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JP2001125578

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DESCRIPTION JP2001125578
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound field reproducing method for reproducing an arbitrary sound field such as a hole in
another space and a device for carrying out the method. By making it possible to reproduce the
difference in sound due to the performance situation such as the direction, it is possible to
reproduce a more realistic sound field.
[0002]
2. Description of the Related Art A conventional method for reproducing an arbitrary sound field
such as a hall in a listening room or a laboratory will be described. As shown in FIG. 2, a sound
source S is set on a stage 12 or the like in a sound field 10 such as a hole to be reproduced, and a
sound receiving point R is set on a passenger seat 14 or the like. The space around the sound
receiving point R is divided into sound receiving element regions R1, R2,..., Rj,..., Rm of
appropriate solid angles centered on the sound receiving point R, as shown in FIG. Do. The
example of FIG. 3 shows an example in which the horizontal plane is divided into eight parts, and
the obliquely upper part is divided into four into twelve in total (m = 12). As shown in FIG. 4 (the
sound receiving element regions R1 to Rm in FIG. 4 and FIG. 6 schematically illustrate the
division form of FIG. 3), using a nondirectional sound source as the sound source S, the sound
source The sound emitted from S to reach the sound receiving point R through the sound field 10
is measured or calculated for each direction by the directional microphone, and the sound
emitted from the sound source S is the sound field based on the measurement or calculation
result. An impulse response when reaching from each of the sound receiving element regions R1
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to Rm through the inside of 10 and reaching the sound receiving point R is determined for each
of the sound receiving element regions R1 to Rm.
[0003]
A system configuration for reproducing the sound field 10 in an arbitrary actual space based on
the impulse responses h1 to hm for each of the sound receiving element areas R1 to Rm is shown
in FIG. Each of the above-mentioned sound receiving element areas around an actual sound
receiving point Rr (usually the central portion in the plane of the space 16) where a listener or a
subject listens in any actual space 16 such as a listening room or a laboratory Speakers SP1 to
SPm are arranged in the direction corresponding to R1 to Rm (FIG. 3) (in FIG. 5, the arrangement
positions of the speakers SP1 to SPm are schematically matched to the display form of the sound
receiving element regions R1 to Rm in FIG. 4) Is shown). Left and right two-channel audio signals
reproduced from a sound source device 18 such as a DAT (digital audio tape recorder) or a CD
(compact disc) player are synthesized into one channel, and an FIR filter 20-1 to 20-m
(convolution operator) is input. In the FIR filters 20-1 to 20-m, the determined impulse responses
h1 to hm are set as parameters of the convolution operation. The one-channel acoustic signal is
convoluted with the FIR filters 20-1 to 20-m to generate acoustic signals (reflected sound signals)
in the respective directions corresponding to the respective sound receiving element regions R1
to Rm. The generated acoustic signals are amplified by the amplifiers 22-1 to 22-m and
reproduced from the corresponding speakers SP1 to SPm, respectively. The sound signals
reproduced from the sound source device 18 on the left and right two channels are reproduced
as direct sound separately from the front left and right positions of the sound receiving point Rr.
In this manner, the listener at the sound receiving point Rr can appreciate the music in the
atmosphere of the audience 14 in the sound field 10 of FIG.
[0004]
The above is a reproduction of the state in which the music played on the stage 12 in FIG. 2 is
listened to at the audience 14, but the state in which the music played on the stage 12 is heard in
real time on the stage 12 is reproduced For example, rehearsal can be performed in the
atmosphere where the player is in the sound field 10. The reproduction method is explained. In
the sound field 10 of FIG. 2, the sound source S on the stage 12 is simultaneously set as a sound
receiving point R. The space around the sound receiving point R (= the sound source S) is divided
into sound receiving element areas R1 to Rm of suitable solid angles centered on the sound
receiving point R, as in FIG. As shown in FIG. 6, a nondirectional sound source is used as the
sound source S, and the sound emitted from the sound source S and passing through the sound
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field 10 to reach the sound receiving point R (= the sound source S) is directed by the directional
microphone. Measured or calculated separately, and based on the measurement or calculation
result, an impulse when sound emitted from the sound source S passes through the sound field
10 and enters from each of the sound receiving element regions R1 to Rm to reach the sound
receiving point R A response is obtained for each of the sound receiving element regions R1 to
Rm.
