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JP2017049225

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DESCRIPTION JP2017049225
Abstract: To provide a sound source tracking device capable of more reliably searching for a
sound source in a search target area. A baffle portion has a plurality of two-dimensionally
arranged microphone elements, a first surface, and a second surface opposite to the first surface,
and fixes the plurality of microphone elements on the first surface. The baffle unit 101 causes
the plurality of microphone elements to collect direct sound reaching the first surface and does
not collect direct sound reaching the second surface. [Selected figure] Figure 2
Sound source search device
[0001]
The present invention relates to a sound source tracking device.
[0002]
There has been proposed a sound source tracking device that performs sound source search
based on the phase difference of sounds (sound waves) generated when reaching a microphone
array arranged in the same plane (for example, Patent Document 1).
[0003]
The sound source tracking device as disclosed in Patent Document 1 has the advantages of
simple structure and high installation.
[0004]
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JP 2011-124749 A
[0005]
However, in the conventional sound source tracking device as disclosed in Patent Document 1,
the phase difference of the sound waves from the sound sources (the sound source on the front
side and the sound source on the back side) that is plane symmetric with respect to the array
surface of the microphone array is Since they are equal, there is a problem that they can not be
distinguished.
That is, in the conventional sound source tracking device, the sound source of the sound source
tracking device which is not the search target area is affected by the sound source on the back
side, and the sound source in the space on the front side of the sound source tracking device
which is the search target region is there.
[0006]
The present invention has been made in view of the above-described circumstances, and an
object thereof is to provide a sound source tracking device capable of more reliably searching for
a sound source in a search target area.
[0007]
In order to achieve the above object, a sound source tracking device according to an aspect of the
present invention includes a plurality of microphone elements, a first surface, and a second
surface opposite to the first surface, And a baffle portion for fixing the plurality of microphone
elements arranged in a two-dimensional array on a surface, and the baffle portion causes the
plurality of microphone elements to pick up direct sound of the sound source on the first surface
side and And the direct sound from the sound source on the second surface side is not collected.
[0008]
Note that some specific aspects of these may be realized using a system, a method, an integrated
circuit, a computer program, or a computer readable medium such as a computer readable CDROM, and the system, the method, It may be realized using any combination of integrated circuit,
computer program and recording medium.
03-05-2019
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[0009]
According to the present invention, it is possible to realize a sound source tracking device
capable of more reliably searching for a sound source in a search target area.
[0010]
FIG. 1 is a diagram showing an example of the configuration of a sound source tracking device
according to the embodiment.
FIG. 2 is a schematic view showing an example of the sound collection device according to the
embodiment.
FIG. 3 is a diagram showing an installation example of the sound collection device according to
the embodiment and an area targeted for sound source search.
FIG. 4A is a diagram showing an installation example of the sound collection device according to
the embodiment.
FIG. 4B is a side view of the sound collection device shown in FIG. 4A.
FIG. 5A is a diagram showing another installation example of the sound collection device
according to the embodiment.
FIG. 5B is a side view of the sound collection device of FIG. 5A.
FIG. 6 is a diagram for explaining the relationship between the sound source that maximizes the
phase difference of the sound waves arriving at the sound collection device 10 shown in FIG. 3
and the arrangement of the plurality of microphone elements. FIG. 7 is a diagram for explaining
the relationship between the sound source and the size of the baffle portion that minimizes the
phase difference of the sound waves arriving at the sound collection device 10 shown in FIG. 3.
FIG. 8 is a diagram showing a search direction of the sound collection device shown in FIG. FIG. 9
is a diagram showing the relationship between the search direction and the angular resolution of
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the sound collection device shown in FIG. FIG. 10 is a diagram showing a circular arrayed
microphone array in the comparative example. FIG. 11 is a diagram for explaining the phase
difference of the sound waves coming from the sound source in the plane-symmetrical direction
in the circular array microphone array in the comparative example shown in FIG. FIG. 12 is a
diagram showing an arrangement example of the microphone array of the sound collection
device in the first modification. FIG. 13 is a view showing an example of the baffle portion of the
sound collection device in the second modification. FIG. 14 is a diagram showing an arrangement
example of microphone arrays of the sound collection device in the third modification.
