Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2013048359 Abstract: To provide a sound field sound collecting and reproducing technique in which the amplitudes of signals reproduced in a wider range than in the prior art coincide. A frequency converter (1) converts a signal collected by a linearly arranged microphone array into a frequency domain signal by Fourier transform. The space-frequency conversion unit 2 converts the frequency domain signal into the space-time frequency domain signal P ˜ (ω) by Fourier transform of space. The conversion filter unit 3 applies a filter F (ω) defined by the following equation to the space-time frequency domain signal P ˜ (ω) to generate a post-filtering signal D ˜ (ω). The spatial frequency inverse transform unit 4 transforms the filtered signal D ˜ (ω) into a frequency domain signal by inverse Fourier transform of space. The frequency inverse transform unit 5 transforms the frequency domain signal into a time domain signal by inverse Fourier transform. [Selected figure] Figure 1 Sound field sound collecting and reproducing apparatus, method and program [0001] The present invention relates to a wave field synthesis technique in which a sound signal is collected by a microphone array installed in a certain sound field, and the sound field is reproduced by a speaker array using the sound signal. [0002] For example, Non-Patent Document 1 describes a wave field synthesis technique in which a microphone array installed in a certain sound field picks up a signal and uses that signal to reproduce the sound field with a speaker array. Technology is known. 09-05-2019 1 [0003] In Non-Patent Document 1, a sound field is reproduced by applying a filter designed in the spacetime frequency domain to a sound pressure distribution obtained from a signal collected by a microphone array. In Non-Patent Document 1, a filter that reproduces the sound pressure gradient calculated from the sound pressure distribution with a speaker array is used as the filter. [0004] Shoichi Koyama, 3 others, "Wavefront synthesis method based on sound pressure gradient acquisition by angular spectrum differentiation," Proceedings of the Acoustical Society of Japan, September 2010 [0005] However, when each of the microphone and the speaker is arranged linearly, in the technique described in Non-Patent Document 1, the amplitudes of the reproduced signals match at only one point, but at positions other than that one point. Amplitude does not match. [0006] An object of the present invention is to provide a sound field sound collecting and reproducing apparatus, method and program in which the amplitudes of signals reproduced in a wider range than in the prior art coincide. [0007] In order to solve the above problems, in the sound field collection and reproduction apparatus according to one aspect of the present invention, the arrangement direction of the microphone arrays arranged in a straight line is an x axis direction, j is an imaginary unit, and ω is a frequency , C is the speed of sound, k = ω / c, kx, n is the wave number in the x-axis direction, n is its index, and the amplitude of the signal reproduced with the speaker array arranged linearly and outputting the time domain signal A space-time frequency domain signal P ˜n (generated from the signal collected by the microphone array with the distance to the linear position where H a conversion filter unit that generates a filtered signal D ˜n (ω) by applying a filter F ˜n (ω) defined by the following equation to ω); 09-05-2019 2 [0008] [0009] The inverse Fourier transform of the spatial and spatial frequency inverse converting portion for converting filtered signal after D ˜ n the (omega) to the frequency domain signal, and the frequency inverse conversion unit for converting a time domain signal by the inverse Fourier transform a frequency domain signal ,including. [0010] In the sound field collection and reproduction apparatus according to another aspect of the present invention, the arrangement 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, and k = Let ω / c, let kx, n be the wave number in the x-axis direction, let n be its index, let yref be the distance between the loudspeaker that is arranged linearly and the time domain signal is output , H0 <(2)> as a second-class Hankel function, a frequency converter for converting a signal collected by the microphone array into a frequency domain signal by Fourier transform, and a space domain signal by space Fourier transform. A filter applying a filter F to n (ω) defined by the following equation to a space frequency conversion unit for converting into a frequency domain signal P to n (ω) and a space-time frequency domain signal P to n (ω) And a conversion filter unit that generates post-processing signals D to n (ω). [0011] [0012] The amplitudes of the reproduced signals can be matched on a predetermined straight line. Thereby, the amplitudes of the signals reproduced in a wider range than in the prior art coincide. [0013] 09-05-2019 3 FIG. 1 is a functional block diagram showing an example of a sound field collection and reproduction device according to a first embodiment. FIG. 2 is a view for explaining an example of the arrangement of a microphone array and a speaker array of the sound field collection and reproduction device according