JP5603307B2 - Sound field recording / reproducing apparatus, method, and program - Google Patents

Description

  The present invention relates to a technique of wave field synthesis that collects a sound signal with a microphone array installed in a certain sound field and reproduces the sound field with a speaker array using the sound signal.

  Non-Patent Document 1, for example, describes a wave field synthesis technique for collecting a signal with a microphone array installed in a certain sound field and reproducing the sound field with the speaker array using the signal. Technologies are known.

  In Non-Patent Document 1, the sound field is reproduced using a filter that is approximately calculated by ignoring the contribution of a minute wave that propagates only in the vicinity of a sound source called an evanescent wave.

Shoichi Koyama, 3 others, “Manipulation of wavefront synthesis position by back propagation calculation”, Proceedings of the Acoustical Society of Japan, September 2010

  However, in Non-Patent Document 1, approximate calculation that ignores the evanescent wave is performed, and the accuracy of sound field reproduction may not be sufficient.

  An object of the present invention is to provide a sound field collecting / reproducing apparatus, method, and program with higher accuracy of sound field reproduction than before.

In order to solve the above problems, in the sound field sound-collecting / reproducing apparatus according to one aspect of the present invention, the microphone array is arranged on the xz plane, j is an imaginary unit, ω is a frequency, and c is a sound velocity. , K = ω / c, k _{x, n} is the wave number in the x-axis direction, n is the index, k _{z, m} is the wave number in the z-axis direction, m is the index, and the sound is picked up by the microphone array Generated based on the signal collected by the microphone array, where d is the distance when the front direction of the speaker array is positive with the position where the signal is reproduced and the speaker array arranged in a plane and outputting the time domain signal. A transform filter unit that generates a filtered signal D to _nm (ω) by applying a filter F to _nm (ω) defined by the following equation to the spatiotemporal frequency domain signal P to _nm (ω) ,

A spatial frequency inverse transform unit that transforms the filtered signal D to _nm (ω) into a frequency domain signal by inverse Fourier transform of space, and a frequency inverse transform unit that transforms the frequency domain signal into a time domain signal by inverse Fourier transform. ,including.

In the sound field sound collecting and reproducing device according to another aspect of the present invention, the microphone array is arranged on the xz plane, j is an imaginary unit, ω is a frequency, c is a sound velocity, and k = ω / c, k _{x, n} is the wave number in the x-axis direction, n is the index, k _{z, m} is the wave number in the z-axis direction, m is the index, and the position and plane to reproduce the signal collected by the microphone array The frequency conversion that converts the signal collected by the microphone array into the frequency domain signal by Fourier transform, where d is the distance when the front direction of the speaker array is positive with the speaker array that is placed in the time domain and outputs the time domain signal And a spatial frequency converter for converting a frequency domain signal into a spatio-temporal frequency domain signal P to _nm (ω) by Fourier transform of the space, and for a spatio-temporal frequency domain signal P to _nm (ω), filter processing by applying a filter F ~ _nm (ω), which is defined Comprising a conversion filter unit which generates post signals D ~ _nm (ω), the.

  By designing the filter by frequency-converting all of the parameters relating to the time axis and the parameters relating to position information, it is not necessary to perform an approximate calculation that ignores the evanescent wave. Therefore, the accuracy of sound source reproduction is higher than in the prior art.

The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 1st embodiment. The figure for demonstrating the example of arrangement | positioning of the microphone array and speaker array of the sound field sound collection reproducing | regenerating apparatus of 1st embodiment. The flowchart which shows the example of the sound field sound collection reproduction | regeneration method of 1st embodiment and 2nd embodiment. The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 2nd embodiment. The figure for demonstrating the example of arrangement | positioning of the microphone array and speaker array of the sound field sound collection reproducing | regenerating apparatus of 2nd embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
As shown in FIG. 2, the sound field collecting and reproducing apparatus and method according to the first embodiment are two-dimensionally configured by N _x × N _z microphones arranged at a position of y = 0 in the first room. Two-dimensional speaker arrays S1-1 and S2-1 composed of microphone arrays M1-1, M2-1,..., MN _x -N _z and N _x × N _z speakers arranged in the second room. ,..., SN _x -N _z is used to reproduce the sound field of the first room formed by the sound generated by the sound source S in the second room.

