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JP2011254144

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2011254144
The present invention provides a listener with a necessary and sufficient number of microphones
that enables a listener to be provided with realistic three-dimensional sound with a relatively
small number of five to seven speakers. SOLUTION: First, second and third microphone pairs are
disposed in an acoustic space, and the first microphone pair is at a position suitable for collecting
indirect sound from a side surface of the acoustic space, The second microphone pair is suitable
for collecting indirect sound from the upper surface of the acoustic space, and the third
microphone pair is suitable for collecting indirect sound from the rear surface of the acoustic
space. The recording method is provided in which each output signal of each microphone pair is
separately recorded. [Selected figure] Figure 1
Recording method, recording medium on which an audio signal is recorded by this recording
method, and delivery method of audio signal
[0001]
The present invention relates to a technique for recording sound using a plurality of
microphones.
[0002]
As an example of sound reproduction technology that makes it possible to reproduce realistic
sounds, a plurality of (for example, five or seven) speakers are arranged so as to surround the
listener, and the sound from these speakers directed to the listener Is an audio reproduction
system of a surround type which outputs a signal (see Non-Patent Document 1).
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In this type of audio reproduction system, it is known that as the number of speakers increases, a
sound with high sense of reality can be obtained. Also, various techniques for recording using
three or more microphones have been proposed so as to be suitable for reproduction in the
surround system (see, for example, Patent Documents 1 to 7). The use of three or more
microphones here means that in the conventional stereo system where recording is performed
using two microphones, the speakers constituting the surround system do not cause problems
such as conflicts from the output signals of these microphones. It is difficult to generate an audio
signal to be given to
[0003]
Japanese Patent Publication No. 3128257 Japanese Patent Laid-Open No. 2005-98251 Japanese
Patent Laid-Open No. 2008-160588 Japanese Patent Laid-Open No. 05-191886 Japanese Patent
Laid-open No. 05-191887 Japanese Patent Laid-Open No. 10-285688 Japanese Patent
Publication No. 10-507892
[0004]
"Multichannel stereophonic sound system with and without accompanying picture",
RECOMMENDATION ITU-R BS. 775-2, Internet <URL: http://www.itu.int/rec/R-REC-BS.775-2200607-I / en>
[0005]
By the way, when listening to music played by an orchestra or the like in an acoustic space such
as a concert hall, not only sounds coming from flat directions such as front, back, left and right,
but also sounds coming from ceiling etc. Good hearing.
However, in the recording technology disclosed in each of Patent Documents 1 to 7, it is difficult
to perform recording so that such a sense of arrival of three-dimensional sound can be
reproduced.
In the techniques disclosed in each of Patent Documents 1 to 7, recording is performed using a
microphone array composed of a plurality of microphones arranged close to each other and
outward, and the horizontal sound field is captured finely. Although it is possible, it is impossible
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to capture the sound field in the height direction finely. Further, as described above, in the
surround sound system, the higher the number of speakers, the higher the sense of reality is
obtained. However, in home audio reproduction systems such as home theaters, the installation
space is limited. An increase in the number of speakers is not desirable. Furthermore, it is not
desirable to increase the number of microphones in the recording process, and it is desirable to
be able to record with a necessary and sufficient number of microphones. The present invention
has been made in view of the above problems, and a sufficient number of sound recordings
capable of providing realistic three-dimensional sound with a relatively small number of five to
seven speakers are necessary and sufficient. It aims at providing the technique performed with a
microphone.
[0006]
In order to solve the above-mentioned problems, the present invention is a recording method for
recording a sound radiated into the acoustic space from a sound source located in front of the
acoustic space, which is composed of microphones each of which is directivity controlled. Each of
the three microphone pairs to be separated by a distance equal to or greater than the distance at
which the volume level of the direct sound from the sound source and the volume level of the
indirect sound are equal to each other. In addition to the microphone pair having the shortest
distance from the sound source, the microphone pair whose directivity is controlled to pick up
indirect sound from the side surface of the acoustic space is the second distance from the sound
source For short microphone pairs, those whose directivity is controlled to pick up indirect sound
from the upper surface of the acoustic space are connected to the microphone pair with the
longest distance from the sound source. Separates the audio signal output from each of the
microphones constituting each of the three pairs of microphones using directivity controlled so
as to pick up indirect sound from the rear face of the acoustic space. And a recording method for
recording on a recording medium.
[0007]
According to such a recording method, sounds coming from different directions are picked up by
the respective microphone pairs, and the output signals of the microphones are separately
recorded.
