JP5826737B2 - Sound field recording / reproducing apparatus, method, and program - Google Patents

Description

  The present invention relates to a wave field synthesis technique for collecting a sound signal with a microphone installed in a certain sound field and reproducing the sound field with a speaker using the sound signal.

  For example, Non-Patent Document 1 discloses 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.

Shoichi Koyama, 3 others, “Spatial-Time Frequency Domain Signal Conversion Method for Sound Field Recording and Reproduction”, Proceedings of the Acoustical Society of Japan, September 2011, p. 635-636

  In the technique described in Non-Patent Document 1, when a linear array is used, if the collected sound field is in a reverberant environment, the reverberation of the reproduced sound field may increase.

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

In order to solve the above-described problem, a sound field collecting and reproducing device according to an aspect of the present invention has a radius R in which the circumferential direction of the baffle is a circumferential direction around the axis of a cylindrical rigid baffle having a radius _{Rb. Assume} that at least two microphones are arranged in each of two or more circles of _m , R _m ≧ R _b , at least two speakers are arranged in a straight line, and a cylindrical rigid baffle The z-axis direction is the cylindrical direction, the circumferential direction of the cylindrical rigid baffle is the φ direction, i is the z-axis direction index, j is the φ-direction index, and ω is the frequency. For the frequency domain signal P _ij (ω) generated based on the received signal, directivity is formed in one predetermined direction for each index i in the z-axis direction by an arbitrary directivity control method. directivity to generate a post-signal P ^MB _i (ω) And control unit, a spatial frequency transformation unit for converting the spatio-temporal frequency domain signal P ~ _n (ω) by the Fourier transform of the directional formation after signal P ^MB _i (ω) space, the spatio-temporal frequency domain signal P ~ _n ( ω), a filter F ~ _n (which converts a spatio-temporal frequency domain signal generated based on signals collected by a one-dimensional microphone array into a spatio-temporal frequency domain signal to be output by a one-dimensional speaker array. and a conversion filter unit that generates a filtered signal _D˜n (ω) by applying ω).

Sound field sound pickup reproducing apparatus according to another aspect of the invention, around the axis of the rigid baffle cylindrical radius R _b of the two or more circles having a radius R _m to the circumferential direction of the baffle and the circumferential direction Assume that at least two microphones are arranged in each, R _m ≧ R _b , at least two speakers are arranged in a straight line, and the axial direction of the cylindrical rigid baffle is the z-axis direction. The cylindrical rigid baffle circumferential direction is φ direction, i is the z-axis direction index, j is the φ-direction index, ω is the frequency, and is generated based on the signal collected by the microphone For the frequency domain signal P _ij (ω), a directivity-formed signal P ^MB _i (generated by forming directivity in one predetermined direction for each index i in the z-axis direction by an arbitrary directivity control method. ω) transformed by Fourier transform of space The spatial frequency domain signals when to output to the spatial frequency domain signal P ~ _n (ω), the one-dimensional speaker array spatial frequency domain signals when generated based on the picked-up signal by one-dimensional microphone array Applying the filter F ~ _n (ω) to be converted into a conversion filter unit for generating a filtered signal D ~ _n (ω), and the filtered signal D ~ _n (ω) by spatial inverse Fourier transform Spatial frequency inverse transform unit for transforming to frequency domain signal D _i (ω), and transforming frequency domain signal D _i (ω) to time domain signal by inverse Fourier transform, and outputting the transformed time domain signal to the speaker A frequency inverse transform unit.

  Even when a linear speaker array is used, a reverberation feeling can be reproduced while reproducing the direct sound of the target sound field by making the microphone array cylindrical. Therefore, the sound field can be reproduced with higher accuracy than in the past.

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 and speaker of 1st embodiment. The figure for demonstrating the example of arrangement | positioning of a microphone. The figure for demonstrating the example of arrangement | positioning of a microphone. The flowchart which shows the example of the sound field sound collection reproduction | regeneration method. The figure for demonstrating the example of arrangement | positioning of the microphone and speaker of 2nd embodiment. The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 2nd embodiment. The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 3rd embodiment. The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 4th embodiment. The functional block diagram which shows the example of the sound field sound collection reproducing | regenerating apparatus of 5th embodiment.

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

[First embodiment]
Sound field sound collection reproducing apparatus and method of the first embodiment, as shown in FIG. 2, are arranged from the axis of the rigid baffle cylindrical radius R _b of the first space at a position away R _m A microphone array composed of N _z × N _φ microphones M1-1, M2-1,..., MN _z −N _φ , and N _z speakers S1 and S2 arranged linearly in the second space. ,..., SN _z is used to reproduce the sound field of the first space formed by the sound generated by the sound source S of the first space in the second space. The first space and the second space are different from each other. In FIG. 2, the sound source S reproduced in the second space is expressed as a sound source S ′. The axial direction of the baffle is the z-axis direction, and the circumferential direction is the φ direction. The number of microphone arrays arranged in the first space in the z-axis direction and the number of speakers arranged in the second space may be different. If the number of microphone arrays in the z-axis direction is larger than the number of speakers arranged in the second space, the reproduction signal may be thinned out. On the other hand, when the number of microphone arrays in the z-axis direction is smaller than the number of speakers arranged in the second space, interpolation may be performed by taking an average of reproduced signals. As a method for performing the interpolation, for example, linear interpolation, sinc interpolation, or the like can be applied.

