference position r Based on the above, the Hankel function H0 (2) The equation expressed by approximating (·) with an exponential function and approximating the trajectory of the primary sound source with continuous uniform linear motion is: TIFF0007799501000015.tif17170(F(ω) is the formula: TIFF0007799501000016.tif16170 is used to obtain the spectrum obtained by Fourier transform. x , ω), and the angular spectrum D̂(k x , ω) to function as a drive signal calculation unit that calculates the drive signal in the time domain. [Effects of the Invention]

[0028] As described above, according to the present invention, when a desired sound field is reproduced in a reproduced sound field by the spectral division method, the amount of calculation required to derive a drive signal for a speaker can be reduced. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a block diagram illustrating an example of the configuration of a sound field reproduction device according to an embodiment of the present invention. [Figure 2] 10 is a flowchart illustrating an example of processing by the sound field reproduction device. [Figure 3] FIG. 1 is a diagram illustrating approximation of the trajectory of a primary sound source. [Figure 4] 10A and 10B are diagrams illustrating an example of processing by a drive signal writing unit. [Figure 5] FIG. 1 is a diagram illustrating a sound field reproduction and synthesis method. [Figure 6]FIG. 2 is a diagram illustrating the arrangement of sound sources in a Cartesian coordinate system. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present invention, when the primary sound source 101 moves on an arbitrary trajectory, the Hankel function H0 (2) (·) is approximated by an exponential function, and the trajectory of the primary sound source 101 is approximated by continuous uniform linear motion, and the angular spectrum D of the driving function of the secondary sound source 102 is found using the functions defined by these approximations.

[0031] As a result, the function representing the acoustic propagation from the primary sound source 101 can be expressed by a simpler function, and the trajectory of the primary sound source 101 is expressed by a trajectory of uniform linear motion, so the function reflecting these can be expressed by a simple formula.

[0032] That is, as will be described later, the integral operation of the above equation (10) can be expressed as an operation of shifting the amplitude and phase of a predetermined function in the spatiotemporal frequency domain, thereby reducing the amount of calculation required for the spectral division method.

[0033] Summary of the Invention First, we will explain the approximation of the angular spectrum D of the driving function of the secondary sound source 102 shown in the above equation (10). For simplicity of explanation, we will assume that z = z for both the primary sound source 101 and the secondary sound source 102. n It is assumed that the primary sound source 101 moves on the xy plane, and the description of the z axis will be omitted below.

[0034] In the above equation (10), the Hankel function H0 (2) (·) is approximated by the Hankel function H0 (2) (·) can be asymptotically (for large values ​​of its argument) approximated by an exponential function, as shown in the following equation:

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[0035] By applying the approximation of the formula (11) to the formula (10), the formula (10) can be expressed as follows:

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[0036] where k y is expressed by the following formula:

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[0037] In addition, the arbitrary sound source position r s The trajectory of (τ) is approximated by a uniform linear motion, and the position (the sound source position r s (τ)) to (x s0 +v x τ,y s0 +v y τ), where (x s0 ,y s0 ) is the source position at time τ=0, and v x ,v y are the movement speeds in the x-axis and y-axis directions, respectively.

[0038] sound source position r s By approximating the trajectory of (τ) with uniform linear motion, the above equation (12) can be expressed as follows:

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[0039] Here, the spectrum F(ω) is obtained by Fourier transforming the following f(τ):

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[0040] In the above equation (15), f(τ) represents an equation in which the amplitude is corrected for the input signal s(τ). In other words, the angular spectrum D of the driving function of the secondary sound source 102 shown in the above equation (14) is expressed by the following frequency with respect to the spectrum F(ω):

number

number

[0041] In this way, by using the formula (14) when calculating the angular spectrum D of the drive function of the secondary sound source 102, it is not necessary to perform the integration operation of the formula (10), and therefore the amount of calculation required for its derivation can be reduced. Therefore, when reproducing a desired sound field in a reproduced sound field by the spectral division method, the amount of calculation required for deriving the drive signal for the speaker can be reduced.

[0042] [Sound field reproduction device] Next, a sound field reproduction device according to an embodiment of the present invention will be described. Fig. 1 is a block diagram showing an example of the configuration of a sound field reproduction device according to an embodiment of the present invention. Fig. 2 is a flowchart showing an example of processing performed by the sound field reproduction device, and n This shows the flow of processing at time T n is assumed to coincide with the timing of the discretized trajectory sampling of the primary sound source 101.