N _x and N _z are arbitrary integers. Microphone array _{M1-1, M2-1, ..., MN x} -N microphone having a speaker array S1-1 constituting the _z, S2-1, ..., the number of speakers constituting the _SN x -N _z is the same is there. The microphones Mi-j constituting the microphone arrays M1-1, M2-1,..., MN _x -N _z are arranged at equal intervals. Speakers constituting the speaker arrays S1-1, S2-1,..., SN _x -N _z are also arranged at equal intervals. Microphone array M1-1, M2-1, ..., and the size of _MN x -N _z, a speaker array S1-1, S2-1, ..., the magnitude of _SN x -N _z are approximately the same. Microphone array M1-1 of the microphones Mi-j, M2-1, ..., position in _MN x -N _z is the speaker Si-j of the speaker array S1-1 corresponding to the respective microphones Mi-j, S2-1 ,..., SN _x −N _z is preferably the same as the position, but may be different. If this position is the same, the sound field can be reproduced more faithfully.

The positions of the microphones constituting the microphone arrays M1-1, M2-1,..., MN _x -N _z arranged at the position of y = 0 in the first room are expressed as r _s = (x _i , 0, z _j ).

  As shown in FIG. 1, the sound field sound collecting and reproducing apparatus according to the first embodiment includes a frequency conversion unit 1, a spatial frequency conversion unit 2, a conversion filter unit 3, a spatial frequency reverse conversion unit 4, a frequency reverse conversion unit 5, and a window function. The process of each step illustrated by FIG. 3 is performed including the part 6, for example.

The two-dimensional microphone arrays M1-1, M2-1,..., MN _x -N _z arranged at the position of y = 0 in the first room collect the sound emitted from the sound source S in the first room. Thus, a time domain signal is generated. The generated signal is sent to the frequency converter 1. A signal at time t in the time domain picked up by the microphone Mi-j of r _s = (x _i , 0, z _j ) is expressed as p _ij (t).

The frequency converter 1 converts the signal p _ij (t) collected by the microphone arrays M1-1, M2-1,..., MN _x −N _z into a frequency domain signal P _ij (ω) by Fourier transform ( Step S1). The generated frequency domain signal P _ij (ω) is sent to the spatial frequency converter 2. ω is a frequency. For example, the frequency domain signal P _ij (ω) is generated by short-time discrete Fourier transform. Of course, the frequency domain signal P _ij (ω) may be generated by other existing methods. For example, the frequency domain signal P _ij (ω) is defined as follows. J in the argument of the function exp is an imaginary unit.

Spatial frequency transformation unit 2, a frequency-domain signal P _ij (omega) into a space-time frequency domain signal P ~ _nm (ω) by the Fourier transform of the space (step S2). The spatio-temporal frequency domain signal P _nm (ω) is calculated for each ω. The converted spatio-temporal frequency domain signal P _nm (ω) is sent to the conversion filter unit 3. Specifically, the spatial frequency conversion unit 2 calculates P _nm (ω) defined by the following equation (1).

k _{x, n} is the wave number in the x-axis direction, n is the index of the wave number k _{x, n} , k _{z, m} is the wave number in the z-axis direction, and m is the index of the wave number k _{z, m} . The wave number is a so-called spatial frequency or angular spectrum. The above formula (1) is an example of conversion to the spatio-temporal frequency domain, and spatial Fourier transform may be performed by other methods.

Conversion filter unit 3 applies a filter F ~ _nm (ω) defined by the following equation to generate a filtered signal after D ~ _nm (ω) with respect to spatio-temporal frequency domain signal P ~ _nm (ω) (Step S3). The filtered signal _D˜nm (ω) is transmitted to the spatial frequency inverse transform unit 4.

d, as illustrated in FIG. 2, the microphone array M1-1, M2-1, ..., _MN x to reproduce the picked-up signal by -N _z position and the speaker array S1-1, S2-1, ..., This is the distance from SN _x -N _z . This distance d is positive in the front direction (y-axis direction) of the speaker arrays S1-1, S2-1,..., SN _x -N _z . If the distance d ′ between the sound source S and the microphone arrays M1-1, M2-1,..., MN _x −N _z is smaller than the distance d in the first room, the speaker array S1-1, A sound source S ′ is reproduced in front of S2-1,..., SN _x -N _z . If the distance d is negative, the microphone array M1-1, M2-1, ..., signal picked up by _MN x -N _z is a speaker array _{S1-1, S2-1, ..., SN x} -N z Reproduced on the back.