As shown in FIG. 3, N _φ microphones are equally spaced in each of N _z circles centered on the axis of the cylindrical rigid baffle and the circumferential direction of the cylindrical rigid baffle. Placed in. N _z and N _φ are predetermined integers of 2 or more. That is, by the two microphones are placed at each of the two circles in the circumferential direction of the baffle and the circumferential direction, the microphone is at least 4 located away R _m from the axis of the baffle.

The radius R _b of the cylindrical rigid baffle and the distance R _m between the baffle axis and the microphone may be any value as long as R _m ≧ R _b . In the case of R _m = R _b , as shown in FIG. 3, the microphone is placed on the surface of the peripheral surface of the cylindrical baffle having a radius R _b (= R _m ). In the case of R _m > R _b , as shown in FIG. 4, the microphone is arranged at a position away from the axis of the cylindrical baffle having the radius R _b by R _m . In other words, the microphone is disposed at a position away from the surface of the peripheral surface of the baffle (R _m -R _b ). For example, the microphone is arranged by being supported by a thin rod-like member protruding vertically from the peripheral surface of the baffle.

N _z circles centering on the baffle axis and having the circumferential direction of the baffle in the circumferential direction are positioned at z _c intervals, for example, with z _c as a predetermined distance. Further, the N _φ microphones arranged in the same circle are positioned at intervals of φ _c degrees, with φ _c being a predetermined angle.

The microphones may be arranged at any interval. That is, each of z _c and φ _c , which is an interval between adjacent microphones, can take an arbitrary value. However, it is possible to reproduce the sound field with high accuracy by arranging the microphones at equal intervals, that is, by setting each of z _c and φ _c that are intervals between adjacent microphones to the same value.

The speakers constituting the speaker array are arranged at equal intervals. The length of the microphone array in the z-axis direction is substantially the same as the length of the speaker array. The positions of the N _z circles with the baffle axis as the center and the circumferential direction of the baffle as the circumferential direction are preferably the same as the positions in the speaker array of the speakers corresponding to the respective circles. good. If this position is the same, the sound field can be reproduced more faithfully.

Distance R _m from the axis of the baffle the microphone is located is, for example, 2cm approximately. As the distance R _m from the baffle axis increases, sharper directivity can be formed, but more microphones are required. The distance R _m from the baffle axis is desirably set experimentally in consideration of the frequency of the signal to be collected. The microphone is arranged toward the outside of the peripheral surface of the cylindrical rigid baffle.

  The speaker may be disposed in the air in the second space in an acoustically transparent state, or may be disposed in the second space in a state that is not acoustically transparent. The acoustically transparent state is a state in which the same transmission characteristic as that of the second space where no speaker is arranged is maintained. For example, the speaker is placed in the air in the second space by being hung with a thread or fixed with a thin rod.

The position of the microphone Mi-j in the first space is (R _m , φ _{m, j} , z _{m, i} ) [i = 1,2,..., N _z , j = 1,2,. N _φ ]. The position of the speaker Si in the second space is expressed as (0,0, z _{s, i} ) [i = 1,2,..., N _z ] in the cylindrical coordinate system.

  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 directivity control unit 2, a spatial frequency conversion unit 3, a conversion filter unit 4, a spatial frequency inverse conversion unit 5, and a frequency inverse unit. The conversion unit 6 and the window function unit 7 are included, for example, and the processing of each step illustrated in FIG. 5 is performed.

The microphones M1-1, M2-1,..., MN _z −N _φ arranged in the first space pick up the sound emitted from the sound source S in the first space and generate a time domain 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-j located at (R _m , φ _{m, j} , z _{m, i} ) is denoted as p _ij (t).

The frequency converter 1 converts the signal p _ij (t) collected by the microphones M1-1, M2-1,..., MN _z −N _φ 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 directivity control unit 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. Further, the frequency domain signal P _ij (ω) may be generated using a method such as overlap add. When the input signal is long or when the signal is continuously input as in real time processing, the processing is performed for each frame such as every 10 ms. The frequency domain signal P _ij (ω) is defined, for example, as in Expression (1). J in the argument of the function exp is an imaginary unit.

The directivity control unit 2 converts the frequency domain signal P _ij (ω) into the post-directivity formation signal P ^MB _i (ω) by performing directivity formation based on the circular harmonic analysis (step S2). The converted directivity-formed signal P ^MB _i (ω) is sent to the spatial frequency conversion unit 3. The directivity control unit 2 forms directivity with respect to the frequency domain signal P _ij (ω) in a predetermined direction φ ₀ by an arbitrary directivity control method for each index i in the z-axis direction. The predetermined direction φ ₀ is a direction in which directivity is formed. For example, φ ₀ is set in advance in the direction in which the speaker is present. Any method may be used as the directivity control method. For example, a well-known directivity control method such as a delay sum beamformer or a minimum dispersion beamformer can be applied.

If the microphone is placed on the surface of the cylindrical rigid baffle, that is, R _m = R _b , calculate P ^MB _i (ω) defined by equation (2). The directivity can be formed with higher accuracy.

N _φ is the number of microphones in the φ direction. W _j is a weight determined based on the index j in the φ direction, for example, as in Expression (3).