[0005]
A system configuration for reproducing the sound field 10 in an arbitrary actual space based on
the impulse responses h1 to hm for each of the sound receiving element areas R1 to Rm is shown
in FIG. The position where the performer plays in any real space 16 such as a listening room or
laboratory (real sound source Sr and real sound receiving point Rr. Usually, the microphone 24 is
disposed above the middle in the plane of the space 16 and the like, and the speakers SP1 to
SPm are arranged in the direction corresponding to the respective sound receiving element areas
R1 to Rm (FIG. 3) around the playing position. They are arranged (in FIG. 7, the arrangement
positions of the speakers SP1 to SPm are schematically illustrated according to the display form
of the sound receiving element regions R1 to Rm in FIG. 6). The sound signal (performance
signal) of one channel collected by the microphone 24 is input to the FIR filters 20-1 to 20-m
(convolution calculator) via the head amplifier 19. In the FIR filters 20-1 to 20-m, the determined
impulse responses h1 to hm are set as parameters of the convolution operation. The 1-channel
acoustic signal is convoluted with the FIR filters 20-1 to 20-m to generate an acoustic signal
(reflected sound signal) in each direction. The generated acoustic signals are amplified by the
amplifiers 22-1 to 22-m and reproduced from the corresponding speakers SP1 to SPm,
respectively. In this way, the performer at the sound source Sr and the sound receiving point Rr
can perform rehearsal in the atmosphere on the stage 12 of the sound field 10 of FIG.
[0006]
According to the conventional sound field reproduction method, the impulse responses h1 to hm
for each of the sound receiving element areas R1 to Rm obtained using the sound source S as
nondirectional are used. However, the impulse response in the actual sound field 10 is affected
by the directional characteristics of the sound source S. For example, a highly directional
instrument such as a trumpet can be played on the stage 12 when facing forward to the seating
14, when playing sideways or playing backward, the audience 14. The sense of hearing changes
greatly for the person who is listening at and also for the performer. However, in the abovedescribed conventional sound field reproduction method, for example, in the system
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configuration of FIG. 7, even if the player directly below the microphone 24 plays the trumpet
and is turned in the horizontal plane, reproduction is made from the speakers SP1 to SPm. The
sound does not change. In other words, it was not possible to reproduce the difference in sound
depending on the directional characteristics of the instrument and the direction of the player.
[0007]
The present invention solves the problems in the above-mentioned prior art, and makes it
possible to reproduce differences in sound due to the performance characteristics such as
directivity characteristics of a sound source such as a musical instrument or the player's
direction, thereby reproducing a more realistic sound field. It is an object of the present invention
to provide a sound field reproducing method and its device which made it possible.
[0008]
According to the sound field reproducing method of the present invention, a space around a
sound source set in a sound field to be reproduced is divided into a sound source element area of
an appropriate solid angle centered on the sound source. The space around the sound receiving
point set in the sound field is divided into a sound receiving element area of an appropriate solid
angle centered on the sound receiving point, and the sound emitted from the sound source is the
sound source element area The impulse response at the time of being emitted from the light
source, passing through the sound field, being incident on each of the sound receiving element
regions and reaching the sound receiving point is calculated for each combination of each sound
source element region and each sound receiving element region or Measured and placed
microphones at an appropriate distance in a direction corresponding to each of the sound source
element areas around an actual sound source in an arbitrary real space, and around an actual
sound receiving point in an arbitrary real space Appropriate distance in the direction
corresponding to each of the sound receiving element areas of A speaker is disposed at a
position, the sound radiated from the actual sound source is picked up by each of the
microphones, and each of the picked-up signals is subjected to a convolution operation using
impulse responses obtained for sound source element regions in the corresponding directions,
Each sound signal generated by the calculation is reproduced from a speaker arranged
corresponding to the sound receiving element area in the corresponding direction.
[0009]
According to this, the impulse response is obtained for each combination of the sound source
element area obtained by dividing the space around the sound source of the sound field to be
reproduced and the sound receiving element area obtained by dividing the space around the
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sound receiving point. A microphone is arranged in each direction corresponding to the sound
source element area in the actual space to be performed, the performance etc. are picked up, and
a speaker is arranged in each direction corresponding to the sound receiving element area in the
actual space to be reproduced. Since the signal picked up in step 2 is convoluted with the
impulse response of the corresponding sound source element area and reproduced with the
speaker of the corresponding sound receiving element area, if a musical instrument having
directivity is to be played, Different sounds are played.
