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JP2014116821

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DESCRIPTION JP2014116821
Abstract: To reproduce the sense of reverberation while reproducing the direct sound of the
target sound field. At least two microphones are arranged in each of two or more circles whose
circumferential direction is a circumferential direction centering on an axis of a baffle of a
cylindrical sound absorbing material. At least two speakers are arranged in a straight line. Let i
be the axial index of the baffle, j be the circumferential index of the baffle, and let ω be the
frequency. The directivity control unit 2 is a predetermined one for each index i in the z-axis
direction by an arbitrary directivity control method for the frequency domain signal P (ω)
generated based on the signal collected by the microphone. The directivity is formed in the
direction, and the directivity-formed signal P (ω) is generated. The spatial frequency converter 3
converts the directivity-formed signal P (ω) into a space-time frequency domain signal P ~ (ω) by
Fourier transform of space. The conversion filter unit 4 applies the filter F ~ (ω) to the space-time
frequency domain signal P ~ (ω) to generate a filtered signal D ~ (ω). [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 installed in a certain sound field, and the sound field is reproduced by
a speaker 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 the signal to
reproduce the sound field with a speaker array. Technology is known.
10-05-2019
1
[0003]
Shoichi Koyama, 3 others, "Spatio-temporal frequency domain signal conversion method for
sound field collection and reproduction", Proceedings of the Acoustical Society of Japan,
September 2011, P. 635-636
[0004]
In the technique described in Non-Patent Document 1, when a linear array is used, there is a
possibility that the reverberation of the reproduced sound field is increased when the sound
pickup field is in a reverberant environment.
[0005]
An object of the present invention is to provide a sound field sound collecting and reproducing
apparatus, method and program capable of reproducing a sound field with higher accuracy than
conventional.
[0006]
In order to solve the above-mentioned subject, sound field sound collection playback device by
one mode of this invention radius Rm which makes the circumferential direction of the baffle
circumferential direction centering on the axis of baffle of the cylindrical sound absorption
material of radius Rb It is assumed that at least two microphones are arranged in each of two or
more circles, Rm> Rb, at least two speakers are linearly arranged, and the axis of the baffle of
cylindrical sound absorbing material The direction was z-axis direction, the circumferential
direction of the baffle of cylindrical sound-absorbing material was φ direction, i was index of zaxis direction, j was index of φ direction, ω was frequency, and sound was collected by
microphone For the frequency domain signal Pij (ω) generated based on the signal, directivity is
formed in one direction predetermined for each index i in the z-axis direction by any directivity
control method, and the directivity formed signal Directivity to generate P <MB> i (ω) Control
unit, a space-frequency conversion unit for converting directivity formed signal P <MB> i (ω)
into space-time frequency domain signal P ~n (ω) by Fourier transform of space, and space-time
frequency domain signal P ~ A filter F ~ for converting space-time frequency domain signals
generated based on signals picked up by the one-dimensional microphone array into space-time
frequency domain signals for outputting by the one-dimensional speaker array for n (ω) and a
conversion filter unit that generates the filtered signal D ~n (ω) by applying n (ω).
[0007]
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2
According to another aspect of the present invention, there is provided a sound field sound
collecting and reproducing apparatus, wherein each of two or more circles of radius Rm whose
circumferential direction is a circumferential direction of the baffle centered on the baffle axis of
the cylindrical sound absorbing material of radius Rb. It is assumed that at least two microphones
are arranged at the same time, Rm> Rb, at least two speakers are arranged in a straight line, and
the axial direction of the baffle of the cylindrical sound absorbing material is the z-axis direction.