A (ω) is a constant and is a complex number determined by the frequency ω. k is the wave number, and can be obtained by k = ω / c, where c is the speed of sound. As described above, R _m is the distance between the baffle axis and the microphone, and φ ₀ is the direction in which directivity is formed. The order N of the sum can be determined as follows, but may be any value as long as it is a positive integer.

H _n ⁽¹⁾ (•) is an n-th order Hankel function of the first kind. The n-th order first-class Hankel function H _n ⁽¹⁾ (x) is defined as follows using the n-order Bessel function J _n (x).

When the microphone is arranged at a position away from the peripheral surface of the cylindrical rigid baffle, that is, when R _m > R _b , the weight W _j in equation (2) is expressed as in equation (4), for example. Determine.

J _n '(・) is the derivative of the nth-order Bessel function J _n (・), and H _n ⁽¹⁾ ' (・) is the derivative of the nth-order Hankel function H _n ⁽¹⁾ (・) It is. J _n ′ (z) and H _n ⁽¹⁾ ′ (z) are defined as follows.

Spatial frequency transformation unit 3, the Fourier transform of the spatial directivity formation after signal P ^MB _i (ω) into a space-time frequency domain signal P ~ _n (ω) (Step S3). The spatio-temporal frequency domain signal P _n (ω) is calculated for each frequency ω. The converted spatio-temporal frequency domain signal P _n (ω) is sent to the conversion filter unit 4. Specifically, the spatial frequency conversion unit 3 calculates P _n (ω) defined by the equation (5).

k _{z, n} is the wave number in the z-axis direction, and n is an index of the wave number k _{z, n} . The wave number is a so-called spatial frequency or angular spectrum. Equation (5) is an example of the transformation into the spatio-temporal frequency domain, and the spatial Fourier transform may be performed by other methods.

The transform filter unit 4 applies a predetermined filter F _n (ω) to the spatio-temporal frequency domain signal P _n (ω) according to the following equation (6) to apply the filtered signal D _n (ω): Is generated (step S4). The filtered signal _D˜n (ω) is transmitted to the spatial frequency inverse transform unit 5.

In Expression (6), the filter F _n (ω) is a spatio-temporal frequency domain for outputting a spatio-temporal frequency domain signal generated based on the signals collected by the one-dimensional microphone array by the one-dimensional speaker array. Anything can be applied as long as it can be converted into a signal.

For example, the conversion filter unit 4 can apply the filter F _n (ω) defined by Expression (7) described in Non-Patent Document 1.

In Expression (7), 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).

R _ref is the distance from the speaker array to the straight line that matches the amplitude, and before and after this, an error occurs in the amplitude. Specifically, the speaker array S1, S2, ..., are the same height as the SN _z, a speaker array S1, S2, ..., there from SN _z in a position apart R _ref, a speaker array S1, S2, ..., The amplitude matches at a position on a straight line parallel to the straight line where SN _z is arranged.

By applying the filter F _n (ω) defined by the equation (6), the amplitude of the signal reproduced in the second space can be made to coincide with a predetermined straight line, so that the range is wider than before. The amplitudes of the signals reproduced in the above match.

The transform filter unit 4 is, for example, “Shoichi Koyama, Kenichi Furuya, Yusuke Hiwasaki,“ Control of sound field reproduction position by phase shift of spatiotemporal spectrum ”, Proc. Of the Acoustical Society of Japan, September 2011, P. . The filter F _n (ω) defined by the equation (8) described in “637-638 (hereinafter referred to as Reference 1)” can be applied.

  In Expression (8), d is the distance between the position where the signal collected by the microphone array is reproduced and the speaker array. This distance d is positive in the front direction of the speaker array.

The transform filter unit 4 is, for example, “Shoichi Koyama, Kenichi Furuya, Yusuke Hiwasaki,“ Sound Field Reproduction Filter Design Method in Spatio-Temporal Frequency Domain Considering Speaker Directivity ”, Proc. Of the Acoustical Society of Japan, 2012. March, p. The filter F _n (ω) defined by Expression (9) described in “913-914 (hereinafter referred to as Reference 2)” can be applied.

In Equation (9), G to _2D are functions obtained by subjecting a two-dimensional free space Green function representing ideal transfer characteristics to a spatial Fourier transform in the z-axis direction. G ~ _sp is a function obtained by Fourier transform of space in the z-axis direction with the pre-measured transfer characteristics between the position of the speaker array in the space where the sound field is reproduced and the position away from that position by R _ref It is.

The filter F _n (ω) defined by the equation (9) constitutes a filter using a transfer characteristic measured in advance. Therefore, by applying the filter F _n (ω) defined by the equation (9), the sound field can be reproduced even if the directivity of the speakers constituting the speaker array is arbitrary. .

In addition, the conversion filter unit 4 can apply, for example, a filter F _n (ω) defined by Expression (10) described in Reference Document 2.

In Equation (10), p and q are preset orders, and d _{p and q} are multipole coefficients obtained by multipole expansion of the transfer characteristics of the speakers constituting the speaker array with orders p and q. For example, one or more of p and q are positive values other than 0, such as setting all of p and q to 1. k _ρ is defined by the following equation.

The filter F _n (ω) defined by the expression (10) constitutes a filter using the transfer characteristics measured in advance. Therefore, by applying the filter F _n (ω) defined by Expression (10), the sound field can be reproduced even if the directivity of the speakers constituting the speaker array is arbitrary. .