The reason is that even if the microphone pair whose distance from the sound source is the
shortest, its placement position is separated by a distance at which the volume level of the direct
sound from the sound source and the volume level of the indirect sound are equal (hereinafter
referred to as critical distance) Because the volume level of the indirect sound reflected by the
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side surface, the upper surface, and the rear surface of the acoustic space is more dominant than
the direct sound from the sound source at the arrangement position of each microphone pair. is
there. For this reason, in the first microphone pair whose distance from the sound source is the
shortest, indirect sound from the side surface of the acoustic space is mainly collected, and in the
second microphone pair whose distance from the sound source is the second shortest, sound is
collected The indirect sound from the upper surface of the space is mainly collected, and the
indirect sound from the rear surface of the acoustic space is mainly collected by the third
microphone pair whose distance from the sound source is the longest.
[0008]
As described above, according to the recording method of the present invention, three kinds of
sounds (indirect sound from the side surface, indirect sound from the upper surface, and the rear
surface) coming from different directions so as to surround the listener. The indirect sound is
picked up by three pairs of microphones (the necessary and sufficient number of microphones in
picking up the sounds coming from those three directions separately). Then, by appropriately
mixing the audio signal recorded by this recording method and the audio signal (hereinafter,
main signal) for reproducing stereo presence, the stereo presence can be obtained by giving each
of the speakers constituting the surround system. In addition to the sound coming to surround
the listener in three dimensions (indirect sound from the side of the acoustic space, indirect
sound from the upper side of the acoustic space, and indirect from the rear side of the acoustic
space Sound is reproduced, and a highly realistic three-dimensional sound with a rich threedimensional effect can be obtained. The main signal may be recorded by a known recording
method.
[0009]
In a more preferable aspect, the second microphone pair whose distance from the sound source
is the second shortest is disposed at the highest position, and the first microphone pair whose
distance from the sound source is the shortest is disposed at the next highest position. It is
characterized by According to such an aspect, it is possible to efficiently collect the sound of the
sound collection target by the second microphone whose main sound collection target is the
indirect sound from the upper surface of the acoustic space. Further, since the direct sound
radiated from the sound source propagates in a spherical wave shape, for each of the
microphones constituting the microphone pair whose distance from the sound source is the
shortest, the width of the sound source when the sound source is viewed from behind the
acoustic space. For each of the microphones corresponding to the microphone pair whose
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distance from the sound source is the second shortest, the space between the sound sources is
wider than that of the sound source. Is preferred. Further, as another aspect of the present
invention, an aspect in which an audio signal recorded by each of the above recording methods is
separately written on a recording medium and provided, an aspect in which the above audio
signal is distributed via a telecommunication line, etc. .
[0010]
It is a figure for demonstrating the recording method of embodiment of this invention. It is a
figure which shows the example of recording of the audio signal to the storage medium by the
recording method. It is a figure which shows an example of the reproduction | regeneration
method of the sound recorded by the same recording method. It is a figure which shows the
structural example of the reproducing | regenerating apparatus which performs the same
reproduction | regeneration method. It is a figure which shows an example of the reproduction |
regeneration method of the sound recorded by the same recording method. It is a figure which
shows the structural example of the reproducing | regenerating apparatus which performs the
same reproduction | regeneration method. It is a figure which shows an example of the
reproduction | regeneration method of the sound recorded by the same recording method. It is a
figure which shows the structural example of the reproducing | regenerating apparatus which
performs the same reproduction | regeneration method. It is a figure which shows an example of
the reproduction | regeneration method of the sound recorded by the same recording method. It
is a figure which shows the structural example of the reproducing | regenerating apparatus
which performs the same reproduction | regeneration method. It is a figure for demonstrating
the arrangement position of each microphone pair in the case where acoustic space is wide and
narrow.
[0011]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. (A: Recording Method of this Embodiment) FIG. 1 is a diagram for explaining a
recording method of the embodiment of the present invention. According to this recording
method, for example, a sound which is played by an orchestra or the like in an acoustic space 1
such as a concert hall is reproduced with a home audio reproduction system such as a 5 (or 7)
channel surround system. It can be recorded so as to reproduce high-feeling three-dimensional
sound. In this recording method, six microphones (microphones 32A, 32B, 34A, 34B, 36A, and
36B) and each of these six microphones are connected, and the output signal of each microphone
is CD (Compact Disk) or DVD ( A recording apparatus (not shown in FIG. 1) for recording on a
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recording medium such as a Digital Versatile Disc) or a hard disk is used.
[0012]
FIG. 1A is a bird's-eye view of the acoustic space 1 in which the six microphones are arranged
from the ceiling side, and FIG. 1B is a sectional view of the acoustic space 1 as viewed from the
left side wall is there. As shown in FIG. 1 (A) and FIG. 1 (B), the acoustic space 1 has a floor 10G
and a ceiling 10H in the shape of a uniform pedestal, four walls (front wall 10C, right side wall
10D, left side wall 10E, and It is a closed space partitioned by the back wall 10F). Explaining in
more detail, the shorter one of the two parallel sides out of the four sides forming the outer
periphery of the floor 10G (the length W (3.5 [m in this embodiment, as shown in FIG. 1 (A), The
front wall 10C stands along the side of) and the longer side (the side of length W + 4a as shown
in FIG. 1A (in this embodiment, a = 1 [m]))) The back wall 10F stands along the side. In the
acoustic space 1, a stage 10A for performing a performance by a member of the orchestra is
provided at a position higher than the spectator seat 10B along the front wall 10C. The distance
to the wall 10F is 12 [m]. Further, as shown in FIG. 1 (B), in the acoustic space 1 of the present
embodiment, the height from the floor 10G to the ceiling 10H is 6 [m].