The circumferential direction of the baffle of the shape of the sound absorbing material is φ
direction, i is an index in the z axis direction, j is an index in the φ direction, ω is a frequency,
and a frequency is generated based on the signal collected by the microphone A directivity
formed signal P <MB> i generated by forming directivity in one direction predetermined for each
index i in the z-axis direction by an arbitrary directivity control method with respect to the area
signal Pij (ω) transformed ω) by Fourier transform of space A space-time frequency domain
signal for outputting a space-time frequency domain signal generated based on a signal collected
by the one-dimensional microphone array to the space frequency domain signal P to n (ω) by the
one-dimensional speaker array By applying a filter F to n (ω) to convert into a filter to generate a
filtered signal D to n (ω), and an inverse Fourier transform of the filtered signal D to n (ω) in
space A space frequency inverse transform unit that converts the frequency domain signal Di
(ω), and a frequency inverse that converts the frequency domain signal Di (ω) to a time domain
signal by inverse Fourier transform and outputs the converted time domain signal to the speaker
And a converter.
[0008]
Even in the case of using a linear speaker array, the microphone array can be made cylindrical,
so that the direct sound of the target sound field can be reproduced while the reverberation can
be reproduced.
Therefore, the sound field can be reproduced with higher accuracy than in the prior art.
[0009]
FIG. 1 is a functional block diagram showing an example of a sound field collection and
reproduction device according to a first embodiment.
The figure for demonstrating the example of arrangement | positioning of the microphone of 1st
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3
embodiment, and a speaker.
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 of 2nd
embodiment, and a speaker.
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.
[0010]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
[0011]
First Embodiment As shown in FIG. 2, the sound field sound collection and reproduction
apparatus and method according to the first embodiment has a position Rm away from the axis
of the baffle of the cylindrical sound absorbing material having the radius Rb of the first space. ,
And a microphone array composed of Nz × Nφ microphones M1-1, M2-1,..., MNz-Nφ, and Nz
speakers S1 and S2 linearly arranged in the second space. The sound field of the first space
formed by the sound generated by the sound source S of the first space is reproduced in the
second space by using the speaker array configured by ..., SNz.
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4
The first space and the second space are mutually different spaces. 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 in
the z-axis direction of the microphone array disposed in the first space and the number of
speakers disposed 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 the average of reproduction signals. As a
method of performing interpolation, for example, linear interpolation or sinc interpolation can be
applied.
[0012]
The sound absorbing material is a material having an ability to absorb sound waves, and ideally
is a material having a sound absorption coefficient of ∞. It is mainly used in buildings for the
purpose of adjusting the sound condition of the room and absorbing the noise. Specific examples
thereof include porous sound absorbing materials such as glass wool and felt, and diaphragm
sound absorbing materials that absorb vibrations using a thin plate. In the present invention, the
type of the sound absorbing material is not limited, and any sound absorbing material may be
used.
[0013]
As shown in FIG. 3, Nφ microphones are equally spaced in each of Nz circles whose
circumferential direction is the circumferential direction of the cylindrical sound absorbing
material baffle with the axis of the cylindrical sound absorbing material baffle as the center. Will
be placed. Nz and Nφ are predetermined integers of 2 or more. That is, by disposing two
microphones in each of two circles whose circumferential direction is the circumferential
direction of the baffle, at least four microphones are disposed at positions Rm away from the axis
of the baffle.
[0014]
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5
The radius Rb of the baffle of the cylindrical sound absorbing material and the distance Rm
between the axis of the baffle and the microphone may be any value as long as Rm> Rb. As
shown in FIG. 4, the microphones are disposed at a position Rm away from the axis of the
cylindrical baffle of radius Rb. In other words, the microphone is placed at a position (Rm-Rb)
away from the surface of the peripheral surface of the baffle. For example, the microphone is
disposed by being supported by a thin rod-like member that protrudes vertically from the
circumferential surface of the baffle.
[0015]
Nz circles having the axis of the baffle as the center and the circumferential direction of the
baffle as the circumferential direction are located at zc intervals, for example, with zc as a
predetermined distance. Further, N.phi. Microphones arranged in the same circle are positioned
at an interval of .phi.c degrees, where .phi.c is a predetermined angle.
[0016]
The microphones may be spaced at any distance. That is, each of the distances zc and φc
between adjacent microphones can take arbitrary values. However, the sound field can be
reproduced with high accuracy by arranging the microphones at equal intervals, that is, setting
the same value to each of zc and φc which are the intervals between adjacent microphones.