The spatial frequency inverse transform unit 5 transforms the filtered signal _D˜n (ω) into the frequency domain signal D _i (ω) by inverse Fourier transform of the space (step S5). The converted frequency domain signal D _i (ω) is sent to the frequency inverse transform unit 6. Specifically, the spatial frequency inverse transform unit 5 calculates the frequency domain signal D _i (ω) defined by the equation (11).

The frequency inverse transform unit 6 transforms the frequency domain signal D _i (ω) into a time domain signal P ^d _i (t) by inverse Fourier transform (step S6). 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 7.

The window function unit 7 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 S7). Window function after a time-domain signal d _i (t) is the speaker array S1, S2, ..., are sent to the SN _z.

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

The speaker arrays S1, S2,..., SN _z reproduce sound based on the time domain signal d _i (t) after the window function. Specifically, with i = 1,..., N _z , the speaker Si located at (0,0, z _{s, i} ) reproduces sound based on the time domain signal d _i (t) after the window function. Thereby, the sound field of the first space can be reproduced in the second space.

Number of channels z-axis direction of the microphone array, if greater 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 channels in the z-axis direction of the microphone array is smaller than the number of speakers constituting the speaker array, interpolation is performed by taking an average of the time domain signals d _i (t) after the window function. Also good. As a method for performing the interpolation, for example, linear interpolation, sinc interpolation, or the like can be applied.

In this way, the microphone array has a cylindrical shape, and directivity is formed in a predetermined direction for each of N _φ microphones arranged in the φ direction on the circumferential surface of the cylindrical rigid baffle. The reflected sound and the like can be suppressed. Therefore, even when a linear speaker array is used, reverberation can be reproduced while reproducing the direct sound of the target sound field. Therefore, the sound field can be reproduced with higher accuracy than in the past.

[Second Embodiment]
Sound field sound collection reproducing apparatus and method of the second embodiment, as shown in FIG. 6, it is arranged from the axis of the rigid baffle cylindrical radius R _b of the first space at a position away R _m A microphone array composed of N _z × N _φ microphones M1-1, M2-1,..., MN _z −N _φ , and K × N _z speakers S1-1, which are arranged in the second space. S2-1, ..., using a speaker array comprised of SK-N _z, the sound field of the first space formed by the sound generated by the sound source S of the first space reproduced in the second space To do.

The arrangement of the microphones arranged in the first space is the same as in the first embodiment. In the speaker array arranged in the second space, N _z speakers arranged in a straight line are arranged in K rows at different heights. The arrangement of N _z speakers arranged in a straight line is the same as in the first embodiment. The speaker rows may be arranged at any interval.

  As shown in FIG. 7, the sound field sound collecting / reproducing apparatus of the second embodiment includes a frequency conversion unit 1, a directivity control unit 2, K spatial frequency conversion units 3-1,..., 3-K, and K pieces. .., 4-K, K spatial frequency inverse transform units 5-1,..., 5-K, K frequency inverse transform units 6-1,. ,..., 7-K, for example, and performs the processing of each step illustrated in FIG.

The directivity control unit 2 of this embodiment duplicates the frequency domain signal P _ij (ω) into K pieces and forms directivities in _K different directions φ _0-1 ,..., Φ _0-K. By doing so, the signal ^PMB _1-i (ω),..., P ^MB _Ki (ω) is converted. For example, the direction in which directivity is formed is set such that the first direction φ _0-1 is set to the direction of the speaker's mouth and the second direction φ _0-2 is set to the direction of the speaker's foot. Any directivity control method may be used as in the first embodiment. The converted directivity-formed signals P ^MB _1-i (ω),..., P ^MB _Ki (ω) are sent to the corresponding spatial frequency conversion units 3-1,.

Subsequent processing may be performed in parallel with processing similar to that of the first embodiment. That is, the directivity-formed signal P ^MB _ki (ω) (1 ≦ k ≦ K) is converted into a spatio-temporal frequency domain signal _P˜kn (ω) by the spatial frequency conversion unit 3-k, and the conversion filter unit 4- sent to k. The spatio-temporal frequency domain signal P ~ _kn (ω) is converted into a filtered signal D ~ _kn (ω) by the transform filter unit 4-k and sent to the spatial frequency inverse transform unit 5-k. The filtered signal _D˜kn (ω) is converted into the frequency domain signal D _ki (ω) by the spatial frequency inverse transform unit 5-k and sent to the frequency inverse transform unit 6-k. The frequency domain signal D _ki (ω) is converted into a time domain signal P ^d _ki (t) by the frequency inverse transform unit 6-k and sent to the window function unit 7-k. Time domain signal P ^d _ki (t) is transformed after the window function in the window function section 7-k time domain signals d _ki (t). Speaker Sk-1, ..., the Sk-N _z, reproduces sound based on after window function time domain signal d _ki (t).

  In this way, the signal picked up by the cylindrical microphone array is formed with directivity in K different directions and reproduced from the speaker arrays arranged in the K rows in the vertical direction, thereby providing a three-dimensional effect in the vertical direction. Can be reproduced with higher accuracy. However, since the range in which directivity is formed is wider than in the first embodiment, there is a possibility that suppression of reflected sound or the like is not sufficient. Therefore, it is necessary to adjust the direction in which directivity is formed in consideration of the environment of the collected sound field.

