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DESCRIPTION JP2006304209
PROBLEM TO BE SOLVED: To obtain a narrow angle directional array microphone device with a
narrow directional beam width and to enable directivity control in a three-dimensional space.
SOLUTION: An array microphone apparatus whose pointing main axis is variable in a plane space
is set as an array microphone unit (AMU), and the AMU pointing main axis variable planes are
arranged in the same plane or three-dimensional plane so as to be parallel. And obtain a main
axis variable method of the array microphone. [Selected figure] Figure 1
Array microphone device and method of changing spindle of array microphone device
[0001]
The present invention is for voice recording and voice recognition that can easily change the
direction of directivity in an environment such as a living room of a home or a meeting room of
an office in which the position of the speaker as the target sound source constantly changes. The
present invention relates to an array microphone device and a method of changing the main axis
of the array microphone device, and more particularly, to a variable-direction main axis array
microphone device capable of achieving further narrowing in two-dimensional space and wideband narrow angle directivity in three-dimensional space. And a method of changing the main
axis of the array microphone device.
[0002]
Conventionally, various proposals have been made for wide-band narrow-angle directional array
microphone devices (hereinafter referred to as AMICs).
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The applicant of the present invention has previously proposed in Patent Document 1 the abovementioned AMIC with a pointing main axis variable. The above-mentioned patent document 1
describes in detail the method of changing the main axis of AMIC and AMIC with a band
frequency of 300 Hz to 5 KHz and a beam width of about 120 degrees by arranging the
microphone capsule on a two-dimensional plane.
[0003]
The AMIC described in Patent Document 1 mentioned above is a non-directional seven
microphone capsule {hereinafter referred to as microphone capsule M (M0 to M6)} as a secondorder plane element (XY plane) as shown in FIG. A capsule M0, a first pair of microphone
capsules M2 and M4 including a microphone capsule M2 and M4 disposed at the center of the
reference microphone capsule M0, and a reference microphone capsule M0 and disposed
orthogonal to the microphone capsules M2 and M4 And a second pair of microphone capsules
M1 and M3 and microphone capsules M5 and M6 arranged at 45 degrees with respect to the
microphone capsules M2 and M4 and the microphone capsules M1 and M3 with the reference
microphone capsule M0 as a center. And a third pair of The reference microphone capsule M0,
the first, second, and third pairs of microphone capsules M2, M4, M1, M3, M5, and M6 are
disposed on the same plane of XY, and these microphone capsules are provided. The main axis of
the directional characteristics can be variably controlled based on M0 · M2, M4 · M1, M3 · M5,
and M6.
[0004]
FIG. 31 is a hardware configuration diagram of an AMIC using the above-described microphone
capsules M0 · M2, M4 · M1, M3 · M5, and M6.
As shown in FIG. 31, A / D converts signals amplified by the amplifiers 8 to 14 into digital signals
so as to amplify the signals from the microphone capsules M0 and M2, M4 and M1, M3 and M5,
and M6. An arithmetic processing unit 22 that performs signal processing on digital signals
converted by the converters 15 to 21 and a recording device or speech recognition unit 23 that
performs recording processing or speech recognition processing on the result of the signal
processing performed by the arithmetic processing unit 22. And consists of.
[0005]
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The A / D converted and sampled digital signal described above is buffered (framing) in a frame
buffer in the processing unit 22. Thereafter, the outputs of the microphone capsules M0, M1 to
M6 are mixed.
[0006]
Next, when all the signals stored in the frame buffer described above are all filled in this frame
buffer, a Hamming window or a Hanning window to reduce the influence of continuous voice
framing as frame processing preprocessing. Window processing is performed.
[0007]
Thereafter, fast Fourier transform (FFT) is used to perform each array microphone signal
processing such as phase conversion and correction of amplitude characteristics.
[0008]
An output process is performed after each of the above processes.
Specifically, since the output processing is frequency analyzed, it can be used for speech analysis
for speech recognition by the speech recognition device 23.
Furthermore, the output may be converted from a signal in the frequency domain to a waveform
signal in the time domain by inverse Fourier transform, and may be used for voice recording or
the like in the recording device 23.