to the first embodiment. The flowchart which shows the example of the sound field sound collection reproducing 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 of the sound field sound collection reproducing ¦ regenerating apparatus of 2nd embodiment, and a speaker array. [0014] Before describing the present invention, first, the related art of the present invention will be described. [0015] First Embodiment The first embodiment is an embodiment of the related art of the present invention. An embodiment of the present invention will be described in the section of [Second Embodiment] described later. [0016] In the sound field collection and reproduction apparatus and method according to the first 09-05-2019 4 embodiment, as illustrated in FIG. 2, a two-dimensional microphone array configured by N ×× Nz microphones disposed at the y = 0 position of the first room. Two-dimensional speaker arrays S1-1, S2-1,..., SNx-Nz comprising M1-1, M2-1,..., MNx-Nz and Nx × Nz speakers arranged in the second room And the sound field of the first room formed by the sound generated by the sound source S is reproduced in the second room. [0017] Nx and Nz are arbitrary integers. The number of microphones constituting the microphone array M1-1, M2-1,..., MNx-Nz is the same as the number of speakers constituting the speaker array S1-1, S2-1,. The microphones Mi-j constituting the microphone arrays M1-1, M2-1,..., MNx-Nz are arranged at equal intervals. Loudspeakers constituting the speaker arrays S1-1, S2-1,..., SNx-Nz are also arranged at equal intervals. Microphone array M1-1, M2-1, ..., and the size of MNx-Nz, speaker array S1-1, S2-1, ..., the magnitude of SNx-Nz is substantially the same. Microphone array M1-1 of the microphones Mi-j, M2-1, ..., position in MNx-Nz is the speaker Si-j of the speaker array S1-1 corresponding to the respective microphones Mi-j, S2-1, ... , SNx-Nz, but may be different. If the positions are the same, the sound field can be reproduced more faithfully. [0018] Let rs = (xi, 0, zj) denote the positions of the microphones constituting the microphone array M11, M2-1,..., MNx-Nz arranged at the y = 0 position of the first room. Do. [0019] 09-05-2019 5 Sound field sound collecting and reproducing apparatus of the first embodiment, the frequency conversion unit 1 as shown in FIG. 1, the spatial frequency conversion unit 2, conversion filter unit 3, the spatial frequency inverse transform unit 4, a frequency inverse transform unit 5 and window function For example, the processing of each step illustrated in FIG. 3 is performed. [0020] The two-dimensional microphone arrays M1-1, M2-1,..., MNx-Nz arranged at the y = 0 position of the first room pick up the sound emitted by the sound source S of the first room Generate a time domain signal. The generated signal is sent to the frequency converter 1. rs = (xi, 0, zj) the signal at time t in the time domain, which is picked up by the microphone Mi-j of is denoted by pij (t). [0021] The frequency converter 1 converts the signals pij (t) collected by the microphone arrays M1-1, M2-1,..., MNx-Nz into frequency domain signals Pij (.omega.) 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, 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 another existing method. For example, frequency domain signal P ij (ω) is defined as follows. J in the argument of the function exp is an imaginary unit. [0022] [0023] Spatial frequency converter 2, by Fourier transform of the spatial converting frequency domain signal Pij the (omega) the spatio-temporal frequency domain signal P ˜ nm (ω) (Step S2). 09-05-2019 6 The space-time frequency domain signal P ˜nm (ω) is calculated for each ω. The converted space-time frequency domain signal P ˜nm (ω) is sent to the conversion filter unit 3. Specifically, the spatial frequency transform unit 2 calculates P to nm (ω) defined by the following equation (1). [0024] [0025] kx, n is the wave number of the x-axis direction, n is the index of the wave number kx, n, kz, m is the wave number of the z-axis direction, m is the index of the wave number kz, m. The wave number is the so-called spatial frequency or angular spectrum. The above equation (1) is an example of conversion to the space-time frequency domain, and Fourier transform of space may be performed by another method. [0026] The conversion filter unit 3 applies a filter F to nm (ω) defined by the following equation to the space-time frequency domain signal P to nm (ω) to generate a post-filtering signal D to nm (ω) (Step S3). The filtered signal D ˜nm (ω) is transmitted to the spatial frequency inverse transform unit 4. [0027] [0028] The spatial frequency inverse transform unit 4 transforms the filtered signal D ˜nm (ω) into a frequency domain signal Dij (ω) by inverse Fourier transform of space (step S 4). 