[0011]
(Findings Based on the Present Invention) As described above, in the conventional sound source
tracking device as disclosed in Patent Document 1, for example, the sound source (surface on the
front side) that is plane symmetric with respect to the array surface of the microphone array.
Since the phase differences (arrival time differences) of the sound waves from the sound source
and the sound source on the back side are equal, there is a problem that they can not be
distinguished. In other words, the conventional sound source tracking device is affected by the
sound source on the back side of the sound source tracking device that is not the search target
area, and can not search for the sound source in the space on the front side of the sound source
tracking device that is the search target area There is a problem that there is.
[0012]
As a method of solving the above-mentioned problem, it is also conceivable to threedimensionally arrange a plurality of microphone elements (microphones) constituting a
microphone array.
[0013]
However, in the case where a plurality of microphone elements are three-dimensionally arranged,
the structure of the sound source tracking device is not simple, and a new problem arises that the
installation becomes low.
Specifically, for example, when arranging a plurality of microphone elements in three
dimensions, the structure of the microphone array is acoustically satisfied such that sound waves
from all directions arrive at each microphone element without disturbing the phase difference.
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And, conditions such as maintaining the strength of the microphone array need to be satisfied.
However, installing a microphone array that satisfies these conditions requires complicated
operations, and the installation becomes low.
[0014]
The present invention has been made in view of the above-mentioned circumstances, and by
suppressing the influence of the sound wave coming from the back side of the microphone array
composed of a plurality of microphone elements, the sound source in the search target area can
be made more reliable. An object of the present invention is to provide a sound source tracking
device that can be searched.
[0015]
A sound source tracking device according to an aspect of the present invention includes a
plurality of microphone elements, a first surface, and a second surface opposite to the first
surface, wherein the plurality of the plurality of microphone elements are two-dimensionally
arrayed on the first surface. A baffle portion for fixing the microphone element, the baffle portion
causes the plurality of microphone elements to pick up the direct sound of the sound source on
the first surface side, and is on the second surface side Do not collect direct sound from the
sound source.
[0016]
That is, by providing the baffle portion, it is possible to cause the sound waves emitted by the
sound source on the second surface side to wrap around, and in the phase difference of the
sound waves reaching the plurality of microphone elements, The phase difference on the two
surfaces can be increased.
Thus, the influence of the sound wave coming from the second surface (rear side) can be
suppressed, so that the sound source in the first surface (front side), that is, the sound source in
the search target area can be more reliably searched.
[0017]
Here, for example, the plurality of microphone elements are arranged inside the outer edge of the
baffle portion by a predetermined length or more.
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[0018]
As a result, in the phase difference of the sound waves reaching the plurality of microphone
elements, the phase difference on the second surface side with respect to the first surface side
can be more reliably increased.
[0019]
Also, for example, a support member for supporting the baffle portion is further provided such
that the first surface of the baffle portion and the installation surface which is a surface on which
the sound source tracking device is installed have a predetermined angle. Good.
[0020]
As a result, in the phase difference of the sound waves reaching the plurality of microphone
elements, the phase difference on the second surface side with respect to the first surface side
can be more reliably increased.
[0021]
Further, for example, the baffle portion may be a circular plate-like member, and the diameter of
the baffle portion may be calculated based on the maximum length of the interval between the
plurality of microphone elements and the predetermined angle. .
[0022]
Here, for example, when the diameter of the baffle portion is d 1, the maximum length is d 0, and
the predetermined angle is θ c, the relationship of (d 0 / COS (θ c)) <d 1 is satisfied. There is.
[0023]
Also, for example, the baffle portion is a rectangular plate-like member, and the side length of the
baffle portion is calculated based on the maximum length of the interval between the plurality of
microphone elements and the predetermined angle. It may be
[0024]
Here, for example, assuming that the side length of the baffle portion is d 1, the maximum length
is d 0, and the predetermined angle is θ c, the relationship of (d 0 / COS (θ c)) <d 1 Meet.
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[0025]
Also, for example, even if the plurality of microphone elements are embedded in the baffle
portion so that the sound hole portions of the plurality of microphone elements are exposed to
the first surface and not exposed to the second surface. Good.