[0009]
Not only the above-mentioned Patent Document 1 but also the conventional AMIC technology
mainly controls the directivity on a two-dimensional plane in which the microphone capsule M is
disposed, and one that can control the directivity in a three-dimensional space is Detailed
investigation has not been made yet because of the problem of the physical structure of the
system. Japanese Patent Application Laid-Open No. 2002-271885
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[0010]
A first problem to be solved by the present invention is to obtain an AMIC in which planar
directivity in a two-dimensional space is further narrowed than the directivity characteristic
disclosed in the above-mentioned Patent Document 1, and the above-mentioned Patent
Document The beam width generated in the two-dimensional AMIC disclosed in 1 is about 120
degrees, and as a social requirement, an AMIC having directivity with a narrow beam width is
desired. A second object of the present invention is to expand directivity from two dimensions to
three dimensions, and a third object of the present invention is an array microphone capable of
directivity control in a two-dimensional plane, which is the vertical direction of the array
microphone In the (three-dimensional direction), the problem that directivity can not be ensured
is made to have variations in the direction of a plurality of array microphones, and by selecting
an array microphone that can ensure one directivity from among them, in a three-dimensional
plane It is an object of the present invention to provide an AMIC and an AMIC main axis variable
method capable of directivity control within a three-dimensional space by controlling the
directivity of
[0011]
The first variable-oriented AMIC according to the present invention has an array microphone unit
whose arrayed main axes are variable in a plane space as an array microphone unit, and variableoriented main planes of a plurality of array microphone units are in the same plane. It arranges,
and makes directivity of a single array microphone unit sharper.
[0012]
The variable-orientation main axis AMIC according to the second aspect of the present invention
has an array microphone unit in which the main axis of orientation is variable in a plane space as
an array microphone unit, and the plurality of array microphone units are parallel to each other.
The array microphone unit is disposed in a three-dimensional space in a plane orthogonal to the
plane to perform directional three-dimensional control.
[0013]
The variable-orientation main axis AMIC according to the third aspect of the present invention is
more directional in an array microphone apparatus including an array microphone unit having
an array microphone in which the main axis is variable only in each plane in two planes
orthogonal to each other. The plane that can be secured is selected, and the main axis and
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directivity are given in the plane direction.
[0014]
According to a fourth aspect of the present invention, there is provided a method of changing the
main axis of the AMIC of the present invention, comprising: a reference microphone capsule; a
first pair of microphone capsules disposed in a one-dimensional direction centered on the
reference microphone capsule; And a second pair of microphone capsules arranged in a twodimensional direction orthogonal to the pair of microphone capsules, and a first microphone
capsule and a pair of second microphone capsules centered on the reference microphone
capsule. Array microphone device with a third pair of microphone capsules arranged to be
arranged, and a directivity controllable plane comprising a reference microphone capsule, a first
pair of microphone capsules, and a second pair of microphone capsules , Reference microphone
capsule and second pair of microphones A directivity controllable plane consisting of a phone
capsule, a third pair of microphone capsules, a directivity control plane consisting of a reference
microphone capsule, a third pair of microphone capsules, and a first pair of microphone capsules
An array microphone device which can be selected is characterized in that its directivity is
narrowed.
[0015]
According to a fifth aspect of the present invention, there is provided a method of changing the
main axis of an AMIC according to the fifth aspect of the present invention, a first microphone
array unit comprising a reference microphone capsule, a first pair of microphone capsules, a
second pair of microphone capsules, a reference microphone capsule and a second microphone
Third array microphone consisting of a pair of microphone capsules, a second array microphone
unit consisting of a third pair of microphone capsules, a reference microphone capsule, a third
pair of microphone capsules, and a first pair of microphone capsules The unit constitutes an
array microphone device, and the directivity controllable plane of the first array microphone unit,
the directivity controllable plane of the second array microphone unit, and directivity control of
the base third array microphone unit Select possible plane It is intended to narrow the directional
characterization of the enabled array microphone device.
[0016]
According to the AMIC and AMIC main axis variable method of the present invention, it is
possible to obtain a wide-axis, narrow-angle directional array microphone with variable main
axis.
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Further, it is possible to obtain an AMIC and an AMIC main axis variable method capable of
reducing the number of microphone capsules M at that time.
Furthermore, it is possible to obtain a main axis variable method capable of controlling directivity
in a three-dimensional space area.
[0017]
First, based on the technology described in Patent Document 1, a method for enhancing the
directivity of AMIC in the planar region described in the background art will be described in
detail.
In Patent Document 1 described with reference to FIG. 30, a first pair of microphone capsules
M2 disposed in the X-axis direction at the positions of distances d <0-2> and d <0-4> with the
reference microphone capsule M0 interposed therebetween. , M4, a pair of second microphone
capsules M1 and M3 disposed in the Y-axis direction at positions of distances d <0-1> and d <03> with the reference microphone capsule M0 interposed therebetween, and a reference Third
microphone capsules M5 and M6 disposed at 45.degree. With the X axis (or Y axis) at the
positions of distances d <0-5> and d <0-6> with the microphone capsule M0 interposed
therebetween When the angle between the Y axis and the sound source S is θ, and the main axis
of directivity is θc (central angle of main axis), a directional beam approximated by the equation
1 representing a Fourier series is generated.
Here, G (θ, θc) can be expressed as a gain, and the constants a and b of Equation 1 can be
represented by equation (i), Equation 2 and Equation 3.
