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JP2005236407

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DESCRIPTION JP2005236407
The present invention provides an acoustic processing device capable of reducing a noise signal
input to a microphone. A sound processing apparatus 10 receives and processes a user's voice,
and a plurality of microphones disposed at a position facing the user in the case 100 and the
case 100 and receiving a voice. 200 and 210, signal processing means 400 for processing the
acoustic signals received by the plurality of microphones 200 and 210 by forming directivity
characteristics in the direction of the user, and a noise source 300 for the microphones 200 and
210. The noise source 300 is disposed at a position other than a position on a straight line
extending in a specific direction indicated by the directivity characteristic from the plurality of
microphones 200 and 210 disposed on the housing 100. [Selected figure] Figure 1-1
Sound processing apparatus, sound processing method and manufacturing method
[0001]
The present invention relates to an acoustic processing apparatus, an acoustic processing
method, and a manufacturing method for processing an acoustic signal acquired from the
outside.
[0002]
In recent years, with the development of telecommunication networks such as the Internet, voice
over IP (VoIP) communication systems using personal computers etc. have begun to spread.
04-05-2019
1
In these systems, it is essential to include sound input / output means for outputting the speech
of the other party while receiving the speech of the user for the call. Generally, a headset is often
used as the sound input / output means.
[0003]
However, there is a problem that the headset imposes a physical burden on the user to limit its
movement. In addition, there is a problem that a mental burden of having to wear a headset
every time a call is given.
[0004]
Therefore, in order to solve these problems, there is a growing expectation to input and output
voices in a hands-free environment. Here, the hands-free environment refers to an environment
in which a device such as a personal computer is equipped with an acoustic input / output device
such as a microphone or a speaker in advance, and a call can be made using the microphone or
the speaker.
[0005]
In a hands free environment, it is not necessary to wear special equipment such as a headset. In
addition, it is not necessary to hold the receiver close to the ear and the mouth as in a general
telephone. In this way, the physical and mental burden on the user during a call can be
significantly reduced.
[0006]
However, when making a call in a hands-free environment, the speech of the other party output
from the speaker may enter the microphone and be input. If the speech of the other party from
the microphone is transmitted back to the other party, it sounds like "kodama", which is not
preferable. In addition, when the other party uses the hands-free environment, the speech folded
back to the other party may be further folded back and transmitted, which may cause a
phenomenon such as howling. Such a phenomenon is known as acoustic echo.
04-05-2019
2
[0007]
In order to solve the problems as described above, an echo cancellation technique has been
proposed in which a signal output from a speaker is subtracted from a signal input to a
microphone to reduce an acoustic echo (see Non-Patent Document 1).
[0008]
In the echo cancellation technique, the output signal of the speaker is weighted appropriately
and subtracted from the signal input to the microphone.
That is, of the signals input to the microphone, the component corresponding to the output signal
of the speaker is deleted. Thereby, acoustic echo can be suppressed.
[0009]
However, the output signal of the speaker and the signal input to the microphone do not
necessarily match. Therefore, echo cancellation makes it difficult to completely cancel the
acoustic echo.
[0010]
Ohga et al., "Sound system and digital processing", The Institute of Electronics, Information and
Communication Engineers
[0011]
According to the acoustic processing apparatus using the microphone array, it is possible to
extract only the acoustic signal from the specified specific direction by giving directional
characteristics in the specific direction, so that the noise signal can be reduced. is there.
[0012]
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3
However, when a microphone array is used to reduce the noise signal, the noise signal may not
be sufficiently reduced if the relationship between the directivity characteristic of the
microphone and the arrangement of the noise source is not appropriate.
Conversely, when the noise source is disposed in a direction that matches the directional
characteristics of the microphone array, the noise signal may be amplified and input to the
microphone.
In such a case, a larger acoustic echo occurs than in the case where the microphone array is not
used, which is not desirable. Therefore, a technique that can reduce noise signals efficiently is
desired.
[0013]
The present invention is made in view of the above, and an object of the present invention is to
provide an acoustic processing device capable of reducing a noise signal input to a microphone.
[0014]
In order to solve the above problems, it is considered to use a method of extracting only an
acoustic signal from a specified specific direction by performing microphone array processing
using a plurality of microphones and giving directional characteristics in a specific direction, The
following invention was conceived.
[0015]
That is, in order to solve the problems described above and achieve the object, the present
invention is an acoustic processing apparatus that receives and processes a user's voice, and a
case, and the user in the case A plurality of microphones disposed at facing positions and
receiving the voice, signal processing means for forming directional characteristics in the
direction of the user, and processing audio signals received by the plurality of microphones; A
noise source for a microphone is provided, and the noise source is disposed at a position
different from a straight line extending in the direction of the directional characteristic from the
plurality of microphones disposed on the housing.