[0013]
The microphones 32A, 32B, 34A, 34B, 36A, and 36B are arranged in the acoustic space 1 as two
pairs of three microphones. Specifically, as shown in FIG. 1A, the microphones 32A and 32B
make a first microphone pair MP-1, the microphones 34A and 34B make a second microphone
pair MP-2, and the microphones 36A and 36B. Third microphone pairs MP-3 are each
configured. In the present embodiment, each of the three microphone pairs plays a role of
picking up indirect sound coming from different directions. Specifically, the sound of the sound
collection target of the first microphone pair MP-1 is reflected by the side surface of the acoustic
space 1 (in the present embodiment, the right side wall 10D or the left side wall 10E) and the
spectator seat 10B It is an indirect sound that comes to The sound of the sound collection target
of the second microphone pair MP-2 is an indirect sound that is reflected by the upper surface
(in the present embodiment, the ceiling 10H) and arrives at the audience seat 10B, and the third
microphone pair MP-3 The sound to be collected is an indirect sound that is reflected by the rear
surface (in the present embodiment, the rear wall 10F) and arrives at the audience seat 10B. As
described above, since each of the three pairs of microphones picks up indirect sounds coming
from different directions from each other and does not pick up direct sounds, the microphones
constituting each microphone pair are unidirectional. It is desirable that the directivity be
controlled, such as sex, and in a further preferred embodiment, it is preferable to use a
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superdirective microphone. This is because the narrower directivity allows the microphones to
efficiently collect the sound of each sound collection target. In the present embodiment,
superdirective microphones are used as the six microphones. The direct sound coming directly
from the sound source on stage 10A (in this embodiment, each component instrument of the
orchestra) to the audience seat 10B is picked up by microphones (not shown in FIG. 1) other than
the six microphones. After being mixed with the indirect sound, it is given to the recording device
as a main signal for reproducing stereo presence. The recording of the main signal may be
performed using a known technique such as a stereo recording technique.
[0014]
As described above, each of the first, second and third microphone pairs plays a role of picking
up indirect sound coming from different directions respectively, and since the direct sound is not
to be picked up, these microphones are not The microphones constituting the pair are disposed
at positions suitable for the respective roles, and the pointing axes thereof are also oriented in
the directions suitable for the respective roles. The present embodiment is characterized in the
arrangement position of these six microphones and the direction of the directivity axis.
Hereinafter, the arrangement positions of these six microphones and the direction of the
directivity axis in the acoustic space 1 will be described.
[0015]
As shown in FIG. 1A, of the three microphone pairs, the first microphone pair MP-1 is at the
position where the distance from the stage 10A is the shortest (the distance from the tip of the
stage 10A to the rear wall 10F by 1 L) Location). Here, 1 L is a distance at which the volume level
of the direct sound emitted from the sound source on the stage 10 A becomes equal to the
volume level of the indirect sound (that is, critical distance), and is 2 m in this embodiment. And
2nd microphone pair MP-2 and 3rd microphone pair MP-3 are arrange | positioned at equal
intervals so that it may distances in the rear wall 10F direction from stage 10A in this order. As
described above, in the present embodiment, the distance from the tip of the stage 10 (A) to the
rear wall 10F is 12 [m] (that is, 6 L), and as shown in FIG. 1 (A), the second microphone The pair
MP-2 is placed at a position separated by a distance of 2 L from the first microphone pair MP-1
in the direction of the back wall 10F (that is, at a position of 3 L = 6 [m] from the tip of the stage
10A). Microphone pair MP-3 at a distance of 2 L from the second microphone pair MP-2 in the
direction of the rear wall 10F (ie, a position at a distance of 5 L from the tip of the stage 10A (in
other words, the rear wall 10F To the stage 10A)). As described above, in the present
embodiment, one or more musical instruments as sound sources are arranged on the stage 10A.
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That is, the first microphone pair MP-1 is the closest to the sound source, the second microphone
pair MP-2 is the second closest to the sound source, and the third microphone pair MP-3 is the
farthest position from the sound source Will be placed. As described above, the reason why the
first microphone pair MP-1 arranged closest to the sound source is also separated by 1 L from
the sound source is to avoid collection of extra sounds (direct sound) other than the sound
collection target It is.