[0017]
The speakers constituting the speaker array are arranged at equal intervals. The length in the zaxis direction of the microphone array and the length of the speaker array are substantially the
same. The positions of Nz circles centered on the axis of the baffle and circumferentially the
circumferential direction of the baffle are preferably the same as the positions in the speaker
array of the speaker corresponding to the respective circles, but may be different . If the
positions are the same, the sound field can be reproduced more faithfully.
[0018]
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6
The distance Rm from the axis of the baffle in which the microphone is disposed is, for example,
about 2 cm. The distance Rm from the baffle axis can form sharp directivity as the value is larger,
but more microphones are required. It is desirable to set the distance Rm from the axis of the
baffle experimentally in consideration of the frequency of the signal to be collected. In addition,
the microphone is disposed outward of the circumferential surface of the baffle of the cylindrical
sound absorbing material.
[0019]
The speaker may be disposed in the air of the second space in an acoustically transparent state,
or may be disposed in the second space in an acoustically non-transparent state. The acoustically
transparent state is a state in which the same transfer characteristic as the transfer characteristic
of the second space in which the speaker is not disposed is maintained. For example, the speaker
is placed in the air of the second space by being suspended by a thread or fixed by a thin rod.
[0020]
The position of the microphone Mi-j in the first space is expressed as (Rm, φm, j, zm, i) [i = 1,
2,..., Nz, j = 1, 2,. Do. The position of the speaker Si in the second space is expressed as (0, 0, zs, i)
[i = 1, 2,..., Nz] in a cylindrical coordinate system.
[0021]
As shown in FIG. 1, the sound field sound collecting and reproducing apparatus according to the
first embodiment includes a frequency converter 1, a directivity controller 2, a spatial frequency
converter 3, a conversion filter 4, a spatial frequency inverse converter 5, and a frequency
inverser. For example, the conversion unit 6 and the window function unit 7 are included, and
the processing of each step illustrated in FIG. 5 is performed.
[0022]
The microphones M1-1, M2-1,..., MNz-Nφ arranged in the first space pick up the sound emitted
by the sound source S in the first space and generate a time domain signal.
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7
The generated signal is sent to the frequency converter 1. A signal of time t collected in time by
the microphone Mi-j located at (Rm, φm, j, zm, i) is denoted as pij (t).
[0023]
The frequency converter 1 converts the signal pij (t) picked up by the microphones M1-1, M21,..., MNz-Nφ into a frequency domain signal Pij (ω) by Fourier transformation (step S1). The
generated frequency domain signal P ij (ω) is sent to the directivity control unit 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. Alternatively, the frequency domain signal Pij (ω) may be generated using a
method such as overlap ad. When the input signal is long or when the signal is continuously
input as in real time processing, processing is performed every frame, for example, every 10 ms.
The frequency domain signal P ij (ω) is defined as, for example, equation (1). J in the argument
of the function exp is an imaginary unit.
[0024]
[0025]
The directivity control unit 2 converts the frequency domain signal Pij (ω) into a directivity
formed signal P <MB> i (ω) by performing directivity formation based on circular harmonic
analysis (step S2).
The converted directivity-formed signal P <MB> i (ω) is sent to the spatial frequency converter 3.
The directivity control unit 2 forms directivity for the frequency domain signal Pij (ω) in a
predetermined direction φ0 by an arbitrary directivity control method for each index i in the zaxis direction. The predetermined direction φ0 is a direction for forming directivity. For
example, φ0 is set in advance in the direction in which the speaker is present. The directivity
control method may use any method. For example, known directivity control techniques such as
delay-sum beamformer and minimum dispersion beamformer can be applied.
[0026]
When the microphone is disposed at a position away from the circumferential surface of the
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8
cylindrical sound absorbing material baffle, it is more accurate by calculating P <MB> i (ω)
defined by the equation (2). Directivity can be formed.
[0027]
[0028]
Nφ is the number of microphones in the φ direction.