For example, if you are playing in the actual space where you are playing, if you play on the
stage of the sound field you are trying to reproduce, turn to a direction corresponding to the
front with respect to the audience, it sounds like you are playing toward the audience, If you play
in the direction corresponding to the backward direction, it sounds like you are playing
backwards to the audience.
In this way, the difference in sound due to the directivity characteristics of the sound source such
as a musical instrument or the performance situation such as the direction of the performer is
reproduced, and a more realistic sound field reproduction becomes possible.
[0010]
In the sound field reproduction method of the present invention, a series of operations of sound
collection by the microphone, convolution operation with an impulse response, and reproduction
by the speaker can be performed in real time, for example. Alternatively, the signal collected by
the microphone may be once recorded, and then the signal may be reproduced, subjected to a
convolution operation with the impulse response, and reproduced by the speaker. Further, in the
sound field to be reproduced, the impulse response can be obtained by setting the sound source
and the sound receiving point, for example, at the same position. Also, in the sound field to be
reproduced, the sound source and the sound receiving point can be set at different positions to
obtain an impulse response. Further, an actual sound source for performing a performance or the
like and an actual sound receiving point for listening can be set, for example, at the same position
in the same space. In addition, it is possible to set an actual sound source for performing music
and the like and an actual sound receiving point for listening in different spaces. Further, the
division form (number of divisions, division pattern) of the sound source element area and the
sound receiving element area can be set to be the same or different. When the actual sound
source for performing a performance etc. and the actual sound receiving point for listening are
set at the same position in the same space, and the division form of the sound source element
area and the sound receiving element area is set equal, The speakers can be arranged in pairs
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according to the division form.
[0011]
According to the sound field reproducing method of the present invention, for example, an actual
space in which a performance is performed by setting the sound source and the sound receiving
point at the same position on the stage in the sound field (hole etc.) to be reproduced (A studio, a
laboratory, etc.) The actual sound source and the actual sound receiving point are set at the same
position, the microphone and the speaker are arranged, the sound collection by the microphone,
the convolution operation with the impulse response, the reproduction by the speaker If the
operation is performed in real time, the player can rehearse in the atmosphere on the stage. Also,
in the sound field to be reproduced, the sound source is set on the stage, the sound receiving
point is set as the audience, each impulse response is determined, and a microphone is arranged
around the actual sound source in the actual space where the performance is performed. The
sound is picked up and recorded, then recorded and played back. Convoluted with each
corresponding impulse response and reproduced from the speakers around the actual sound
receiving point, the performer's own performance at the audience You can see what it sounds
like. Also, in the sound field to be reproduced, the sound source is set on the stage, the sound
receiving point is set as the audience, each impulse response is determined, and a microphone is
arranged around the actual sound source in the actual space where the performance is
performed. Are collected, recorded, convoluted with each corresponding impulse response in real
time, and played from a speaker around an actual sound receiving point in another actual space,
a live concert etc. will be performed between remote places be able to.
[0012]
The sound field reproduction apparatus according to the present invention divides the space
around the sound source set in the sound field to be reproduced into sound source element
regions of appropriate solid angles centered on the sound source, and receives the sound source
area set in the sound field. The space around the sound point is divided into a sound receiving
element area of an appropriate solid angle centered on the sound receiving point, and the sound
emitted from the sound source is emitted from each of the sound source element areas and
passes through the sound field. And a convolution operator set for each combination of each
sound source element area and each sound receiving element area as a parameter of the
convolution operation as an impulse response when entering each sound receiving element area
and reaching the sound receiving point An adder for adding and synthesizing an output signal of
each of the convolutional operators for each corresponding sound receiving element area, and an
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appropriate direction corresponding to each of the sound source element areas around an actual
sound source in an arbitrary actual space. Micro placed at distance And a speaker disposed at an
appropriate distance in a direction corresponding to each of the sound receiving element areas
around an actual sound receiving point in any actual space; Sound is picked up by each of the
microphones, each of the picked up signals is subjected to a convolution operation with the
impulse response regarding the sound source element region in the corresponding direction by
the convolution operator, and each sound signal generated by the operation is The abovementioned adder adds and synthesizes each of the sound receiving element areas in the
corresponding directions, and reproduces them from the speakers arranged corresponding to the
respective sound receiving element areas. According to this sound field reproduction apparatus,
the sound field reproduction method of the present invention can be implemented. In this case,
the sound source and the sound receiving point are set at the same position in the sound field to
be reproduced, the actual sound source and the actual sound receiving point are set at the same
position in the same space, and collected by the microphone If a series of operations of sound,
the convolution operation and the addition synthesis, and the reproduction by the speaker are
performed in real time, the performer can perform rehearsals, for example, in the atmosphere on
the stage.