In the above equation (2), the distance d appears in the function exp, that is, in the phase of the filter _F˜nm (ω). Therefore, by controlling the phase of the filter _F˜nm (ω), the position where the signals collected at the distance d, that is, the microphone arrays M1-1, M2-1,..., MN _x −N _z are reproduced is controlled. can do. Further, the filter _F˜nm (ω) defined by the above equation (2) is simpler than the filter described in Non-Patent Document 1, and the filter _F˜nm (ω) defined by the above equation (2). The amount of calculation for obtaining is small and the calculation speed is fast.

The spatial frequency inverse transform unit 4 transforms the filtered signal _D˜nm (ω) into the frequency domain signal D _ij (ω) by inverse spatial Fourier transform (step S4). The converted frequency domain signal D _ij (ω) is sent to the frequency inverse transform unit 5. Specifically, the spatial frequency inverse transform unit 4 calculates a frequency domain signal D _ij (ω) defined by the following equation (3).

The frequency inverse transform unit 5 transforms the frequency domain signal D _ij (ω) into a time domain signal P ^d _ij (t) by inverse Fourier transform (step S5). The time domain signal P ^d _ij (t) obtained for each frame by the inverse Fourier transform is appropriately shifted to obtain a linear sum to be a continuous time domain signal. For the inverse Fourier transform, an existing method such as a short-time discrete inverse Fourier transform may be used. The time domain signal P ^d _ij (t) is sent to the window function unit 6.

The window function unit 6 generates a post-window function time domain signal d _ij (t) by multiplying the time domain signal P ^d _ij (t) by the window function (step S6). After the window function time domain signal d _ij (t) is the speaker array S1-1, S2-1, ..., it is sent to the _SN x -N _z.

For example, a so-called tukey window function w _ij defined by the following equation is used as the window function. N _tpr is the number of points to which the taper is applied, and is an integer of 1 or more and N _x or N _z . Of course, other window functions may be used.

The speaker arrays S1-1, S2-1,..., SN _x -N _z reproduce sound based on the time domain signal _dij (t) after the window function. Specifically, as i = 1,..., N _x , j = 1,..., N _z , the speaker Si-j reproduces sound based on the time domain signal _dij (t) after the window function. Thereby, the wavefront of the position of y = 0 in the first room second room loudspeaker array S1-1, S2-1, ..., and reproduced in SN _x -N _z, the sound field of the first room Can be reproduced in the second room.

When the number of microphones constituting the microphone array is larger than the number of speakers constituting the speaker array, the post-window function time domain signal _dij (t) may be thinned out. On the other hand, when the number of microphones constituting the microphone array is smaller than the number of speakers constituting the speaker array, interpolation may be performed by averaging the time domain signal _dij (t) after the window function. Good.

Hereinafter, the reason why the filter _F˜nm (ω) is expressed as the above formula (2) will be described.

The position vector of the reproduction region is r = (x, y, z), and the position vector of the secondary sound source plane is r ₀ = (x ₀ , 0, z ₀ ). If the sound pressure distribution of the frequency ω in the reproduction region is P (r, ω) and the driving signal of the secondary sound source is D (r ₀ , ω), the following relational expression can be written.

Here, G (rr ₀ , ω) is a transfer function between r and r ₀ . Here, G (rr ₀ , ω) is approximated as a monopole characteristic.

  Here, k = ω / c is the wave number, and c is the speed of sound. When the above equation (4) is Fourier-transformed in the x-axis direction and the z-axis direction, the result is as follows.

Here, k _x and k _z represent wave numbers or spatial frequencies in the x-axis direction and the z-axis direction, respectively. The spatial frequency region is indicated by “~”. Here, the Fourier transform of the space is defined as follows.

  Next, the first type Rayleigh integration is introduced.

  When the Fourier transform of the space is performed on this equation, the following equation is obtained.

  here,

  It is.

  The driving signal of the secondary sound source is obtained as follows by the equations (5) and (6).

Consider shifting the reproduction position to a plane having a distance d in front of the secondary sound source plane (hereinafter referred to as the reproduction plane). At this time, from the spatiotemporal spectrum P ~ (k _x , d, k _z , ω) of the sound pressure distribution on the reproduction plane, the spatiotemporal spectrum P ~ (k _x , 0, k _z , ω) is obtained by the principle of near-field acoustic holography as follows.