In the equations (2) and (3), θW indicates a beam width, and it is described in the abovementioned patent document 1 that θW = 60 ° is suitable. Here, the distances d <0-2> = d <04>, d <0-1> = d <0-3>, and d <0-5> = d <0-6>.
[0018]
<img class = "EMIRef" id = "200947221-00003" />
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[0019]
[0020]
[0021]
[0022]
Considering such microphone capsules M0 to M6 as array microphone units (hereinafter
referred to as AMU), the AMUs are arranged as shown in FIG.
In FIG. 1, as shown in FIG. 30, a reference AMU (UNIT0) consisting of seven microphone capsules
M0, M1, M2, M3, M4, M5, M6 and the same arrangement arrangement as the AMU (UNIT0) of
this reference AMU (UNIT 1 to UNIT 6) of the first pair AMU (UNIT 2) and AMU (UNIT 4)
arranged in the X-axis direction of the two-dimensional plane centering on AMU (UNIT 0) of
reference and AMU (UNIT 0) of reference And a second pair of AMUs (UNIT1) and AMU (UNIT3)
disposed in the Y-axis direction of the two-dimensional plane orthogonal to the first pair of AMUs
(UNIT2) and AMU (UNIT4) And a first pair of AMU (UNIT 2) and AMU (UNIT 4) arranged in the
direction of the X axis of the second plane with the AMU (UNIT 0) of A third pair of AMUs
(UNIT5) and AMUs (UNIT6) arranged in the XY axis plane at an angle of 45 degrees with respect
to the second pair of AMUs (UNIT1) and AMUs (UNIT3) arranged in the Y-axis direction of The
standard AMU (UNIT 0), the first, second and third pairs of AMUs (UNIT 2, UNIT 4), (UNIT 1,
UNIT 3), (UNIT 5, UNIT 6) are two-dimensional planes on the same X and Y axes. The main axis
25 of the directional characteristics of the reference AMU (UNIT 0) and the first to sixth AMUs
(UNIT 1 to UNIT 6) disposed on the top can be variably controlled.
[0023]
The directivity main axis 25 of each AMU (UNIT0 to UNIT6) described above is taken as an angle
θC, the positions of the reference AMU (UNIT0) and the sound source S are separated by R, and
the angle with a sound source S is θ, constant k = w / c.
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Here, c: sound velocity, w: angular frequency.
Now, assuming that the signal at the sound source S is expressed by Equation 4, from each unit
with M00, M01, M02, M03, M04, M05, and M06 as reference microphones at time t of each
AMU (UNIT0 to UNIT6) The signals output by the conventional calculation method are expressed
by Equations 5 to 11.
[0024]
[0025]
[0026]
[0027]
[0028]
[0029]
[0030]
[0031]
[0032]
If the output of each AMU is calculated as shown in Eq. 12 to Eq. 15 from the result of
computation in each AMU (UNIT 0 to UNIT 6), the following Eq. 16 to Eq. The mixing signals xA1
(t) to xD1 (t) shown in step S4 of FIG. 2 are obtained.
[0033]
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[0034]
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
Here, when focusing on xA1 (t) of Expression 16, if d1 is reduced so as to be considered as kd1
<< 1, Expression 20 below holds, and Expressions 21 to 22 hold similarly.
Further, XA1 (w) is obtained by frequency-converting xA1 (t), and XM00 (w) is obtained by
frequency-converting the signal xM00 (t) observed by the reference microphone of UNIT0.
Likewise, the frequency-converted version of x (t) will be represented as X (w) (xM00 (t) is the
number 4).
[0042]
[0043]
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Similarly,
[0044]
Further, cosx in the equations (18) and (19) becomes the following equation by Taylor expansion.
Here, λ is an error term.
[0045]
であるから、
[0046]
[0047]
It is expressed as
Therefore, the following equation holds.
[0048]
Also, similarly, the following equation holds.
となる。
Where the error terms λ ', λ <">,
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[0049]
[0050]
とする。
By combining these signals as in Eq. 29, the following directional characteristics can be found in
a wide band.
That is, as shown in FIG. 13, the directivity characteristic becomes G × G of the square of the
gain G as shown by the broken line as compared to the gain G (equation 1) of the AMU alone
shown by the solid line. It is possible to
The horizontal axis in FIG. 13 represents the angle θ (degrees), and the vertical axis represents
the gain.
[0051]
[0052]
A flowchart of the narrow directivity method in the above-described configuration will be
described with reference to FIG.
In the first step S1 of FIG. 2, the arithmetic processing unit 22 described with reference to FIG.
31 determines whether the power supply voltage is on.
If the power is on, sampling and framing are performed in the second step S2, and in the third
step S3, each AMU is represented by the operation of each AMU (UNIT 0 to UNIT 6) using the
conventional method. The arithmetic processing unit 22 calculates an audio signal from a sound
source S whose output is expressed by Equations 5 to 11.