[0013]
Further, according to the sound field reproduction device of the present invention, the space
around the sound source set in the sound field to be reproduced is divided into sound source
element regions of appropriate solid angles centering on the sound source, The space around the
sound receiving point set in the position is divided into sound receiving element areas of
appropriate solid angles centered on the sound receiving point, and the sound emitted from the
sound source is emitted from each of the sound source element areas Impulse response when
entering the sound receiving element area through the sound field and reaching the sound
receiving point as a parameter of the convolution operation for each combination of the sound
source element area and the sound receiving element area A set convolution unit, an adder for
adding and synthesizing an output signal of each convolution unit for each corresponding sound
receiving element region, and each sound source element region around an actual sound source
in an arbitrary actual space Placed at an appropriate distance in the corresponding direction
Microphone, a recording / reproducing apparatus for recording and reproducing a signal
collected by the microphone, and an appropriate distance in a direction corresponding to each of
the sound receiving element areas around an actual sound receiving point in any actual space
And a speaker disposed at the position of (d), and the sound emitted from the actual sound
source is collected by the microphones and recorded by the recording and reproducing
apparatus, and after the recording, the sound is reproduced and reproduced. Each of the
collected sound signals of each of the microphones is convoluted with the impulse response of
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the sound source element area in the corresponding direction by the convolution operation unit,
and each acoustic signal generated by the operation is processed in the corresponding direction
by the adder. Addition synthesis is performed for each of the sound receiving element areas, and
reproduction is performed from the speakers arranged corresponding to the respective sound
receiving element areas. According to this sound field reproduction apparatus, the player himself
can confirm how his performance sounds, for example, in the audience. In addition, when the
signal collected and recorded by the microphone arranged at the position of the appropriate
distance of the direction corresponding to each sound source element area around the actual
sound source in the actual space is prepared in advance, the sound recording Sound field
reproduction can also be performed by a reproduction-only device instead of the reproduction
device.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described. Here, it is assumed that the sound field 10 of FIG. 2 is reproduced. (First Embodiment)
A case where a state in which the user performs on the sound source S on the stage 12 and
listens to the sound receiving point R in the customer seat 14 is reproduced (referred to as a
guest seat mode). Explain). As shown in FIG. 8, the space around the sound source S
(approximately hemispherical space on the floor) is a sound source element area S1, S2,..., Si,. To
divide. The example of FIG. 8 shows an example in which the horizontal plane is divided into
eight parts, and the obliquely upper part is divided into four into twelve in total (n = 12). Also, as
shown in FIG. 9, the space around the sound receiving point R (generally hemispherical space on
the floor) is a sound receiving element area R1, R2,... Of an appropriate solid angle centered on
the sound receiving point R. Divide into Rj, ..., Rm. In the example of FIG. 9, an example (n, m =
12) divided into 12 in the same form as the sound source element area of FIG. 8 is shown. As
shown in FIG. 10 (the sound source element regions S1 to Sn and the sound receiving element
regions R1 to Rm in FIG. 10 schematically show the division forms in FIGS. 8 and 9), they are
emitted from the sound source S. Impulse sound from one of the sound source element regions
S1 to Sn, passing directly or reflected through the sound field 10 and entering from one of the
sound receiving element regions R1 to Rm to reach the sound receiving point R Responses are
calculated or measured for combinations of all sound source element regions S1 to Sn and all
sound receiving element regions R1 to Rm. Thereby, n О m kinds of impulse responses hi, j (i =
1, 2,..., N, j = 1, 2,..., M) shown in Table 1 are obtained.