[0026]
Note that some specific aspects of these may be realized using a recording medium such as a
system, a method, an integrated circuit, a computer program, or a computer readable CD-ROM,
and the system, the method, It may be realized using any combination of integrated circuits,
computer programs or recording media.
[0027]
Hereinafter, a sound source tracking device according to an aspect of the present invention will
be specifically described with reference to the drawings.
Each embodiment described below shows one specific example of the present invention.
The numerical values, shapes, materials, components, arrangement positions of the components,
and the like described in the following embodiments are merely examples, and are not intended
to limit the present invention.
Further, among the components in the following embodiments, components not described in the
independent claim indicating the highest concept are described as arbitrary components.
In all the embodiments, the contents of each can be combined.
[0028]
In the embodiment described below, the distance of the sound source searched by the sound
source tracking device is sufficiently long with respect to the size of the microphone array, and
the sound wave reaching the microphone array from the sound source can be regarded as a
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plane wave I am assuming a relationship.
More specifically, a distance of approximately three to five times the size of the microphone
array is assumed.
[0029]
Embodiment [Overall Configuration of Sound Source Search Device 1] FIG. 1 is a diagram
showing an example of a configuration of a sound source search device 1 in the present
embodiment.
[0030]
The sound source tracking device 1 searches for the sound source and specifies the position of
the sound source based on the strength and the phase difference of the collected sound wave.
In the present embodiment, as shown in FIG. 1, the sound source tracking device 1 includes the
sound collection device 10, the signal processing unit 11, and the display unit 12.
Each component will be described in detail below.
[0031]
[Sound Collection Device 10] FIG. 2 is a schematic view showing an example of the sound
collection device 10 in the present embodiment.
(A) of FIG. 2 shows a case where the sound collection device 10 is seen from the front, and (b) of
FIG. 2 shows a case where the sound collection device 10 is seen from the side.
FIG. 3 is a diagram showing an installation example of the sound collection device according to
the embodiment and an area targeted for sound source search.
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[0032]
The sound collection device 10 includes a baffle portion 101 and a microphone array 102 as
shown in FIG.
[0033]
The microphone array 102 is composed of a plurality of nondirectional microphone elements
having high sensitivity to sound pressure.
The plurality of microphone elements are arranged inside the outer edge of the baffle portion
101 by a predetermined length or more.
Here, the plurality of microphone elements are, for example, sound sensors.
Also, the plurality of microphone elements may be condenser-type microphone chips
manufactured using semiconductor manufacturing technology.
The microphone chip has a diaphragm that is displaced by sound pressure and has a function of
converting a sound signal into an electrical signal. Here, the plurality of microphone elements
may be embedded in the baffle portion 101 so that the sound holes of the plurality of
microphone elements are exposed to the first surface and not exposed to the second surface. In
the present embodiment, as shown in FIG. 2, the microphone array 102 includes the microphone
element m1 to the microphone element m8 (eight microphone elements), and the microphone
element m1 to the microphone element m8 have a ring shape (annular shape). It is arranged as.
Also, the microphone element m1 to the microphone element m8 are embedded in the baffle
portion 101 so that the sound hole of the microphone element is exposed to the first surface
(front surface 101a) and not exposed to the second surface (back surface 101b) There is.
[0034]
In the following, the case where the microphone array 102 includes eight microphone elements
m1 to m8 will be described as an example, but the present invention is not limited to this case.
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The microphone array 102 may be configured by at least three microphone elements, but sound
can be collected more accurately as the number of microphone elements is larger.
[0035]
The baffle portion 101 has a first surface and a second surface opposite to the first surface, and
fixes a plurality of microphone elements (microphone elements m1 to m8) two-dimensionally
arrayed on the first surface. Then, the baffle unit 101 causes the plurality of microphone
elements to collect direct sound from the sound source on the first surface side, and does not
collect direct sound from the sound source on the second surface side. The baffle section 101
can cause sound waves emitted by the sound source on the second surface side to wrap around,
so the phase difference of the sound waves reaching the multiple microphone elements is greater
than the phase difference on the first surface side. This is because the phase difference on the
side can be increased. Further, the baffle portion 101 can increase the sensitivity of the
microphone array 102 by about 6 db due to the baffle effect.
