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JP2012049965

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DESCRIPTION JP2012049965
The present invention provides a sound field sound collecting and reproducing technique capable
of forming a sound image on the front of a speaker array even when the position of a sound
source collected by a microphone array and the signal of the sound source are unknown.
SOLUTION: A speaker in which a delay unit 2 comprises a plurality of speakers and a plurality of
sound signals collected by microphone arrays M1-1, M2-1, ..., MN-N composed of a plurality of
microphones. Delays according to the distances between the speakers of the arrays S1-1, S2-1,...,
SN'-N 'and the plurality of focal points are made into a plurality of delay signals corresponding to
the respective speakers. The adding unit 4 adds a plurality of delay signals corresponding to the
respective speakers to obtain an output signal corresponding to the respective speakers.
[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 sound signals are
collected by a microphone array installed in a certain sound field, and the sound field is
reproduced by a speaker array using the sound signals.
[0002]
Wavefront synthesis is a technology that virtually reproduces the sound field of a remote place
using a plurality of microphones and speakers.
03-05-2019
1
Non-Patent Document 1 describes a technique for forming a sound image on the front of a
speaker array by forming one focus on the front of the speaker array as shown in FIG. .
[0003]
Komiyama Setsu, Nakayama Yasushige, Ono Kazuho, and Koizumi Satoru, “A loudspeaker-array
to control sound image distance”, Acoust. Sci. & Tech. 24, 2003, p. 242-249
[0004]
However, in the technique described in Non-Patent Document 1, it is necessary to perform signal
processing after previously knowing the position of the sound source collected by the
microphone array and the signal of the sound source. Therefore, when the position of the sound
source collected by the microphone array is unknown, there is a problem that the technology
described in Non-Patent Document 1 can not be used.
[0005]
The present invention provides a sound field collection and reproduction apparatus, method, and
program capable of forming a sound image on the front surface of a speaker array even when the
position of a sound source collected by a microphone array and the signal of the sound source
are unknown. To aim.
[0006]
In order to solve the above-mentioned problems, a plurality of sound signals collected by a
microphone array consisting of a plurality of microphones are arranged at each distance between
each speaker of a speaker array consisting of a plurality of speakers and a plurality of focal
points. Accordingly, the plurality of delay signals corresponding to the respective speakers are
delayed.
A plurality of delay signals corresponding to each speaker are added to obtain an output signal
corresponding to each speaker.
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[0007]
Even when the position of the sound source collected by the microphone array and the signal of
the sound source are unknown, a sound image can be formed on the front of the speaker array.
[0008]
FIG. 1 is a functional block diagram of an example of a sound field collection and reproduction
device according to a first embodiment.
FIG. 2 is a view for explaining an example of the arrangement of a microphone array, a speaker
array, and a focus array of the sound field collection and reproduction device according to the
first embodiment. The functional block diagram of the example of the sound field sound
collection reproducing | regenerating apparatus of 2nd embodiment. The figure for
demonstrating the example of arrangement | positioning of the microphone array of the sound
field sound collection reproducing | regenerating apparatus of 2nd embodiment, a speaker array,
and a focus array. The flowchart which shows the example of the sound field sound collection
reproduction method. The figure for demonstrating the focus of a prior art. The figure for
demonstrating the example of the focus of this invention.
[0009]
Hereinafter, an embodiment of the present invention will be described with reference to the
drawings.
[0010]
First Embodiment The sound field collection and reproduction apparatus and method according
to the first embodiment uses the two-dimensional microphone array and the two-dimensional
speaker array disposed on a plane, and the first room z shown in FIG. The wavefront at position =
z0 is reproduced by forming an array of focal points at the position z = z2 of the second room.
The array of foci consists of multiple foci, as illustrated in FIG.
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[0011]
The sound field collection and reproduction apparatus according to the first embodiment, as
shown in FIG. 1, includes microphone arrays M1-1, M2-1,..., MNx-Ny, speaker arrays S1-1, S2-1,. Ny ', the window function part 1, the delay part 2, the amplification part 3, and the addition part
4 are included, for example. In this example, the delay unit 2 includes the delay units 2-1-1, 2-21,..., 2-Nx-Ny, and the amplification unit 3 includes the amplification units 3-1-1, 3-1-2,. , And 3Nx-Ny, and the adder 4 includes the adders 4-1-1, 4-2-1,..., 4-Nx'-Ny '.
[0012]
The sound collection in the first room is performed by two-dimensional microphone arrays M1-1,
M2-1,..., MNx-, each of which comprises Nx × Ny microphones arranged on the z = z0 plane of
the first room. A two-dimensional speaker array S1-1 composed of Nx ′ × Ny ′ speakers
arranged on the plane of z = z1 of the second room, the reproduction of the sound field in the
second room being performed by Ny, It carries out by S2-1, ..., SNx '-Ny'.
