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JP2016149612

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DESCRIPTION JP2016149612
PROBLEM TO BE SOLVED: To provide a microphone interval control device capable of rapidly
controlling a microphone interval according to frequency characteristics of noise components.
SOLUTION: This device is premised on a plurality of microphones fixedly installed. Since the
microphone spacing is changed by the combination of two of the plurality of microphones, the
microphone spacing is selected through selecting two capture signals to be output to the device
of the next stage. For this selection, a feature quantity representing the number of times the
inclination direction of the signal waveform changes and the magnitude thereof in a capture
signal of a predetermined microphone is calculated. The feature quantity reflects the degree of
inclusion of the high frequency component, and two capture signals are selected according to the
calculated feature quantity. [Selected figure] Figure 1
Microphone interval control device and program
[0001]
The present invention relates to a microphone spacing control device and program, and can be
applied to, for example, suppressing noise components in an input signal captured by a plurality
of microphones.
[0002]
As a technology for suppressing noise components using a microphone array having a plurality
of microphones, the technology described in Patent Document 1 can be mentioned.
[0003]
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In the technology described in Patent Document 1, it is assumed that signal processing is
performed using a microphone array configured of two microphones whose positional
relationship is fixed.
However, conventionally, the positional relationship of the microphones provided for signal
processing is not necessarily fixed.
For example, as shown in FIG. 9, a microphone array having three or more microphones may be
applied, and two microphones may be selected from among the microphone arrays based on
some criteria to perform signal processing.
[0004]
By the way, while the directivity of the low frequency component becomes sharper as the
distance between the two microphones becomes wider, an error due to the space sampling
theorem occurs in the high frequency component. Conversely, the narrower the microphone
spacing, the wider the directivity of the low frequency component, but the more accurate the
directivity of the high frequency component. As described above, the band in which sharp
directivity is formed changes in accordance with the microphone spacing. Therefore, in the case
of performing background noise suppression processing using a microphone array, appropriate
noise suppression processing can be realized by switching the microphone interval according to
the frequency characteristic of the noise component. For example, when background noise
occurs such that power is concentrated in the low frequency component, a microphone array
with a wide microphone interval is used to sharpen the directivity of the low frequency
component, and By properly reflecting the components, the noise suppression effect is
sufficiently exhibited.
[0005]
As described above, in order to enhance the effect of the microphone array under various noises,
control of the distance between the microphones constituting the microphone array is performed
according to the frequency characteristic of the noise component. Here, as a method of
examining the frequency characteristic of the noise component, conventionally, a method of
03-05-2019
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extracting a frequency component of interest using a filter such as a low pass filter or a high pass
filter has been adopted.
[0006]
JP, 2013-126026, A JP, 2014-106337, A
[0007]
Naofumi Aoki,”A Band Extension Technique for
Narrow−Band Telephony Speech Based on Full Wave
Rectification”, IEICE Trans.
Commun.,Vol. E93−B(3),pp.729−731, 2010
[0008]
However, in the method of grasping the frequency characteristics of noise components using a
conventional filter, (i) filter processing can not follow sudden fluctuations in the noise
characteristics because processing delay is involved, In such a case, there is a problem that realtime property is lost due to an increase in the amount of computation, and cost increases due to
securing of necessary resources (for example, memory).
[0009]
Therefore, a microphone interval control device and program capable of rapidly controlling the
microphone interval according to the frequency characteristic of the noise component are
desired.
[0010]
The microphone spacing control device according to the first aspect of the present invention
comprises: (1) the number of times and the magnitude of the change in the inclination direction
of the signal waveform in the captured signal of the microphone based on at least one captured
signal among the captured signals by the plurality of microphones Feature amount calculating
means for calculating a feature amount reflecting the degree of inclusion of the high frequency
component, and (2) two captured signals to be output to the next stage device according to the
calculated feature amount And microphone spacing optimization means for adjusting the
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microphone spacing between the output microphones.