[0043] This sound field reproduction device 1 includes a movement speed calculation unit 10, a drive function calculation unit 11, a drive signal calculation unit 12, a drive signal writing unit 13, and a buffer (playback buffer) 14. The buffer 14 is a playback buffer that stores drive signals for a secondary sound source 102 and plays back sounds of a desired sound field in a playback sound field using the drive signals.

[0044] The moving speed calculation unit 10 calculates the moving speed T n The position of the primary sound source 101 in (x n ,y n) is input (step S201). Then, the moving speed calculation unit 10 calculates the moving speed T n-1 ,T n The position of the primary sound source 101 in (x n-1 ,y n-1 ),(x n ,y n ) based on time T n The moving speed of the primary sound source 101 (v x ,v y ) (step S202). The moving speed calculation unit 10 calculates the moving speed T n The moving speed of the primary sound source 101 (v x ,v y ) is output to the driving function calculation unit 11.

[0045] movement speed v x is the moving speed of the primary sound source 101 in the x-axis direction, and the moving speed v y is the moving speed of the primary sound source 101 in the y-axis direction.

[0046] Specifically, the moving speed calculation unit 10 calculates the moving speed at time T n The previous orbit sampling time T n-1 to the current time T n The primary sound source 101 is assumed to be moving at a constant speed in a straight line between the time x ,v y ) is calculated.

number

number

[0047] 3 is a diagram illustrating the approximation of the trajectory of the primary sound source 101. An arbitrary trajectory of the primary sound source 101 is sampled at a fixed trajectory sampling period (times T1, T2, ...). Then, the trajectory of the primary sound source 101 is approximated so that it moves at a uniform linear motion between the trajectory sampled positions during the time period between times T1, T2, ....

[0048] That is, the moving speed calculation unit 10 approximates an arbitrary trajectory of the primary sound source 101 to a trajectory of uniform linear motion at the trajectory sampling period, and calculates the moving speed (v x ,v y ) is calculated.

[0049] 1 and 2, the driving function calculation unit 11 receives the time T n The moving speed of the primary sound source 101 (v x ,v y ) and time T n The position of the primary sound source 101 in (x n ,y n ), and then input the preset sound speed c and reference position (x, y r ,z r ) y value y r The driving function calculation unit 11 also inputs the time T n-1 From time T n An input signal s(τ) that is a sound source signal of the primary sound source 101 in the time period from is input (step S203).

[0050] The driving function calculation unit 11 calculates the driving function at time T n The previous orbit sampling time T n-1 The position of the primary sound source 101 in (x n-1 ,y n-1 ) to the position (x s0 ,y s0 ) and time T n-1 The timing is set to t=0.

[0051] The driving function calculation unit 11 calculates the driving function at time T n The moving speed of the primary sound source 101 (v x ,v y ), time T n-1 From time T n The input signal s(τ) in the time period between n-1 The position of the primary sound source 101 in (x n-1 ,y n-1 ) at the position (x s0 ,y s0 ), and the preset sound speed c and reference position (x, yr ,z r ) y value y r Based on this, the wave number k in the x-axis direction is calculated using the equations (14) and (15). x and the angular spectrum D̃(k x , ω) is calculated (step S204).

[0052] Specifically, the driving function calculation unit 11 obtains the spectrum F(ω) by Fourier transforming f(τ) in the above formula (15). Then, as shown in the above formula (14), the driving function calculation unit 11 shifts the frequency shown in the above formula (16) and the phase shown in the above formula (17) with respect to the spectrum F(ω), thereby obtaining the angular spectrum D(k x ,ω).

[0053] The driving function calculation unit 11 calculates the driving function at time T n The angular spectrum D̂(k x , ω) to the drive signal calculation unit 12.

[0054] The drive signal calculation unit 12 receives the drive function from the drive function calculation unit 11 at time T n The angular spectrum D̂(k x , ω) is input to the drive signal calculation unit 12. Then, the drive signal calculation unit 12 calculates the angular spectrum D(k x , ω) is inverse Fourier transformed into a time domain excitation signal D(x,t) for the secondary sound source 102 with the x value in the xyz space and the time t as variables (step S205).