[0036]
Further, the baffle portion 101 may be arranged such that the first surface and the installation
surface which is the surface on which the sound source tracking device 1 is installed have a
predetermined angle θ c. By arranging so as to have a predetermined angle, it is possible to
make the phase difference of the sound waves of the sound source on the first surface side
smaller than the phase difference of the sound waves of the sound source on the second surface
side.
[0037]
Here, assuming that the baffle portion 101 is formed of, for example, a circular plate-like
member, the diameter d 1 of the baffle portion 101 has a maximum length d 0 of the distance
between the plurality of microphone elements and a predetermined angle θ c. It can be
calculated based on The details will be described later, so the description thereof is omitted here.
[0038]
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10
In the present embodiment, the first surface corresponds to the front surface 101a shown in FIG.
2B, and the second surface corresponds to the back surface 101b shown in FIG. 2B. The baffle
portion 101 is formed of, for example, a circular plate-like member as shown in FIG. 2A, and is
installed so as to make a predetermined angle θ c with the installation surface 51 such as the
ground Be done. Further, as shown in FIG. 3, the first surface side (front surface 101 a side) of
the baffle portion 101 is the region X of the sound source search target, and the second surface
side (back surface 101 b side) of the baffle portion 101 is It is a region Y not subject to sound
source search. In addition, the baffle part 101 may be comprised with members, such as a metal,
a wood, and a resin material, which do not let a sound wave pass or attenuate | damp sufficiently
even if it passes. Further, the baffle portion 101 may be made of a plate-like member made of an
artificial material which solidifies homogeneous fibers such as particle board, chip board, wood
cement board, apiton plywood and the like with an adhesive and applies high pressure. Further,
the baffle portion 101 may be formed of a strong (highly rigid) and heavy (high specific gravity)
plate-like member similar to the baffle plate supporting the speaker unit.
[0039]
(Installation Method) A method for installing the sound collection device 10 so that the baffle
portion 101 and the installation surface 51 form a predetermined angle will be described below
by way of example.
[0040]
FIG. 4A is a diagram showing an installation example of the sound collection device 10 according
to the embodiment.
FIG. 4B is a side view of the sound collection device shown in FIG. 4A. FIG. 5A is a diagram
showing another installation example of the sound collection device according to the
embodiment. FIG. 5B is a side view of the sound collection device of FIG. 5A.
[0041]
For example, as shown in FIGS. 4A and 4B, the sound collection device 10 is installed by the
support member 103 supporting the baffle portion 101 such that the baffle portion 101 and the
installation surface 51 form a predetermined angle. In addition, the method of installing so that
03-05-2019
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the baffle part 101 and the installation surface 51 make a predetermined angle may use the
support member 103 which supports the 2nd surface (back surface) of the baffle part 101, as
shown to FIG. 4A and 4B. Not limited to. For example, as shown in FIGS. 5A and 5B, a support
member 103A that supports the lower end portion of the baffle portion 101 may be used. That
is, any support member may be used as long as the baffle portion 101 and the installation
surface 51 can be installed at a predetermined angle.
[0042]
(Method of Calculating the Diameter d 1) Next, a method of calculating the diameter d 1 of the
baffle portion 101 will be described. First, the relationship between the diameter d 1 of the baffle
portion 101, the maximum length d 0 of the interval between the plurality of microphone
elements, and the predetermined angle θ c will be described with reference to FIGS. The method
of calculating the diameter d 1 of the lens will be described.
[0043]
FIG. 6 is a diagram for explaining the relationship between the sound source that maximizes the
phase difference of the sound waves arriving at the sound collection device 10 shown in FIG. 3
and the arrangement of the plurality of microphone elements. More specifically, FIG. 6 shows a
sound source A in which the phase difference τ A15 of the sound waves arriving at the
microphone element m1 and the microphone element m5 is maximum, and how sound waves
arrive from the sound source A to each microphone element It is shown schematically. In other
words, in the area X of the sound source search target, from the sound source A located in a
direction parallel to the array surface (the first surface in the present embodiment) of the
plurality of microphone elements (microphone elements m1 to m8) The phase difference τ A15
of the sound waves arriving at the element m1 and the microphone element m5 is maximized.