[Third embodiment]
Sound field sound collection reproducing apparatus and method of the third embodiment, similarly to the second embodiment, the radius R _b of the cylindrical axis of the rigid baffle of the first space is located at a distance R _m N _z × N _phi number of microphones M1-1 which are, M2-1, ..., a microphone array consisting of _MN z -N _φ, the second K × disposed in a space of N _z number of speakers S1-1 , S 2-1,..., SK-N _z and a sound field of the first space formed by the sound generated by the sound source S of the first space in the second space. Reproduce.

  As shown in FIG. 8, the sound field sound collecting and reproducing apparatus according to the third embodiment includes a frequency conversion unit 1, a directivity control unit 2, a spatial frequency conversion unit 3, a conversion filter unit 4, a spatial frequency inverse conversion unit 5, and a frequency inverse unit. The conversion unit 6 and the window function unit 7 are included as in the first embodiment, and the output switching unit 8 is further included, for example.

Directivity control section 2 of this embodiment, the direction phi ₀ to form a directional and arbitrarily set, set direction phi ₀ in by forming a directional beamforming after signal P ^MB _i (ω ). The converted directivity-formed signal P ^MB _i (ω) is sent to the spatial frequency conversion unit 3. The processing from the spatial frequency conversion unit 3 to the window function unit 7 is the same as that in the first embodiment.

The post-window function time domain signal d _i (t) generated by the window function unit 7 is sent to the output switching unit 8. The output switching unit 8 refers to the direction φ ₀ that forms the directivity set in the directivity control unit 2 and switches the speaker train to be reproduced. Which speaker row is to be reproduced is previously associated with the direction φ _{0 in} which directivity is formed. For example, assuming that the speaker arrays arranged in the second space are arranged in two rows and the directivity is formed in a direction higher than the middle of the speaker rows, the speakers S1-1 arranged at a high position. , ..., reproduces the S1-N _z after window function time from the area signal d _i (t). In the case of forming the directivity to a lower direction than the middle of the speaker array, low placed speaker positions S2-1, ..., reproduces the S2-N _z after window function time from the area signal d _i (t) .

  In this way, the directionality control unit 2 can arbitrarily set the direction in which the directivity is formed, and the height of the sound source is increased by associating the direction in which the directivity is formed with the height of the speaker to be reproduced. Can be accurately reproduced.

[Fourth embodiment]
Sound field sound collection reproducing apparatus and method of the fourth embodiment, like the first embodiment, the radius R _b of the cylindrical axis of the rigid baffle of the first space is located at a distance R _m A microphone array composed of N _z × N _φ microphones M1-1, M2-1,..., MN _z −N _φ , and N _z speakers S1, arranged linearly in the second space. S2, ..., using a speaker array comprised of SN _z, to reproduce the sound field of the first space formed by the sound generated by the sound source S of the first space with the second space.

  As shown in FIG. 9, the sound field sound collecting and reproducing apparatus according to the fourth embodiment includes a frequency conversion unit 1, a directivity control unit 2, a spatial frequency conversion unit 3, a conversion filter unit 4, a spatial frequency reverse conversion unit 5, and a frequency reverse unit. The conversion unit 6 and the window function unit 7 are included in the same manner as in the first embodiment, and a weighted addition unit 9 is further included, for example.

Similar to the second embodiment, the directivity control unit 2 of this embodiment replicates the K frequency domain signals P _ij (ω) into K different directions φ _0-1 ,. By forming the directivity at _0-K , the signal P ^MB _1-i (ω),..., P ^MB _Ki (ω) is converted. The converted directivity-formed signals P ^MB _1-i (ω),..., P ^MB _Ki (ω) are sent to the weighted addition unit 9.

Weighted addition unit 9, directional formed after signal _{^{P MB 1-i (ω)}} , ..., P MB Ki (ω) weighting coefficients w ₁ as defined respectively in advance, ..., summing the weighted with w _K By doing so, the signal P ^w _i (ω) after forming the weighted directivity is generated. The generated weighted directivity-formed signal P ^w _i (ω) is sent to the spatial frequency converter 3. Weighting coefficients w _1, ..., w _K is the direction to form a directivity phi _0-1, ..., it is defined in association with phi _0-K. The processing after the spatial frequency conversion unit 3 is the same as that in the first embodiment.

For example, if the first direction φ _0-1 is set to the direction of the speaker's mouth and the second direction φ _0-2 is set to the direction of the speaker's foot, the first direction φ _0-1 the weights w ₁ applied after beamforming to form a directional signal P ^MB _1-i (ω) set large, the second direction phi _0-2 beamforming after signal P ^MB forming directivity in _By setting the weight w ₂ applied to _2-i (ω) to be large, the stereoscopic effect in the vertical direction can be reproduced with high accuracy while making the signal components including the speaker's speech stand out.

[Fifth embodiment]
Sound field sound collection reproducing apparatus and method of the fifth embodiment, similarly to the second embodiment, the radius R _b of the cylindrical axis of the rigid baffle of the first space is located at a distance R _m A microphone array composed of N _z × N _φ microphones M1-1, M2-1,..., MN _z −N _φ , and L × N _z speakers S1-1 arranged in the second space. , S 2-1,..., SL-N _z and a sound field of the first space formed by the sound generated by the sound source S of the first space in the second space. Reproduce.