09-05-2019 7 The converted frequency domain signal Dij (ω) is sent to the frequency inverse transform unit 5. Spatial frequency inverse transform unit 4, specifically calculated defined as a frequency domain signal Dij (omega) by the following equation (3). [0029] [0030] The frequency inverse transform unit 5 transforms the frequency domain signal Dij (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 and linearly summed to be a continuous time domain signal. As 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. [0031] The window function unit 6 multiplies the time domain signal P <d> ij (t) by the window function to generate a post-window function time domain signal dij (t) (step S6). Window function after a time-domain signal dij (t) is the speaker array S1-1, S2-1, ..., sent to SNx-Nz. [0032] For example, a so-called Tukey window function wij defined by the following equation is used as a window function. Ntpr is a score to which a taper is applied, and is an integer of 1 or more and Nx and Nz or less. Of course, other window functions may be used. [0033] 09-05-2019 8 [0034] Speaker array S1-1, S2-1, ..., SNx-Nz reproduces sound based on the post-window function time domain signal dij (t). Specifically, the speaker Si-j reproduces the sound based on the time-domain signal after the window function dij (t) as i = 1,..., Nx, j = 1,. Thereby, the wave front at the position y = 0 of the first room is reproduced by the speaker arrays S1-1, S2-1,..., SNx-Nz of the second room, and the sound field of the first room is It can be reproduced in two rooms. [0035] If the number of microphones constituting the microphone array is larger than the number of speakers constituting the speaker array, the time-domain signal dij (t) may be thinned after the window function. On the other hand, when the number of microphones constituting the microphone array is smaller than the number of speakers constituting the speaker array, the interpolation may be performed by averaging the time domain signal dij (t) after the window function. . [0036] Hereinafter, the reason why the filter F to nm (ω) is expressed as the above equation (2) will be described. [0037] The position vector of the reproduction area is r = (x, y, z), and the position vector of the secondary sound source plane is r0 = (x0, 0, z0). Assuming that the sound pressure distribution of the frequency ω in the reproduction region is P (r, ω) and the drive signal of the secondary sound source is D (r0, ω), the following relational expression can be written. 09-05-2019 9 [0038] [0039] Here, G (r−r 0, ω) is a transfer function between r and r 0. Here, G (r−r 0, ω) is approximated as a monopole characteristic. [0040] [0041] Here, k = ω / c is the wave number and c is the speed of sound. The Fourier transform of space in the x-axis direction and z-axis direction of the above equation (4) is as follows. [0042] [0043] Here, kx and kz represent wave numbers or spatial frequencies in the x-axis direction and z-axis direction, respectively. The spatial frequency domain is indicated by "˜". Here, the Fourier transform of space is defined as follows. [0044] 09-05-2019 10 [0045] Next, we introduce the first kind Rayleigh integration. [0046] [0047] By applying Fourier transform of space to this equation, the following equation is obtained. [0048] [0049] ここで、 [0050] [0051] である。 [0052] By the equations (5) and (6), the drive signal of the secondary sound source is obtained as follows. [0053] [0054] In the above equation, D ˜ (kx, kz, ω) corresponds to the filtered signal D ˜ nm (ω), and P ˜ (kx, 0, kz, ω) is the space-time frequency domain signal P ˜ nm Corresponding to (ω), 2jky corresponds to the filter F ˜nm (ω). 09-05-2019 11 Thus, the filter F ˜nm (ω) is expressed as the above equation (2). [0055] Second Embodiment The second embodiment is an embodiment of the present invention. [0056] In the second embodiment, as shown in FIG. 5, one-dimensional microphone arrays M1, M2,... Configured of Nx microphones linearly arranged at the positions of y = 0 and z = 0 in the first room. , MNx and one-dimensional speaker arrays S1, S2,..., SNx consisting of Nx speakers arranged linearly in the second room, formed by the sound generated by the sound source S The sound field of the first room is reproduced in the second room. As a result, the number of microphones, the number of speakers, and the number of channels can be reduced, which makes the implementation relatively easy. [0057] Nx is an arbitrary integer. The number of microphones configuring the microphone arrays M1, M2,..., MNx is the same as the number of speakers configuring the speaker arrays S1, S2,. Microphone array M1, M2, ..., microphone Mi constituting the MNx are equally spaced. Further, the speakers constituting the speaker arrays S1, S2,..., SNx are also arranged at equal intervals. The size of the microphone arrays M1, M2,..., MNx and the size of the speaker arrays S1, S2,. 09-05-2019 12 It is preferable that the positions of the microphones Mi in the microphone arrays M1, M2, ..., MNx are the same as the positions in the speaker arrays S1, S2, ..., SNx of the speakers Si corresponding to the respective microphones Mi. Also good. If the positions are the same, the sound field can be reproduced more faithfully. [0058] The positions of the microphones constituting the microphone arrays M1, M2,..., MNx arranged at the y = 0, z = 0 positions of the first room are represented by rs = (xi, 0, 0). [0059] As shown in FIG. 4, the sound field sound collecting and reproducing apparatus according to the second embodiment includes a frequency converter 1, a space frequency converter 2, a conversion filter 3, a space frequency inverse converter 4, a frequency inverse converter 5, and a window function. For example, the processing of each step illustrated in FIG. 3 is performed. [0060] The microphone arrays M1, M2,..., MNx arranged at the y = 0, z = 0 positions of the first room pick up the sound emitted by the sound source S of the first room and generate a time domain signal. Generate The generated signal is sent to the frequency converter 1. rs = (xi, 0,0) a signal at time t of the picked-up time domain microphone Mi of is denoted by pi (t). [0061] The frequency converter 1 converts the signal pi (t) collected by the microphone arrays M1, M2,..., MNx into a frequency domain signal Pi (ω) by Fourier transformation (step S1). 