Wj is a weight determined as shown in equation (3), for example, based on the index j in the φ
direction.
[0029]
[0030]
A (ω) is a constant, which is a complex number determined by the frequency ω.
k is a wave number, and c can be obtained by k = ω / c, where c is the speed of sound.
As described above, Rm is the distance between the axis of the baffle and the microphone, and
φ0 is the direction forming directivity. The order N of the summation can be determined as
follows, but may be any value as long as it is a positive integer.
[0031]
[0032]
Hn <(1)> (·) is a first-class Hankel function of n-th order, and Jn (·) is a Bessel function of n-th
10-05-2019
9
order.
The n-th first kind Hankel function Hn <(1)> (x) and the n-th order Bessel function Jn (x) are
defined as follows.
[0033]
[0034]
The spatial frequency conversion unit 3 converts the directivity-formed signal P <MB> i (ω) into
space-time frequency domain signals P to n (ω) by Fourier transform of space (step S3).
The space-time frequency domain signal P ~n (ω) is calculated for each frequency ω. The
converted space-time frequency domain signals P to n (ω) are sent to the conversion filter unit 4.
Specifically, the spatial frequency transform unit 3 calculates P ~n (ω) defined by the equation
(4).
[0035]
[0036]
kz, n is a wave number in the z-axis direction, and n is an index of the wave number kz, n.
The wave number is the so-called spatial frequency or angular spectrum. Equation (4) is an
example of conversion to the space-time frequency domain, and Fourier transform of space may
be performed by another method.
[0037]
The conversion filter unit 4 applies a predetermined filter F to n (ω) to the space-time frequency
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10
domain signal P to n (ω) according to the following equation (5) to filter the filtered signal D to n
(ω) Are generated (step S4). The post-filtering signals D to n (ω) are transmitted to the space
frequency inverse transform unit 5.
[0038]
[0039]
In the equation (5), the filters F to n (ω) are space-time frequency domains for outputting,
through the one-dimensional speaker array, space-time frequency domain signals generated
based on the signals picked up by the one-dimensional microphone array. Anything that converts
to a signal can be applied.
[0040]
For example, the conversion filter unit 4 can apply the filters F to n (ω) defined by the equation
(6) described in Non-Patent Document 1.
[0041]
[0042]
In the equation (6), H0 <(2)> is the second Hankel function for 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).
[0043]
[0044]
Rref is the distance from the speaker array to the straight line for matching the amplitude, and an
error occurs in the amplitude before and after this.
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Specifically, the speaker arrays S1, S2, ..., SNz have the same height, and are spaced apart from
the speaker arrays S1, S2, ..., SNz by Rref, and the speaker arrays S1, S2, ..., SNz are arranged. The
amplitudes match at straight line positions parallel to the straight line.
[0045]
By applying the filters F to n (ω) defined by the equation (6), the amplitudes of the signals
reproduced in the second space can be made to coincide in a predetermined straight line, so that
a wider range than in the prior art The amplitudes of the signals reproduced by are identical.
[0046]
In addition, the conversion filter unit 4 is, for example, “Shoichi Koyama, Kenichi Fuya, Keisuke
Niwazaki,“ Control of sound field reproduction position by phase shift of space-time spectrum
”, Proceedings of the Acoustical Society of Japan, September 2011, P . The filters F to n (ω)
defined by the equation (7) described in “637-638 (hereinafter referred to as reference 1)” can
be applied.
[0047]
[0048]
In equation (7), d is the distance between the position at which 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.
[0049]
In addition, the conversion filter unit 4 is, for example, “Shoichi Koyama, Kenichi Fuya, Keisuke
Niwazaki,“ Sound Field Reproduction Filter Design Method in Spatio-temporal Frequency
Domain Considering Speaker Directivity, ”Proceedings of the Acoustical Society of Japan, 2012
March, P. The filters F to n (ω) defined by the equation (8) described in “913 to 914
(hereinafter referred to as reference 2)” can be applied.