[0055] Specifically, the drive signal calculation unit 12 calculates the angular spectrum D(k x, ω) to obtain a driving function D(x, ω) in the time-frequency domain. The driving signal calculation unit 12 then performs an inverse Fourier transform on the driving function D(x, ω) in the time-frequency domain to obtain a driving signal D(x, t) in the time domain. This driving signal D(x, t) is calculated for each speaker (for each x (for each x coordinate value) specified by the position of the speaker) that constitutes the speaker array that is the secondary sound source 102.

[0056] The drive signal calculation unit 12 calculates the n The time domain excitation signal D(x, t) of the secondary sound source 102 in the above equation is output to the excitation signal writing unit 13 .

[0057] The drive signal writing unit 13 receives the drive signal from the drive signal calculation unit 12 at time T n The time domain excitation signal D(x, t) of the secondary sound source 102 in is input, and the excitation signal D(x, t) is written into the buffer 14 (step S206).

[0058] 4 is a diagram illustrating an example of processing by the drive signal writing unit 13. Here, the time domain drive signal D(x, t) of the secondary sound source 102 calculated by the drive signal calculation unit 12 and input to the drive signal writing unit 13 is n-1 From time T n is a signal corresponding to the input signal s(τ) in the time period between

[0059] As shown in Figure 4, at time T n Processing (time T n-1 From time T n The time length (time length of the drive signals D1 and D2) of the time domain drive signal D(x, t) of the secondary sound source 102 corresponding to the process using the time period up to the time T n-1 From time T n This can be longer than the time length from the primary sound source 101 to the reference position (x, y r ,z r ) and the distance from the secondary sound source 102 to the reference position (x, y r ,z r This is because delays and other factors caused by the difference in distance between the

[0060] In this case, the drive signals already written in the buffer 14 at time T n-1 The time domain beyond (time T n-1 From time T n-1 +a2) and the drive signal calculation unit 12 calculates the drive signal D0 at time T n The drive signal D(x, t) (time T n-1 From time T n Time T n Among the drive signals D1 and D2 between the time T n-1 From time T n-1 The driving signal D1 in the time domain between a1 and a2 overlaps on the time axis. a1 and a2 are positive real numbers.

[0061] Therefore, the drive signal writing unit 13 calculates the time T n When the drive signal D(x, t) (D1 and D2) calculated by the process above is written to the buffer 14, the time T n-1 For the drive signal D0 exceeding the time T n-1 Time T n-1 +a2 and writes the addition result into the buffer 14. n-1 +a2 and after (time T n-1 +a2 to time T n The drive signal D2) up to +a1 is written to the buffer 14 as is.

[0062] As a result, the buffer 14 stores the time T n-1 From time T n-1 The drive signal D0+D1 is written as the drive signal for the time domain up to +a2, and the drive signal D0+D1 is written as the drive signal for the time domain up to +a2. n-1 +a2 to time T n The drive signal D2 is written as the drive signal for the time domain up to +a1.

[0063] The buffer 14 shown in FIG. 4 indicates a buffer corresponding to each speaker that constitutes the speaker array that is the secondary sound source 102, and similar processing is performed for each speaker.

[0064] That is, the drive signal calculation unit 12 calculates the time domain drive signal D(x, t) of the secondary sound source 102 for each speaker (for each x (for each x coordinate value) specified by the position of the speaker) that constitutes the speaker array, which is the secondary sound source 102. Then, the drive signal writing unit 13 writes the time domain drive signal D(x, t) of the secondary sound source 102 into the buffer 14 for each speaker that constitutes the speaker array, which is the secondary sound source 102.

[0065] Returning to Figures 1 and 2, the sound field reproduction device 1 determines whether or not the input signal s(τ) has a continuation (step S207), and if it determines that there is a continuation (step S207: Y), it increments n to set it to n+1 (step S208) and proceeds to step S201.

[0066] This allows the next orbit sampling time (current time) T n The position of the primary sound source 101 in (x n ,y n ) is input, and the time T n The processing of steps S201 to S206 is performed for the input signal s(τ). n Based on time T n-1 From time T n The signal in the time period between is used.

[0067] If the sound field reproduction device 1 determines in step S207 that the input signal s(τ) has no continuation (step S207: N), the sound field reproduction device 1 ends the processing.