[0044]
Therefore, the maximum of the phase difference (arrival time difference) τ A15 of the sound
wave arriving from the sound source in the region X (front side) of the sound source search
target to the microphone element m1 and the microphone element m5 is using the speed C of
the sound in the air. It can be expressed as (Expression 1).
[0045]
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τ A15 = d 0 / C (Expression 1)
[0046]
FIG. 7 is a diagram for explaining the relationship between the sound source and the size of the
baffle portion that minimizes the phase difference of the sound waves arriving at the sound
collection device 10 shown in FIG. 3.
More specifically, FIG. 7 shows the sound source B in which the phase difference τ B15 of the
sound waves arriving at the microphone element m1 and the microphone element m5 is
minimized, and the appearance of the sound wave from the sound source B to each microphone
element. It is shown schematically.
In other words, the microphone element m1 and the microphone element from the sound source
B located in the direction parallel to the installation surface 51, passing through the array center
of the microphone elements (microphone elements m1 to m8) in the area Y outside the sound
source search target The phase difference τ B15 of the sound waves arriving at m5 is
minimized.
[0047]
Therefore, the minimum of the phase difference τ B15 of the sound wave arriving from the
sound source in the region Y (rear side) not to be subjected to the sound source search to the
microphone element m1 and the microphone element m5 can be expressed as (Expression 2).
[0048]
τ B15 = d 1 * COS (θ c) / C (Equation 2)
[0049]
Here, if the relationship of the following (Expression 3) is satisfied, it is possible to distinguish
even sound sources that are plane-symmetrical with respect to the array surface of the
microphone array 102 (a plurality of microphone elements).
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In the sound source tracking device 1 that detects a sound source based on phase information,
the phase difference with respect to the sound source in the region Y (rear side) outside the
sound source search target is always larger than the sound source in the region X (front side) is
there.
[0050]
τ A15 <τ B15 (Equation 3)
[0051]
Therefore, the diameter d 1 of the baffle portion 101 may be calculated so as to satisfy the
relationship of the solved equation 4 by substituting the equations 1 and 2 into the equation 3.
[0052]
d 0 / COS (θ c) <d 1 (Equation 4)
[0053]
Here, for example, when the predetermined angle θ c is 60 °, since COS (θ c) = 0.5, the
diameter d 1 of the baffle portion 101 is the maximum length d 0 of the distance between the
plurality of microphone elements. Is calculated to be greater than twice the
Although it is theoretically possible when the predetermined angle θ c is 0 ° or 90 °, it may
not be included if the predetermined angle θ c is 0 ° or 90 ° for the reason described below.
[0054]
(Predetermined Angle θ c) The relationship between the angular resolution of the sound
collection device 10 and the predetermined angle θ c will be described with reference to FIGS. 8
and 9.
FIG. 8 is a diagram showing a search direction θ d of the sound collection device 10 shown in
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FIG.
FIG. 9 is a diagram showing the relationship between the search direction of the sound collection
device 10 shown in FIG. 8 and the angular resolution.
Here, as shown in FIG. 8, an angle based on the normal direction of the first surface (front
surface 101a) of the sound collection device 10, that is, the normal direction of the array surface
of the microphone array 102 (a plurality of microphone elements) is searched It is assumed that
the direction θ d. On the other hand, in the graph shown in FIG. 9, it is assumed that there is a
performance of angular resolution = 1.degree. At vertical (.theta. = 0.degree.) With an interval
.DELTA.d = 40 mm between two microphone elements constituting the microphone array 102.
The angular resolution for each direction θ d is shown. That is, the angular resolution on the
vertical axis shown in FIG. 9 indicates an error when a target object separated in the search
direction θ d is detected. The phase difference between the microphone elements is calculated
as constant.