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[0050]
[0051]
In equation (8), G ~2D is a function obtained by performing Fourier transform of space in the zaxis direction on a two-dimensional free space Green's function representing an ideal transfer
characteristic.
G ~ sp is a function obtained by performing Fourier transform of space in the z-axis direction on
the pre-measured transfer characteristic between the position of the speaker array in the space
where the sound field is reproduced and the position away from the position by Rref. is there.
[0052]
The filters F to n (ω) defined by the equation (8) constitute filters using transfer characteristics
measured in advance.
Therefore, by applying the filters F to n (ω) defined by the equation (8), it is possible to
reproduce the sound field even if the directivity of the speakers constituting the speaker array is
any directivity. .
[0053]
Further, the conversion filter unit 4 can apply, for example, the filters F to n (ω) defined by the
equation (9) described in the reference document 2.
[0054]
[0055]
In equation (9), p and q are pre-set orders, and dp and q are multipole coefficients obtained by
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multipole expansion of the transfer characteristics of the speakers constituting the speaker array
with orders p and q.
For example, at least one of p and q is a non-zero positive value, such as setting all of p and q to
one.
kρ is defined by the following equation.
[0056]
[0057]
The filters F to n (ω) defined by the equation (9) constitute filters using transfer characteristics
measured in advance.
Therefore, by applying the filters F to n (ω) defined by the equation (9), it is possible to
reproduce the sound field even if the directivity of the speakers constituting the speaker array is
any directivity. .
[0058]
The spatial frequency inverse transform unit 5 transforms the post-filtering signals D to n (ω)
into a frequency domain signal Di (ω) by inverse Fourier transform of space (step S 5).
The converted frequency domain signal Di (ω) is sent to the frequency inverse transform unit 6.
Specifically, the space frequency inverse transform unit 5 calculates the frequency domain signal
Di (ω) defined by the equation (10).
[0059]
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[0060]
The frequency inverse transform unit 6 transforms the frequency domain signal Di (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 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 7.
[0061]
The window function unit 7 multiplies the time domain signal P <d> i (t) by the window function
to generate a window function after time domain signal di (t) (step S7).
The post-window function time domain signal di (t) is sent to the loudspeaker arrays S1, S2, ...,
SNz.
[0062]
For example, a so-called Tukey window function wi defined by the following equation is used as
the window function. Ntp is a score to which a taper is applied, and is an integer of 1 or more
and Nz or less. Of course, other window functions may be used.
[0063]
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[0064]
The speaker arrays S1, S2,..., SNz reproduce sound based on the window function after time
domain signal di (t).
Specifically, the speaker Si located at (0, 0, zs, i) reproduces the sound based on the window
function after time domain signal di (t) as i = 1,. Thereby, the sound field of the first space can be
reproduced in the second space.
[0065]
If the number of channels in the z-axis direction of 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 channels in the z-axis
direction of 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 or the like. Good. As a method of performing interpolation, for example,
linear interpolation or sinc interpolation can be applied.
[0066]
As described above, the microphone array has a cylindrical shape, and directivity is formed in a
predetermined direction for each of N.phi. Microphones disposed in the .phi. Direction of the
peripheral surface of the baffle of the cylindrical sound absorbing material, thereby coming from
different directions Reflection sound etc. can be suppressed. Therefore, even in the case of using
a linear speaker array, 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 prior art.
[0067]
Second Embodiment As shown in FIG. 6, the sound field collection and reproduction apparatus
and method according to the second embodiment has a position Rm away from the axis of the
baffle of the cylindrical sound absorbing material of the radius Rb of the first space. , And a
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microphone array including Nz × Nφ microphones M1-1, M2-1,..., MNz-Nφ, and K × Nz
speakers S1-1, disposed in the second space. The sound field of the first space formed by the
sound generated by the sound source S of the first space is reproduced in the second space using
the speaker array configured of S2-1, ..., SK-Nz .
[0068]
The arrangement of the microphones disposed in the first space is the same as in the first
embodiment.
In the speaker array arranged in the second space, Nz speakers arranged linearly are arranged in
K rows at different heights. The arrangement of the Nz speakers arranged linearly is the same as
that of the first embodiment. The rows of speakers may be spaced at any distance.