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[0053]
In the next fourth step S4, the arithmetic processing unit 22 mixes the outputs of AMU (UNIT0 to
UNIT6) based on the above equations (12) to (15) to obtain equations (16) to (19).
Further, the fifth step S5 performs the calculations of the above equation 20 to the equation 28
and combines them based on the equations 16 to 28 as shown in the equation 29 of the sixth
step S6. , Narrow narrow-band directional characteristics are found.
[0054]
In the next seventh step S7, the off state of the power supply voltage is checked to return to the
second step S2 if NO, and to the end if YES.
[0055]
In the above configuration and operation, if AMU is arranged as it is in a two-dimensional space
area as shown in FIG. 1, the number of microphone capsules M0 to M6 becomes as large as 7 ×
7 = 49, and 49 physical As the distances d1 and d2 between the AMUs become large due to the
microphone capsule having a size, the distance d1 in each of the above-described formulas
deviates from the condition of kd1 << 1.
[0056]
Therefore, the number of microphone capsules represented by a double circle in FIG. 3 (the
double circle is the center microphone of each AMU) and the number of microphone capsules M
represented by a single circle, that is, the entire It arrange ¦ positions so that the number of
objects of the microphone capsule M may be reduced.
The triangle symbol in FIG. 3 represents the relationship of the AMU with the double circle at the
center, and represents the use of the output signal from the microphone capsule M located at the
tip of the triangle symbol.
As shown by the phantom lines in a hexagonal shape, combined use between each AMU (in FIG.
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3, there are many microphone capsules, so A / D converters and amplifiers equal in number to
this number are required.
In the above, it is possible to input the same signal to the program for each AMU (UNIT 0 to UNIT
6) after the digital conversion.
According to the arrangement of the microphone capsule M, the same effect as shown in FIG. 1
can be obtained with a total of 19 pieces of 12 pieces of single circles and 7 pieces of double
circles.
Furthermore, the distances d1 and d2 can be reduced by reducing the number of microphone
capsules.
[0057]
Further, for example, as shown in FIG. 4, in order to reduce the number of microphone capsules
M in the entire AMU, through the reference microphone capsules M5 and M6 of the UNITs 5 and
6 in FIG. As shown in FIG. 4, the microphone capsules (M) 34 and 35 marked with x in a single
circle are omitted and shown in FIG. 4 by rotating 90 degrees clockwise and shifting UNIT 5 and
UNIT 6 as shown in FIG. The microphone capsules (M) 34 and 35 can be reduced to 17 in
number.
At this time, it is necessary to align the main axes of directivity by changing the direction of each
AMU.
Therefore, it is necessary to perform directivity control by adding the deflection angle θS shown
in FIG. 4 to θC of Expression 29 with respect to the deflected AMU (UNITs 5 and 6).
[0058]
Furthermore, in order to reduce the number of microphone capsules M and to shorten the
distance between the sound reception points, the configuration of AMU (UNIT 0 to UNIT 6) as
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shown in FIG. 5 can be adopted.
As described in detail in the conventional patent document 1, a pair of microphone capsules M
centered on a certain point, and a second pair of microphones orthogonal to the first pair of
microphone capsules M centered on this point It is described that the signals to be observed at
the central point can be synthesized by adding the outputs of the capsule M and applying a
correction in the frequency domain.
[0059]
Using this, for example, in the configuration shown in FIG. 3, as shown in FIG. 5, the points
surrounded by the microphone capsules M39, 40, 41, 42 and 41, 42, 43, 44 (indicated by
broken lines It is possible to extract the signal to be detected at the position of the virtual
microphone capsule 36 (37, 38) of the single circle and double circle).
Thus, in the arrangement shown in FIG. 5, the actual microphone capsule to be originally placed
in the position indicated by the dashed circle surrounded by four microphone capsules M is
replaced by virtual microphone capsules 36, 37, 38. Can be omitted.
By this, the arrangement in the case of FIG. 5 adds four microphone capsules (M) 40, 40a, 44,
44a indicated by crosses in circles, and eight actual microphone capsules 36.times.2, 37.times.
The number of microphone capsules M is reduced by replacing a total of 8-4 = 4 of 2, 38 x 4
with virtual microphone capsules, and by configuring AMU (UNIT 0 to UNIT 6) as in FIG. The
number of microphone capsules M can be reduced and the distance d of the sound receiving
point can be shortened.
[0060]
Next, configurations for controlling three-dimensional directivity will be described with reference
to FIGS. 6A to 6D.
Here, in order to simplify the explanation, the case in which the directivity of the AMU is cardioid
will be described.