[0011]
The microphone spacing control program according to a second aspect of the present invention
is a computer that, according to (1) at least one capture signal among capture signals from a
plurality of microphones, changes the inclination direction of the signal waveform in the capture
signal of the microphone Feature amount calculating means for calculating the feature amount
reflecting the degree of inclusion of the high frequency component and representing the size
thereof, and (2) outputting two to the next stage device according to the calculated feature
amount. It is characterized in that it functions as a microphone space optimization means for
adjusting the microphone space between the microphones that output the capture signal.
[0012]
According to the present invention, it is possible to provide a microphone interval control device
and program capable of rapidly controlling the microphone interval according to the frequency
characteristic of the noise component.
[0013]
It is a block diagram which shows the structure of the microphone space | interval control
apparatus of 1st Embodiment.
It is a block diagram which shows the detailed structure of the microphone selection control part
in the microphone space | interval control apparatus of 1st Embodiment.
It is explanatory drawing which shows the structure of the modGI / selection control signal
corresponding | compatible memory | storage part (table) in the microphone selection control
part in the microphone space | interval control apparatus of 1st Embodiment.
It is a block diagram which shows the structure of the microphone space | interval control
apparatus of 2nd Embodiment.
It is explanatory drawing which shows the structure of modGI / selection / delay control signal
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corresponding | compatible memory | storage part (table) in the microphone selection * delay
control part in the microphone space | interval control apparatus of 2nd Embodiment.
It is a block diagram which shows the structure of the microphone space | interval control
apparatus of 3rd Embodiment. It is explanatory drawing which shows the structure of the modGI
/ microphone position corresponding memory | storage part (table) in the microphone
movement control part in the microphone space | interval control apparatus of 3rd Embodiment.
It is a block diagram which shows the structure of the microphone space | interval control
apparatus of 4th Embodiment. It is explanatory drawing of a microphone array.
[0014]
(A) First Embodiment A first embodiment of a microphone spacing control apparatus and
program according to the present invention will be described with reference to the drawings.
[0015]
(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the configuration
of the microphone distance control device 10 of the first embodiment, and a microphone capture
signal output from the microphone distance control device 10 is The microphone array
processing unit 20 to be input is also described.
[0016]
In the configuration of the microphone distance control device 10 shown in FIG. 1, the
components excluding the three microphones m1 to m2 may be constructed by connecting
various hardware-related components, and the CPU It may be constructed to realize the function
by applying an execution configuration of a program such as ROM, RAM and the like.
Regardless of which construction method is applied, the functional detailed configuration of the
microphone interval control device 10 is as shown in FIG.
[0017]
In FIG. 1, the microphone interval control device 10 according to the first embodiment includes
first to third microphones m1 to m3, a modGI calculation unit 11, a microphone selection control
unit 12, and a microphone selection unit 13.
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[0018]
The first to third microphones m1 to m3 capture sound waves such as surrounding sound and
sound and convert the sound waves into electric signals (analog signals).
Each of the microphones m1 to m3 has no directivity or loose directivity in the front direction
described later.
Although not shown in FIG. 1, an analog / digital converter is provided to convert captured
signals (analog signals) from the microphones m1 to m3 into digital signals, and the captured
signal s1 (n) converted into digital signals is provided. It is made to be given to ~ s3 (n). Here,
“n” is a parameter representing time, but the description will be omitted in the following
description.
[0019]
In the case of the first embodiment, the first to third microphones m1 to m3 are arranged in a
straight line in this order, and the microphone spacing D 12 of the first and second microphones
m1 and m2 is the second And the microphone spacing D 23 of the third microphones m 2 and m
3. Naturally, the microphone spacing D 13 of the first and third microphones m1 and m3 is the
microphone spacing D 12 of the first and second microphones m1 and m2, and the microphone
spacing of the second and third microphones m2 and m3. It is wider than D23.
[0020]
Capture signals s1 to s3 from the first to third microphones m1 to m3 are provided to the
microphone selection unit 13. The microphone selection unit 13 has a 3-input 2-output
configuration, and according to the selection control signal cntlmic output from the microphone
selection control unit 12, two capture signals are acquired from the three capture signals s1 to
s3 input thereto. The signals SA and SB are selected and supplied to the microphone array
processing unit 20. The microphone selection unit 13 includes, for example, two two-input oneoutput switches sw1 and sw2. The first switch sw1 selects one of the capture signals s1 and s2,
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and a microphone is selected as one capture signal SA after selection. The second switch sw2
selects one of the capture signals s2 and s3 and supplies it to the microphone array processing
unit 20 as the other capture signal SB after selection.