[0013]
Nx, Ny, Nx 'and Ny' are arbitrary integers.
Nx and Nx 'may be different. Also, Ny and Ny 'may be different. That is, the number of
microphones constituting the microphone array and the number of speakers constituting the
speaker array do not have to be the same, and the microphones constituting the microphone
array and the speakers constituting the speaker array need to be in one-to-one correspondence.
There is no.
[0014]
The position rm of the microphone Mj-j constituting the two-dimensional microphone array M11, M2-1,..., MNx-Ny arranged at the position of z = z0 in the first room is (xi, yj, z0) Represent.
The sound signal of time t collected in the microphone Mi-j is represented as f (i, j, t).
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[0015]
The position rs of the speaker Sn-m constituting the two-dimensional speaker array S1-1, S2-1,...,
SNx'-Ny 'arranged at the position of z = z1 of the second room (xn, yn, z1 It is expressed as). An
output signal applied to the speaker nm is represented by g (n, m, t).
[0016]
The two-dimensional microphone arrays M1-1, M2-1,..., MNx-Ny arranged at the position z = z0
of the first room pick up the sound emitted by the sound source S of the first room Generate a
time domain sound signal. The generated sound signal is sent to the window function unit 1. As
described above, the sound signal at time t in the time domain collected by the microphone Mi-j
is represented as f (i, j, t).
[0017]
The window function unit 1 multiplies the sound signal f (i, j, t) by the window function to
generate a window function after-sound signal fw (i, j, t) (step S1). The window function
aftersound signal fw (i, j, t) is sent to the delay unit 2. As a window function, a so-called Turkey
window function w (i, j) defined by the following equation is used, for example. Ntpr is a score to
which a taper is applied, and is an integer of 1 or more and Nx and Ny or less.
[0018]
The delay unit 2 delays the window function after-sound signal fw (i, j, t) in accordance with the
distance between each speaker Sn-m and each of the plurality of focal points, and a plurality of
them correspond to each speaker Sn-m. Of the delay signal (step S2). A focal array consisting of a
plurality of focal points is arranged at the position z = z2 of the second room. The number of
focal points making up the focal array is the same as the number of microphones. The position
rs' of the focus fi-j is expressed as (xi ', yj', z2), where i = 1, 2, ..., Nx, j = 1, 2, ..., Ny.
[0019]
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The focal arrays f1-1, f2-1,..., FNx-1 are preferably formed in a plane on the front surface of the
speaker arrays S1-1, S2-1,. There is no need to form it. Similarly, the microphone arrays M1-1,
M2-1,..., MNx-Ny and the speaker arrays S1-1, S2-1,..., SNx'-Ny 'do not have to be formed in a
planar shape.
[0020]
The distances between the focus arrays f1-1, f2-1,..., FNx-Ny and the speaker arrays S1-1, S2-1,.
The closer this distance is, the better the focus formation accuracy and the better the quality of
the reproduced sound field.
[0021]
In this example, the delay unit 2-i-j sets the window function aftertone signal fw (j, j, t) as i = 1,
2,..., Nx, j = 1, 2,. The delay signal fw (i, j, t-(rij nm / c)) is obtained by delaying according to the
distance rij between the speaker Sn-m and the focus fi-j. Here, c is a high speed, and r ij nm is the
distance between the speaker Sn-m and the focus fi-j.
[0022]
In each delay unit 2-j-j, Nx 'x Ny' delayed signals fw (j, j, t-(rij nm / c)) corresponding to Nx 'x Ny'
speakers Sn-m are generated Be done. The generated delayed signal is sent to the amplification
unit 3.
[0023]
There are several ways to delay the signal. Here, a method of giving a delay by a first-order allpass filter will be described. This method approximately realizes a time delay within sample unit
time in the case of digital processing. A filter expression Hij (n, m, z) giving a delay of r ij nm / c
is expressed as follows.
03-05-2019
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[0024]
Here, dij and αij are coefficients determined by the delay time. fs is a sampling frequency in the
case of performing digital processing, and └ · ┘ means rounding off after the decimal point.
[0025]
Therefore, it is possible to give a time delay to the post-window function signal fw (i, j, t) as
follows.
[0026]
The amplification unit 3 applies a smaller gain to the plurality of delay signals as the distance
between each speaker and each of the plurality of focal points increases, to obtain a plurality of
amplified signals corresponding to each of the speakers (step S3).
The generated amplified signal is sent to the adder 4. By the processing of the amplification unit
3, it is possible to maximize the SN ratio at the focal position.