[0055]
From the graph shown in FIG. 9, the normal direction of the array surface of the microphone
array 102 (searching direction θ d = 0 ° in the graph) has the best angular resolution, and the
error doubles if the searching direction It is understood that the performance is extremely
degraded because
[0056]
That is, it can be understood that if the array plane of the microphone array 102 is directed at an
inclination of up to about 60 ° with respect to the direction in which the object of sound source
search is present, sound source search can be performed with high accuracy.
Therefore, it is not necessary to set the predetermined angle θ c to 0 ° except in the case where
there is an object for sound source search in the direction (directly upward direction)
perpendicular to the installation surface 51.
[0057]
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Then, in order to use the sound collection device 10 with a good angular resolution, the
predetermined angle θ c may be changed according to the position of the object to be subjected
to the sound source search. For example, in a region X targeted for sound source search, there is
a distance of several hundred meters from the sound source tracking device 1 and a sound
emitted by a flying object hovering at a position of 10 m from the installation surface 51
(ground) is detected (sound collection) Suppose you want to In this case, with respect to the
flying object, the angle from the installation surface 51 is about 10 ° to 20 ° with reference to
the point at which the sound source tracking device 1 is installed. Therefore, in order to
accurately perform sound source search at this angle, the predetermined angle θ c may be set to
about 45 ° to 60 °. That is, in order to accurately source-search an object to be subjected to
sound source search at a position away from the sound source tracking device 1, the normal
direction of the array surface of the microphone array 102 is directed in the direction where the
object is located. The predetermined angle θ c may be determined so that d is about 30 °.
[0058]
[Signal processing unit 11] The signal processing unit 11 performs processing of signals (eight
signals in FIG. 1) output from a plurality of microphone elements to identify a sound source or
specify the position of the sound source. Can. More specifically, the signal processing unit 11 A /
D (Analog to Digital) converts signals output from a plurality of microphone elements, and
converts the signals into time signals or frequency domain signals, and then converts the
plurality of microphones into a plurality of microphones. Calculation processing based on the
phase difference between elements is performed to localize or identify the arrival direction of
sound. The signal processing unit 11 may be an arithmetic device such as a PC physically
connected to a plurality of microphone elements of the sound collection device 10, and is a
central processing unit (CPU) configuring the sound source tracking device 1 It is also good.
[0059]
In the present embodiment, since the signal processing unit 11 can remove the influence of the
sound from the sound source on the back side (area Y) of the sound collection device 10, the
signal processing unit 11 A sound source located at a distant position and having a small
incoming sound to the sound collection device 10 can also be identified and located. The signal
processing unit 11 causes the display unit 12 to display the processing result.
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[0060]
Note that the signal processing unit 11 may generate a sound source image signal indicating the
position of the specified sound source as a processing result, and cause the display unit 12 to
display the processing result.
[0061]
Further, in the present embodiment, the sound source search is performed based on the phase
difference of the sound waves input to each of the plurality of arranged microphone elements.
Here, as a method of sound source search, generally, methods such as a beam forming method
(BF method), sound intensity (SI method), and envelope intensity method (EI method) are known.
In the SI method and the EI method, it is possible to search directly for the direction of arrival of
sound. In the BF method, the intensity distribution of sound pressure can be used to obtain the
direction of the maximum position of the sound pressure as a sound source. All of these
techniques are widely known techniques and are not the gist of the present invention, so detailed
description of the sound source search technique is omitted.
[0062]
[Display Unit 12] The display unit 12 displays the processing result of the signal processing unit
11. The display unit 12 is, for example, a display, and displays, as a processing result of the
signal processing unit 11, for example, the area X and the position of the sound source in the
area X.
[0063]
[Effects, etc.] As described above, according to the present embodiment, since the influence of the
sound wave coming from the second surface (rear side) can be suppressed, the sound source of
the first surface (front side), that is, the search target The sound source tracking device 1 capable
of more reliably searching for a sound source in a region can be realized.
[0064]
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Further, in the sound source tracking device 1 according to the present embodiment, the
plurality of microphone elements are arranged inside the outer edge of the baffle portion 101 by
a predetermined length or more, and the installation surface and the first surface of the baffle
portion 101 and the installation surface have a predetermined angle. Have.