[0021]
The capture signals SA and SB given to the microphone array processing unit 20 can be
expressed as a combination of the capture signals s1 to s3 before selection: (i) s1 and s2, (ii) s2
and s3, and (iii) s1 and s3. is there. The distance between the two microphones corresponding to
these three combinations is D 12, D 23 and D 13 respectively. Therefore, it can be said that the
microphone selection unit 13 selects the microphone distance.
[0022]
In the case of the first embodiment, the capture signal s1 output from the first microphone m1 is
given to the modGI calculation unit 11. The modGI calculation unit 11 calculates the modGI value
modGI of the capture signal s1 and supplies the obtained modGI value modGI to the microphone
selection control unit 12. For example, the modGI calculation unit 11 calculates the modGI value
modGI for the capture signal s1 according to equation (1).
[0023]
The modGI value will be briefly described (see Patent Document 2 for details). modGI means
modified gradient index (hereinafter referred to as GI). The GI before being corrected is described
in Non-Patent Document 1.
[0024]
GI is an index for measuring the number of times the inclination direction of the signal waveform
changes and its magnitude. GI is obtained by dividing the sum of absolute differences of
successive samples when the direction of inclination changes by the square root of the power of
the frame. Therefore, GI tends to increase as the number of changes in inclination in one frame
increases, and increases as the amount of change when the inclination changes increases. From
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such a property, it can be said that GI is directly connected to the amount of high frequency
components included in the input waveform.
[0025]
However, since GI uses a parameter that takes only a binary value of 0 or 2 that is a variable Δn
(n) and a large number of jumps with time occur frequently, the value becomes irregularly large
or small. It has the characteristic of "dooming".
[0026]
Since modGI has the property that the GI value goes wild (it has a large jump), it has a high
correlation with the GI, but has a high correlation with the GI, and a new feature that the change
with a large jump is stabilized. It has been proposed as a quantity.
modGI is the power of the second-order difference of the calculation target signal normalized by
the “power of the calculation target signal” for an arbitrary signal (the capture signal s1 in the
present application) of the feature amount calculation target (this is a constant Defined as
doubled).
[0027]
Since modGI has a high correlation with GI, it functions as a stable index for measuring the
number of times the signal waveform inclination direction changes and its magnitude, and also
reflects the amount of high frequency components included in the input waveform Function.
[0028]
As described above, since modGI is directly connected to the amount of high frequency
components included in the signal waveform (captured signal s1), the frequency characteristics
of the noise component can be estimated by observation of modGI, and moreover, modGI
Because the operation is simple, there is no increase in cost.
Therefore, modGI is used as an index (parameter) for estimating the frequency characteristic of
the noise component.
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[0029]
The equation (1) is the same equation as equation (13) of Patent Document 2, but the modGI
value is obtained by applying equations (5) and (10) to (12) described in Patent Document 2 It is
also possible to calculate modGI.
[0030]
The microphone selection control unit 12 generates three capture signals s1 to s2 to 2 based on
the modGI value modGI of the capture signal s1 obtained by the modGI calculation unit 11, in
other words, based on the frequency characteristic of the noise component in the capture signal
s1. A selection control signal cntlmic for selecting one capture signal is generated and supplied to
the microphone selection unit 13.
[0031]
FIG. 2 is a block diagram showing the detailed configuration of the microphone selection control
unit 12.
In FIG. 2, the microphone selection control unit 12 includes a modGI acquisition unit 21, a modGI
matching / selection control signal generation unit 22, a modGI / selection control signal
correspondence storage unit 23, and a selection control signal transmission unit 24.
[0032]
The modGI acquisition unit 21 takes in the modGI value modGI obtained by the modGI
calculation unit 11.