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Now, let AMU consisting of five microphone capsules M0, M1, M2, M3 and M4 shown in FIG. 6A
be one unit unit, and a plurality of AMUs in a three dimensional space as shown in FIG. The AMU
is placed in the x, y, z axis plane of the three-dimensional space in a plane parallel to and
orthogonal to this plane.
[0061]
A specific arrangement configuration of the three-dimensional arrangement of the AMU of FIG.
6B ( AMU UNIT 26 and UNIT 46 in the z-axis direction are assumed to be upper and lower on
the XY axis plane) is shown in FIG.
Here, in the casing 45, for example, microcapsules M having a diameter of 6 mm are arranged in
a configuration shown in FIG. 6A in the unit 06 of the AMU.
Now consider the AMU of FIG. 6A, FIG. 6B and combinations thereof. As described above, for
example, signals observed by two pairs of microphone capsules M1, M3 and M2, M4 constituting
AMU of UNIT 06, x1 Unit 06 (t), x 3 Unit 06 (t), x 2 Unit 06 (t), x 4 Unit 06 (t) Thus, for the signal
x0Unit06 (t) observed by the reference microphone capsule M0, xAUnit06 (t) and xBUnit06 (t)
respectively satisfy the following Eq. 30 and Eq. 31 under the condition of kd1 << 1: Generate a
signal to be represented. Here, d1 is an interval of each microphone.
[0062]
[0063]
Further, cos (φ + φC) having an arbitrary phase difference φC is generated as in the following
equation 32.
[0064]
If this thing is used, in order to give a cardioid characteristic to arbitrary directions gamma in xy
plane in FIG. 6C,
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[0065]
Determined by
The directivity obtained here can be considered as Gcard (γ, γC) shown in Equation 34.
The above equations (30) to (34) are for a single unit (UNIT 06), but the configuration in which
these units (UNIT 06 to UNIT 46) are combined will be described by equations (35) to (47).
[0066]
As in the case where each UNIT is combined in the same manner as described above, the signal
output as a result of the above-described cardioid calculation in UNIT 06 to UNIT 46 can be
expressed by the following equation 35 for expressing the sound source:
[0067]
The outputs of UNIT 06 to UNIT 46 can be obtained as in Equations 36 to 40.
[0068]
[0069]
[0070]
[0071]
[0072]
[0073]
The equations (43), (44), (45) and (46) are derived from the mixing operation of the equations
(41) and (42).
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[0074]
[0075]
[0076]
[0077]
[0078]
When these are recombined by the equation 47, directivity is obtained for θ and γ as shown in
FIG. 6C.
In the case of the cardioid in Eq. 47, unlike Eq. 29, there are no cos 2θ and sin 2θ components.
[0079]
[0080]
A flowchart of the operation in the above-described configuration will be described with
reference to FIG.
In the first step ST1 of FIG. 7, the inside of the arithmetic processing unit 22 described in FIG. 31
determines whether or not the power supply voltage is on.
If the power is on, sampling and framing are performed in the second step ST2, and in the third
step ST3, the arithmetic processing unit 22 performs the operation of the above AMU (UNIT 06
to UNIT 46) according to Eqs.
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[0081]
In the next fourth step ST4, mixing of AMU (UNIT 06 to UNIT 46) is calculated based on the
arithmetic processing unit 22.
That is, the calculations of Formula 43 and Formula 44 are performed based on Formula 41 and
Formula 42.
Further, the fifth step ST5 performs operations of the equations 45 and 46, and the arithmetic
processing unit 22 combines them based on the operations of the equations 45 and 46 as shown
in the equation 47 of the sixth step ST6. It enables three-dimensional spindle control in a wide
band.
[0082]
In the next seventh step ST7, the off state of the power supply voltage is checked to return to the
beginning of the second step ST2 if NO, and to the end if YES.
[0083]
In FIG. 6B and FIG. 6D, the case where five microphone capsules M were arrange ¦ positioned in
AMU was demonstrated, but seven microphone capsules M0-M6 were made into a unit unit
similarly to having shown in FIG. 1 as shown in FIG. It is natural that the above-described logic
can be applied to a configuration in which AMUs (UNIT 08 to UNIT 68) are three-dimensionally
arrayed.
In the case of FIG. 8, the UNIT 18 and UNIT 38 are arranged around the UNIT 08 in the x-axis
plane, and the UNIT 58 and UNIT 68 are arranged around the UNIT 08 located in the xy-axis
plane at 45 ° from the x axis. It arranges UNIT28 and UNIT48 up and down centering on
UNIT08.
[0084]
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Further, FIGS. 9A to 9C explain the case of selecting and controlling the AMU plane in which the
directivity is enhanced in which the directivity main axis is variable only in each plane of the
microphone capsules M0 to M6 placed in two orthogonal planes. Do.
