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DESCRIPTION JP2007005969

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DESCRIPTION JP2007005969
An object of the present invention is to reduce the computational load on a microphone array
device in order to achieve directivity for an arbitrary sound source position. Further, the present
invention provides a microphone array device having directivity for any plurality of sound
sources without performing complicated signal processing. A plurality of microphones 11-1 to
11-n are disposed in rotational symmetry. Thereby, uniform directional characteristics can be
obtained in any direction. Moreover, it becomes possible to provide multiple directivity
simultaneously. Furthermore, it becomes possible to perform signal processing on audio signals
from the microphones 11-1 to 11-n by the same algorithm. Therefore, estimation of the sound
source position and control of directivity can be performed by the same algorithm for any sound
source position. Further, since the signal processing for each sound reception signal can be
performed by the same algorithm, it is possible to reduce the calculation load. [Selected figure]
Figure 2
Microphone array device
[0001]
The present invention relates to a microphone array device having a plurality of microphones,
and more particularly to a microphone device having directivity characteristics at a sound source
position.
[0002]
The microphone array device comprises a plurality of microphones, and performs delay addition
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processing on audio signals received by the microphones to realize arbitrary directivity or
estimate the position of a sound source. It is possible.
In the conventional microphone array device, the microphones are disposed one-dimensionally or
at equal intervals in the x, y and z directions (see, for example, Patent Document 1). By disposing
the microphone in this manner, the directivity is realized by specifying the sound source position
from the phase difference of the sound signal from the microphone and the like and determining
the delay amount.
[0003]
JP 2000-134688 A
[0004]
However, the conventional microphone array device has the following problems.
First, when microphones are arranged one-dimensionally, it is possible to realize directivity and
estimate the position of a sound source only in a plane.
[0005]
In addition, when microphones are arrayed at equal intervals in the x, y and z directions,
calculation values for realizing three-dimensional directivity and estimating the voice position
become large because the values calculated for each direction are synthesized. . In addition, it has
been difficult to emphasize the audio signal by the delay addition process depending on the
position of the sound source, and it is difficult to estimate the position of the sound source.
[0006]
Therefore, the present invention has been made to solve the problems as described above, and it
is an object of the present invention to reduce the calculation load in the microphone array
device in realizing directivity for any sound source position.
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[0007]
Another object of the present invention is to provide a microphone array device capable of
achieving directivity for any of a plurality of sound sources without performing complicated
signal processing.
[0008]
In order to solve the problems as described above, the microphone array device according to the
present invention is characterized by comprising a plurality of microphones arranged in
rotational symmetry and a delay addition means for adding a delay to the output signal of each
microphone. I assume.
[0009]
In the above microphone array device, a plurality of delay addition means may be provided, and
the delay addition means may add different delay amounts to output signals of the plurality of
microphones.
[0010]
Further, in the above microphone array device, sampling means for sampling output signals of a
plurality of microphones at a predetermined sampling interval, storage means for holding a
plurality of sampled output signals for a predetermined time, delaying and adding means from
each microphone The apparatus may further comprise delay amount control means for changing
the delay amount to be added to the output signal.
[0011]
According to the present invention, by disposing the microphones in rotational symmetry, it is
possible to share a common signal processing algorithm, which makes it possible to reduce the
computational load.
Also, by disposing the microphones in rotational symmetry, for example, on a spherical surface, a
hemispherical surface, a cylindrical side surface, a conical surface, or on a circumference, it is
possible to realize any directivity.
[0012]
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Further, according to the present invention, by providing a plurality of delay addition means, it is
possible to give an arbitrary plurality of directivity with the same algorithm.
[0013]
Furthermore, according to the present invention, by changing the delay amount to be added to
the output signal from each microphone in the delay and addition means, it becomes possible to
give arbitrary plural directivity with the same algorithm.
[0014]
First Embodiment Hereinafter, a first embodiment of the present invention will be described in
detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the microphone array device according to
the present embodiment.
The microphone array apparatus 1 according to the present embodiment includes a plurality of
microphones 11 (11-1 to 11-n) and a delay addition unit 12 that performs delay addition
processing on the sound reception signals received by the microphones 11. Configured
[0015]
The microphones 11-1 to 11-n are configured by known microphones such as omnidirectional
microphones.