The modGI collation / selection control signal generation unit 22 obtains (generates) the
selection control signal cntlmic by extracting corresponding information in the modGI / selection
control signal correspondence storage unit 23 using the captured modGI value modGI as a key. .
The modGI / selection control signal correspondence storage unit 23 stores a plurality of ranges
of modGI values modGI and a selection control signal associated with the ranges. The selection
control signal transmission unit 24 transmits the selection control signal cntlmic obtained by the
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modGI comparison / selection control signal generation unit 22 to the microphone selection unit
13.
[0033]
FIG. 3 is an explanatory view showing a configuration example of the modGI / selection control
signal correspondence storage unit 23, and FIG. 3 shows a case of a table configuration. In the
example of FIG. 3, the range of possible values of the modGI value modGI is divided into three
using two boundary values α and β (β> α).
[0034]
If the modGI value modGI acquired by the modGI acquiring unit 21 falls within the range of the
smallest value, that is, if modGI ≦ α, the capture signals s1 and s3 from the first and third
microphones m1 and m3 are selected The content is "10" of the selection control signal cntlmic.
Since the distance D 13 between the first and third microphones m1 and m3 is the maximum of
three intervals, it is a suitable distance when the frequency characteristic of the noise component
in the capture signal s1 is closer to the lower frequency.
[0035]
When modGI value modGI acquired by the modGI acquiring unit 21 belongs to an intermediate
range, that is, when α <modGI ≦ β, the capture signals s2 and s3 from the second and third
microphones m2 and m3 are selected The content is "01" of the selection control signal cntlmic.
Since the distance D23 between the second and third microphones m2 and m3 is in the middle of
the three intervals, it is preferable if the frequency characteristic of the noise component in the
captured signal s1 is neither low nor high. It is.
[0036]
When the modGI value modGI acquired by the modGI acquiring unit 21 belongs to the largest
range, that is, in the case of β <modGI, selection control for selecting the capture signals s1 and
s2 from the first and second microphones m1 and m2 The content "11" of the signal cntlmic is
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set. Since the interval D 12 of the first and second microphones m 1 and m 2 is the smallest of
the three intervals, it is a suitable interval when the frequency characteristic of the noise
component in the capture signal s 1 is closer to the high frequency.
[0037]
The upper bit of the 2-bit selection control signal cntlmic defines the input terminal that becomes
valid for the first switch sw1 of the microphone selection unit 13. The upper bit “1” is the a
input terminal of the first switch sw1. Is valid, and the upper bit "0" indicates that the b input
terminal of the first switch sw1 is valid. The lower bit of the 2-bit selection control signal cntlmic
defines the input terminal which becomes effective of the second switch sw2 of the microphone
selection unit 13. The lower bit “1” is an input terminal of the second switch sw2. Is valid, and
the lower bit "0" indicates that the b input terminal of the second switch sw2 is valid.
[0038]
The microphone array processing unit 20 performs processing based on a known method as an
input signal from a microphone array composed of two microphones, of the two captured signals
SA and SB inputted. For example, in the case where the microphone array processing unit 20
forms a directivity signal as the output signal out, the microphone array processing unit 20 has
an internal configuration as shown in FIG. Thus, the output signal out (n) is obtained.
[0039]
(A-2) Operation of First Embodiment Next, the operation of the microphone distance control
device 10 according to the first embodiment will be described. Below, it demonstrates in order of
whole operation | movement and the operation | movement in the microphone selection control
part 12. FIG.
[0040]
First to third capture signals s1 to s3 obtained by capturing first and third microphones m1 to
m3 with sound waves such as ambient sound and sound are given to the microphone selection
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unit 13. In addition, the first capture signal S1 is given to the modGI calculation unit 11.
[0041]
The modGI value modGI for the first capture signal s1 is calculated by the modGI calculation unit
11 based on the equation (1), and the obtained modGI value modGI is given to the microphone
selection control unit 12. Then, the microphone selection control unit 12 selects two capture
signals from the three capture signals s1 to s3 based on the calculated modGI value modGI, that
is, based on the frequency characteristics of the noise component in the capture signal s1. The
selection control signal cntlmic to be generated is generated and supplied to the microphone
selection unit 13.