[0015]
(Table 1) h1,1: Impulse response h1,2 of sound radiated from the sound source S, exiting from
the sound source element area S1, passing through the sound field 10, entering from the sound
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receiving element area R1 and reaching the sound receiving point R 2: Impulse response of
sound emitted from the sound source S, coming out of the sound source element area S1, passing
through the sound field 10, entering from the sound receiving element area R2 and reaching the
sound receiving point R и и и и и и и h1 m: Impulse response of a sound emitted from the sound
source S, exiting from the sound source element area S1, passing through the sound field 10,
entering from the sound receiving element area Rm and reaching the sound receiving point R h2,
1: radiation from the sound source S Of the sound source element region S2, passing through the
sound field 10, entering from the sound receiving element region R1 and reaching the sound
receiving point R h2,2: emitted from the sound source S, the sound source element region S2 Out
of the sound field 10, enter from the sound receiving element region R2, and reach the sound
receiving point R Impulse response of sound и и и и и h2, m: emitted from the sound source S,
leaving the sound source element area S 2, passing through the sound field 10, entering from the
sound receiving element area Rm to reach the sound receiving point R Impulse response of
sound и и и и и и и hn, 1: emitted from the sound source S, exit from the sound source element area
Sn, pass through the sound field 10, enter from the sound receiving element area R1, and reach
the sound receiving point R Impulse response hn, 2 of sound: Impulse response of sound emitted
from the sound source S, coming out of the sound source element area Sn, passing through the
sound field 10, entering from the sound receiving element area R2 and reaching the sound
receiving point R. и и и Hn, m: Impulse response of sound radiated from the sound source S,
coming out of the sound source element area Sn, passing through the sound field 10, entering
from the sound receiving element area Rm and reaching the sound receiving point R
[0016]
An example of the system configuration for reproducing the sound field in an arbitrary actual
space based on the determined impulse response hi, j is shown in FIG.
The acoustic characteristics of the actual space 26 where the performer plays, the floor surface is
reflective with a predetermined sound absorption coefficient, and the sound absorption dead
characteristics other than the floor surface (characteristics such as semi-anechoic chamber,
studio, etc.) Do. Directional microphones MC1 to MCn are arranged toward the sound source Sr
in directions corresponding to the respective sound source element areas S1 to Sn (FIG. 8)
around the actual sound source Sr (playing position) in the space 26 In FIG. 1, the arrangement
positions of the microphones MC1 to MCn are schematically illustrated according to the display
form of the sound source element regions S1 to Sn in FIG. The acoustic characteristics in the
actual space 32 where the listener listens to the playing sound are desirably dead characteristics.
In the space 32, around the actual sound receiving point Rr (listening position), the speakers SP1
to SPm are directed to the sound receiving point Rr in the direction corresponding to each of the
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sound receiving element areas R1 to Rm (FIG. 9). Arranged (in FIG. 1, the arrangement positions
of the speakers SP1 to SPm are schematically illustrated according to the display form of the
sound receiving element areas R1 to Rm in FIG. 10).
[0017]
The performer plays at the position of the sound source Sr in the space 26 for playing. The
performance sounds are collected by the microphones MC1 to MCn, respectively, and are
multichannel-recorded by the DAT 40 through the head amplifier 38. When the performance is
over, play the recorded performance. The collected sound signals of the microphones MC1 to
MCn reproduced from the DAT 40 are input to the FIR matrix circuit 42. The FIR matrix circuit
42 adds and synthesizes the n О m FIR filters (convolution operator) in which each impulse
response hi, j is set as a parameter, and the output signals of the respective FIR filters having
common receiving element regions Adders are arranged in a matrix.
[0018]
A configuration example of the FIR matrix circuit 42 is shown in FIG. The FIR matrix circuit 42
includes n input lines 44-1 to 44-n for inputting the collected sound signals of the microphones
MC1 to MCn, and m output lines for outputting signals supplied to the speakers SP1 to SPm. 461 to 46-m, and a series connection circuit of an equalizer 48, an FIR filter 51 (convolution unit),
and an attenuator 52 is disposed at n О m intersections of these input / output lines, and the
input / output lines It connects between each other. In the FIR filter 51, parameters of an impulse
response obtained for each combination of the corresponding sound source element area and the
sound receiving element area are set. The equalizer 48 is for correcting the characteristics of the
speaker, and the attenuator 52 is for adjusting the level individually. Normally, once both are set,
it is not necessary to change as long as the same system configuration is used. The sound pickup
signals of the microphones MC1 to MCn input from the input lines 44-1 to 44-n are convoluted
with the impulse response for each corresponding sound source element area to be an acoustic
signal (direct sound, reflected sound, reverberation) Are generated, and the audio signals of the
corresponding sound receiving element regions are added and synthesized, and output from the
corresponding output lines 46-1 to 46-m.