  As shown in FIG. 10, the sound field sound collecting / reproducing apparatus of the fifth embodiment includes a frequency conversion unit 1, a directivity control unit 2, L spatial frequency conversion units 3-1, ..., 3-L, and L pieces. Transform filter units 4-1,..., 4-L, L spatial frequency inverse transform units 5-1,..., 5-L, L frequency inverse transform units 6-1,. ., 7-L are included in the same manner as in the second embodiment, and a weighted addition unit 9 is further included, for example.

Similar to the second embodiment, the directivity control unit 2 of this embodiment replicates the K frequency domain signals P _ij (ω) into K different directions φ _0-1 ,. By forming the directivity at _0-K , the signal P ^MB _1-i (ω),..., P ^MB _Ki (ω) is converted. Of the converted directivity-formed signals P ^MB _1-i (ω),..., P ^MB _Ki (ω), H post-directivity-formed signals P ^MB _hi (ω) (1 ≦ h ≦ H) are It is sent to the weighted adder 9. The other G post-directivity formation signals P ^MB _gi (ω) (1 ≦ g ≦ G) are sent to the corresponding spatial frequency conversion units 3-2,. However, K> L, K = H + G, and L = G + 1.

The weighted addition unit 9 of this embodiment includes H weighting factors w ₁ that predetermine the input H post-directivity forming signals P ^MB _1-i (ω),..., P ^MB _Hi (ω). ,..., W _H to generate a weighted directivity-formed signal P ^w _i (ω). The generated weighted directivity-formed signal P ^w _i (ω) is sent to the spatial frequency conversion unit 3-1. The processes after the spatial frequency conversion units 3-1, ..., 3-L are the same as those in the second embodiment.

  As described above, the directivity of the signals collected by the cylindrical microphone array is formed in different K directions, the weights of some signals are added, and the speaker array arranged in L rows in the vertical direction. By reproducing from the above, the three-dimensional effect in the vertical direction can be reproduced. By weighted addition of signals corresponding to a plurality of directions within a range that does not greatly affect direction recognition by human hearing, the stereoscopic effect in the vertical direction can be accurately reproduced even with a small number of speakers.

[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 space or the reproducing device arranged in the second space. In other words, the frequency conversion unit 1, the directivity control unit 2, the spatial frequency conversion unit 3, the conversion filter unit 4, the spatial frequency reverse conversion unit 5, the frequency reverse conversion unit 6, the window function unit 7, the output switching unit 8, the weight Each process of the appending unit 9 may be executed by a sound collecting device arranged in the first space, or may be executed by a reproducing device arranged in the second space. The signal generated by the sound collection device is transmitted to the reproduction device.

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

  The window function processing by the window function unit 7 may be performed at any stage or in multiple stages. That is, the window function unit 7 is arranged between the microphone array and the frequency conversion unit 1, between the frequency conversion unit 1 and the directivity control unit 2, between the directivity control unit 2 and the spatial frequency conversion unit 3, and directivity. Between the control unit 2 and the weighted addition unit 9, between the weighted addition unit 9 and the spatial frequency conversion unit 3, between the spatial frequency conversion unit 3 and the conversion filter unit 4, and between the conversion filter unit 4 and the spatial frequency inverse It may be provided between at least one between the conversion unit 5, between the spatial frequency reverse conversion unit 5 and the frequency reverse conversion unit 6, and between the frequency reverse conversion unit 6 and the output switching unit 8. 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 7 may not be provided. In this case, with i = 1,..., _Nz , the speaker Si reproduces the sound based on the time domain signal ^Pd _i (t).

  As long as the sound field sound collecting / reproducing apparatus includes the directivity control unit 2, it may not include other units. For example, the sound field sound collecting / reproducing device may include a directivity control unit 2, a spatial frequency inverse transform unit 3, a transform filter unit 4, a spatial frequency inverse transform unit 5, and a frequency inverse transform unit 6. Further, the sound field sound collecting / reproducing apparatus may include a frequency converter 1, a directivity controller 2, and a spatial frequency converter 3.

  You may perform simultaneously the process of the frequency converter 1, the process of the directivity control part 2, and the process of the spatial frequency converter 3. Similarly, the process of the spatial frequency inverse transform unit 5 and the process of the frequency inverse transform unit 6 may be performed simultaneously. Further, the spatial frequency conversion unit 3 and the spatial frequency inverse conversion unit 5 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 Directivity control part 3 Spatial frequency conversion part 4 Conversion filter part 5 Spatial frequency reverse conversion part 6 Frequency reverse conversion part 7 Window function part 8 Output switching part 9 Weighted addition part

Claims (16)

And at least two microphones are arranged in each of the two or more circles having a radius R _m to the circumferential direction of the center axis of the rigid baffle cylindrical radius R _b above baffle and the circumferential direction, R _m ≧ R _b , at least two speakers are arranged in a straight line, the axial direction of the baffle is the z-axis direction, the circumferential direction of the baffle is the φ direction, and i is an index in the z-axis direction Where j is the index in the φ direction, ω is the frequency,
For the frequency domain signal P _ij (ω) generated based on the signal collected by the microphone, directivity is set in one direction predetermined for each index i in the z-axis direction by an arbitrary directivity control method. A directivity control unit that generates and generates a signal P ^MB _i (ω) after directivity formation;
A spatial frequency conversion unit that converts the signal P ^MB _i (ω) after directivity formation into a spatio-temporal frequency domain signal P to _n (ω) by Fourier transform of the space;
Spatio-temporal frequency for outputting a spatio-temporal frequency domain signal generated based on signals collected by a one-dimensional microphone array to a spatio-temporal frequency domain signal P ~ _n (ω) by a one-dimensional speaker array Applying a filter F ~ _n (ω) that converts to a region signal, and generating a filtered signal D ~ _n (ω),
Sound field collection and playback device including The sound field collecting and reproducing apparatus according to claim 1,
R _m = R _b , c is the speed of sound, k = ω / c, H _n ⁽¹⁾ (·) is the nth-order first-class Hankel function, φ ₀ is the direction in which directivity is formed, N Is an arbitrary positive integer, and A is a complex number determined based on the frequency ω,
The directivity control unit applies a filter W _j defined by the following equation based on the index j in the φ direction to the frequency domain signal P _ij (ω) to generate a signal P ^MB _i ( ω)