[0042]
Of the three capture signals s1 to s3 from the first to third microphones m1 to m3, two capture
signals SA and SB indicated by the selection control signal cntlmic are selected by the
microphone selection unit 13 and the microphone array processing unit Given to 20.
[0043]
Then, in the microphone array processing unit 20, the two capture signals SA and SB are
processed based on a known method as an input signal from a microphone array composed of
two microphones.
[0044]
Next, the detailed operation of the microphone selection control unit 12 will be described.
[0045]
The modGI value modGI obtained by the modGI calculation unit 11 is taken in by the modGI
acquisition unit 21 and given to the modGI comparison / selection control signal generation unit
22.
The modGI collation / selection control signal generation unit 22 uses the captured modGI value
modGI as a key to execute collation with the modGI / selection control signal correspondence
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storage unit 23 and the range to which the acquired modGI value modGI belongs The selection
control signal cntlmic (see FIG. 3) is extracted from the modGI / selection control signal
correspondence storage unit 23.
Then, the selection control signal cntlmic is transmitted by the selection control signal
transmission unit 24 to the microphone selection unit 13.
[0046]
(A-3) Effects of the First Embodiment As described above, according to the first embodiment,
frequency characteristics of noise components in the capture signal s1 (in other words, capture
signals s1 to s3) according to the modGI value modGI The microphone array can be configured
by selecting two microphones suitable for noise component processing (for example, noise
suppression) based on the estimation result, and a processing unit that processes captured
signals from the microphone array. Processing accuracy can be improved.
Here, since the modGI value modGI is used as a parameter reflecting the frequency characteristic
of the noise component, the processing delay is small and the calculation is easy.
[0047]
By applying the microphone interval control device 10 of the first embodiment to, for example, a
communication terminal (smart phone, mobile phone terminal, etc.), a video conference system,
etc., effects such as improvement of call sound quality can be expected, and By applying the
microphone distance control device 10 according to the embodiment to, for example, a car
navigation system or a voice command input device of a home electric appliance, an effect such
as improvement of speech recognition accuracy can be expected. For example, smartphones are
carried by users under various environments, and the background noise (background noise when
the window is closed) of the car in which the wearer gets in is lower in the low frequency
component compared to outside the vehicle It is Also, the characteristics of background noise in
the vicinity of voice command input devices for car navigation systems are, for example, whether
the traveling speed is fast or slow, whether an air conditioner is used or not, and further windows
of cars (especially front row windows) It changes greatly with various conditions, such as
whether it is open or closed. It is very effective to apply the microphone distance control device
10 of the first embodiment to a device in which the characteristics of such background noise are
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variously changed.
[0048]
(B) Second Embodiment Next, a second embodiment of the microphone spacing control device
and program according to the present invention will be described with reference to the drawings.
[0049]
FIG. 4 is a block diagram showing the configuration of the microphone distance control device
10A of the second embodiment, and the same or corresponding parts as in FIG. 1 according to
the first embodiment described above are given the same or corresponding reference numerals.
Is shown.
[0050]
In FIG. 4, the microphone interval control device 10A of the second embodiment includes the
first to third microphones m1 to m3, the modGI calculation unit 11, the microphone selection /
delay control unit 12A, the microphone selection unit 13, and the application delay selection unit
Have fourteen.
[0051]
In the case of the first embodiment described above, the first to third microphones m1 to m3 are
arranged in a straight line in this order.
In the case of the second embodiment, the three microphones m1 to m3 are not linear but fixedly
arranged at the positions of three vertices of a triangle (for example, a right triangle or an obtuse
triangle) as shown in FIG. There is.
However, the magnitude relationship of the microphone intervals is the same as in the first
embodiment.
That is, the microphone spacing D 12 of the first and second microphones m 1 and m 2 is
narrower than the microphone spacing D 23 of the second and third microphones m 2 and m 3,
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and the microphone spacing of the first and third microphones m 1 and m 3 D 13 is wider than
the microphone spacing D 12 of the first and second microphones m 1 and m 2 and the
microphone spacing D 23 of the second and third microphones m 2 and m 3.