[0016]
The microphones constituting each of the first, second and third microphone pairs are arranged
in the acoustic space 1 at different intervals for each microphone pair. More specifically, each of
the microphones 32A and 32B constituting the first microphone pair MP-1 is disposed at an
interval corresponding to the width of the sound source in the width direction. For example, in
the case where a plurality of musical instruments serving as sound sources are disposed across
the entire stage 10A, as shown in FIG. 1A, the stage when the stage 10A is viewed from the back
wall 10F side of the acoustic space 1 The space W is arranged at the same width W as the width
10A (ie, the width of the sound source). The microphones 34A and 34B constituting the second
microphone pair MP-2 have a wider interval than that in the first microphone pair MP-1 (in the
present embodiment, as shown in FIG. 1A, W + 2a). The microphones 36A and 36B, which are
disposed at a slightly smaller interval than the first microphone pair MP-3, are arranged at a
narrower interval than that in the first microphone pair MP-1 (shown in FIG. 1A). (W-a spacing)
is spaced apart.
[0017]
In addition, as shown in FIG. 1B, of the first, second and third microphone pairs, the second
microphone pair MP-2 is at the highest position (that is, the position closest to the ceiling 10H:
this embodiment) In the form, it is arranged at the height of 4.5 m from the floor 10G). This is
because, as described above, the second microphone pair MP-2 picks up indirect sound from the
upper surface of the acoustic space 1 as a sound collection target. The third microphone pair MP3 is disposed at the lowest position (in this embodiment, at a height of 2.5 m from the floor 10G),
and the first microphone pair MP-1 is located between them. (Desirably, a position between the
second microphone pair MP-1 and the third microphone pair MP-3). Note that FIG. 1B
exemplifies a case where the first microphone pair MP-1 is disposed at a height of 3 m from the
floor 10G. As shown in FIG. 1B, in the present embodiment, each of the six microphones is
supported at each position by the microphone stand 40 whose height can be adjusted, but the
method of suspending from the ceiling 10 H You may arrange each microphone by.
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[0018]
Then, each of the microphones included in each of the first, second and third microphone pairs
does not pick up an extra sound (sound outside the sound collection target), and the directional
axes of each of the microphones are selected. It is arranged in the direction of arrival of sound.
Specifically, each of the microphones 32A and 32B included in the first microphone pair MP-1
has its directivity axis directed to the closer one of the right side wall 10D and the left side wall
10E (FIG. 1 (A ), The microphone 32A is disposed such that the directivity axis is directed to the
left side wall 10E) such that the directivity axis is directed to the right side wall 10D. This is
because the sound of the sound collection target of the first microphone pair MP-1 is an indirect
sound that arrives from the side surface of the acoustic space 1 (that is, the right side wall 10D
and the left side wall 10E) to the spectator seat 10B. Similarly, since the sound of the sound
collection target of the second microphone pair MP-2 is an indirect sound arriving from the
upper surface of the acoustic space 1 to the passenger seat 10B, the second microphone pair
MP-2 is configured The microphones 34A and 34B are arranged with their pointing axes directed
in the direction of the upper surface of the acoustic space 1 (ie, the ceiling 10H). And since the
sound of the sound collection object of the third microphone pair MP-3 is an indirect sound
arriving from the rear face of the acoustic space 1 to the passenger seat 10B, the microphones
constituting the third microphone pair MP-3 36A and 36B are arranged with their pointing axes
directed in the direction of the rear face of acoustic space 1 (i.e., back wall 10F).
[0019]
As described above, the second and third microphone pairs are disposed at a distance greater
than the critical distance from the sound source. Therefore, it is considered that the direct sound
is sufficiently attenuated at the arrangement position of these microphone pairs. In addition, in
the present embodiment, the microphone pair (i.e., the second microphone pair MP-2) for
collecting indirect sound from the upper surface of the acoustic space 1 is disposed closest to the
upper surface. A microphone pair for picking up indirect sound from the rear surface (i.e., a third
microphone pair MP-3) is disposed closest to the rear surface. For this reason, it is possible to
efficiently collect the sound of the sound collection target in the microphone pair. Furthermore,
in the present embodiment, since each microphone pair is configured to be directivity-controlled,
the effect of efficiently collecting the sound of the sound collection target can be further
enhanced. In particular, at the arrangement position of the first microphone pair MP-1, although
it is considered that the volume level of the direct sound and the volume level of the indirect
sound from the side surface are substantially equal, the directivity controlled microphone In this
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embodiment, since the first microphone pair MP-1 is configured using the superdirective
microphone, it is possible to efficiently collect the sound of the sound collection target (that is,
indirect sound from the side surface) It is possible to
[0020]
The audio signals output from each of the microphones 32A, 32B, 34A, 34B, 36A and 36B are
supplied to the recording apparatus together with the left and right channel components of the
main signal, and separately recorded on a recording medium such as a CD by the recording
apparatus. Ru. For example, assuming that the audio signals output from each of the
microphones 32A, 32B, 34A, 34B, 36A and 36B are audio signals S2A, S2B, S4A, S4B, S6A and
S6B, the recording device is as shown in FIG. Then, each of the six types of audio signals and the
right channel component MSR and the left channel component MSL of the main signal are
written to separate records (or tracks) of the recording medium. The above is the recording
method of this embodiment.