Thus, the sound source tracking device 1 can distinguish even sound sources that are planesymmetrical with respect to the array surface of the microphone array 102 (a plurality of
microphone elements). In the sound source tracking device 1 for searching a sound source based
on phase information, the phase difference with respect to the sound source of the region Y (rear
side) outside the sound source search target is always larger than the sound source of the region
X (front side) It is from.
[0065]
On the other hand, as a comparative example, in the conventional sound source tracking device,
the phase difference of the sound waves from the sound sources (the sound source on the front
side and the sound source on the back side) becomes plane symmetric with respect to the array
surface of the microphone array. Can not. This will be described more specifically using FIG. 10
and FIG. FIG. 10 is a diagram showing a circular arrayed microphone array 802 in the
comparative example. FIG. 11 is a diagram for explaining the phase difference of the sound
waves coming from the sound source in the plane-symmetrical direction in the circular array
microphone array 802 in the comparative example shown in FIG. As shown in FIG. 10, the
circular array microphone array 802 in the comparative example is constituted by eight
microphone elements (microphone element p1 to microphone element p8), and the maximum
length of the interval between the microphone elements is L 0. In this case, the phase difference
(arrival time difference) of the sound waves arriving from the sound source R on the front side
and the sound source S on the rear side to the microphone element p1 and the microphone
element p5 is τ R15 = L 0 * COS (θ r) / C And τ S15 = L 0 * COS (θ s) / C. Since the sound
source R on the front side and the sound source S on the rear side are plane-symmetrical sound
sources, θr = θs. That is, since the phase differences are equal (τ R15 = τ S15), the circular
array microphone array 802 in the comparative example can not distinguish between the sound
source R and the sound source S.
[0066]
Furthermore, in the sound source tracking device 1 according to the present embodiment, the
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phase difference to the sound source in the region Y (rear side) outside the sound source search
target is always larger than the sound source in the region X (front side) of the sound source
search target. It is possible to remove the influence of the (back side) sound source. Thereby, the
sound source tracking device 1 according to the present embodiment can more reliably search
for a sound source that is in a search target area and has a small arriving sound. That is, the area
Y (rear side) can be excluded from the sound source search range, and in the case of the sound
source of the area X (front side) targeted for the sound source search, the sound source with a
small reaching sound can be searched more reliably be able to.
[0067]
(Modification 1) FIG. 12 is a view showing an arrangement example of the microphone array
102A of the sound collection device 10A in Modification 1. FIG. The same components as those
in FIG. 2 are denoted by the same reference numerals, and the detailed description will be
omitted.
[0068]
Although the plurality of microphone elements constituting the microphone array 102 are
described as being annularly arranged in the above-described embodiment, the present invention
is not limited thereto. For example, a pentagonal shape or an octagonal shape may be arranged.
This is because the distance between the two microphone elements determines the measurable
frequency (upper limit of the frequency). Further, for example, as shown in FIG. 12, a plurality of
microphone elements constituting the microphone array 102A may be arranged.
[0069]
In the example shown in FIG. 12, among the plurality of microphone elements constituting the
microphone array 102A, the microphone elements m1, m3, m5 and m7 are arranged in a ring
shape, and the other microphone elements n1, n2, n3 and n4 are arranged in the circle It is
arranged inside the ring. Thus, the distance from the outer edge of the baffle portion 101 may be
intentionally changed for some of the plurality of microphone elements constituting the
microphone array 102A. In this way, the phase difference between the sound wave coming from
the sound source in the area X (front side) targeted for sound source search and the sound wave
coming from the sound source in the area Y (back side) not targeted for sound source search
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changes You can have it. Thereby, the sound source in the first surface (front side), that is, the
sound source in the search target area can be more reliably searched.
[0070]
(Modification 2) FIG. 13 is a view showing an example of the baffle portion 101B of the sound
collection device 10B in Modification 2. As shown in FIG.
[0071]
In the embodiment described above, the baffle portion 101 is described as being a circular platelike member, but may not necessarily be circular, and may be, for example, a rectangular platelike member as shown in FIG. .
[0072]
In this case, the length of the side of the baffle portion 101B can be calculated based on the
maximum length of the interval between the plurality of microphone elements and the
predetermined angle.