[0016]
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4
In the sound processing apparatus according to the present invention, a position on a straight
line extending in a specific direction of a directional characteristic formed by the signal
processing means is a noise source which is a generation source of noise signals other than a
target audio signal to be input to a microphone. It is placed at a position other than.
Thereby, a phase difference can be generated between the audio signal and the noise signal.
Therefore, the signal processing means can separate the speech signal and the noise signal, and
can enhance the speech only on the speech signal, that is, can reduce the noise signal.
[0017]
Hereinafter, an embodiment of a sound processing apparatus according to the present invention
will be described in detail based on the drawings.
The present invention is not limited by this embodiment.
[0018]
Embodiment 1 FIG. 1A is an external view of a sound processing apparatus according to the
present invention. The sound processing device 10 is a laptop personal computer. In the case
100 of the sound processing apparatus 10, a first microphone 200, a second microphone 210
(for example, a nondirectional microphone or the like), and a speaker 300 are disposed.
[0019]
The first microphone 200, the second microphone 210, and the speaker 300 are all disposed on
the surface on which the display screen 120 is disposed. The first microphone 200 and the
second microphone 210 receive an acoustic signal, that is, mainly the voice from the user.
Further, the speaker 300 outputs an audio signal. The user can make a call, for example, by VoIP
using the first microphone 200 or the like.
04-05-2019
5
[0020]
The user faces the display surface 100 and utilizes the sound processing apparatus 10 as shown
in FIG. Therefore, in order to efficiently receive the voice from the user and to output the voice to
the user, each of the first microphone 200, the second microphone 210, and the speaker 300 is
the acoustic processing device. When 10 is used, it is arrange | positioned in the position which
faces a user.
[0021]
FIG. 2 is a block diagram showing a functional configuration of the signal processing unit 400. As
shown in FIG. The signal processing unit 400 includes a delay unit 410 and an amplifier 420.
The delay unit 410 performs delay processing on the sound signal received by the first
microphone 200. Further, the amplifier 420 adds the acoustic signal subjected to the delay
processing by the delay unit 410 and the acoustic signal received by the second microphone 210
and outputs the added signal.
[0022]
Hereinafter, the processing in the signal processing unit 400 will be described in detail. The
target signal comes from the direction of Θs shown in FIG. 2 with respect to the two
microphones 200 and 210. Here, the target signal is an audio signal emitted by the user among
audio signals received by the first microphone 200 and the second microphone 210.
[0023]
The timing at which the second microphone 210 receives the target signal is delayed by τs from
the timing at which the first microphone 200 receives the target signal. Here, τs is expressed by
the following equation. τs = d · sinΘs / c (Expression 1) In Expression 1, d represents the
distance between the first microphone 200 and the second microphone 210. Also, c represents
the speed of sound.
04-05-2019
6
[0024]
The delay of the arrival time causes a phase shift between the target signal received by the first
microphone 200 and the target signal received by the second microphone 210. Therefore, the
delay processing of D1 (= τs) corresponding to the phase difference τs is added to the target
signal received by the first microphone 200 by the delay unit 410. Thereby, the phases of the
two target signals received by the first microphone 200 and the second microphone 210 can be
matched.
[0025]
Furthermore, the amplifier 420 adds the target signal after delay processing by the delay unit
410 and the target signal received by the second microphone 210 to the first microphone 200
and the second microphone 210 from the direction of Θs. An incoming target signal can be
emphasized.
[0026]
As described above, by subjecting one of the target signals to delay processing by the delay unit
410 and then adding the two target signals, it becomes possible to form a directional
characteristic in a specific direction.
[0027]
On the other hand, in the signal input from other than the specific direction, that is, the noise
signal, the value of the target signal and Θ s are different.
Therefore, even if delay processing is performed by the delay unit 410, the same phase as the
target signal is not generated.
Therefore, it is not emphasized by the addition process. As a result, a dead angle of the directivity
characteristic is formed in a direction other than the specific direction.
[0028]
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7
By the above processing by the signal processing unit 400, since the directivity characteristic can
be formed in the specific direction, that is, the direction of the user by the delay and sum array
system, only the acoustic signal from the specific direction can be emphasized. Furthermore, the
acoustic signal coming from the dead angle direction of the directivity characteristic can be
reduced.
[0029]
FIGS. 3 and 4 are diagrams for explaining the positional relationship between the first and
second microphones 200 and 210 and the speaker 300. FIG. As described with reference to FIG.
2, in order to emphasize only the target signal and reduce the noise signal, the phase difference
between the target signals reaching each of the first microphone 200 and the second
microphone 210 and the noise It is desirable that the phase difference between the signals at the
first and second microphones 200 and 210 be different.
