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JP2017005517

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DESCRIPTION JP2017005517
Abstract: [Problem] To provide a sound collector that can reduce the sound coming from the
back direction to the front surface by devising the parabolic reflector shape. A sound collector is
provided with a parabola reflector at a focal position on the front surface and a parabola reflector
for picking up sound through the mike, wherein the sound of the back of the parabola reflector is
provided on the outer periphery of the parabola reflector The rear sound diffraction preventing
portion is provided to prevent the rear side from coming around to the front. [Selected figure]
Figure 1
Sound collector
[0001]
The present invention relates to a sound collector that places a microphone at the focal position
of a parabolic reflector and picks up distant sounds through the microphone.
[0002]
There is one using a parabolic reflector as a sound collector for collecting distant sounds.
The parabolic reflector is a reflector having a parabolic curved surface, and has a focal point like
a lens.
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[0003]
FIG. 8 (a) shows an example of a sound collector using a conventional parabolic reflector. This
sound collector is a sound collector in which a microphone (parabola microphone) is installed on
a parabolic reflector. When the microphone 3 is installed on the concave side of the front surface
of the parabolic reflector 2, the sound from a distance is as shown in FIG. As shown by the arrow
in (b), the light is reflected by the parabolic reflector 2 and collected by the microphone 3
installed at the focal position. As a result, a large gain can be obtained as compared with the case
where the microphone alone picks up sound, and distant sounds can be picked up clearly.
[0004]
In parabolic microphones, it is desirable not to pick up any sound other than the sound collection
target. However, for example, a person may stand and talk on the back side of the sound
collector. If there is such a sound source on the back of the parabolic reflector 2, that back sound
will move to the front, and the diffracted sound that has been rolled back will overlap at the focal
point where the parabolic microphone is installed, and the sound from the sound collection
object It reduces the clarity.
[0005]
In order to solve this, there is a parabolic reflector in which two microphones having different
directivity are installed. One is a cardioid microphone directed to the front of the parabolic
reflector, and the other is a superdirective microphone opposite to the parabolic reflector, ie,
directed to the sound source, and the audio signal collected by these two microphones is By
adding at an appropriate ratio, only a target distant sound is effectively collected, and an
unnecessary sound from the back and the side is not picked up (Patent Document 1).
[0006]
Unexamined-Japanese-Patent No. 10-224882 gazette
[0007]
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However, this method requires the use of two microphones, one of which has the problem of
requiring a special microphone called a superdirective microphone.
Furthermore, processing for adding the signals collected by the two microphones is also
required, and the configuration is complicated, and there is a problem that the cost is increased
correspondingly.
[0008]
The present invention has been proposed in view of the above, and an object thereof is a sound
collector which can reduce the sound from coming from the back direction to the front by adding
a device to the parabolic reflector shape. It is to provide.
[0009]
The invention according to claim 1 is a sound collector provided with a parabolic reflector
provided with a microphone 3 at a focal position on the front surface and picking up sound
through the microphone 3, wherein the outer peripheral portion of the parabolic reflector 2
Furthermore, the back surface sound diffraction preventing portion 4 is provided to prevent the
sound of the back surface of the parabolic reflector from coming around to the front surface.
The invention according to claim 2 is characterized in that, in the sound collector according to
claim 1, the back sound diffraction prevention unit 4 is provided over the entire outer peripheral
portion of the parabolic reflector 2. The invention according to claim 3 is characterized in that, in
the sound collector according to claim 1, the back sound diffraction preventing portion 4 is
curved toward the front to form a protruding cross-section semicircular shape. The invention
according to claim 4 is characterized in that, in the sound collector according to claim 1, the back
surface sound diffracting portion 4 has a Y-shaped cross section or a T-shaped cross section.
[0010]
According to the present invention according to claims 1 to 4, since the back surface sound
diffraction preventing portion 4 is provided on the outer periphery of the parabolic reflector 2, it
is possible to attenuate the sound on the back surface from coming around to the front surface.
Can be picked up clearly. In addition, since this sound collector has a simple structure in which
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the back surface sound diffraction prevention unit 4 is integrally provided on the outer periphery
of the parabolic reflection plate 2, cost increase can be prevented, and the strength of the
parabolic reflection plate 2 by the back surface sound diffraction prevention unit 4 Also has the
advantage of improving.
[0011]
(A) is a schematic front view of the sound collector concerning 1st Example of this invention, (b)
shows the same side view. It is explanatory drawing of the calculation model of sound pressure
distribution with respect to a sound collector. It is operation ¦ movement explanatory drawing
which shows the flow of the parabolic reflector back sound of a sound collector, (a) is this
invention, (b) shows a conventional product. (A), (b) is explanatory drawing which shows the
state of sound pressure distribution of 1st Example of this invention, (c), (d) shows the state of
sound pressure distribution of the prior art example in contrast with this invention. FIG. 1 is a
perspective view of a sound collector according to a first embodiment of the present invention.
(A) is a schematic front view of 2nd Example of this invention, (b) is a side view. One use example
of the present invention is shown. (A) is a schematic front view of a prior art example, (b) shows
operation ¦ movement explanatory drawing.