[0073]
More specifically, by setting the diameter d 1 of the baffle portion 101 to the side length d 1 of
the baffle portion 101B, calculation may be performed so as to satisfy the relationship of
(Expression 4) in the same manner.
That is, assuming that the length of the side of the baffle portion 101B is d 1, the maximum
length of the spacing between the plurality of microphone elements is d 0, and the
predetermined angle is θ c, (d 0 / COS (θ c)) < It may be calculated to satisfy the relationship of
d 1.
[0074]
(Modification 3) FIG. 14 is a view showing an arrangement example of the microphone array 102
of the sound collection device 10C in the modification 3.
[0075]
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20
In the above-described embodiment (for example, FIG. 2 and the like) and modification 2 (for
example, FIG. 13), it is assumed that the central position of the baffle portion and the central
position of the microphone array Although explained, it is not limited to it.
As shown in FIG. 14, the center position of the baffle portion 101B may not coincide with the
center position of the microphone array 102 (microphone element m1 to microphone element
m8).
[0076]
(Modification 4) In the embodiment described above, the sound collection device 10 has been
described as being installed on the installation surface 51 as it is, but it is not limited thereto.
The center position of the baffle portion 101 may be installed so as to be about 1 m higher than
the installation surface 51.
[0077]
Although the sound source tracking device and the like according to one or more aspects of the
present invention have been described above based on the embodiments and the modifications,
the present invention is not limited to the embodiments and the like.
Without departing from the spirit of the present invention, various modifications as may occur to
those skilled in the art may be applied to this embodiment, or a configuration constructed by
combining components in different embodiments may be one or more of the present invention. It
may be included within the scope of the embodiments. For example, the following cases are also
included in the present invention.
[0078]
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21
(1) For example, the above-described sound source tracking device may further include an
imaging and photographing means such as a camera. In this case, the above-described sound
source tracking device may have a camera disposed at the center of the microphone array of the
sound collection device, or may have a camera at a position different from the sound collection
device.
[0079]
More specifically, the captured image obtained by the camera is input to the signal processing
unit, and the signal processing unit 11 superimposes a sound source image indicating the
position of the specified sound source on the input captured image, It may be displayed on the
display unit 12 as a processing result.
[0080]
(2) The above signal processing unit may be specifically a computer system including a
microprocessor, a ROM, a RAM, a hard disk unit, a display unit, a keyboard, a mouse and the like.
A computer program is stored in the RAM or the hard disk unit. Each device achieves its function
by the microprocessor operating according to the computer program. Here, the computer
program is configured by combining a plurality of instruction codes indicating instructions to the
computer in order to achieve a predetermined function.
[0081]
(3) Some or all of the components constituting the above signal processing unit may be
configured from one system LSI (Large Scale Integration: large scale integrated circuit). The
system LSI is a super-multifunctional LSI manufactured by integrating a plurality of components
on one chip, and more specifically, a computer system including a microprocessor, a ROM, a
RAM, and the like. . A computer program is stored in the RAM. The system LSI achieves its
functions as the microprocessor operates in accordance with the computer program.
[0082]
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(4) Some or all of the components constituting the signal processing unit described above may be
configured from an IC card or a single module that can be detached from each device. The IC
card or the module is a computer system including a microprocessor, a ROM, a RAM, and the
like. The IC card or the module may include the super multifunctional LSI described above. The
IC card or the module achieves its function by the microprocessor operating according to the
computer program. This IC card or this module may be tamper resistant.
[0083]
INDUSTRIAL APPLICABILITY The present invention can be used for a sound source tracking
device using a plurality of microphone elements, and in particular, a sound source with a small
arrival sound in a search target area such as a radio control helicopter, drone, helicopter or plane
located relatively far from the sound source tracking device. It is available for a searchable sound
source search device.
[0084]
DESCRIPTION OF SYMBOLS 1 sound source search apparatus 10, 10A, 10B, 10C sound
collection apparatus 11 signal processing part 12 display part 51 installation surface 101 baffle
part 101a front surface 101b back surface 102, 102A microphone array 103, 103A support
member 802 circular array microphone array
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