FIG. 9A shows the arrangement of the three-dimensionally arranged microphone capsules M, and
as shown in the perspective view of FIG. 9C which is illustrated three-dimensionally for easy
understanding, the reference microphone capsule arranged on the XY plane A pair of array
microphones consisting of microphone capsules M1 and M3 arranged on the left and right X
axes centering on M0 and microphone capsules M5 and M6 similarly arranged on the Y axis of
the XY plane centering on the reference microphone capsule M0 And a pair of array
microphones composed of microphone capsules M2 and M4 disposed above and below with
respect to the XY plane on the YZ plane or the XZ plane centering on the reference microphone
capsule M0.
Here, θ and γ similar to those described above are formed as shown in FIG. 9B.
Also, the distance between the microphones is d1.
Now, in FIG. 9A to FIG. 9C, considering the signals input to each microphone capsule M in the xz
plane in consideration of the incident angles θ and γ, the following can be obtained based on
the signal of the sound source S of Eq. Formula 49 to formula 53 are represented.
However, let R be the distance between the sound source S and the reference microphone
capsule M0.
[0085]
[0086]
[0087]
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[0088]
[0089]
[0090]
The mixing process can be derived from Eq. 56 and Eq. 57 and Eq. 58 and Eq. 59 under the
condition of kd1 << 1 by Eq. 54 and Eq. 55.
[0091]
[0092]
[0093]
[0094]
[0095]
[0096]
When the sound source is thus positioned at the elevation angle γ, the above equation is
obtained.
From these, when the incident angles are calculated (estimated) as θA and θB from Eq. 58 and
Eq. 59, respectively,
[0097]
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[0098]
Get
However, since the variable range of θA and θB is a part of 0 to π, θA and θB deal with Eq.
62 and Eq.
[0099]
[0100]
[0101]
A flowchart for selecting an optimum pointing direction in a predetermined plane on which a
plurality of microphone capsules M0 to M6 are arranged in the configuration shown in FIGS. 9A
and 9C described above will be described with reference to FIG.
In the first step STE1 of FIG. 10, the arithmetic processing unit 22 described in FIG. 31
determines whether or not the power supply voltage is on.
If the power is on, sampling and framing processing is performed in the second step STE2, and in
the third step STE3, the above-described mixing operation of the AMU is performed by the
arithmetic processing unit 22 using the equations 54 and 55 using the equations 54 and 55 Or
calculate equation (57).
[0102]
In the next fourth step STE4, operations of Equations 58 and 59 are performed.
Further, the calculation of Equations 60 to 63 is performed in the fifth step STE5, and it is
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determined whether the absolute value of θA <'>-θB <'> is larger than the reference difference
absolute value D in the sixth step STE6. .
If the sixth step STE6 is NO, the process proceeds to the seventh step STE7 to select an AMU
using the microphone capsules M0 to M4.
If the sixth step STE6 is YES, an AMU on another plane with good directivity is selected.
[0103]
In the next ninth step STE9, the off state of the power supply voltage is checked to return to the
beginning of the second step STE2 if NO, and to the end if YES.
In the above-described configuration, the sound source on the plane, that is, the estimated value
of the incident angle when assuming the elevation angle γ = 0 is θA <'> = θB <'>.
However, when the elevation angle γ increases, it becomes as shown in FIG.
The horizontal axis in FIG. 11 represents the incident angle θ (°) from the actual sound source,
and the vertical axis represents the estimated values of the incident angle (θA ′, θB ′)
derived from acos / asin in Eqs. Represents
Further, the difference absolute value ¦ θA <'>-θB <'> ¦ of the estimated values θA ′ and θB
′ of the incident angles is as shown in FIG.
In FIG. 12, the horizontal axis represents the incident angle θ (°) from the sound source, and
the vertical axis represents the difference absolute value (¦ θA'-θB '¦) (°) of the estimated
incident angle value derived from acos / asin. Represents the).
The data are shown in Tables 8 to 14 below.
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Due to the value of γ, the estimated values (θA ′, θB ′) do not match.
Thus, as the difference becomes larger, the directional array of these combinations does not
function much.
Therefore, by using the microphone capsules M1, M5, M3 and M6 in other planes, for example,
by changing the target pointing axis, efficient directivity control can be performed.
For example, the absolute value of θA <'>-θB <'> may be used as a reference.
[0104]
[0105]
[0106]
[0107]
[0108]
[0109]
[0110]
[0111]
[0112]
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[0113]
[0114]
[0115]
[0116]
[0117]
[0118]
Furthermore, by combining signals of the points included in the microphone capsule M
(microphone capsule M0), further reduction of the microphone capsule M and reduction of the
distance between the microphone capsules M can be achieved.
As a judgment standard based on the absolute value of θA <'>-θB <'>, for example, about 37.5
degrees is a suitable value.
When the incident angle φ is near 45 degrees, this threshold does not necessarily search for a
plane that is close to correct. However, when the incident angle φ is near 0 or 90 °, this
function is effective and directivity is effectively exhibited. It is possible to select a microphone in
a plane that can be created.