[0027]
In this example, it is assumed that i = 1, 2,..., Nx, j = 1, 2,..., Ny, and Nx ′ × Ny ′ amplification
units 3-ij are generated by delay units 2-ij. Nx 'x Ny' amplified signals (1 / rijnm) fw (i, j, t-(rijnm)
by multiplying the delay signal fw (i, j, t-(rijnm / c)) / C)) is obtained. In each amplification unit 3i-j, an amplification signal (1 / rij nm) fw (i, j, t- (rij nm / c)) corresponding to each speaker Sn-m
is obtained.
[0028]
The adding unit 4 adds a plurality of amplified signals corresponding to the respective speakers
Sn-m to generate an output signal g (n, m, t) corresponding to the respective speakers Sn-m (step
S4). The output signal g (n, m, t) is applied to the speaker Sn-m.
03-05-2019
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[0029]
In this example, amplified signals (1 / rijnm) fw (i, j, t-(rijnm / c)) corresponding to the respective
speakers Sn-m are obtained in the respective amplification units 3-i-j. Therefore, the amplified
signal (1 / rijnm) fw (i, j, t-(rijnm / c)) of the speaker Sn-m obtained in each amplification unit 3-i-j
is added to obtain the speaker Sn-m. The output signal g (n, m, t) corresponding to
[0030]
The above signal processing can be performed regardless of the position of the sound source in
the first room. Therefore, even if the position of the sound source in the first room and the signal
of the sound source are unknown, it is possible to reproduce in the second room a sound field in
which the sound source is on the front of the speaker array.
[0031]
The size of the wavefront to be reproduced is about the same as the area of the plane collected
by the microphone arrays M1-1, M2-1,..., MNx-Ny.
[0032]
Second Embodiment While the sound field collection and reproduction apparatus and method of
the first embodiment use a two-dimensional microphone array and a two-dimensional speaker
array, the sound field collection and reproduction apparatus and method of the second
embodiment A one-dimensional microphone array and a one-dimensional speaker array are used.
As a result, the number of microphones, the number of speakers, and the number of channels can
be reduced, which makes the implementation relatively easy.
[0033]
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The sound field collection and reproduction apparatus according to the first embodiment, as
shown in FIG. 1, includes microphone arrays M1-1, M2-1,..., MNx-1, speaker arrays S1-1, S2-1,. 1,
a window function unit 1, a delay unit 2, an amplification unit 3, and an addition unit 4, for
example. In this example, the delay unit 2 includes the delay units 2-1-1 and 2-2-1,..., 2-Nx-1, and
the amplification unit 3 includes the amplification units 3-1-1 and 3-1. ..., 3-Nx-1, and the
addition unit 4 includes addition units 4-1-1, 4-2-1, ..., 4-Nx'-1.
[0034]
Sound collection in the first room is performed by one-dimensional microphone arrays M1-1,
M2-1,..., MNx-1 composed of Nx microphones arranged on the z = z0 straight line of the first
room. And the reproduction of the sound field in the second room is a one-dimensional speaker
array S1-1, S2 consisting of Nx 'monopole-shaped speakers arranged on the z = z1 straight line of
the second room -1, ..., SNx'-1 is performed.
[0035]
Nx and Nx 'are arbitrary integers.
Nx and Nx 'may be different. That is, the number of microphones constituting the microphone
array and the number of speakers constituting the speaker array do not have to be the same, and
the microphones constituting the microphone array and the speakers constituting the speaker
array need to be in one-to-one correspondence. There is no.
[0036]
The position rm of the microphone Mj-1 constituting the one-dimensional microphone array M11, M2-1,..., MNx-1 arranged at the position z = z0 of the first room is (xi, y0, z0) Represent. The
sound signal of time t collected in the microphone Mi-1 is represented as f (i, t).
[0037]
The position rs of the speaker Sn-1 constituting the one-dimensional speaker array S1-1, S2-1,...,
SNx'-1 arranged at the position of z = z1 of the second room (xn, y1, z1) It represents. An output
03-05-2019
9
signal applied to the speaker n-1 is denoted as g (n, t).
[0038]
The one-dimensional microphone arrays M1-1, M2-1,..., MNx-1 arranged at the position z = z0 of
the first room pick up the sound emitted by the sound source S of the first room Generate a time
domain sound signal. The generated sound signal is sent to the window function unit 1. As
described above, the sound signal at time t in the time domain collected by the microphone Mi-1
is represented as f (i, t).
[0039]
The window function unit 1 multiplies the sound signal f (i, t) by the window function to generate
a window function after-sound signal fw (i, t) (step S1). The window function aftersound signal fw
(i, t) is sent to the delay unit 2. As a window function, a so-called Turkey window function w (i)
defined by the following equation is used, for example. Ntpr is a score to which a taper is applied,
and is an integer of 1 or more and Nx or less.