[0052]
Here, the direction (directivity) of the sound wave intended by the designer of the device (for
example, voice command input device) on which the microphone distance control device 10A is
mounted is the first and third microphones m1 and m3. Suppose that it is the orthogonal
direction of the line segment to connect. In this case, since the three microphones m1 to m3 are
fixedly arranged at the positions of the three vertexes of the triangle, selection is made when the
first and third microphones m1 and m3 are selected as the two microphones. There is no time
difference in components from the direction intended by the designer in the later two captured
signals SA and SB, but when the first and second microphones m1 and m2 are selected as the
two microphones, When the second and third microphones m2 and m3 are selected as the two
microphones, the two captured signals SA and SB after selection have components shown from
the direction intended by the designer as shown in FIG. A time difference corresponding to the
distance L of
[0053]
Therefore, in the second embodiment, the provision delay selection unit 14 is provided. The
application delay selection unit 14 cancels the time difference between the capture signals SA
and SB from the two selected microphones according to the selection result of the two
microphones from the three microphones m1 to m3.
[0054]
The provision delay selection unit 14 may be configured as shown in FIG. 4 as an example,
although the detailed configuration is not limited as long as the above-described function can be
exhibited. In the following, it is assumed that the delay amount (time) corresponding to the
distance L is d. The application delay selection unit 14 has a delay unit 14A1 that delays the
capture signal SA by a time d, and a 2-input 1-output switch 14A2 that switches whether to pass
the capture signal SA as it is or to pass the delay signal from the delay unit 14A1. The delay unit
14B1 delays the capture signal SB by time d, and the 2-input 1-output switch 14B2 switches
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whether to pass the capture signal SB as it is or to pass the delay signal from the delay unit
14B1. The two switches 14A1 and 14B1 select the a input terminal when the control bit is "1",
and select the b input terminal when the control bit is "0".
[0055]
When the first and third microphones m1 and m3 are selected as the two microphones, since the
time lag does not occur between the two captured signals SA and SB after the selection, the
provision delay selection unit 14 selects the microphone selection unit The two acquisition
signals SA and SB from 13 may be provided to the microphone array processing unit 20 without
delaying both. Further, when the second and third microphones m2 and m3 are selected as the
two microphones, there is a relationship in which the captured signal SB side is advanced by the
time difference d between the two captured signals SA and SB after the selection. The provision
delay selection unit 14 may delay only the capture signal SB by the time difference d and provide
it to the microphone array processing unit 20. Furthermore, when the first and second
microphones m1 and m2 are selected as the two microphones, there is a relationship in which
the captured signal SA side is advanced by the time difference d between the two captured
signals SA and SB after the selection. The provision delay selection unit 14 may delay only the
capture signal SA by the time difference d and provide it to the microphone array processing unit
20.
[0056]
The microphone selection / delay control unit 12A performs modGI / selection according to the
first embodiment so as to realize the above-described delay control on the capture signal after
microphone selection, in accordance with the selection of (the capture signal of) the microphone.
Instead of the control signal correspondence storage unit 23, a modGI / selection / delay control
signal correspondence storage unit 23A is provided.
[0057]
FIG. 5 is an explanatory view showing a configuration example of the modGI / selection / delay
control signal correspondence storage unit 23A, which corresponds to FIG. 3 of the first
embodiment described above.
[0058]
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The modGI / selection / delay control signal correspondence storage unit 23A also receives
(captured signals from) two microphones m1 to m3 (captured signals from three microphones
m1 to m3 according to the range to which the modGI value modGI acquired by the modGI
obtaining unit 21 belongs. The selection control signal cntlmic can be obtained.
In addition to this, the modGI / selection / delay control signal correspondence storage unit 23A
selects according to the range to which the modGI value modGI acquired by the modGI
acquisition unit 21 belongs, in other words, according to the combination of the two selected
microphones. A delay control signal cntld1 for eliminating the time difference between the
subsequent acquisition signals SA and SB can be obtained.
The delay control signal cntldl controls the assignment delay selection unit 14 as described
above.