  By substituting this equation into the above equation (6 '), the following equation is obtained.

For this reason, the filter _F˜nm (ω) is expressed by the above equation (2).

  Thus, by designing the filter by frequency-converting all of the time axis parameter and the position information parameter, it is not necessary to perform an approximate calculation that ignores the evanescent wave. Therefore, the accuracy of sound source reproduction is higher than in the prior art.

[Second Embodiment]
The second embodiment is an embodiment of the present invention.

As shown in FIG. 5, the sound field sound collecting / reproducing apparatus and method of the second embodiment includes N _x microphones arranged linearly at positions y = 0 and z = 0 in the first room. , MN _x and one-dimensional speaker arrays S 1, S 2,..., SN _x composed of N _x speakers arranged linearly in the second room. The sound field of the first room formed by the sound generated by the sound source S is reproduced in the second room. Thereby, since the number of microphones, the number of speakers, and the number of channels can be reduced, mounting becomes relatively easy.

N _x is an arbitrary integer. Microphone array M1, M2, ..., the number and the speaker array S1 of microphone constituting the MN _x, S2, ..., the number of speakers constituting the SN _x is the same. Microphones Mi constituting the microphone arrays M1, M2,..., MN _x are arranged at equal intervals. Further, the speakers constituting the speaker arrays S1, S2,..., SN _x are also arranged at equal intervals. Microphone array M1, M2, ..., and the size of MN _x, speaker array S1, S2, ..., the magnitude of SN _x is about the same. Microphone array M1, M2 of the microphones Mi, ..., position in MN _x is speaker Si speaker array S1, S2 corresponding to the respective microphones Mi, ..., but it is desirable that the same as the position in the SN _x, different May be. If this position is the same, the sound field can be reproduced more faithfully.

Representing the position of each microphone constituting the microphone arrays M1, M2,..., MN _x arranged at positions y = 0, z = 0 in the first room as r _s = (x _i , 0,0). To.

  As shown in FIG. 4, the sound field sound collecting and reproducing apparatus according to the second embodiment includes a frequency conversion unit 1, a spatial frequency conversion unit 2, a conversion filter unit 3, a spatial frequency reverse conversion unit 4, a frequency reverse conversion unit 5, and a window function. The process of each step illustrated by FIG. 3 is performed including the part 6, for example.

The microphone arrays M1, M2,..., MN _x arranged at positions y = 0, z = 0 in the first room pick up the sound emitted from the sound source S in the first room and Generate a signal. The generated signal is sent to the frequency converter 1. A signal at time t in the time domain picked up by the microphone Mi of r _s = (x _i , 0,0) is expressed as p _i (t).

The frequency converter 1 converts the signal p _i (t) collected by the microphone arrays M1, M2,..., MN _x into a frequency domain signal P _i (ω) by Fourier transform (step S1). The generated frequency domain signal P _i (ω) is sent to the spatial frequency converter 2. ω is a frequency. For example, the frequency domain signal P _i (ω) is generated by short-time discrete Fourier transform. Of course, the frequency domain signal P _i (ω) may be generated by other existing methods. For example, the frequency domain signal P _i (ω) is defined as follows. J in the argument of the function exp is an imaginary unit.

Spatial frequency converter 2, by Fourier transform of the spatial converting the frequency domain signal P _i and (omega) the spatio-temporal frequency domain signal P ~ _n (ω) (Step S2). The spatio-temporal frequency domain signal P _n (ω) is calculated for each ω. The converted spatio-temporal frequency domain signal P _n (ω) is sent to the conversion filter unit 3. Specifically, the spatial frequency conversion unit 2 calculates P _n (ω) defined by the following equation (7).

k _{x, n} is a wave number in the x-axis direction, and n is an index of the wave number k _{x, n} . The wave number is a so-called spatial frequency or angular spectrum. The above equation (7) is an example of conversion to the spatio-temporal frequency domain, and spatial Fourier transform may be performed by other methods.

Conversion filter unit 3 applies a filter F ~ _n (ω) which is defined by the following equation to generate a filtered signal after D ~ _n (ω) with respect to spatio-temporal frequency domain signal P ~ _n (ω) (Step S3). The filtered signal _D˜n (ω) is transmitted to the spatial frequency inverse transform unit 4.