[0019]
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In FIG. 1, the acoustic signals output from the output lines 46-1 to 46-m of the FIR matrix circuit
42 are amplified by the amplifiers 47-1 to 47-m, and the corresponding speakers SP1 to SPm in
the space 32 are amplified. Supplied to and regenerated. Table 2 shows combinations of
microphones used for sound collection, impulse responses used for convolution, and speakers
used for reproduction.
[0020]
(Table 2) Microphone Impulse Response Speaker MC1 h1,1 SP1 MC1 h1,2 SP2 и и и и и и и и и и и и и и и и
ииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии
и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и. , m SPm и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и
ииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии
ииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии
иииииииииииииииииииииииииииииииииии
[0021]
From the above, in the entire space 32 where the listener is present, where: Si: sound collection
signal ri by the microphone MCi (i = 1, 2,..., N) ri: speaker SPi (i = 1, 2,. The reproduction signal r,
which is the reproduction signal according to.
As a result, the state where the music played on the stage 12 in the sound field 10 of FIG. 2 is
being listened to by the audience 14 is reproduced including the directivity characteristic of the
musical instrument and the direction of the performer. In other words, the difference between
instruments with different directional characteristics, such as trumpet and violin, flute and piano,
appears in the playback sound field. In addition, when the player faces the wall, the return from
that position is strong, and when the player faces away from the wall, the return is weak.
[0022]
Using the system configuration of FIG. 1, for example, a performer plays in the space 26, records
it in the DAT 40, and after recording, the player reproduces it in the space 32 and the performer
listens, so that the performer himself can It can be seen how the performance sounds in the
audience 14. The space 26 for performing music and the space 32 for listening may not
necessarily be separate, and the microphones MC1 to MCn and the speakers SP1 to SPm may be
disposed together using a common space. In this case, if n = m, the microphones MC1 to MCn
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and the speakers SP1 to SPm can be arranged in pairs. Further, although one DAT 40 is used for
recording and reproduction in FIG. 1, a recording device and a reproducing device are prepared
separately in the spaces 26 and 32, and there is a space 32 in the space 26. It can also be carried
to the place where it is to be played and reproduced by the reproduction device to reproduce the
sound field. Further, in the system configuration of FIG. 1, the spaces 26 and 32 are separate
spaces, the DAT 40 is eliminated, sound collection, convolution operation and reproduction are
performed in real time, and the performance in the space 26 is listened to in the space 32. If so, a
live concert can be performed in the atmosphere in the sound field 10 of FIG. 2 using the
communication line between the spaces 26 and 32 in the remote place.
[0023]
(Second Embodiment) A case where a player reproduces a state in which he or she plays in the
atmosphere on the stage 12 in the sound field 10 of FIG. 2 (referred to as a stage mode. Explain).
In this case, the sound source S on the stage 12 also serves as the sound receiving point R. As
shown in FIG. 8, the space around the sound source S is divided into sound source element
regions S1, S2,..., Si,. The example of FIG. 8 shows an example in which the horizontal plane is
divided into eight parts, and the obliquely upper part is divided into four into twelve (n = 12) in
total. Also, the space around the sound receiving point R (here, the space around the sound
source S is common. Is divided into sound receiving element areas R1, R2,..., Rj,..., Rm of suitable
solid angles centered on the sound receiving point R. As shown in FIG. In the example of FIG. 9,
an example (n, m = 12) divided into 12 in the same form as the sound source element area of FIG.
8 is shown. As shown in FIG. 12 (the sound source element regions S1 to Sn and the sound
receiving element regions R1 to Rm in FIG. 12 schematically illustrate the division forms in FIGS.
8 and 9), they are emitted from the sound source S. Impulse sound from one of the sound source
element regions S1 to Sn, passing directly or reflected through the sound field 10 and entering
from one of the sound receiving element regions R1 to Rm to reach the sound receiving point R
Responses are calculated or measured for combinations of all sound source element regions S1
to Sn and all sound receiving element regions R1 to Rm. Thereby, n О m kinds of impulse
responses hi, j (i = 1, 2,..., N, j = 1, 2,..., M) shown in Table 1 are obtained.