[0030]
In the sound processing apparatus 10, the speaker 300 is a main noise source. Therefore, the
arrangement position of the speaker 300 needs to be determined in relation to the arrangement
position of the first microphone 200 and the second microphone 210. Specifically, the speaker
300 is disposed so that the phase difference between the acoustic signal from the speaker 300
and the target signal is different.
[0031]
Hereinafter, specific positions of the speaker 300 will be described. First, as a premise, the
directivity of the target signal is formed in the direction of Θs from the perpendicular bisector h
of the line segment d connecting the first microphone 200 and the second microphone 210 in
FIG. 3. In this case, the target signal and the noise signal have the same phase difference because
the speaker is disposed on a straight line k passing through the user who emits the target signal
and the middle point c of the line segment d. It is.
[0032]
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8
Strictly speaking, as shown in FIG. 4, an angle Θs1 formed by the straight line m passing through
the first microphone 200 and the user and a straight line n passing through the second
microphone 210 and the user as shown in FIG. The angle Θs2 formed by h is different from each
other, but in the present embodiment, the distance between the first microphone 200 and the
second microphone 210, that is, the distance of the straight line d is the midpoint c of the
straight line d and the user. It is assumed that Θ s 1 Θ s 2 Θ s by assuming that it is sufficiently
small compared to the distance between
[0033]
Therefore, when the speaker serving as the voice source of the noise signal is disposed at a
position on the straight line k, the phase difference between the target signal and the noise signal
matches, and the noise signal is also emphasized.
On the other hand, when it is arranged at a position different from the position on the straight
line k, only the target signal can be emphasized because the phase difference of the target signal
and the phase difference of the noise signal are different.
[0034]
That is, by arranging the speaker 300 at a position other than the position on the straight line k
determined by the directivity of the microphone array shown in FIG. 3 and FIG. It can be
effectively reduced.
[0035]
Furthermore, since the sound signal output from the speaker and input to the microphone can be
reduced, it is possible to solve the problem that the speech of the call partner is returned to the
call partner.
[0036]
FIG. 5 is a view showing an example of the arrangement position of the speaker 300. As shown in
FIG.
04-05-2019
9
The speakers 300a and 300b shown in FIG. 5 are disposed at positions other than the position
on the straight line k.
As described above, by arranging the speaker 300 on a straight line extending from the two
microphones in a specific direction corresponding to the directivity characteristic, it is possible to
reduce the noise signal by the speaker 300 and to amplify only the target signal.
[0037]
On the other hand, the speakers 300c and 300d shown in FIG. 5 are arranged at positions on the
straight line k. As described above, when the speaker 300 is disposed along the direction in
which the directivity characteristic is shown, the noise signal can not be reduced because a phase
difference does not occur between the noise signal and the target signal from the speaker 300,
which is not desirable.
[0038]
The position of the speaker 300 shown in FIG. 1 corresponds to a position different from the
position on the straight line k shown in FIG. Therefore, in the sound processing apparatus 10
according to the present embodiment, the noise signal can be efficiently reduced.
[0039]
In the present embodiment, first, the first microphone 200 and the second microphone 210 are
disposed at a position facing the user. Then, the arrangement position of the speaker 300 is
determined based on the directivity characteristic of the microphone array formed by the first
microphone 200 and the second microphone 210.
[0040]
As another example, the position of the speaker 300 may be determined first. The positions of
the first microphone 200 and the second microphone 210 in this case will be described with
04-05-2019
10
reference to FIG.
[0041]
When the position of the user and the position of the speaker 300 are in the relation as shown in
FIG. 6, when the first microphone 200a and the second microphone 210a are arranged, a
straight line p connecting the speaker 300, the middle point c and the speaker 300 Coincides
with a straight line k connecting the middle point c and the user. That is, the speaker 300 is
disposed at the position on the straight line k. Therefore, since the phase difference between the
noise signal from the speaker 300 and the target signal from the user does not occur, the noise
signal can not be reduced.
[0042]
On the other hand, when the first microphone 200 b and the second microphone 210 b are
arranged, a straight line p ′ connecting the middle point c ′ of the straight line d ′ connecting
the second microphone 210 b and the second microphone 210 b and the speaker 300 is a
middle point It does not match the straight line k 'that connects c' and the user. Therefore, there
is a phase difference between the noise signal from the speaker 300 and the target signal from
the user. Therefore, the noise signal can be reduced by the processing by the signal processing
unit 400.
[0043]
As described above, a straight line connecting the middle point of the straight line connecting the
second microphone 210 b and the second microphone 210 b and the speaker 300 extends in a
specific direction from the first line 200 connecting the middle point and the user. It is desirable
to arrange the first microphone 200 and the second microphone 210 at positions other than the
positions on the straight line.
[0044]
Here, the positions of the plurality of nondirectional microphones serving as the reference of the
straight line extending in the specific direction may be, for example, in the case of two
nondirectional microphones, their midpoint positions.