Here, H ₀ ⁽²⁾ is the second kind Hankel function when n = 0. The second kind Hankel function H _n ⁽²⁾ is defined as follows using the first kind Bessel function J _n (x) and the second kind Bessel function Y _n (x).

As shown in FIG. 5, Y _ref represents the distance between the speaker arrays S1, S2,..., SN _x and a linear position that matches the amplitude of the reproduced signal.

Here, as illustrated in FIG. 5, d is the microphone array M1, M2, ..., the position and the speaker array S1, S2 of reproducing a signal picked up by MN _x, ..., is the distance between the SN _x. This distance d is a speaker array S1, S2, ..., it is the front direction (y-axis direction) a positive SN _x. Source S and the microphone array M1 in a first room, M2, ..., if the distance between the MN _x d 'is smaller than the distance d, in the second room, the speaker array S1, S2, ..., in front of SN _x Sound source S 'is reproduced. If the distance d is negative, the microphone array M1, M2, ..., signals picked up by MN _x is a speaker array S1, S2, ..., are reproduced at the back of the SN _x.

In the above equation (8), the distance d appears in the function exp, that is, in the phase of the filter F _n (ω). Thus, by controlling the phase of the filter F ~ _n (ω), the distance d, i.e. microphone arrays M1, M2, ..., it is possible to control the position of reproducing a signal picked up by MN _x. Further, the filter F _n (ω) defined by the above equation (8) is simpler than the filter described in Non-Patent Document 1, and the filter F _n (ω) defined by the above equation (8). The amount of calculation for obtaining is small, and the calculation amount is fast.

The spatial frequency inverse transform unit 4 transforms the filtered signal _D˜n (ω) into the frequency domain signal D _i (ω) by inverse Fourier transform of the space (step S4). The converted frequency domain signal D _i (ω) is sent to the frequency inverse transform unit 5. Specifically, the spatial frequency inverse transform unit 4 calculates a frequency domain signal D _i (ω) defined by the following equation (9).

The frequency inverse transform unit 5 transforms the frequency domain signal D _i (ω) into the time domain signal P ^d _i (t) by inverse Fourier transform (step S5). The time domain signal P ^d _i (t) obtained for each frame by the inverse Fourier transform is appropriately shifted to obtain a linear sum to be a continuous time domain signal. For the inverse Fourier transform, an existing method such as a short-time discrete inverse Fourier transform may be used. The time domain signal P ^d _i (t) is sent to the window function unit 6.

The window function unit 6 multiplies the time domain signal P ^d _i (t) by the window function to generate a post-window function time domain signal d _i (t) (step S6). Window function after a time-domain signal d _i (t) is the speaker array S1, S2, ..., it is sent to the SN _x.

For example, a so-called Tukey window function w _i defined by the following equation is used as the window function. N _tpr is the number of points to which the taper is applied, and is an integer from 1 to N _x . Of course, other window functions may be used.

The speaker arrays S1, S2,..., SN _x reproduce sound based on the time domain signal d _i (t) after the window function. Specifically, with i = 1,..., N _x , the speaker Si reproduces sound based on the time domain signal d _i (t) after the window function.

As a result, the wavefront at the position y = 0 in the first room is reproduced by the speaker arrays S1, S2,..., SN _x in the second room, and the sound field of the first room is reproduced in the second room. can do.

At this time, the amplitude of the reproduced signal matches at a position on a straight line represented by y _ref . Specifically, as shown in FIG. 5, the speaker array S1, S2, ..., are the same height as the SN _x, speaker array S1, S2, ..., in a position at a distance y _ref from SN _x, speaker array S1, S2, ..., amplitude coincides with the position on the straight line and a straight line parallel to the SN _x is located.

The number of microphones constituting the microphone array is, if more than the number of speakers constituting the speaker array may thinned window function after a time-domain signal d _i (t). On the other hand, when the number of microphones constituting the microphone array is smaller than the number of speakers constituting the speaker array, interpolation may be performed by taking an average of the time domain signals d _i (t) after the window function. Good.

Hereinafter, the reason why the filter F _n (ω) is expressed as the above equation (8) will be described.

Consider reproducing only the xy plane using a linear array. The position vector of the reproduction area is r = (x, y, 0), and the position vector of the secondary sound source plane is r ₀ = (x ₀ , ₀ , 0). If the sound pressure distribution of the frequency ω in the reproduction region is P (r, ω) and the driving signal of the secondary sound source is D (r ₀ , ω), the following relational expression can be written.