In addition, when the incident angle φ is close to 45 degrees, it is considered that the
effectiveness does not greatly depend on either surface.
[0119]
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24
Hereinafter, the effects based on the above-described respective embodiments of the present
invention will be described with the simulated waveforms of FIGS. 13 to 17.
In FIG. 13, the abscissa represents the angle θ (degrees) and the ordinate represents the gain,
and the graph represents the gain G shown in equation 1 and the value of G × G indicating the
square of the gain G.
FIG. 14 is a polar expression graph depicting the directivity characteristic G of a single unit when
the beam principal axis in the XY plane is 0 degree and the directivity characteristic G × G of a
system in which multiple processing is performed on the unit; FIG. Although the directional
characteristics G of a single unit and the directional characteristics G × G of a system in which
multiple processing is performed on a unit are drawn at 0 degree, the respective gains are
different, so the polar expression normalized with the maximum value is represented. FIG. 16 is a
polar expression graph depicting directivity characteristics G of a single unit when the beam
principal axis is 135 degrees and directivity characteristics G × G of a system in which multiple
processing is performed on the unit, FIG. 17 shows 135 degrees of the beam principal axis The
directivity characteristics G of a single unit and the directivity characteristics G × G of a system
in which multiple processing is performed on a unit are drawn. However, since each gain is
different, the maximum value is normal. It is the very expression graph.
[0120]
Next, based on the arrangement of AMU in FIG. 3, simulations for each frequency in the XY plane
are shown in FIGS.
FIG. 18 shows the directivity characteristics of a single unit whose beam axis is set at 0 degrees,
and FIG. 19 shows the directivity characteristics of a single unit whose beam axis in the XY plane
is set at 0 degrees and normalized with the maximum value.
Fig. 20 shows the directivity characteristics of a single unit whose beam axis is set at 135
degrees, Fig. 21 shows the directivity characteristics of a single unit whose beam axis is set at
135 degrees and normalized with the maximum value, and Fig. 22 sets the beam axis at 0
degrees Figure 23 shows the directivity of the system with the beam axis set at 0 degrees and
normalized with the maximum, Figure 24 shows the directivity of the system with the beam axis
set at 135 degrees, and Figure 25 shows the beam axis The directivity characteristics of the
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system set at 135 degrees and normalized with the maximum value, Fig. 26 is the directivity
characteristics showing the unit and the system with the beam axis set at 0 degrees, and Fig. 27
the beam axis set at 0 degrees, each maximum 28 shows the directivity with the beam axis set to
135 degrees and the directivity with the unit and system written together, and FIG. 29 sets the
beam axis to 135 degrees with each maximum value. regular A directional characteristic shown
together with the unit and the system.
As can be understood from the above-mentioned results, it is possible to narrow the beam width
of the directivity characteristic.
[0121]
As described above, according to the array microphone device and the method of changing the
main axis of the array microphone device of the configurations of claims 1 and 7 of the present
invention, directivity is controlled by arranging a plurality of AMUs arranged in a twodimensional plane. It is possible to obtain a more narrow beam width of the directivity
characteristic.
[0122]
According to the array microphone device and the method for changing the main axis of the
array microphone device of the present invention, the directivity can be controlled in a threedimensional direction by arranging a plurality of AMUs arranged three-dimensionally. The thing
is obtained.
[0123]
According to the configuration of claim 3 of the present invention, it is an arrayed microphone
device of variable directional main axis type in which a plurality of microphone capsules whose
directional main axes are variable only in each plane within two planes orthogonal to each other
are array microphone units. Thus, it is possible to obtain a variable orientation main axis array
microphone device capable of selecting a plane in which the directivity is emphasized and
providing the orientation main axis and the orientation in the plane direction.
[0124]
According to the constructions of claims 4 and 5 of the present invention, it is possible to obtain
an array microphone apparatus capable of reducing the number of microphone capsules
arranged in two or three dimensions.
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[0125]
FIG. 6 is a layout diagram of a microphone capsule for realizing directivity narrowing in a twodimensional plane of the array microphone device of the present invention.
It is a flowchart for operation ¦ movement description of FIG.
It is explanatory drawing of the number reduction method of the number of microphone capsules
at the time of array microphone unit formation in the two-dimensional plane of the array
microphone apparatus of this invention.
It is explanatory drawing of the other reduction method which reduces the number of objects of
the microphone capsule similar to FIG.
It is explanatory drawing of the other reduction method which reduces the number of objects of
the microphone capsule similar to FIG.
It is an arrangement ¦ positioning figure of the microphone capsule which implement ¦ achieves
directivity control in the three-dimensional plane of the array microphone apparatus of this
invention.