[0021]
(B: Method of Reproducing Sound Recorded by the Recording Method) Next, a method of
reproducing the sound recorded by the above recording method will be described. In a multichannel surround system, an audio signal recorded on a recording medium such as a CD is read
by a CD drive or the like, and each of the audio signals (or an audio signal obtained by
appropriately mixing the audio signals) is multi-channeled The sound is reproduced by giving
each speaker included in the surround system. The problem here is how to assign the audio
signal recorded on the recording medium by the recording method of this embodiment to each
speaker of the multi-channel surround system. The following cases are included in the case of
performing sound reproduction in a 5-channel (or 5.1 channel) surround system and in the case
of reproducing sound in a 7-channel (or 7.1 channel) surround system as an example. How to
assign an audio signal to each speaker. In the following, the method of reproducing the low
frequency speaker corresponding to 0.1 channel in the 5.1 and 7.1 channel surround systems is
not directly relevant to the present invention, and thus the detailed description is omitted.
[0022]
(B-1: Reproduction Method in Five-Channel Surround System) FIG. 3A shows a center channel
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speaker C, a right channel speaker R, a left channel speaker L, a right surround speaker RS, and a
left surround speaker LS so as to surround a listener. It is a figure which shows an example of the
5-channel surround system arrange | positioned. The arrangement position of each speaker (the
position shown by each angle in FIG. 3A) in the 5-channel surround system and the role of each
speaker are specified in detail in Non-Patent Document 1.
[0023]
In the five-channel surround system shown in FIG. 3A, the main signal and the output signal of
the first microphone pair MP-1 (output signals of the microphones 32A and 32B: the sound
indicated by the symbol S1 in FIG. 3B) An audio signal representing a sound in the space 1 is
appropriately mixed to generate an audio signal to be given to each of the right channel speaker
R and the left channel speaker L, and an output signal of the third microphone pair MP-3
(microphones 36A and 36B The output signal of: audio signal representing the sound in the
acoustic space 1 indicated by the code S3 in FIG. 3B) may be given to the right surround speaker
RS and the left surround speaker LS. Although the detailed description is omitted, the audio
signal to be given to the center channel speaker C may be generated from the main signal.
[0024]
FIG. 4 reads out each audio signal from the recording medium (the recording medium on which
the audio signal is recorded in the mode shown in FIG. 2 above) on which the audio signal is
recorded by the recording method of this embodiment. 4A shows an example of the
configuration of a reproduction apparatus 50A that generates an audio signal to be provided to
each of the five speakers shown in FIG. 3A. As shown in FIG. 4, the reproduction device 50A
includes a signal reading unit 510A and a mixer unit 520A. The signal reading unit 510A is, for
example, a CD drive, reads the audio signals S2A, S2B, S6A, and S6B recorded in the recording
medium, and the right channel component MSR and the left channel component MSL of the main
signal, Give to 520A.
[0025]
Mixer unit 520A supplies each of the five speakers shown in FIG. 3A based on audio signals S2A,
S2B, S6A, and S6B supplied from signal reading unit 510A and the left and right channel
components of the main signal. An audio signal is generated and output (however, the illustration
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and the description of the audio signal given to the center channel speaker C are omitted). More
specifically, as shown in FIG. 4, the mixer unit 520A mixes the right channel component MSR of
the main signal with the audio signal S2A (that is, the output signal of the microphone 32A) and
provides the same to the right channel speaker R. A signal is generated, and the left channel
component MSL of the main signal and the audio signal S2B (that is, the output signal of the
microphone 32B) are mixed to generate an audio signal to be supplied to the left channel speaker
L. The mixing ratio at the time of generating the audio signal to be given to each of the left
channel speaker L and the right channel speaker R may be appropriately determined by the
mixing engineer based on the experience and the aural feeling. Further, the mixer unit 520A
supplies the audio signal S6A (output signal of the microphone 36A) read from the recording
medium to the right surround speaker RS, and supplies the audio signal S6B (output signal of the
microphone 36B) to the left surround speaker LS.
[0026]
Each audio signal output from the playback device 50A is subjected to D / A conversion by a D /
A converter (not shown) and amplification by a power amplifier (also not shown), and then to a
center channel speaker C, right channel speaker R, left A sound corresponding to the audio signal
that is given to each of the channel speaker L, the right surround speaker RS, and the left
surround speaker LS is output from each speaker. As a result, by the sounds outputted from the
center channel speaker C, the right channel speaker R and the left channel speaker L, the stereo
presence and the indirect sound from the side surface of the acoustic space 1 are reproduced,
and the right surround speaker RS and the left The indirect sound from the rear face of the
acoustic space 1 is reproduced by the sound output from the surround speaker LS, so that stereo
presence can be obtained at the position of the listener in FIG. It gives you the feeling of being
surrounded by indirect sounds coming from the side and the back.