[0069]
The sound field collection and reproduction device according to the second embodiment
includes, as shown in FIG. 6, a frequency converter 1, a directivity controller 2, K spatial
frequency converters 3-1,. .., 4-K, K spatial frequency inverse transform units 5-1,..., 5-K, K
frequency inverse transform units 6-1,. , And 7-K, for example, to perform the processing of each
step illustrated in FIG.
[0070]
The directivity control unit 2 of this embodiment copies K frequency domain signals P ij (ω) to K
and forms directivity in K different directions φ 0 1 to φ 0 to K respectively. After directivity
formation, the signal is converted to P <MB> 1-i (ω),..., P <MB> Ki (ω).
For example, as the direction for forming directivity, the first direction φ 0-1 is set to the
direction of the mouth of the speaker, and the second direction φ 0-2 is set to the direction of
the foot of the speaker. The directivity control method may use any method as in the first
embodiment. Converted directivity formed signals P <MB> 1-i (ω),..., P <MB> Ki (ω) are sent to
corresponding spatial frequency conversion units 3-1,. .
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[0071]
The subsequent processes may be performed in parallel with the processes similar to the first
embodiment. That is, the directivity formed signal P <MB> ki (ω) (1 ≦ k ≦ K) is converted to the
space-time frequency domain signal P ~kn (ω) by the space frequency conversion unit 3-k, and
the conversion filter unit Sent to 4-k. The space-time frequency domain signals P to kn (ω) are
converted into post-filtering signals D to kn (ω) by the conversion filter unit 4-k, and are sent to
the space frequency inverse transform unit 5-k. The post-filtering signal D to kn (ω) is converted
to a frequency domain signal Dki (ω) by the spatial frequency inverse transform unit 5-k, and is
sent to the frequency inverse transform unit 6-k. The frequency domain signal Dki (ω) is
converted into a time domain signal P <d> ki (t) by the frequency inverse converter 6-k, and is
sent to the window function unit 7-k. The time domain signal P <d> ki (t) is converted into a
window function after time domain signal dk-i (t) by the window function unit 7-k. The speakers
Sk-1,..., Sk-Nz reproduce sound based on the window function after time domain signal dk-i (t).
[0072]
In this manner, the directivity of the signals collected by the cylindrical microphone array is
formed in K different directions, and reproduced from the speaker array arranged in the K rows
in the vertical direction, so that the three-dimensional effect in the vertical direction is achieved.
Can be reproduced with higher precision. However, since the range in which the directivity is
formed is wider compared to the first embodiment, there is a possibility that the suppression of
the reflected sound and the like may not be sufficient. Therefore, it is necessary to adjust the
direction in which the directivity is formed in consideration of the environment of the sound
collection field.
[0073]
Third Embodiment The sound field sound collecting and reproducing apparatus and method
according to the third embodiment is the same as the second embodiment in that the distance
Rm is away from the axis of the baffle of the cylindrical sound absorbing material of the radius
Rb of the first space. A microphone array composed of Nz × Nφ microphones M1-1, M2-1,...,
MNz-Nφ arranged at positions, and K × Nz speakers S1-1 arranged in the second space , S2-1,...,
SK-Nz 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 Do.
[0074]
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The sound field sound collection and reproduction apparatus according to the third embodiment
includes, as shown in FIG. 7, 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 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.
[0075]
The directivity control unit 2 of this embodiment can arbitrarily set the direction φ0 forming
directivity, and by forming the directivity in the set direction φ0, the directivity formed signal P
<MB> i (ω Convert to).
The converted directivity-formed signal P <MB> i (ω) is sent to the spatial frequency converter 3.
The processes from the spatial frequency conversion unit 3 to the window function unit 7 are the
same as in the first embodiment.