These microphones 11-1 to 11-n are disposed in rotational symmetry.
For example, as shown in FIG. 2, a plurality of microphones 11 (11-1 to 11-n) may be disposed at
predetermined intervals on the surface of the base 13 having a spherical shape.
The base 13 can be acoustically transparent by using a wire frame or the like.
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[0016]
The delay addition units 12 correspond to the microphones 11-1 to 11-n, respectively, and add
delay amounts to the sound reception signals from the microphones 11a to 11n. The delay
circuit 121-1 to 121-n comprises an addition circuit 122 for adding the audio signal to which the
delay amount is added, and performs delay addition processing on the sound reception signal
from the microphones 11-1 to 11-n .
By this delay addition processing, the time difference of the sound reception signal arriving from
a specific position or direction is corrected to be in phase, and by adding the in-phased sound
reception signal, only the voice signal coming from that position or direction is It becomes
possible to emphasize. The method of estimating the position of the sound source from the sound
reception signal and the method of setting the delay amount will be described later.
[0017]
In such a microphone array device 1, when the sound reception signal received by each of the
microphones 11-1 to 11-n is input to the delay addition unit 12, delay addition processing is
performed on the input sound reception signal. An audio signal in which a sound coming from
any direction according to the delay time given by each of the delay circuits 121-1 to 121-n is
emphasized is output from the output terminal.
[0018]
In the present embodiment, as described above, the plurality of microphones 11-1 to 11-n are
disposed on the spherical surface.
Thus, by appropriately setting the delay times given by the delay circuits 121-1 to 121-n, it is
possible to obtain directivity characteristics uniformly in any direction. Further, the delay
addition unit 12 can perform signal processing on the sound reception signal from each of the
microphones 11 (11-1 to 11-n) by the same algorithm.
[0019]
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Therefore, in the present embodiment, estimation of the sound source position and control of
directivity can be performed with the same algorithm for any sound source position. Further,
since the signal processing for each sound reception signal can be performed by the same
algorithm, it is possible to reduce the calculation load.
[0020]
The above-described microphone array device 1 can realize a plurality of directivities having no
unevenness in any direction and has a small calculation load, and thus can be applied to, for
example, a sensor or the like.
[0021]
In addition, when the microphones are disposed in a spherical shape as in the present
embodiment, for example, by setting the microphone device 1 to a ceiling, sound source
detection in the direction of 360 degrees becomes possible.
As described above, in the present embodiment, since 360-degree sound source detection is
possible, the unnecessary sound is distinguished by FFT analysis of the sound desired to be
acquired and the unnecessary sound by the time direction sound pressure change and the like.
The pointing direction can be controlled in the direction. By directing the pointing direction to
the sound source position in this manner, it is possible to pick up a sound aimed at with a good S
/ N ratio without picking up unnecessary sounds such as noise of an air conditioner.
[0022]
Further, in the present embodiment, a band pass filter may be provided to transmit only a signal
of a predetermined frequency band with respect to the output of the delay addition unit 12. This
makes it possible to identify a sound source having a specific frequency component.
[0023]
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The shape of the base on which the microphones 11 are disposed is not limited to the abovedescribed spherical shape as long as the plurality of microphones 11 (11-1 to 11-n) are disposed
in rotational symmetry, and may be set freely as appropriate. Can. For example, as shown in FIG.
3, a plurality of microphones 11 (11-1 to 11-n) may be disposed at predetermined intervals on
the side surface of the base 14 having a cylindrical shape. Besides, it may be disposed on a
hemispherical surface, a conical surface, a cylindrical surface, or on a circumference.
[0024]
Next, a method of estimating the sound source position will be described with reference to FIG.
First, the delay addition unit 12 detects input signal levels of all the microphones 11 (11-1 to 11n), and obtains a two-dimensional sound pressure distribution on the surface of the base on
which the microphones are installed. Specifically, among the detected input signal levels, the
maximum sound pressure and a sound pressure distribution lower by a predetermined ratio from
the maximum sound pressure are determined. Next, the center in this low sound pressure
distribution is determined, and this center position is estimated as the maximum sound pressure
position. When the maximum sound pressure position is estimated, the delay addition unit 12
determines the direction of the maximum sound pressure position from the center of the rotation
axis of the base on which the microphones are disposed in rotational symmetry as the direction
of the sound source.