[0027]
(B-2: Modification of Reproduction Method in Five-Channel Surround System) Now, in the aspect
described above, indirect sound from the upper surface of the acoustic space 1 is not reproduced,
and there is a possibility that the three-dimensional effect may be insufficient. Therefore, an
audio signal to be given to each of the right channel speaker L and the left channel speaker R of
the 5-channel surround system is a main signal, an output signal of the first microphone pair MP1, and a second microphone pair MP-2. An output signal (an audio signal representing a sound in
the acoustic space 1 indicated by a symbol S2 in FIG. 3B) is generated by mixing as appropriate,
and is supplied to each of the right surround speaker RS and the left surround speaker LS. An
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audio signal is generated by mixing the output signal of the second microphone pair MP-2 and
the output signal of the third microphone pair MP-3, as shown in FIG. The sound corresponding
to the indirect sound from the surface may be reproduced from the virtual speakers VR and VL.
Specifically, the indirect sound coming from the upper right of the acoustic space 1 is reproduced
from the virtual speaker VR by the sound output from the right channel speaker R and the sound
output from the right surround speaker RS, and output from the left channel speaker L The
indirect sound that comes from the upper left of the acoustic space 1 from the virtual speaker VL
is reproduced by the sound that is generated and the sound that is output from the left surround
speaker LS.
[0028]
FIG. 6 is a diagram showing a configuration example of the reproduction device 50B that realizes
the reproduction of the sound from the virtual speakers VR and VL. As shown in FIG. 6, the
reproducing apparatus 50B includes a signal reading unit 510B and a mixer unit 520B. The
signal reading unit 510B is different from the above-described signal reading unit 510A in that
all six types of audio signals recorded on the recording medium are read and supplied to the
mixer unit 520B. Further, mixer section 520B differs from mixer section 520A described above
in that it generates audio signals to be provided to each of right channel speaker R, left channel
speaker L, right surround speaker RS, and left surround speaker LS in the following manner. As
shown in FIG. 6, for the audio signal to be supplied to the right channel speaker R, the mixer unit
520B includes the right channel component MSR of the main signal, the audio signal S2A, and
the audio signal S4A (output signal of the microphone 34A). The audio signal generated by
mixing appropriately and given to the left channel speaker L is generated by appropriately
mixing the left channel component MSL of the main signal, the audio signal S2B, and the audio
signal S4B (output signal of the microphone 34B) Do. Furthermore, the mixer unit 520B
appropriately mixes and generates the audio signal S4A and the audio signal S6A for the audio
signal to be supplied to the right surround speaker RS, and the audio signal S4B and the audio for
the audio signal to be supplied to the left surround speaker LS. The signal S6B is appropriately
mixed and generated. According to such an aspect, indirect sounds coming from the side, upper,
and rear directions are reproduced so as to surround the listener in a three-dimensional manner,
and highly realistic three-dimensional sound with a rich three-dimensional effect can be obtained.
[0029]
Further, as shown in FIG. 7, a multi-channel surround system configured to arrange a pair of left
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and right speakers HR and HL in a position higher than the above-mentioned five speakers in an
existing 5-channel surround system (namely, Non-Patent Document 1) In the 3D surround
system which is an extension of the defined 5-channel surround system), the audio signal may be
assigned to each speaker using the playback device 50C having the configuration shown in FIG.
As shown in FIG. 8, the reproduction device 50C includes a signal reading unit 510B and a mixer
unit 520C. As apparent from the comparison between FIG. 8 and FIG. 4, the mixer unit 520C
generates an audio signal to be given to each of the center channel speaker C, the right channel
speaker R, and the left channel speaker L in the same manner as the mixer unit 520A described
above. . Specifically, the mixer unit 520C mixes the right channel component MSR of the main
signal with the left channel component MSL to generate an audio signal to be supplied to the
center channel speaker C. The mixer unit 520C mixes the right channel component MSR of the
main signal with the audio signal S2A to generate an audio signal to be supplied to the right
channel speaker R, mixes the left channel component MSL with the audio signal S2B, and mixes
the left channel. An audio signal to be supplied to the speaker L is generated. Then, as shown in
FIG. 8, the mixer unit 520C, as shown in FIG. 8, the audio signal S4A for the speaker HR, the
audio signal S4B for the speaker HL, the audio signal S6A for the right surround speaker RS, and
the audio signal for the left surround speaker LS Each signal S6B is applied. According to this
aspect as well, indirect sounds coming from the side, upper, and rear directions can be
reproduced so as to surround the listener in three dimensions, and highly realistic threedimensional sound with a rich three-dimensional effect can be obtained.