Sound field recording and playback device. The sound field collecting and reproducing apparatus according to claim 1,
R _m > R _b , c is the speed of sound, k = ω / c, J _n (・) is an nth-order Bessel function, and H _n ⁽¹⁾ (・) is an n-th order first-class Hankel function. , J _n '(・) is the derivative of the nth-order Bessel function J _n (・), and H _n ⁽¹⁾ ' (・) is the derivative of the nth-order Hankel function H _n ⁽¹⁾ (・) And φ ₀ is the direction in which directivity is formed, N is an arbitrary positive integer, and A is a complex number determined based on the frequency ω,
The directivity control unit applies a filter W _j defined by the following equation based on the index j in the φ direction to the frequency domain signal P _ij (ω) to generate a signal P ^MB _i ( ω)

Sound field recording and playback device. In the sound field collecting and reproducing device according to any one of claims 1 to 3,
As for the speaker, it is assumed that at least two speakers arranged in a straight line are arranged in K rows,
The directivity control unit replicates the frequency domain signal P _ij (ω) into K pieces, and forms directivities in different K directions.
Sound field recording and playback device. In the sound field sound collecting and reproducing device according to any one of claims 1 to 4,
The weighted directivity-formed signal P ^{w is obtained} by performing weighted addition to the post-directivity-formed signal P ^MB _i (ω) using a weighting factor determined in association with the direction in which the directivity is formed. a weighted adder that generates _i (ω),
Sound field collection and playback device including And at least two microphones are arranged in each of the two or more circles having a radius R _m to the circumferential direction of the center axis of the rigid baffle cylindrical radius R _b above baffle and the circumferential direction, R _m ≧ R _b , at least two speakers are arranged in a straight line, the axial direction of the baffle is the z-axis direction, the circumferential direction of the baffle is the φ direction, and i is an index in the z-axis direction Where j is the index in the φ direction, ω is the frequency,
For the frequency domain signal P _ij (ω) generated based on the signal collected by the microphone, directivity is set in one direction predetermined for each index i in the z-axis direction by an arbitrary directivity control method. For the spatio-temporal frequency domain signal P ~ _n (ω) obtained by transforming the generated directivity-formed signal P ^MB _i (ω) by spatial Fourier transform, the signal collected by the one-dimensional microphone array Apply the filter F ~ _n (ω) to convert the spatio-temporal frequency domain signal generated based on the spatio-temporal frequency domain signal to be output by a one-dimensional speaker array, and the filtered signal D ~ _n (ω) A conversion filter section for generating
A spatial frequency inverse transform unit that transforms the filtered signal D to _n (ω) into a frequency domain signal D _i (ω) by inverse Fourier transform of the space;
A frequency inverse transform unit for transforming the frequency domain signal D _i (ω) into a time domain signal by inverse Fourier transform and outputting the transformed time domain signal to the speaker;
Sound field collection and playback device including The sound field collecting and reproducing device according to claim 6,
R _m = R _b , c is the speed of sound, k = ω / c, H _n ⁽¹⁾ (·) is the nth-order first-class Hankel function, φ ₀ is the direction in which directivity is formed, N Is an arbitrary positive integer, and A is a complex number determined based on the frequency ω,
The conversion filter unit, the frequency domain signal P _ij (ω) with respect to, phi directivity formation after signal P ^MB generated by applying a filter W _j is defined by the following equation based on the index j _The spatio-temporal frequency domain signal generated based on the signals collected by the one-dimensional microphone array is used as the primary order for the spatio-temporal frequency domain signal P ~ _n (ω) obtained by transforming _i (ω) by spatial Fourier transform. Applying a filter F ~ _n (ω) that converts to a spatio-temporal frequency domain signal for output by the original speaker array to generate a filtered signal D ~ _n (ω),

Sound field recording and playback device. The sound field collecting and reproducing device according to claim 6,
R _m > R _b , c is the speed of sound, k = ω / c, J _n (・) is an nth-order Bessel function, and H _n ⁽¹⁾ (・) is an n-th order first-class Hankel function. , J _n '(・) is the derivative of the nth-order Bessel function J _n (・), and H _n ⁽¹⁾ ' (・) is the derivative of the nth-order Hankel function H _n ⁽¹⁾ (・) And φ ₀ is the direction in which directivity is formed, N is an arbitrary positive integer, and A is a complex number determined based on the frequency ω,
The conversion filter unit, the frequency domain signal P _ij (ω) with respect to, phi directivity formation after signal P ^MB generated by applying a filter W _j is defined by the following equation based on the index j _The spatio-temporal frequency domain signal generated based on the signals collected by the one-dimensional microphone array is used as the primary order for the spatio-temporal frequency domain signal P ~ _n (ω) obtained by transforming _i (ω) by spatial Fourier transform. Applying a filter F ~ _n (ω) that converts to a spatio-temporal frequency domain signal for output by the original speaker array to generate a filtered signal D ~ _n (ω),