Here, G (rr ₀ , ω) is a transfer function between r and r ₀ . Similar to the first embodiment, G (rr ₀ , ω) is approximated as a monopole characteristic.

  Here, k = ω / c is the wave number, and c is the speed of sound. When the above equation (10) is Fourier-transformed in the x-axis direction, the result is as follows.

Here, k _x represents the wave number or spatial frequency in the x-axis direction. The spatial frequency region is indicated by “~”. Here, the Fourier transform of the space is defined as follows.

  Next, a two-dimensional type 1 Rayleigh integral is introduced.

  here,

It is. H ₀ ⁽²⁾ is the second kind Hankel function. When the Fourier transform of the space is performed on this equation, the following equation is obtained.

  here,

It is. Also,

Thus, the driving signal of the secondary sound source is obtained as follows.

Consider shifting the reproduction position to a straight line with a distance d ahead of the secondary sound source line (hereinafter referred to as a reproduction line). At this time, from the spatiotemporal spectrum P ~ (k _x , d, 0, ω) of the sound pressure distribution on the reproduction line, the spatiotemporal spectrum P ~ (k _x , 0,0) of the sound pressure distribution on the two-dimensional sound source plane , ω) can be obtained as follows by the principle of near-field acoustic holography.

  By substituting this equation into the above equation (12 '), the following equation is obtained.

For this reason, the filter _F˜n (ω) is expressed as the above equation (8).

  Thus, by designing the filter by frequency-converting all of the time axis parameter and the position information parameter, it is not necessary to perform an approximate calculation that ignores the evanescent wave. Therefore, the accuracy of sound source reproduction is higher than in the prior art.

[Modifications, etc.]
Each unit constituting the sound field sound collecting / reproducing device may be provided in either the sound collecting device arranged in the first room or the reproducing device arranged in the second room. In other words, the processes of the frequency conversion unit 1, the spatial frequency conversion unit 2, the conversion filter unit 3, the spatial frequency reverse conversion unit 4, the frequency reverse conversion unit 5, and the window function unit 6 are arranged in the first room. It may be executed by a sound collecting device or may be executed by a playback device arranged in the second room. The signal generated by the sound collection device is transmitted to the reproduction device.

  The positions of the first room and the second room are not limited to those shown in FIGS. The first room and the second room may be adjacent to each other or separated from each other. Also, the orientation of the first room and the second room may be any.

  The window function processing by the window function unit 6 may be performed at any stage or in multiple stages. That is, the window function unit 6 is provided between the microphone array and the frequency conversion unit 1, between the frequency conversion unit 1 and the spatial frequency conversion unit 2, between the spatial frequency conversion unit 2 and the conversion filter unit 3, and between the conversion filter unit. 3 and the spatial frequency inverse transform unit 4, between the spatial frequency inverse transform unit 4 and the frequency inverse transform unit 5, and between at least one between the frequency inverse transform unit 5 and the window function unit 6. May be. When the window function processing is performed on the signal input to each section, each section of the sound field sound collecting / reproducing apparatus performs the window function processing in the same manner as described above instead of the input signal. The processed signal is processed.

Further, the window function unit 6 may not be provided. In this case, in the first embodiment _{i = 1, ..., N x} , j = 1, ..., to play the sound based on the speaker Si-j is the time domain signal P ^d _ij (t) as a _{N z,} the In the second embodiment, i = 1,..., N _x and the speaker Si reproduces the sound based on the time domain signal P ^d _i (t).

  As long as the sound field sound collecting / reproducing apparatus includes the conversion filter unit 3, the sound field collecting / reproducing device may not include other units. For example, the sound field sound collecting / reproducing apparatus may include a transform filter unit 3, a spatial frequency inverse transform unit 4, and a frequency inverse transform unit 5. Further, the sound field sound collecting / reproducing apparatus may include a frequency conversion unit 1, a spatial frequency conversion unit 2, and a conversion filter unit 3.

  You may perform the process of the frequency converter 1 and the process of the spatial frequency converter 2 simultaneously. Similarly, the process of the spatial frequency inverse transform unit 4 and the process of the frequency inverse transform unit 5 may be performed simultaneously. Further, the spatial frequency conversion unit 2 and the spatial frequency inverse conversion unit 4 may be interchanged.