09-05-2019 13 The generated frequency domain signal Pi (ω) is sent to the spatial frequency converter 2. ω is a frequency. For example, the frequency domain signal Pi (ω) is generated by short time discrete Fourier transform. Of course, the frequency domain signal Pi (ω) may be generated by another existing method. For example, the frequency domain signal Pi (ω) is defined as follows. J in the argument of the function exp is an imaginary unit. [0062] [0063] The spatial frequency transform unit 2 transforms the frequency domain signal Pi (ω) into the space-time frequency domain signal P ˜n (ω) by Fourier transform of space (step S 2). The space-time frequency domain signals P ˜n (ω) are calculated for each ω. The converted space-time frequency domain signals P to n (ω) are sent to the conversion filter unit 3. Spatial frequency converter 2, in particular to calculate the P ˜ n (omega) which is defined by the following equation (7). [0064] [0065] kx, n is a wave number in the x-axis direction, and n is an index of the wave number kx, n. The wave number is the so-called spatial frequency or angular spectrum. The equation (7) is an example of a conversion to the spatio-temporal frequency domain may be performed a Fourier 09-05-2019 14 transform of the space by the other methods. [0066] The conversion filter unit 3 applies the filter F to n (ω) defined by the following equation to the space-time frequency domain signal P to n (ω) to generate a post-filtering signal D to n (ω) (Step S3). The post-filtering signals D to n (ω) are transmitted to the spatial frequency inverse transform unit 4. [0067] [0068] Here, H0 <(2)> is the second Hankel function in the case of n = 0. The second Hankel function Hn <(2)> is defined as follows using the first Bessel function Jn (x) and the second Bessel function Yn (x). [0069] [0070] As shown in FIG. 5, Yref represents the distance between the speaker arrays S1, S2,..., SNx and the linear position where the amplitudes of the reproduced signals are adjusted. [0071] The spatial frequency inverse transform unit 4 transforms the post-filtering signals D to n (ω) into a frequency domain signal Di (ω) by inverse Fourier transform of space (step S 4). The converted frequency domain signal Di (ω) is sent to the frequency inverse transform unit 5. 09-05-2019 15 Spatial frequency inverse transform unit 4, specifically calculated defined as a frequency domain signal Di (omega) by the following equation (9). [0072] [0073] The frequency inverse transform unit 5 transforms the frequency domain signal Di (ω) into a 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 and linearly summed to be a continuous time domain signal. As 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. [0074] 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 di (t) (step S6). The post-window function time domain signal di (t) is sent to the loudspeaker arrays S1, S2, ..., SNx. [0075] For example, a so-called Tukey window function wi defined by the following equation is used as a window function. Ntpr is a score to which a taper is applied, and is an integer of 1 or more and Nx or less. Of course, other window functions may be used. [0076] 09-05-2019 16 [0077] The speaker arrays S1, S2,..., SNx reproduce sound based on the window function after time domain signal di (t). Specifically, the speaker Si reproduces a sound based on the window function after time domain signal di (t) as i = 1,..., Nx. [0078] Thereby, the wave front at the position y = 0 of the first room is reproduced by the speaker arrays S1, S2, ..., SNx of the second room, and the sound field of the first room is reproduced in the second room be able to. [0079] At this time, the amplitudes of the reproduced signals match at the position on the straight line represented by yref. Specifically, as shown in FIG. 5, the speaker array S1, S2,..., SNx has the same height, and is separated from the speaker array S1, S2,. The amplitudes coincide at positions on a straight line parallel to the straight line where S2, ..., SNx are arranged. [0080] When the number of microphones constituting the microphone array is larger than the number of speakers constituting the speaker array, the time-domain signal di (t) may be thinned after the window function. 