Sound field recording and playback device. The sound field collecting and reproducing apparatus according to any one of claims 6 to 8,
As for the speaker, it is assumed that at least two speakers arranged in a straight line are arranged in K rows,
The directivity-formed signal P ^MB _i (ω) is a signal generated by replicating the frequency domain signal P _ij (ω) into K pieces and forming directivities in different K directions. Is,
Sound field recording and playback device. In the sound field collecting and reproducing device according to any one of claims 6 to 9,
The spatio-temporal frequency domain signals P to _n (ω) are weighted with respect to the directivity-formed signal P ^MB _i (ω) by using a weighting factor determined in association with the direction in which the directivity is formed. It is a signal obtained by transforming the weighted directivity-formed signal P ^w _i (ω) generated by the addition by spatial Fourier transform,
Sound field collection and playback device including The sound field collecting and reproducing apparatus according to any one of claims 6 to 8,
As for the speaker, it is assumed that at least two speakers arranged in a straight line are arranged in K rows,
An output switching unit that switches a speaker that outputs the time domain signal based on a direction in which the signal P ^MB _i (ω) is formed with directivity,
Sound field collection and playback device including In the sound field sound collecting and reproducing device according to any one of claims 6 to 11 ,
Upper Symbol frequency domain signal D _i (ω) or the time domain signal is a signal that the window function processing is performed by a predetermined window function,
Sound field recording and playback device. And at least two microphones are arranged in each of the two or more circles having a radius R _m to the circumferential direction of the center axis of the rigid baffle cylindrical radius R _b above baffle and the circumferential direction, R _m ≧ R _b , at least two speakers are arranged in a straight line, the axial direction of the baffle is the z-axis direction, the circumferential direction of the baffle is the φ direction, and i is an index in the z-axis direction Where j is the index in the φ direction, ω is the frequency,
For the frequency domain signal P _ij (ω) generated based on the signal collected by the microphone, directivity is set in one direction predetermined for each index i in the z-axis direction by an arbitrary directivity control method. A directivity control unit that generates and generates a signal P ^MB _i (ω) after directivity formation,
Sound field collection and playback device including And at least two microphones are arranged in each of the two or more circles having a radius R _m to the circumferential direction of the center axis of the rigid baffle cylindrical radius R _b above baffle and the circumferential direction, R _m ≧ R _b , at least two speakers are arranged in a straight line, the axial direction of the baffle is the z-axis direction, the circumferential direction of the baffle is the φ direction, and i is an index in the z-axis direction Where j is the index in the φ direction, ω is the frequency,
The directivity control unit is predetermined for each index i in the z-axis direction by an arbitrary directivity control method for the frequency domain signal P _ij (ω) generated based on the signal collected by the microphone. A directivity control step that forms directivity in one direction and generates a signal P ^MB _i (ω) after directivity formation;
A spatial frequency conversion step, wherein the spatial frequency conversion unit converts the directivity-formed signal P ^MB _i (ω) into a spatio-temporal frequency domain signal P to _n (ω) by Fourier transform of the space;
The transform filter unit outputs a spatio-temporal frequency domain signal generated based on signals collected by the one-dimensional microphone array to the spatio-temporal frequency domain signals P to _n (ω) by the one-dimensional speaker array. Applying a filter F ~ _n (ω) that converts to a spatio-temporal frequency domain signal for generating a filtered signal D ~ _n (ω),
Sound field collection and playback method including And at least two microphones are arranged in each of the two or more circles having a radius R _m to the circumferential direction of the center axis of the rigid baffle cylindrical radius R _b above baffle and the circumferential direction, R _m ≧ R _b , at least two speakers are arranged in a straight line, the axial direction of the baffle is the z-axis direction, the circumferential direction of the baffle is the φ direction, and i is an index in the z-axis direction Where j is the index in the φ direction, ω is the frequency,
The conversion filter unit applies a predetermined one for each index i in the z-axis direction by an arbitrary directivity control method for the frequency domain signal P _ij (ω) generated based on the signal collected by the microphone. A spatio-temporal frequency domain signal P ~ _n (ω) obtained by transforming the directivity-formed signal P ^MB _i (ω) generated by forming directivity in the direction by spatial Fourier transform is collected by a one-dimensional microphone array. Apply the filter F ~ _n (ω) to convert the spatio-temporal frequency domain signal generated based on the sounded signal into a spatio-temporal frequency domain signal for output by a one-dimensional speaker array, and then the filtered signal D ~ transform filter step to generate _n (ω);
A spatial frequency inverse transform unit transforms the filtered signal D to _n (ω) into a frequency domain signal D _i (ω) by spatial inverse Fourier transform,
A frequency inverse transform unit transforms the frequency domain signal D _i (ω) into a time domain signal by inverse Fourier transform, and outputs the transformed time domain signal to the speaker.
Sound field collection and playback method including   14. A sound field sound recording / reproducing program for causing a computer to function as each part of the sound field sound collecting / reproducing apparatus according to claim 1.

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