[0068] As described above, according to the sound field reproduction device 1 of the embodiment of the present invention, the moving speed calculation unit 10 calculates the moving speed at the trajectory sampling time T n The position of the primary sound source 101 in (x n ,y n) and enter the time T n-1 ,T n The position of the primary sound source 101 in (x n-1 ,y n-1 ),(x n ,y n ) based on time T n The moving speed of the primary sound source 101 (v x ,v y ) is calculated.

[0069] The driving function calculation unit 11 calculates the driving function at time T n The moving speed of the primary sound source 101 (v x ,v y ), time T n-1 From time T n The input signal s(τ) in the time period between n-1 The position of the primary sound source 101 in (x n-1 ,y n-1 ) at the position (x s0 ,y s0 ), and the preset sound speed c and reference position (x, y r ,z r ) y value y r Based on this, the angular spectrum D̂(k x ,ω) is calculated.

[0070] The equations (14) and (15) are the Hankel function H0 (2) This is an equation obtained by approximating (·) by an exponential function and approximating the trajectory of the primary sound source 101 by continuous uniform linear motion. x , ω) is expressed by an arithmetic expression in which the amplitude and phase of the spectrum F(ω) obtained by Fourier transforming the function f(τ) of the above equation (15) are shifted.

[0071] The drive signal calculation unit 12 calculates the n The angular spectrum D̂(k x ,ω) is inverse Fourier transformed to obtain the time T nThe time domain excitation signal D(x, t) of the secondary sound source 102 at

[0072] The drive signal writing unit 13 writes the drive signal at time T n When writing the time domain excitation signal D(x,t) (D1 and D2) of the secondary sound source 102 at time T n-1 For the drive signal D0 exceeding the time T n-1 Time T n-1 The drive signal D1 up to +a2 is added to the drive signal D0 and written, and at time T n-1 The drive signal D2 after +a2 is written as is.

[0073] In this way, in the sound field reproduction and synthesis method using a speaker array, which is a linearly arranged secondary sound source 102, when the primary sound source 101 moves on an arbitrary trajectory, the function representing the acoustic propagation from the primary sound source 101 is approximated, and the trajectory is approximated by a continuous uniform linear motion. As a result, the angular spectrum D̂(k x , ω) can be reduced.

[0074] In other words, when a desired sound field is reproduced as a reproduced sound field by the vector division method, the amount of calculation required to derive a drive signal for a speaker can be reduced.

[0075] Here, the trajectory of the primary sound source 101 is approximated to a linear one by continuous uniform linear motion. According to the experiment by the inventor of the present application, n The results show that by shortening the interval between the two to a certain extent, the approximation can be made unnoticeable. Therefore, the processing according to the embodiment of the present invention can be implemented even in hardware and software with low machine power, and users of the sound field reproduction device 1 can enjoy sound field synthesis in a wide range of playback environments.

[0076] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the technical concept thereof.

[0077] A normal computer can be used as the hardware configuration of the sound field reproduction device 1 according to the embodiment of the present invention. The sound field reproduction device 1 is configured by a computer equipped with a CPU, a volatile storage medium such as RAM, a non-volatile storage medium such as ROM, an interface, etc.

[0078] The functions of the movement speed calculation unit 10, the drive function calculation unit 11, the drive signal calculation unit 12, the drive signal writing unit 13 and the buffer 14 provided in the sound field reproduction device 1 are each realized by having a CPU execute a program that describes these functions.

[0079] These programs are stored in the storage medium and are read and executed by the CPU. These programs can also be stored in a storage medium such as a magnetic disk (e.g., a floppy disk, a hard disk), an optical disk (e.g., a CD-ROM, a DVD), or a semiconductor memory and distributed, or can be transmitted and received via a network. [Explanation of symbols]

[0080] 1. Sound field reproduction device 10 Movement speed calculation section 11. Driving function calculation unit 12 Drive signal calculation unit 13 Drive signal writing unit 14 buffers 101 Primary Sound Source 102 Secondary Sound Source P is the sound pressure in the desired sound field P̂ Angular spectrum of sound pressure in the desired sound field G Transfer function from a secondary sound source to each point in the reproduced sound field Ĝ Angular spectrum of the transfer function from the secondary sound source to each point in the reproduced sound field D Driving function of secondary sound source D̂ Angular spectrum of the driving function of a second-order sound source (x n ,y n ) Position of the primary sound source (v x ,v y ) Moving speed of the primary sound source s(τ) Input signal (sound source signal of the primary sound source) c speed of sound (x,y r ,z r ) Reference position