[0076]
The post-window function time domain signal di (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 φ0
forming the directivity set in the directivity control unit 2 and switches the speaker string to be
reproduced. Which speaker string is to be reproduced is previously associated with the direction
φ0 forming directivity. For example, assuming that the speaker array arranged in the second
space is arranged in two rows, and directivity is formed in a direction higher than the middle of
the speaker row, the speaker S1-1 arranged in the high position is formed. ,..., S1-Nz to reproduce
the post-window function time domain signal di (t). When directivity is formed in a direction
lower than the middle of the speaker array, the post-window function time domain signal di (t) is
reproduced from the speakers S2-1,..., S2-Nz arranged at low positions.
[0077]
In this manner, the directivity control unit 2 can arbitrarily set the direction in which the
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directivity is formed, and by associating the direction in which the directivity is formed with the
height of the speaker to be reproduced, the height of the sound source is heightened. The
accuracy can be reproduced.
[0078]
Fourth Embodiment The sound field collection and reproduction apparatus and method
according to the fourth embodiment are the same as in the first embodiment except that the
distance Rm is from the axis of the baffle of the cylindrical sound absorbing material having the
radius Rb of the first space. A microphone array composed of Nz × Nφ microphones M1-1, M21,..., MNz-Nφ arranged at positions, and Nz speakers S1, linearly arranged in the second space
The sound field of the first space formed by the sound generated by the sound source S of the
first space is reproduced in the second space using the speaker array configured of S2,..., SNz.
[0079]
The sound field sound collection and reproduction apparatus according to the fourth
embodiment includes, as shown in FIG. 8, 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 The transformation unit 6 and the window function
unit 7 are included as in the first embodiment, and further, for example, the weighted addition
unit 9 is included.
[0080]
Similar to the second embodiment, the directivity control unit 2 of this embodiment copies K
frequency domain signals P ij (ω), and sets K copies of each of K different directions φ 0-1 to φ
0 -K. After forming the directivity, the signals after conversion are converted into signals P <MB>
1-i (ω),..., P <MB> Ki (ω).
The converted directivity-formed signals P <MB> 1-i (ω),..., P <MB> Ki (ω) are sent to the
weighted addition unit 9.
[0081]
The weighted addition unit 9 weights each of the directivity-formed signals P <MB> 1-i (ω),..., P
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<MB> Ki (ω) using predetermined weighting factors w1,. Weighted directivity after formation P
<w> i (ω) is generated by adding.
The generated weighted directivity-formed signal P <w> i (ω) is sent to the spatial frequency
converter 3.
The weighting factors w1,..., WK are determined in association with the directions φ0-1,. The
processes after the space frequency conversion unit 3 are the same as in the first embodiment.
[0082]
For example, assuming that the first direction φ0-1 is set to the direction of the mouth of the
speaker and the second direction φ0-2 is set to the direction of the foot of the speaker,
directivity in the first direction φ0-1 The directivity after formation signal P <MB> 1-i (ω) is set
to a large weight w1, and the directivity is formed in the second direction φ0-2. The directivity
after formation signal P <MB> 2 By setting the weight w2 applied to -i (ω) large, it is possible to
reproduce the three-dimensional effect in the vertical direction with high accuracy while
highlighting the component of the signal including the utterance of the speaker.
[0083]
[Fifth Embodiment] The sound field sound collecting and reproducing apparatus and method
according to the fifth embodiment is the same as the second embodiment except that the
distance Rm is from the axis of the baffle of the cylindrical sound absorbing material having the
radius Rb of the first space. A microphone array composed of Nz × Nφ microphones M1-1, M21,..., MNz-Nφ arranged at positions, and L × Nz speakers S1-1 arranged in the second space ,
S2-1,..., SL-Nz 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 Do.
[0084]
The sound field collection and reproduction device according to the fifth embodiment includes,
as shown in FIG. 9, a frequency converter 1, a directivity control unit 2, L spatial frequency
converters 3-1,. , 4-L, L spatial frequency inverse transform units 5-1,..., 5-L, L frequency inverse
transform units 6-1,. Window function units 7-1, ..., 7-L in the same manner as in the second
embodiment, and further include, for example, a weighted addition unit 9.