It is a flowchart for operation ¦ movement description of FIG.
It is an arrangement ¦ positioning figure of the microphone capsule which implement ¦ achieves
directivity control in the three-dimensional plane of the array microphone apparatus of this
invention.
It is explanatory drawing of the selection method of a plane area ¦ region with a sufficient
directivity in the three-dimensional plane of the array microphone apparatus of this invention.
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It is a flowchart for operation ¦ movement description of FIG.
It is a diagram which shows the relationship between incident angle (theta) A <'>, (theta) B <'>,
and the incident angle of a sound source.
It is a diagram which shows the relationship between incident angle (theta) A <'>, (theta) B <'>,
and the incident angle of a sound source. It is a graph which shows the difference of the
directional characteristics in the gain G of several 1 type ¦ formula, and G2 of gain G * G in XY
plane. The directional characteristics G of a single unit and the directional characteristics G × G
of a system in which multiple processing is performed on a unit when the beam principal axis of
the XY plane obtained by polar form conversion of gain G and gain G × G shown in FIG. It is a
graph (1). When the beam principal axis of the XY plane obtained by polar conversion of gain G
and gain G × G shown in FIG. It is graph (2) normalized (because the gain of G and GxG differs)
with each maximum value. The directional characteristics G of a single unit and the directional
characteristics G × G of a system in which multiple processing is performed on a unit when the
beam principal axis of the XY plane obtained by polar form conversion of gain G and gain G × G
shown in FIG. It is a graph (3). The directivity characteristics G of a single unit and the directivity
characteristics G × G of a system in which multiple processing is performed on a unit when the
beam principal axis of the XY plane obtained by polar conversion of gain G and gain G × G
shown in FIG. It is a graph (4) normalized by each maximum value. It is a directional
characteristic graph (5) of the simulation for every frequency when the beam principal axis of the
unit single-piece ¦ unit in XY plane based on arrangement ¦ positioning of AMU of FIG. 3 is set to
0 degree. It is a directional characteristic graph (6) of the simulation for every frequency
normalized by the maximum value of the directional characteristic gain when the beam principal
axis of the unit single-piece ¦ unit in XY plane based on arrangement ¦ positioning of AMU of FIG.
3 is set to 0 degree. . It is a directional characteristic graph (7) of the simulation for every
frequency when the beam principal axis of the unit single-piece ¦ unit in XY plane based on
arrangement ¦ positioning of AMU of FIG. 3 is set to 135 degree. It is a directional characteristic
graph (8) of the simulation for every frequency normalized by the maximum value of the
directional characteristic gain when the beam principal axis of the unit single-piece ¦ unit in XY
plane based on arrangement ¦ positioning of AMU of FIG. 3 is set to 135 degree. . It is a
directional characteristic graph (9) of the simulation for every frequency when the beam
principal axis of the system in XY plane based on arrangement ¦ positioning of AMU of FIG. 3 is
set to 0 degree. It is a directional characteristic graph (10) of the simulation for every frequency
normalized by the maximum value of the directional characteristic gain when the beam principal
axis of the system in XY plane based on arrangement ¦ positioning of AMU of FIG. 3 is set to 0
degree.
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It is a directional characteristic graph (11) of the simulation for every frequency when the beam
principal axis of the system in XY plane based on arrangement ¦ positioning of AMU of FIG. 3 is
set to 135 degree. It is a directional characteristic graph (12) of the simulation for every
frequency normalized by the maximum value of the directional characteristic gain when the
beam principal axis of the system in XY plane based on arrangement ¦ positioning of AMU of FIG.
3 is set to 135 degree. It is a directivity characteristic graph (13) of the simulation for every
frequency when the beam principal axis of the unit in the XY plane based on arrangement of
AMU of Drawing 3 is set to 0 degrees. Directivity graph of simulation for each frequency
normalized with the maximum value of each directivity property gain when the beam principal
axis of unit and system in the XY plane is set to 0 degree based on the arrangement of AMU in
Fig. 3 (14 ). It is a directivity characteristic graph (15) of the simulation for every frequency when
the beam principal axis of the unit in the XY plane based on arrangement of AMU of Drawing 3 is
set to 135 degrees. The directivity characteristic graph of the simulation for each frequency
normalized by the maximum value of each directivity characteristic gain when the beam principal
axis of the unit and system in the XY plane is set to 135 degrees based on the arrangement of
AMU in FIG. ). It is an arrangement ¦ positioning figure of the microphone capsule in the twodimensional plane of the conventional array microphone apparatus. It is a systematic diagram
showing the hardware constitutions of the conventional array microphone device.
Explanation of sign
[0126]
M, M0 to M6, 36 to 44 .. Microphone capsule, 24 .. Sound source, 25 .. Main axis, UNIT0 to
UNIT6 .... Array microphone unit (AMU), 45 .. Casing
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