[0059]
According to the second embodiment, the same effect as that of the first embodiment can be
obtained. In addition to this, according to the second embodiment, even if there is a shift in the
sound wave capture timing from the predetermined direction among the plurality of
microphones, the shift is eliminated and the microphone array processing of the selected capture
signal is performed. Can be given to the department.
[0060]
As in FIG. 1 according to the first embodiment, even when a plurality of microphones are
disposed on one straight line, if the predetermined direction is not orthogonal to the straight line,
as in the second embodiment, It is necessary to provide a means for eliminating such a capture
timing deviation.
[0061]
(C) Third Embodiment Next, a third embodiment of the microphone spacing control device and
program according to the present invention will be described with reference to the drawings.
[0062]
FIG. 6 is a block diagram showing the configuration of the microphone distance control device
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10B according to the third embodiment, and the same or corresponding parts as in FIG. 1
according to the first embodiment described above are given the same or corresponding
reference numerals. Is shown.
[0063]
In FIG. 6, a microphone distance control device 10B according to the third embodiment includes
two microphones mf, mm, a modGI calculation unit 11, a microphone movement control unit
12B, and a microphone movement mechanism 15.
[0064]
Of the two microphones mf and mm, one microphone mf is fixedly provided, and the other
microphone mm is provided movable by the microphone movement control unit 12B.
The moving direction of the microphone mm is a direction approaching or away from the fixedly
installed microphone mf.
That is, in the case of this third embodiment, although the number of microphones is two, the
distance between the two microphones mf and mm can be changed.
[0065]
The microphone moving mechanism 15 is a mechanism for moving the movable microphone
mm, and the detailed configuration thereof is not limited.
One example is as follows.
The microphone moving mechanism 15 includes a stepping motor as a drive source, and a pinion
is attached to a rotating shaft of the stepping motor. The rack engaged with the pinion is linearly
movable by a guide, and a movable microphone mm is fixedly attached to a part of the rack such
as the side surface or the back surface.
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[0066]
The modGI calculation unit 11 calculates the modGI value modGI of the capture signal s1 output
from the microphone mf, and supplies the obtained modGI value modGI to the microphone
movement control unit 12B.
[0067]
The microphone movement control unit 12B optimizes the distance between the two
microphones mf and mm based on the calculated modGI value modGI, in other words, based on
the frequency characteristic of the noise component in the capture signal s1. The movement
amount is determined, and a movement control signal cntlmv is supplied to the microphone
movement mechanism 15.
[0068]
The internal configuration of the microphone movement control unit 12B is not limited as long
as the above-described function can be exhibited.
An example is as follows.
The microphone movement control unit 12B stores (information of) the current position 12B1 of
the microphone mm. Further, the microphone movement control unit 12B associates the range to
which the modGI value modGI belongs with the position of the microphone mm suitable for the
range, and the modGI / microphone position correspondence storage unit (table) as shown in FIG.
7 Has built-in 23B. The microphone movement control unit 12B extracts the position of the
microphone mm suitable for the calculated modGI value modGI from the modGI / microphone
position correspondence storage unit (table) 23B, and the difference between the extracted
position and the current position 12B1 of the microphone mm. The movement control signal
cntlmv for moving the microphone mm to the position taken out from the position 12 B 1 of the
current microphone mm is generated and supplied to the microphone movement mechanism 15.
[0069]
Also according to the third embodiment, modGI reflecting the frequency characteristics of the
noise component in the captured signal is calculated, and the distance between the two
microphones is controlled accordingly. Therefore, the third embodiment is the same as the first
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embodiment. It can produce an effect.
[0070]
(D) Fourth Embodiment Next, a fourth embodiment of the microphone spacing control device and
program according to the present invention will be described with reference to the drawings.
[0071]
FIG. 8 is a block diagram showing the configuration of the microphone distance control device
10C of the fourth embodiment, and the same or corresponding parts as in FIG. 1 according to the
first embodiment described above are given the same or corresponding reference numerals. Is
shown.