[0040]
The delay unit 2 delays the window function after-sound signal fw (i, t) according to the distance
between each speaker Sn-1 and each of the plurality of focal points, and a plurality of delays
corresponding to each of the speakers Sn-1 Let it be a signal (step S2). A focal array consisting of
a plurality of focal points is arranged at the position z = z2 of the second room. The number of
focal points making up the focal array is the same as the number of microphones. The position rs
'of the focus fi-1 is represented as (xi', y2, z2), where i = 1, 2,.
[0041]
The focus array is desirably formed linearly on the front surface of the speaker arrays S1-1, S21,..., SNx'-1, but is not necessarily formed linearly. Similarly, the microphone arrays M1-1, M21,..., MNx-1 and the speaker arrays S1-1, S2-1,.
03-05-2019
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[0042]
The distances between the focus arrays f1-1, f2-1,..., FNx-1 and the speaker arrays S1-1, S2-1,...,
SNx'-1 can be set arbitrarily. The closer this distance is, the better the focus formation accuracy
and the better the quality of the reproduced sound field.
[0043]
The provision of the delay can be performed in the same manner as in the first embodiment.
[0044]
In this example, the delay unit 2-i-1 sets i = 1, 2,..., Nx, the window function after-sound signal fw
(j, t), and the distance between each speaker Sn-1 and the focus fi-1 Delaying according to r ij
obtains a delayed signal fw (i, t-(rinm / c)).
Here, c is a high speed, and rinm is the distance between the speaker Sn-m and the focus fi-j.
[0045]
In each delay unit 2-j-1, Nx 'delayed signals fw (j, t-(rinm / c)) corresponding to the Nx' speakers
Sn-1 are generated. The generated delayed signal is sent to the amplification unit 3.
[0046]
The amplification unit 3 applies a smaller gain to the plurality of delay signals as the distance
between each speaker and each of the plurality of focal points increases, to obtain a plurality of
amplified signals corresponding to each of the speakers (step S3). The generated amplified signal
is sent to the adder 4.
[0047]
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In this example, i = 1, 2,..., Nx−i−1 have gains of 1 for Nx ′ delayed signals fw (i, t− (rinm / c))
generated by the delay unit 2-i−1. By multiplying / rinm, Nx 'amplified signals (1 / rinm) fw (i, t(rinm / c)) are obtained. In each amplification unit 3-i-1, an amplification signal (1 / rinm) fw (i, t(rinm / c)) corresponding to each speaker Sn-1 is obtained.
[0048]
The adding unit 4 adds a plurality of amplified signals corresponding to each speaker Sn-1 to
obtain an output signal g (n, t) corresponding to each speaker Sn-1 (step S4). The output signal g
(n, t) is applied to the speaker Sn-m.
[0049]
In this example, amplified signals (1 / rinm) fw (i, t-(rinm / c)) corresponding to the respective
speakers Sn-1 are obtained in the respective amplification units 3-i-1. Therefore, the amplified
signal (1 / rinm) fw (i, t-(rinm / c)) of the speaker Sn-1 obtained in each amplification unit 3-i-1 is
added to correspond to the speaker Sn-1 Output signal g (n, t).
[0050]
The above signal processing can be performed regardless of the position of the sound source in
the first room. Therefore, even if the position of the sound source in the first room and the signal
of the sound source are unknown, it is possible to reproduce in the second room a sound field in
which the sound source is on the front of the speaker array.
[0051]
[Modifications, Etc.] Each part constituting the sound field sound collecting and reproducing
apparatus may be provided in either the sound collecting apparatus arranged in the first room or
the reproduction apparatus arranged in the second room. In other words, the processes of the
window function unit 1, the delay unit 2, the amplification unit 3, and the addition unit 4 may be
03-05-2019
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executed by the sound collection device disposed in the first room, or may be performed in the
second room It may be executed by the arranged playback device. The signal generated by the
sound collection device is transmitted to the reproduction device.
[0052]
The positions of the first room and the second room are not limited to those shown in FIGS. 2
and 4. The first room and the second room may be adjacent or separated from each other. Also,
the orientation of the first room and the second room may be any.
[0053]
The amplification unit 3 may not be present. In this case, the adding unit 4 adds the delay signals
of the respective speakers Sn-m to obtain an output signal corresponding to the respective
speakers Sn-m.
[0054]
Also, the window function unit 1 may not be necessary. In this case, the delay unit 2 or the
amplification unit 3 may perform the same processing as described above using f (i, j, t) instead
of fw (i, j, t).
[0055]
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.
[0056]
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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.
[0057]
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.
[0058]
1 window function unit 2 delay unit 3 amplification unit 4 addition unit
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