[0025]
In the case of a spherical microphone array, since the contours of the sound pressure distribution
are generally concentric, it is easy to find the center of the sound pressure distribution. Even
when the contour is not concentric, it is possible to obtain the maximum sound pressure position.
[0026]
When the direction of the sound source is determined, as shown in FIG. 4, the microphone M1
closest to the direction of the sound source is detected, the straight line connecting the
microphone M1 and the sound source is extended to the center O of the rotation axis, and on the
straight line OM1. Identify the microphone M2 on a vertical line.
[0027]
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Next, the phase difference is determined from the input signal of each of the microphones M1
and M2.
The arrival time difference may be determined by directly correlating the two input signals from
the microphones M1 and M2.
[0028]
Next, the calculated phase difference or time difference is converted into a distance based on the
speed of sound. Assuming that this value is d, the radius of the base on which the microphones
M1 and M2 are disposed in rotational symmetry is r, and the distance between the microphone
M1 and the sound source is l, the distance between the microphone M2 and the sound source is l
+ d. The positional relationship of can be represented in FIG. As shown in FIG. 4, since the sound
source, the microphone M2 and the center O constitute a right triangle, the following equation
(1) holds.
[0029]
(l+d)<2>=(l+r)<2>+r<2>・・・(1)
[0030]
From the above equation (1), the following equation (2) is obtained.
[0031]
l=(2r<2>−d<2>)/{2(d−r)} ・・・(2)
[0032]
Therefore, by obtaining the distance difference d between the two microphones M1 and M2 and
the sound source, it is possible to obtain the distance 1 between the microphone M1 and the
sound source from the above equation (2).
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Thereby, the direction and position of the sound source can be estimated from the sound
reception signal of the microphone.
[0033]
Next, a method of setting the delay amount to be added to the sound reception signal from each
microphone will be described with reference to FIG.
First, assuming that an angle formed by the microphone M1 closest to the sound source, the
center O of the rotation axis of the base where the microphones are arranged rotationally
symmetrically, and an arbitrary microphone Mn other than M1, the microphone Mn and the
sound source The distance x can be obtained from the following equation (3).
[0034]
x = {r <2> + (l + r) <2> −2r (l + r) cos φ} <1/2> (3)
[0035]
The spread addition unit 12 sets the delay amount so that the output signals of all the
microphones have the same phase, based on the distances between the microphones and the
sound source thus obtained.
At this time, the delay amount to be set to the output signal of the microphone M1 closest to the
sound source is maximum.
[0036]
Further, in the above equation (3), r and φ are determined by the configuration of the base in
which the microphones are arranged in rotational symmetry, so if l is determined from the above
equation (2), The distance can be determined.
[0037]
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Second Embodiment Next, a second embodiment of the present invention will be described.
FIG. 6 is a block diagram showing the configuration of the microphone array device according to
the present embodiment.
In the present embodiment, the same components as those in the first embodiment described
above are denoted by the same names and reference numerals, and the description will be
appropriately omitted.
[0038]
The microphone array device 2 according to the present embodiment has a plurality of
microphones 11-1 to 11-n disposed on a rotationally symmetric, for example, spherical base, and
a delay and addition process on the sound reception signals of these microphones 11 And a
directivity parameter control unit 21 for inputting directivity parameters to the delay addition
units 12a to 12m. Here, the directivity parameter refers to the microphones 11-1 in the delay
circuits 121 a-1 to 121 a-n, 121 b-1 to 121 b-n, ..., 121 m-1 to 121 m-n of the delay addition
units 12 a to 12 m. It is a delay amount to be added to each of the sound reception signals from
1 to 11-n.
[0039]
The directivity parameter control unit 21 is a functional unit that sets directivity parameters for
each delay addition unit 12. As for these directivity parameters, the delay amount is set so as to
reinforce the phase signal from an arbitrary direction for each of the delay and addition units
12a to 12m. The directivity parameter may be set in advance, or may be set in accordance with
the user's operation input.