[0085]
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Similar to the second embodiment, the directivity control unit 2 of this embodiment copies K
frequency domain signals P ij (ω), and sets K copies of each of K different directions φ 0-1 to φ
0 -K. After forming the directivity, the signals after conversion are converted into signals P <MB>
1-i (ω),..., P <MB> Ki (ω).
H directional post-formation signals P <MB> hi (ω) (1 ≦ 0) among the converted directivity postformation signals P <MB> 1-i (ω),..., P <MB> Ki (ω) h ≦ H) is sent to the weighted addition unit
9.
The other G directional post-forming signals P <MB> gi (ω) (1 ≦ g ≦ G) are sent to the
corresponding spatial frequency conversion units 3-2 to 3-L.
ただし、K>Lとし、K=H+Gとし、L=G+1とする。
[0086]
The weighted addition unit 9 of this embodiment is configured to receive H predetermined
directivity post-forming signals P <MB> 1-i (ω),..., P <MB> Hi (ω) in advance. Weighted
weighting factors w 1,..., W H generate weighted directional pattern-formed signals P <w> i (ω).
The generated weighted directional post-forming signal P <w> i (ω) is sent to the spatial
frequency converter 3-1. The processes after the spatial frequency conversion units 3-1,..., 3-L
are the same as in the second embodiment.
[0087]
In this manner, a speaker array is formed in L columns in the vertical direction after forming
directivity in K different directions from which signals collected by the cylindrical microphone
array are different, and adding weights of some of the signals. By reproducing from, it is possible
to reproduce the three-dimensional effect in the vertical direction. By weighting and adding
signals corresponding to a plurality of directions within a range that does not significantly affect
the direction recognition by human hearing, it is possible to reproduce the vertical sense in the
vertical direction with high accuracy even with a small number of speakers.
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[0088]
[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 space or
the reproduction apparatus arranged in the second space. In other words, frequency conversion
unit 1, directivity control 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 7, output switching unit 8, weights The processing of each of the addition and addition units
9 may be performed by a sound collection device disposed in the first space, or may be
performed by a reproduction device disposed in the second space. The signal generated by the
sound collection device is transmitted to the reproduction device.
[0089]
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 or separated from each other. Also, the
orientation of the first space and the second space may be any.
[0090]
The processing of the window function by the window function unit 7 may be performed at any
stage, or may be performed in multiple stages. That is, the window function unit 7 has directivity
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, 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, the conversion filter unit 4
and the spatial frequency inverse It may be provided between the conversion unit 5, between the
spatial frequency inverse conversion unit 5 and the frequency inverse conversion unit 6, or
between at least one of the frequency inverse conversion unit 6 and the output switching unit 8.
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
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[0091]
In addition, the window function unit 7 may be omitted. In this case, the speaker Si reproduces
the sound based on the time domain signal P <d> i (t) as i = 1,..., Nz.
[0092]
As long as the sound field sound collecting and reproducing apparatus includes the directivity
control unit 2, it does not have to include other units. For example, the sound field sound
collecting and reproducing apparatus may be configured by the directivity control unit 2, the
spatial frequency inverse conversion unit 3, the conversion filter unit 4, the spatial frequency
inverse conversion unit 5, and the frequency inverse conversion unit 6. Further, the sound field
sound collecting and reproducing apparatus may be configured of the frequency conversion unit
1, the directivity control unit 2, and the spatial frequency conversion unit 3.
[0093]
The processing of the frequency conversion unit 1, the processing of the directivity control unit
2, and the processing of the spatial frequency conversion unit 3 may be performed
simultaneously. 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
space frequency conversion unit 3 and the space frequency inverse conversion unit 5 may be
interchanged.
[0094]
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.
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[0095]
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.
[0096]
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.
[0097]
Reference Signs List 1 frequency conversion unit 2 directivity control unit 3 space frequency
conversion unit 4 conversion filter unit 5 space frequency inverse conversion unit 6 frequency
inverse conversion unit 7 window function unit 8 output switching unit 9 weighted addition unit
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