[0024]
By the way, in an actual hall, the sound arriving at the sound receiving point R, whether in the
customer seat or on the stage, is further reflected by the floor or the like to be reflected again to
reach the sound receiving point R again. In the guest-seat mode, since the sound collection by the
microphone and the reproduction by the speaker are not performed simultaneously (or
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performed in a separate space), the impulse response may be created including repetition of the
reflection of the sound reaching the sound reception point R. However, in the stage mode, since
sound collection by the microphone and reproduction by the speaker are simultaneously
performed, the sound reproduced by the speaker is collected by the microphone to form a
feedback loop. In this case, if the impulse response is created including repetition of the
reflection of the sound reaching the reception point R, the amount of increase in the reflection
sound by the feedback loop is weighted, and more reflections are heard than on the actual stage.
It will be generated. Therefore, in the stage mode, since the feedback loop can not be eliminated,
it is preferable to use an impulse response without repetition of reflection of the sound reaching
the sound receiving point R instead. That is, in the case of calculating the impulse response in the
stage mode, it is assumed that the sound ray which has once reached the sound receiving point R
is annihilated there and the reflection is not repeated any more.
[0025]
A system configuration for reproducing the sound field in an arbitrary actual space based on the
determined impulse response hi, j is shown in FIG. The acoustic characteristics of the actual
space 50 where the performer plays and listens in real time, the floor surface is reflective with a
predetermined sound absorption coefficient, and the dead characteristics of sound absorption
other than the floor surface (semi-anechoic chamber , Studio etc.). Directional microphones MC1
to MCn are arranged toward the sound source Sr in the direction corresponding to the respective
sound source element areas S1 to Sn (FIG. 8) around the actual sound source Sr (performance
position) in the space 50 (see FIG. In Fig. 13, the arrangement positions of the microphones MC1
to MCn are schematically illustrated according to the display form of the sound source element
areas S1 to Sn in Fig. 12). The speakers SP1 to SPm are directed to the sound receiving point Rr
in the direction corresponding to each of the sound receiving element areas R1 to Rm (FIG. 9)
around the actual sound receiving point Rr (listening position) in the space 50 Arranged (in FIG.
13, the arrangement positions of the speakers SP1 to SPm are schematically illustrated according
to the display form of the sound receiving element areas R1 to Rm in FIG. 12). If n = m, the
microphones MC1 to MCn and the speakers SP1 to SPm can be arranged in pairs.
[0026]
The player plays at the position of the sound source Sr in the space 50. The performance sounds
are collected by the microphones MC1 to MCn, respectively, and are input to the FIR matrix
circuit 42 through the head amplifier 38. The FIR matrix circuit 42 adds and synthesizes n О m
FIR filters (convolution operation units) in which each impulse response hi, j is set as a
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13
parameter, and output signals of the FIR filters having common receiving element regions These
adders are arranged in a matrix, for example, as shown in FIG. The sound pickup signals of the
microphones MC1 to MCn input from the input lines 44-1 to 44-n are convoluted with the
impulse response for each corresponding sound source element area to be an acoustic signal
(direct sound, reflected sound, reverberation) Are generated, and the audio signals of the
corresponding sound receiving element regions are added and synthesized, and output from the
corresponding output lines 46-1 to 46-m.
[0027]
In FIG. 13, the acoustic signals output from the output lines 46-1 to 46-m of the FIR matrix
circuit 42 are amplified by the amplifiers 47-1 to 47-m, and the corresponding speakers SP1 to
SPm in the space 32 are amplified. Supplied to and regenerated. The combination of a
microphone used for sound collection and an impulse response used for convolution and a
speaker used for reproduction is the same as that shown in Table 2 above. In order to prevent
howling, an echo canceller 54 is disposed, and a signal obtained by subtracting the output signals
of the speakers SP1 to SPm disposed in pairs from the collected sound signals of the
microphones MC1 to MCn is sent to the FIR matrix circuit 42. input.
[0028]
Thus, in the entire space 50, the reproduction signal r represented by the equation (1) is
reproduced. As a result, the state where the player himself plays in the atmosphere on the stage
12 in the sound field 10 of FIG. 2 is reproduced. Therefore, if the system configuration of FIG. 13
is used, the player can perform rehearsals in the atmosphere on the stage 12.
[0029]
In the above embodiments, each sound source element area and each sound receiving element
area are divided so as not to overlap each other with the adjacent element areas, but divided so
as to partially overlap with the adjacent element areas. You can also. In this way, the sound to be
positioned between the adjacent speakers can be reproduced by simultaneously reproducing the
sound with the two speakers.
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14
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