[0030]
(B-3: Reproduction Method in 7-Channel Surround System) Further, it is possible to realize
reproduction of sound in a 7-channel surround system by using the above-mentioned
reproduction device 50C. FIG. 9 encircles the listener with center channel speaker C, right
channel speaker R, left channel speaker L, first right surround speaker RS1, first left surround
speaker LS1, second right surround speaker RS2 and second left surround speaker LS2. It is a
figure which shows an example of 7 channel surround system (or 7.1 channel surround system
which added the subwoofer (not shown)) arrange | positioned as mentioned above. Refer to NonPatent Document 1 for details of the arrangement position and use of each speaker in this 7channel surround system. In this 7-channel surround system, each audio signal may be assigned
as shown in FIG.
[0031]
As apparent from comparison between FIG. 10 and FIG. 8, the way of assigning audio signals to
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each of the center channel speaker C, the right channel speaker R and the left channel speaker L
is the same as that in FIG. The reproduction device 50C of FIG. 10 assigns the output signal of
the second microphone pair MP-2 to the first right surround speaker RS1 and the first left
surround speaker LS1, and the second right surround speaker RS2 and the second left surround
speaker LS2 Is different from the case of FIG. 8 only in that the output signal of the third
microphone pair MP-3 is assigned. That is, the mixer unit 520C of the reproduction apparatus
50C shown in FIG. 10 mixes the audio signal S4A to the first right surround speaker RS1, the
audio signal S4B to the first left surround speaker LS1, and the audio to the second right
surround speaker RS2. The signal S6A is provided to the second left surround speaker LS2, and
the audio signal S6B is provided. That is, in the seven-channel surround system shown in FIG. 9,
the first right surround speaker RS1 and the first left surround speaker LS1 perform the roles of
the speakers HR and HL of FIG. 7 in the same manner as the second right surround speaker RS2
and the second left surround. The speaker LS2 plays the role of the right surround speaker RS
and the left surround speaker LS in FIG. According to this aspect as well, indirect sounds coming
from the side, upper, and rear directions can be reproduced so as to surround the listener in
three dimensions, and highly realistic three-dimensional sound with a rich three-dimensional
effect can be obtained.
[0032]
As described above, according to the present embodiment, three types of sounds coming from
different directions so as to surround the listener (that is, indirect sounds coming from the side,
upper and rear directions of the acoustic space 1) Are picked up by three pairs of microphones
(ie, the necessary and sufficient number of microphones in picking up the indirect sound from
each of the side, upper and rear faces separately) and each separately recording medium Is
recorded in Then, the audio signals recorded in this way are appropriately mixed and given to
each speaker of the multi-channel surround system to three-dimensionally surround the listener
in a surround system having a relatively small number of speakers such as five or seven
channels. It becomes possible to reproduce the sound.
[0033]
(C: Other Embodiments) Although the first embodiment of the present invention has been
described above, the following modifications may of course be added. (1) In the embodiment
described above, in the acoustic space 1 in which the distance from the stage 10A to the rear
wall 10F is 6L, the first microphone pair is separated from the sound source by 1L in the
direction of the rear wall 10F. Microphone pair at a position 3 L apart from the first microphone
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pair (a position 2 L away from the first microphone pair), and a third microphone pair at a
position 5 L apart from the second microphone pair 2 L from the second microphone pair
Position). That is, in the embodiment described above, the three pairs of microphones are equally
spaced (2 L intervals) between the position where the volume level of the direct sound from the
sound source and the volume level of the indirect sound become equal and the rear wall 10F. It
was arranged. However, the arrangement position of each microphone pair is not limited to this,
and may be determined appropriately in consideration of the size of the acoustic space 1.
[0034]
For example, when the distance from the tip of the stage 10A to the rear wall 10F is longer than
6L, as shown in FIG. 11A, the first microphone pair MP-1 is separated by 1L from the stage 10A.
The second microphone pair MP-2 is separated from the first microphone pair MP-1 by 2L, and
the third microphone pair MP-3 is separated from the second microphone pair MP-2 by 2L. It
should be arranged. On the other hand, when the distance from the tip of the stage 10A to the
rear wall 10F is shorter than 6L, as shown in FIG. 11B, the first microphone pair MP-1 is
separated from the stage 10A by 1L. The second microphone pair MP-2 and the third
microphone pair MP-3 may be arranged in the following manner. That is, the distance between
the first microphone pair MP-1 and the back wall 10F is divided into five equal parts, and the
second microphone pair MP-2 is separated from the first microphone pair MP-1 by 2 l. It is
sufficient to dispose the third microphone pair MP-3 at a position separated by 2 l from the
second microphone pair MP-2 (in other words, 1 l from the back wall 10F toward the stage 10A).