  The sound field sound collecting / reproducing apparatus can be realized by a computer. In this case, the processing content of each part of this apparatus is described by a program. Then, by executing this program on a computer, each unit in this apparatus is realized on the computer.

  The program describing the processing contents can be recorded on a computer-readable recording medium. In this embodiment, these apparatuses are configured by executing a predetermined program on a computer. However, at least a part of these processing contents may be realized by hardware.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Frequency conversion part 2 Spatial frequency conversion part 3 Conversion filter part 4 Spatial frequency reverse conversion part 5 Frequency reverse conversion part 6 Window function part

Claims (11)

The microphone array is arranged on the xz plane, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, k _{x, n} is the wave number in the x-axis direction, and n is the An index, k _{z, m} is the wave number in the z-axis direction, m is the index, and a position where the signal collected by the microphone array is reproduced and a speaker array arranged in a plane and outputting a time domain signal The distance when the front direction of the speaker array is positive is d,
Filtered signal by applying filter F ~ _nm (ω) defined by the following equation to spatio-temporal frequency domain signal P ~ _nm (ω) generated based on the signal collected by the microphone array A conversion filter unit for generating D to _nm (ω);

A spatial frequency inverse transform unit that transforms the filtered signal D to _nm (ω) into a frequency domain signal by inverse Fourier transform of space;
A frequency inverse transform unit for transforming the frequency domain signal into a time domain signal by inverse Fourier transform;
Sound field collection and playback device including The microphone array is arranged on the xz plane, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, k _{x, n} is the wave number in the x-axis direction, and n is the An index, k _{z, m} is the wave number in the z-axis direction, m is the index, and a position where the signal collected by the microphone array is reproduced and a speaker array arranged in a plane and outputting a time domain signal The distance when the front direction of the speaker array is positive is d,
A frequency converter that converts the signal collected by the microphone array into a frequency domain signal by Fourier transform;
A spatial frequency converter that converts the frequency domain signal into a spatio-temporal frequency domain signal P to _nm (ω) by Fourier transform of space;
A conversion filter unit that generates a filtered signal D to _nm (ω) by applying a filter F to _nm (ω) defined by the following equation to the spatio-temporal frequency domain signal P to _nm (ω):

Sound field collection and playback device including The array direction of the microphone arrays arranged in a straight line is the x-axis direction, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, and k _{x, n} is the wave number in the x-axis direction. Where n is the index, y _ref is the distance between the speaker array that is linearly arranged and the time domain signal is output, and the linear position that matches the amplitude of the reproduced signal, and H ₀ ⁽²⁾ is the second As a seed Hankel function, the distance when the front direction of the speaker array between the position where the signal collected by the microphone array is reproduced and the speaker array is positive is d,
Signals after filtering by applying filters F to _n (ω) defined by the following equations to spatio-temporal frequency domain signals P to _n (ω) generated based on the signals collected by the microphone array A conversion filter unit for generating D to _n (ω);

A spatial frequency inverse transform unit that transforms the filtered signal D to _n (ω) into a frequency domain signal by spatial inverse Fourier transform,
A frequency inverse transform unit for transforming the frequency domain signal into a time domain signal by inverse Fourier transform;
Sound field collection and playback device including The array direction of the microphone arrays arranged in a straight line is the x-axis direction, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, and k _{x, n} is the wave number in the x-axis direction. Where n is the index, y _ref is the distance between the speaker array that is arranged in a straight line and the time domain signal is output, and the position where the amplitude of the reproduced signal is matched, and H ₀ ⁽²⁾ is the second kind Hankel function And d is the distance when the front direction of the speaker array between the position where the signal collected by the microphone array is reproduced and the speaker array is positive.
A frequency converter that converts the signal collected by the microphone array into a frequency domain signal by Fourier transform;
A spatial frequency converter that converts the frequency domain signal into a spatio-temporal frequency domain signal P _n (ω) by Fourier transform of space;
A transform filter unit that generates a filtered signal D to _n (ω) by applying a filter F to _n (ω) defined by the following equation to the spatio-temporal frequency domain signal P to _n (ω):