[0040]
The plurality of delay addition units 12a to 12m delay the delay amount of the sound reception
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signal from each of the microphones 11-1 to 11-n based on the directivity parameter input from
the directivity parameter control unit 21. 121a-1 to 121a-n, 121b-1 to 121b-n,..., 121m-1 to
121m-n, and a delay addition is performed by the addition circuit 122 to add the sound
reception signal to which the delay amount is added. Do the processing. As a result, from the
delay adders 12a to 12m, audio signals from positions or directions according to the directivity
parameters are emphasized and output.
[0041]
Next, the operation of the microphone array device 2 will be described. First, the directivity
parameter control unit 21 sets directivity parameters to be input to the delay addition units 12a
to 12m.
[0042]
When sound reception signals received by the microphones 11-1 to 11-n are input to the delay
addition units 12a to 12m, the directivitys set to the delay addition units 12a to 12m with
respect to the sound reception signals A delay addition process is performed based on the sex
parameter. Here, in the sound reception signal input to the delay addition units 12a to 12m, the
delay amount specified by the directivity parameter set to each of the delay addition units 12a to
12m is one of the delay circuits 121a to 121a-n, 121b-1 to 121b-n, ..., 121m-1 to 121m-n. The
sound receiving signals to which these delay amounts are respectively added are added by the
adding circuits 122a to 122m, the voice signal arriving from the position or direction
corresponding to the directivity parameter is emphasized, and is output from the output terminal.
[0043]
As described above, since different directivity parameters are set for each of the delay addition
units 12a to 12m, the audio signal output from the output terminal has a plurality of directivity
characteristics. This directional characteristic can be provided up to the number of delay adders
12a to 12m at the maximum. As described above, according to the present embodiment, the
directivity parameter is set for each of the delay addition units 12a to 12m, and different delay
amounts are simply set to the sound reception signals from the microphones 11. It is possible to
have multiple directivity of
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[0044]
Since the microphone array device 2 described above can have a plurality of directional
characteristics, it can be applied to, for example, a sensor or the like.
[0045]
In the microphone array device 2 described above, when the position of the sound source to be
removed is known, the delay amount may be selected so as not to direct the directivity
characteristic in that direction.
For example, it is possible to prevent howling by not directing the directional characteristic in the
direction of the speaker.
[0046]
Third Embodiment Next, a third embodiment of the present invention will be described. FIG. 7 is
a block diagram showing the configuration of the microphone array device according to the
present embodiment. In the present embodiment, the same components as those in the first and
second embodiments described above are denoted by the same names and reference numerals,
and the description will be appropriately omitted.
[0047]
The microphone array device 3 according to the present embodiment has a plurality of
microphones 11-1 to 11-n disposed on a rotationally symmetric, for example, spherical base, and
sound reception signals of these microphones 11-1 to 11-n. Is sampled for a fixed period
(hereinafter referred to as “sampling period”. And the delay addition unit 12 performing delay
addition processing on the reception signal stored in the storage unit 31, and the directivity
parameter is input to the delay addition unit 12 The directivity parameter control unit 21, a
switch 32 for switching and outputting the output from the delay addition unit 12, a plurality of
output buffers 33-1 to 33-m for storing the output from the switch 32, directivity parameter
control The timing control unit 34 synchronizes the unit 21 with the switch 32. Such a
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microphone array device 3 realizes a plurality of directivity characteristics by performing a
plurality of delay addition processes while changing directivity with respect to a sound reception
signal of one sampling period.
[0048]
The storage unit 31 can store successive audio signals one by one every one sampling period by
providing at least two sets of memories corresponding to the microphones 11-1 to 11-n.
[0049]
The directivity parameter control unit 21 stores a plurality of directivity parameters set in
advance, and switches to one cycle within one sampling period based on a synchronization signal
from the timing control unit 34 described later, and sequentially switches them. It is sent to the
delay addition unit 12.
[0050]
The delay addition unit 12 performs delay addition processing on the sound reception signal of
the predetermined sampling period stored in the storage unit 31 based on the directivity
parameter input from the directivity parameter control unit 21.