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 di (t) after the window function. . [0081] 09-05-2019 17 Hereinafter, the reason why the filters F to n (ω) are expressed as the above equation (8) will be described. [0082] Consider reproducing only on the xy plane using a linear array. The position vector of the reproduction region is r = (x, y, 0), and the position vector of the secondary sound source plane is r0 = (x 0, 0, 0). Assuming that the sound pressure distribution of the frequency ω in the reproduction region is P (r, ω) and the drive signal of the secondary sound source is D (r0, ω), the following relational expression can be written. [0083] [0084] Here, G (r−r 0, ω) is a transfer function between r and r 0. Similar to the first embodiment, G (r−r 0, ω) is approximated as a monopole characteristic. [0085] [0086] Here, k = ω / c is the wave number and c is the speed of sound. The Fourier transform of space in the x-axis direction of the above equation (10) is as follows. [0087] 09-05-2019 18 [0088] Here, kx represents the wave number or spatial frequency in the x-axis direction. The spatial frequency domain is indicated by "˜". Here, the Fourier transform of space is defined as follows. [0089] [0090] Next, we introduce a two-dimensional first-class Rayleigh integral. [0091] [0092] ここで、 [0093] [0094] である。 H0 <(2)> is the second Hankel function. By applying Fourier transform of space to this equation, the following equation is obtained. 09-05-2019 19 [0095] [0096] ここで、 [0097] [0098] である。 また、 [0099] [0100] Thus, the drive signal of the secondary sound source is obtained as follows. [0101] [0102] In the above equation, D ˜ (kx, ω) corresponds to the filtered signal D ˜ n (ω), and P ˜ (kx, 0,0, ω) is the space-time frequency domain signal P ˜ n (ω). 4kexp (-jkρyref) / H0 <(2)> (kρyref) corresponds to the filters F to n (ω). Thus, the filter F ˜n (ω) is expressed as the above equation (8). [0103] 09-05-2019 20 [Modifications, Etc.] Each part constituting the sound field sound collecting and reproducing apparatus may be provided in either the sound collecting apparatus arranged in the first room or the reproduction apparatus arranged in the second room. In other words, processing of each of the frequency conversion unit 1, the space frequency conversion unit 2, the conversion filter unit 3, the space frequency inverse conversion unit 4, the frequency inverse conversion unit 5, and the window function unit 6 is arranged in the first room It may be performed by the sound collection apparatus, or may be performed by the reproduction apparatus arranged in the second room. The signal generated by the sound collection device is transmitted to the reproduction device. [0104] The positions of the first room and the second room are not limited to those shown in FIGS. 2 and 5. The first room and the second room may be adjacent or separated from each other. Also, the orientation of the first room and the second room may be any. [0105] The processing of the window function by the window function unit 6 may be performed at any stage, or may be performed in multiple stages. That is, the window function unit 6 is 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 a conversion filter unit 3 and at least one of the space frequency inverse transform unit 4, the 09-05-2019 21 space frequency inverse transform unit 4, and the frequency inverse transform unit 5, and at least one of the frequency inverse transform unit 5 and the window function unit 6. May be When processing of the window function is performed on the signal input to each part of each part of the sound field collection and reproduction device, processing of the window function is performed in the same manner as described above instead of the input signal. Process the signal after the [0106] In addition, the window function unit 6 may be omitted. In this case, in the first embodiment, the speaker Si-j reproduces the sound based on the time domain signal P <d> ij (t) as i = 1,..., Nx, j = 1,. In the second embodiment, the speaker Si reproduces sound based on the time domain signal P <d> i (t) as i = 1,. [0107] As long as the sound field sound collecting and reproducing apparatus includes the conversion filter unit 3, it does not have to include other units. For example, the sound field sound collection and reproduction apparatus may be configured of the conversion filter unit 3, the spatial frequency inverse conversion unit 4, and the frequency inverse conversion unit 5. Further, the sound field sound collecting and reproducing apparatus may be configured of the frequency conversion unit 1, the spatial frequency conversion unit 2, and the conversion filter unit 3. [0108] The processing of the frequency conversion unit 1 and the processing of the spatial frequency conversion unit 2 may be performed 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. Also, the space frequency conversion unit 2 and the space frequency inverse conversion unit 4 may be interchanged. 09-05-2019 22 [0109] The sound field sound collecting and 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. And each part in this apparatus is implement ¦ achieved on a computer by running this program by computer. [0110] The program describing the processing content can be recorded in a computer readable recording medium. Further, in this embodiment, these devices are configured by executing a predetermined program on a computer, but at least a part of the processing contents may be realized as hardware. [0111] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [0112] Reference Signs List 1 frequency conversion unit 2 space frequency conversion unit 3 conversion filter unit 4 space frequency inverse conversion unit 5 frequency inverse conversion unit 6 window function unit 09-05-2019 23

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