. Further, in the above embodiment, the first microphone pair MP-1 arranged closest to the sound
source is arranged at a distance of 1 L from the sound source, but it goes without saying that the
first microphone pair MP-1 may be arranged at a distance longer than 1 L. good. The point is
that the first microphone pair MP-1 arranged closest to the sound source is arranged at a
distance of the critical distance or more from the sound source, and the three microphone pairs
are equally spaced Any mode is acceptable.
[0035]
Further, regarding the arrangement intervals of the microphones constituting each microphone
pair, in consideration of the influence of direct sound, an interval according to the width of the
sound source (i.e., the first microphone pair MP-1 arranged closest to the sound source) ,
Microphones 32A and 32B are preferably spaced apart by a distance equal to or wider than the
width of the sound source, and then, for the second microphone pair MP-2 arranged near the
sound source, at the first microphone pair It is preferable to place the microphones 34A and 34B
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at a larger spacing than the ones. This takes into consideration that the sound wave propagates
in space while spreading in a spherical wave shape. As for the third microphone pair MP-3
arranged at the position farthest from the sound source, the influence of direct sound is
considered to be smaller compared to the first and second microphone pairs, so the arrangement
of its constituent microphones With regard to the spacing, the spacing may be such that each
microphone included in the microphone pair MP-3 can pick up sounds that are uncorrelated with
each other.
[0036]
(2) In the embodiment described above, superdirective microphones are used as the microphones
forming the first, second and third microphone pairs. As described above, the sound of the sound
collection target is determined for each of the microphones so as not to collect the sound other
than the extra sound collection target. If the acoustic space 1 is not so wide as compared to the
volume level of the sound emitted by the sound source, and the sound other than the sound
collection target is not sufficiently attenuated at the arrangement position of each microphone,
use the superdirective microphone It is preferable to actively pick up indirect sound components
excluding direct sounds, but the acoustic space 1 is sufficiently wide and sounds (direct sounds)
other than the sound collection target are sufficiently attenuated at the arrangement position of
each microphone. In this case, it is not necessary to use superdirective microphones, and
microphones with wider directivity (such as general unidirectional microphones) may be used.
The point is that a microphone whose directivity is appropriately controlled may be used
according to the balance of the size of another sound with respect to the sound of the sound
collection target, the size of the acoustic space, and the like.
[0037]
(3) In the embodiment described above, the direction of the directional axis of the constituent
microphones was determined when arranging each microphone pair. However, microphones that
can control directivity as microphones that make up each microphone pair (for example,
microphones that can direct the directivity axis in any direction or control the size of the
directivity angle by a control signal supplied from the outside) ), And directivity control may be
performed electrically after installation.
[0038]
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(4) In the embodiment described above, the ceiling 10H is flat, but it may be considered to be
dome-shaped (concave). As described above, if the ceiling of the acoustic space is dome-shaped,
adjust the directivity axes of the microphone pair that picks up the indirect sound from the
ceiling as appropriate (for example, point the directivity axis at the boundary between the ceiling
and the side wall) The undesirable effects resulting from the shape of the dome-shaped ceiling
may be avoided.
[0039]
(5) In the embodiment described above, the audio signal output from each of the microphones
32A, 32B, 34A, 34B, 36A, and 36B is separately written on a recording medium such as a CD,
and the audio signal read from the recording medium An audio signal to be given to each speaker
of the multi-channel surround system is generated based on. However, the audio signal output
from each of the above microphones is distributed via a telecommunication line such as the
Internet, and an audio signal to be provided to each speaker of the multi-channel surround
system is generated based on the audio signal distributed in this manner. It is good. Note that, as
an example of a reproduction apparatus that generates an audio signal to be given to each
speaker of a multi-channel surround system based on an audio signal distributed via a
telecommunication line as described above, the above-described reproduction apparatus 50A (or
The signal reading unit 510A (in the reproducing devices 50B and 50C, the signal reading unit
510B) of the devices 50B and 50C is replaced with a communication interface unit (for example,
Network Interface Card) that transmits and receives data via a telecommunication line Things can
be considered. According to such an aspect, an audio signal recorded by the recording method of
the present invention is distributed without using a recording medium such as a CD, and a sense
of reality is enriched using a multi-channel surround system such as a 5-channel surround
system. It becomes possible to reproduce three-dimensional sound.
[0040]
DESCRIPTION OF SYMBOLS 1 ... acoustic space, 10A ... stage, 10B ... audience seat, 10C ... front
wall, 10D ... right side wall, 10E ... left side wall, 10F ... back wall, 10G ... floor, 10H ... ceiling, 32A,
32B, 34A, 34B, 36A, 36B: Microphone, 50A, 50B, 50C: Reproduction device, 510A, 510B: Signal
reading unit, 520A, 520B, 520C: Mixer unit, C: Center channel speaker, L: Left channel speaker,
R: Right channel speaker, LS ... Left surround speaker, RS ... Right surround speaker.
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