[0012]
FIG. 1 (a) is a schematic front view of the sound collector 1 according to the first embodiment of
the present invention, FIG. 1 (b) is a schematic side view, 2 is a parabolic reflector whose front is
curved on a concave surface, 3 is its focal point A microphone 4 provided at the position is a
back sound diffraction preventing portion provided over the entire outer periphery of the
parabolic reflector 2.
[0013]
The present invention is characterized in that the parabolic reflector 2 is provided with a back
sound diffraction preventing portion 4 having a semicircular cross section with the front surface
projecting in an arc shape forward.
Since the back surface sound diffraction prevention part 4 provided in the shape of a flange on
the outer periphery of the parabolic reflection plate 2 is integrally provided with the parabolic
reflection plate 2, there is an advantage that the strength is also improved.
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[0014]
FIG. 2 shows a point collector 5 having a sound pressure level of 90 dB at a distance of 2 m in
the back direction of the parabolic reflector 2 in the sound collector provided with the
conventional parabolic reflector 2 without the back surface sound diffraction prevention part 4
of 30 cm in diameter. The case of measuring the sound pressure distribution in the periphery of
the parabolic reflector when it is present is shown.
[0015]
When a sound source is present on the back side of the parabolic reflector 2, as shown by the
arrows in the conventional product, the back sound a wraps around the front of the parabolic
reflector 2 as shown by the arrow.
[0016]
However, as shown in FIG. 3 (a), in the present invention, since the back surface sound diffraction
preventing portion 4 is provided on the outer periphery of the parabolic reflector 2, the back
surface sound a is a concave curved portion on the back surface. It is easy to flow to the back
side along the diffraction prevention part 4 and the diffraction to the front side of the parabolic
reflector 2 is prevented or attenuated.
[0017]
FIG. 4 shows the sound pressure distribution around the parabolic reflector calculated using the
calculation method shown in FIG.
[0018]
4 (a) and 4 (b) show the sound pressure distribution of the product of the present invention
having the back sound diffraction prevention unit 4, FIG. 4 (a) shows the sound pressure
distribution at a frequency of 2 kHz, and FIG. 4 (b) shows a frequency of 4 kHz. The sound
pressure distribution at
[0019]
On the other hand, FIGS. 4C and 4D show the case of the conventional example without the back
surface sound diffraction preventing unit 4, and FIG. 4C shows the sound pressure distribution at
a frequency of 2 kHz, and FIG. The sound pressure distribution at a frequency of 4 kHz is shown.
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[0020]
The scales shown on the right of each of the figures (a) to (d) show the sound pressure in color
and numerical value.
The sound pressure changes from 30 dB to 90 dB from the lower part to the upper part of the
scale, and this is shown by the shade of color.
[0021]
In the present invention shown in FIGS. 4 (a) and 4 (b), the amount of back noise is small, and the
microphone setting position on the front surface of the parabolic reflector 2 is approximately 72
dB to 70 dB.
[0022]
On the other hand, in the conventional example, as shown in FIGS. 4 (c) and 4 (d), the sound
pressure is about 84 dB around the microphone installation position.
[0023]
As described above, according to the present invention, since the back surface sound diffraction
preventing portion 4 is provided, the energy of the sound coming around to the front surface is
reduced, and it can be said that the sound from the back surface picked up by the microphone 3
can be attenuated.
Therefore, by acoustically reducing the sound from the back surface direction of the parabolic
reflector 2, it is possible to clearly pick up the target distant sound source.
[0024]
On the other hand, in the conventional example shown in FIGS. 4 (c) and 4 (d), it is understood
that the back sound is diffracted at the paraboloid peripheral edge and the interference wave is
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generated at the front of the parabola by the sound wave.
It can be seen that, at the position where the microphone 3 in the center in the front direction of
the parabola is installed, the sound pressure becomes strong due to the overlapping of the
interference waves, which is approximately 84 dB.
[0025]
FIG. 5 shows a perspective view of the first embodiment of the present invention.
The microphone 3 is provided at the focal position of the parabolic reflector 2 by the support 3 a.
Reference numeral 6 denotes a grip provided on the back of the parabolic reflector 2.
[0026]
FIG. 6 shows a second embodiment of the present invention in which the back sound diffraction
preventing portion 4 'is formed in a Y-shaped cross section.
The operation and effect of the second embodiment are substantially the same as those of the
first embodiment.
Also, it may be T-shaped in cross section.
[0027]
FIG. 7 shows an example of use of the present invention.
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For example, in the case of a fire of building 7, when a resident on a floor above the floor where
fire 8 is out loses a refuge, evacuates on the roof 9 and seeks help, the sound collector 1 of the
present invention If the rescuer 10 is directed to the evacuees 11 on the roof, a cry for help of
the evacuees 11 can be picked up, whereby an appropriate rescue operation can be performed.
[0028]
In addition, it is possible to pick up the moan of the person under the house destroyed by the
large earthquake, and the present invention is useful for lifesaving activities at the time of
disaster, and has great industrial usefulness.
[0029]
DESCRIPTION OF SYMBOLS 1 sound collector 2 parabola reflector 3 microphone 4 back sound
diffraction prevention part 5 point sound source 6 holding part 7 building 8 fire 9 roof 10
rescuer
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