[0072]
In FIG. 8, a microphone interval control device 10C according to the fourth embodiment includes
a voice section detection unit in addition to the first to third microphones m1 to m3, the modGI
calculation unit 11C, the microphone selection control unit 12 and the microphone selection unit
13. It has sixteen.
[0073]
The voice section detection unit 16 detects whether or not the first capture signal s1 is a voice
section by a known voice detection technology, and provides the detection result V to the modGI
calculation unit 11C.
[0074]
The modGI calculation unit 11C of the fourth embodiment calculates the modGI value modGI for
the capture signal s1 when the detection result V represents a non-speech segment, and
immediately before the detection result V represents a speech segment. The modGI value modGI
is maintained, and the modGI value modGI updated only in the non-voice section as described
above is given to the microphone selection control unit 12.
[0075]
Therefore, in the fourth embodiment, the review of the microphone interval is performed only in
the non-voice section (in other words, the noise section).
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[0076]
According to the fourth embodiment, since the selection of the microphone is controlled by
updating the modGI value only in the non-voice section, higher effects can be expected compared
to the first embodiment.
[0077]
(E) Other Embodiments In each of the above embodiments, the case where modGI is applied is
shown, but the GI before correction (refer to equation (4) in Patent Document 2) also changes the
inclination direction of the signal waveform. Since this is an index for measuring the size, GI may
be applied instead of modGI in each of the above embodiments.
[0078]
In the above embodiments, it has been described that the microphone interval is constantly
reviewed. However, the frequency characteristic of the background noise is often steady, and the
apparatus is configured to perform the microphone interval temporarily or intermittently. You
may configure.
For example, when the power of the communication terminal is turned on, the review of the
microphone interval may be activated only at the start of use of the device, and thereafter, may
be stopped.
[0079]
In the first, second, and fourth embodiments for selecting the microphones, the number of
microphones is three, but the number of microphones is of course not limited to three.
[0080]
In each of the above-mentioned embodiments, although what showed the modGI value given to
various control parts from one capture signal s1 was shown, the acquisition method of the modGI
value given to various control parts is not limited to this.
For example, modGI values may be calculated for each of three types of captured signals s1, s2,
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and s3, and an average value or median value of the obtained three modGI values may be used as
a modGI value to be given to the control unit.
[0081]
In the third embodiment, only one microphone can be moved, but both microphones may be
moved together.
[0082]
In the above, an alternative embodiment in which the selection of the microphone and the
movement of the microphone have been described has been described, but an embodiment may
be configured in which the selection of the microphone and the movement of the microphone are
combined.
The point is that the distance between the microphones from which the two captured signals
input to the microphone array are obtained can be controlled to the modGI value.
[0083]
In each of the above embodiments, the control signal is switched as soon as the modGI value
belongs to a new range. However, the control signal may be switched only when the modGI value
continues to belong to a new range a predetermined number of times. .
[0084]
Some microphone array processing units have a delay unit inside (see FIG. 4 of Patent Document
1).
The delay unit in the microphone array processing unit may be diverted as the delay unit in the
application delay selection unit 14 in the second embodiment.
[0085]
Although the audio signal has been described as the target sound in the above, the technical
03-05-2019
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concept of the present invention can be applied even when the acoustic signal such as a
mechanical sound is the target sound.
[0086]
In each of the above embodiments, an apparatus and program for immediately processing a
capture signal from the microphone array are shown, but the present invention is also applied to
the case where the capture signal from the microphone array is recorded on a recording medium
and reproduced. be able to.
[0087]
m1 to m3, mf, mm, ... microphones, 10, 10A, 10B, 10C, ... microphone spacing control devices,
11, 11C, ... modGI calculation units, 12 ... microphone selection control units, 12A ... microphone
selection / delay control units, 12B ... Microphone movement control unit, 13: microphone
selection unit, 14: application delay selection unit, 15: microphone movement mechanism, 16:
voice section detection unit, 21: modGI acquisition unit, 22: modGI check and selection control
signal generation unit, 23: modGI / selection control signal correspondence storage unit, 23A ...
modGI / selection / delay control signal correspondence storage unit, 24 ... selection control
signal transmission unit.
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