Claims

1. A sound field reproduction device that generates a drive signal for reproducing a sound field formed by a moving primary sound source using a speaker array of a secondary sound source, Let s(τ) be the sound source signal of the primary sound source at time τ, and H 0 (2) Let (·) be the 0th order Hankel function of the second kind, ω be the angular frequency, c be the speed of sound, and k x is the wave number in the x-axis direction, and y r , z r Let be the y and z values ​​of the linear reference position, and (x s (τ), y s (τ), z s (τ)) is the position of the primary sound source at the time τ, The angular spectrum D(k x , ω) is the formula for the angular spectrum by the spectral division method: When the primary sound source and the secondary sound source are arranged on an xy plane and the description regarding the z axis is omitted, The n-th (n is an integer equal to or greater than 1) trajectory sampling time T n The position (x n , y n ) and enter the time T n-1 , T n The position (x n-1 , y n-1 ), (x n , y n ) at time T n The moving speed of the primary sound source (v x , v y a moving speed calculation unit that calculates the moving speed; Time T n-1 From time T n signal s(τ) between time T n-1 The position (x n-1 , y n-1 ) at the position (x s0 , y s0 ), and the preset sound speed c and y value y of the reference position r Based on the above, the Hankel function H 0 (2) (·) is approximated by an exponential function, and the trajectory of the primary sound source is approximated by continuous uniform linear motion to obtain the following equation: (F(ω) is the formula: is used to obtain the angular spectrum D(k x a driving function calculation unit that calculates the The angular spectrum D(k x a drive signal calculation unit that calculates the drive signal in the time domain by performing an inverse Fourier transform on the time domain signal (ω, ω); A sound field reproduction device comprising:

2. 2. The sound field reproduction device according to claim 1, a buffer in which the drive signal is stored; a drive signal writing unit that writes the drive signal calculated by the drive signal calculation unit into the buffer, The drive signal writing unit writes the calculated drive signals (D1 and D2) from time T n-1 to time T n corresponding to the signal s(τ) to the buffer when writing the drive signals (D1 and D2) calculated from time T n-1 to time T n exceeding time T n + a1 to the buffer. When writing, the drive signal (D0) from time T n-1 to time T n-1 exceeding time T n-1 + a2 is added with the calculated drive signal (D1) from time T n-1 to time T n-1 + a2 and written, and the calculated drive signal (D2) from time T n-1 + a2 to time T n + a1 is written as it is. A sound field reproduction apparatus characterized by this.

3. a computer constituting a sound field reproduction device that generates a drive signal for reproducing a sound field formed by a moving primary sound source using a speaker array of a secondary sound source; Let s(τ) be the sound source signal of the primary sound source at time τ, and H 0 (2) Let (·) be the 0th order Hankel function of the second kind, ω be the angular frequency, c be the speed of sound, and k x is the wave number in the x-axis direction, and y r , z r Let be the y and z values ​​of the linear reference position, and (x s (τ), y s (τ), z s (τ)) is the position of the primary sound source at the time τ, The angular spectrum D(k x , ω) is the formula for the angular spectrum by the spectral division method: When the primary sound source and the secondary sound source are arranged on an xy plane and the description regarding the z axis is omitted, The n-th (n is an integer equal to or greater than 1) trajectory sampling time T n The position (x n , y n ) and enter the time T n-1 , T n The position (x n-1 , y n-1 ), (x n , y n ) at time T n The moving speed of the primary sound source (v x , v y a moving speed calculation unit that calculates Time T n-1 From time T n signal s(τ) between time T n-1 The position (x n-1 , y n-1 ) at the position (x s0 , y s0 ), and the preset sound speed c and y value y of the reference position r Based on the above, the Hankel function H 0 (2) (·) is approximated by an exponential function, and the trajectory of the primary sound source is approximated by continuous uniform linear motion to obtain the following equation: (F(ω) is the formula: is used to obtain the angular spectrum D(k x , ω), and The angular spectrum D(k x , ω) to function as a drive signal calculation unit that calculates the drive signal in the time domain by performing an inverse Fourier transform.

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