Sound field collection and playback device including In the sound field recording and reproducing device according to claim 1 or 3 ,
The space-time frequency domain signal, the filter processed signal, at least one signal of the transformed time domain signal by a frequency domain signal and the frequency inverse conversion unit converted by the spatial frequency inverse converting unit, predetermined A signal that has been subjected to window function processing by a window function.
Sound field recording and playback device. In the sound field sound collecting and reproducing device according to claim 2 or 4,
At least one of the signal collected by the microphone array, the frequency domain signal converted by the frequency converter , the spatio-temporal frequency domain signal, and the filtered signal is subjected to window function processing by a predetermined window function. Is the signal made,
Sound field recording and playback device. The microphone array is arranged on the xz plane, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, k _{x, n} is the wave number in the x-axis direction, and n is the An index, k _{z, m} is the wave number in the z-axis direction, m is the index, and a position where the signal collected by the microphone array is reproduced and a speaker array arranged in a plane and outputting a time domain signal The distance when the front direction of the speaker array is positive is d,
The conversion filter unit applies a filter F to _nm (ω) defined by the following equation to the spatio-temporal frequency domain signal P to _nm (ω) generated based on the signals collected by the microphone array. A conversion filter step for generating a filtered signal D ~ _nm (ω),

A spatial frequency inverse transform unit transforms the filtered signal D to _nm (ω) into a frequency domain signal by inverse Fourier transform of the space, and a spatial frequency inverse transform step,
A frequency inverse transform unit that transforms the frequency domain signal into a time domain signal by inverse Fourier transform;
Sound field collection and playback method including The microphone array is arranged on the xz plane, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, k _{x, n} is the wave number in the x-axis direction, and n is the An index, k _{z, m} is the wave number in the z-axis direction, m is the index, and a position where the signal collected by the microphone array is reproduced and a speaker array arranged in a plane and outputting a time domain signal The distance when the front direction of the speaker array is positive is d,
A frequency conversion step in which a frequency conversion unit converts a signal collected by the microphone array into a frequency domain signal by Fourier transformation;
A spatial frequency conversion unit that converts the frequency domain signal into a spatio-temporal frequency domain signal P to _nm (ω) by Fourier transform of the space; and
Conversion filter portion, by applying a filter F ~ _nm (ω) defined by the following equation to generate a filtered signal after D ~ _nm (ω) with respect to the space-time frequency domain signal P ~ _nm (ω) A transform filter step;

Sound field collection and playback method including The array direction of the microphone arrays arranged in a straight line is the x-axis direction, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, and k _{x, n} is the wave number in the x-axis direction. Where n is the index, y _ref is the distance between the speaker array that is linearly arranged and the time domain signal is output, and the linear position that matches the amplitude of the reproduced signal, and H ₀ ⁽²⁾ is the second As a seed Hankel function, the distance when the front direction of the speaker array between the position where the signal collected by the microphone array is reproduced and the speaker array is positive is d,
The transform filter unit applies a filter F _n (ω) defined by the following equation to the spatio-temporal frequency domain signal P _n (ω) generated based on the signals collected by the microphone array. A conversion filter step for generating a filtered signal D ~ _n (ω),

A spatial frequency inverse transform unit transforms the filtered signal D to _n (ω) into a frequency domain signal by inverse Fourier transform of space,
A frequency inverse transform unit that transforms the frequency domain signal into a time domain signal by inverse Fourier transform;
Sound field collection and playback method including The array direction of the microphone arrays arranged in a straight line is the x-axis direction, j is the imaginary unit, ω is the frequency, c is the speed of sound, k = ω / c, and k _{x, n} is the wave number in the x-axis direction. Where n is the index, y _ref is the distance between the speaker array that is arranged in a straight line and the time domain signal is output, and the position where the amplitude of the reproduced signal is matched, and H ₀ ⁽²⁾ is the second kind Hankel function And d is the distance when the front direction of the speaker array between the position where the signal collected by the microphone array is reproduced and the speaker array is positive.
A frequency conversion step in which a frequency conversion unit converts a signal collected by the microphone array into a frequency domain signal by Fourier transformation;
A spatial frequency transforming step, wherein the spatial frequency transforming unit transforms the frequency domain signal into a spatiotemporal frequency domain signal P to _n (ω) by Fourier transform of the space;
Conversion filter portion, by applying a filter F ~ _n (ω) which is defined by the following equation to generate a filtered signal after D ~ _n (ω) with respect to the space-time frequency domain signal P ~ _n (ω) A transform filter step;

Sound field collection and playback method including Sound field sound collecting reproduction program for causing a computer to function as each section of sound field sound collecting and reproducing apparatus according to any one of claims 1 to 6.

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