04-05-2019
11
Or, it may be the position of any one nondirectional microphone. Thus, the position of any one
nondirectional microphone among a plurality of nondirectional microphones may be provided, or
an intermediate position thereof may be provided.
[0045]
Thus, the position of the speaker 300 may be determined, and the positions of the first
microphone 200 and the second microphone 210 may be determined based on the position of
the speaker 300. Thereby, even when the position where the speaker 300 should be arranged is
limited, the noise signal can be efficiently transmitted by determining the positions of the first
microphone 200 and the second microphone 210 according to the position of the speaker 300. It
can be reduced.
[0046]
Second Embodiment An acoustic processing device 10 according to a second embodiment
corresponds to a user tracking array system. The sound processing apparatus 10 according to
the first embodiment forms the directivity characteristic of the microphone array by the delay
and sum array method. That is, by disposing the speaker at a position other than the straight line
determined by the directivity characteristic, the noise signal output from the speaker is reduced.
[0047]
The sound processing apparatus 10 according to the second embodiment determines the
arrangement positions of the first microphone 200, the second microphone 210, and the speaker
300 based on the directivity characteristics of the sound reception signal formed by the user
tracking microphone array. ing. In this point, the sound processing apparatus 10 according to the
present embodiment is different from the sound processing apparatus 10 according to the first
embodiment.
[0048]
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12
In the delay-sum array type microphone array, it is assumed that the user exists only in a specific
direction. Therefore, when the user moves and the direction of the user can not be specified in
one direction, it can not be used.
[0049]
A user tracking array system has been proposed to solve this problem. According to this method,
when the user moves within a certain range, the movement can be tracked to form the
directional characteristic sequentially (Nagata et al., "User tracking two-channel microphone
"Consideration on Array", Journal of the Institute of Electronics, Information and Communication
Engineers, A Vol. J82−A No.6 pp.860−866、1999)。
[0050]
FIG. 7 is a diagram for explaining the directivity characteristic of the sound reception signal
formed by the user tracking type microphone array. Here, Θt represents the range to be tracked.
The speaker 300 is disposed at a position outside this tracking range.
[0051]
An acoustic signal from within the tracking range is tracked by the tracking means and received
by the microphone. Therefore, in order to make the phase difference between the noise signal
and the target signal different, it is necessary to place the speaker 300 outside the tracking
range.
[0052]
FIG. 8 is a view showing an example of the arrangement position of the speaker 300. As shown in
FIG. The speakers 300 a and 300 b shown in FIG. 8 are disposed outside the tracking range 500.
As described above, by arranging the speaker 300 outside the tracking range 500, the phase
difference between the noise signal and the target signal can be made different. Therefore, the
noise signal from the speaker 300 can be reduced, and only the target signal can be amplified.
04-05-2019
13
[0053]
On the other hand, the speakers 300 g and 300 h shown in FIG. 8 are disposed inside the
tracking range 500. As described above, when the speaker 300 is disposed inside the tracking
range 500, the phase difference between the noise signal by the speaker 300 and the phase
difference between the target signal become the same, so the noise signal can not be reduced.
Not desirable.
[0054]
As described above, in the case of the user tracking microphone array, since there is a width at a
position where no phase difference occurs, the sound processing apparatus 10 according to the
first embodiment is arranged by disposing the speaker 300 avoiding this region. Similarly, the
noise signal from the speaker 300 can be reduced and only the target signal can be amplified.
[0055]
As described above, the sound processing apparatus according to the present invention is useful
for acquiring an audio signal from the outside, and is particularly suitable for reducing a noise
signal and emphasizing a target signal.
[0056]
FIG. 2 is an external view of the sound processing apparatus 10;
FIG. 2 is a view showing a user using the sound processing apparatus 10;
FIG. 7 is a block diagram showing a functional configuration of a signal processing unit 400. It is
a figure for demonstrating the positional relationship of the 1st microphone 200 and the 2nd
microphone 210, and the speaker 300. FIG. It is a figure for demonstrating the positional
relationship of the 1st microphone 200 and the 2nd microphone 210, and the speaker 300. FIG.
It is a figure which shows the example of the arrangement position of the speaker 300. FIG. It is a
figure for demonstrating the position of the 1st microphone 200 and the 2nd microphone 210
concerning another example. It is a figure for demonstrating the directional characteristic of the
04-05-2019
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sound reception signal formed of a user tracking type | mold microphone array. It is a figure
which shows the example of the arrangement position of the speaker 300. FIG.
Explanation of sign
[0057]
DESCRIPTION OF SYMBOLS 10 Sound processing apparatus 100 Display surface 120 Display
screen 200, 210 Microphone 300 Speaker 400 Signal processing part 410 Delay device 420
Amplifier
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