In the present embodiment, with respect to a plurality of directivity parameters set in advance,
the directivity parameter control unit 21 performs delay addition processing each time the
directivity parameter is switched within one sampling period.
[0051]
The switch 32 is switched based on a synchronization signal of a timing control unit 34
described later.
Thereby, the audio signal output from the delay addition unit 12 is sent out to any one of the
output buffers 33-1 to 33-m in synchronization with the timing at which the directivity
parameter switches.
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[0052]
The output buffers 33-1 to 33-m are provided corresponding to the quantity of directivity
parameters that can be set in the directivity parameter control unit 21, and the sound reception
signal input by the delay addition unit 12 via the switch 32 is output. Hold and output for one
sampling period.
[0053]
The timing control unit 34 generates a synchronization signal for synchronizing and switching
the plurality of directivity parameters of the directivity parameter control unit 21 and the switch
32 within one sampling period, and inputs the synchronization signal to the directivity parameter
control unit 21 and the switch 32. .
[0054]
Next, the operation of the microphone array device 3 will be described.
First, a plurality of directivity parameters are set in advance in the directivity parameter control
unit 21 by operation input by a user or the like, and stored in a memory (not shown).
The directivity parameter can be freely set as appropriate, for example, the directivity
characteristic desired by the user.
[0055]
Next, a sound receiving operation is performed by each of the microphones 11-1 to 11-n, and a
sound receiving signal for one sampling period is sequentially stored in the storage unit 31.
When the sound reception signals of the microphones 11-1 to 11-n are stored in the storage unit
31, the delay addition processing is performed by the delay addition unit 12 based on a plurality
of directivity parameters. That is, the plurality of directivity parameters stored in the directivity
parameter control unit 21 are switched to one delay period within one sampling period
according to the synchronization signal from the timing control unit 34 and sequentially input to
the delay addition unit 12. The above-mentioned delay addition processing is repeated each time
the directivity parameters stored in the directivity parameter control unit 21 are switched. As a
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result, the delay addition unit 12 outputs a plurality of audio signals having different directivity
characteristics from the sound reception signal for one sampling period stored in the storage unit
31.
[0056]
The audio signal output from the delay addition unit 12 is selectively output to any one of the
output buffers 33-1 to 33-m by the switch 32. The switch 32 switches the output destination of
the audio signal from the delay addition unit 12 in synchronization with the timing at which the
directivity parameter of the directivity parameter control unit 21 is switched by the
synchronization signal of the timing control unit 34. Therefore, each output buffer 33-1 to 33-m
stores an audio signal having the same directional characteristic, and one sampling period until
the delay addition processing result for the sound reception signal for the next sampling period is
overwritten. Hold that value.
[0057]
As described above, in this embodiment, a plurality of directivity parameters are set, and these
directivity parameters are sequentially switched within one sampling period. As a result, a
plurality of delay addition processes are performed on the sound reception signals for one
sampling period from each of the microphones 11-1 to 11-n, and as a result, the same algorithm
has arbitrary plural directivity. It is possible to
[0058]
It is a block diagram showing composition of a microphone array device concerning a 1st
embodiment of the present invention. It is a figure for demonstrating an example of arrangement
| positioning of a microphone. It is a figure for demonstrating the other example of arrangement
| positioning of a microphone. It is a figure for demonstrating the estimation method of the
direction and position of a sound source. It is a figure for demonstrating the setting method of
delay amount. It is a block diagram showing composition of a microphone array device
concerning a 2nd embodiment of the present invention. It is a block diagram showing
composition of a microphone array device concerning a 3rd embodiment of the present
invention.
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Explanation of sign
[0059]
1, 2, 3 ... microphone array devices 11, 11 11-1 to 11-n ... microphones 12, 12a to 12m ... delay
addition units 121-1 to 121-n, 121a-1 to 121a-n, 121b- 1 to 121b-n, 121m-1 to 121m-n ... delay
circuit, 122, 122a to 122m ... addition circuit, 13, 14 ... base, 21 ... directivity parameter control
unit, 31 ... storage unit, 32 ... switch, 33 -1 to 33-m: output buffer, 34: timing control unit.
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