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JP2010025802

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DESCRIPTION JP2010025802
PROBLEM TO BE SOLVED: In a disaster or accident site, sound source search is continued even
under conditions where it is difficult for the searcher to continue searching, a weak sound is
efficiently detected, and deformable to support search and rescue operations of survivors
Provision of sound source search equipment. A sound source search apparatus according to the
present invention has a signal input unit having a microphone array consisting of a plurality of
microphones on a material whose shape can be freely deformed and an AD converter for
converting acoustic signals of a plurality of channels into digital signals. And means for
determining the relative positional relationship of the plurality of microphones provided in the
signal input unit, and controlling the directivity of the signal input unit by signal processing
based on the positional relationship of the microphones determined by the means; The sound
source tracking device includes a signal processing unit that recombines signals of a plurality of
channels, and a signal output unit that converts the signals recombined by the signal processing
unit into an analog signal and acoustically outputs the analog signal. [Selected figure] Figure 1
Sound source search device
[0001]
The present invention relates to a sound source search apparatus using information
communication equipment, and more particularly to a sound source search apparatus using a
deformable superdirective microphone array using three-dimensional acoustic technology, signal
processing technology and the like.
[0002]
04-05-2019
1
In order to rescue as many people as possible in disaster affected areas, it is important to find
survivors quickly.
As a tool to support the search for survivors, a device has been proposed in which a camera, a
microphone, a speaker, a light, etc. are integrally attached to the tip of a telescopic rod (Patent
Documents 1 and 2). Because the range is limited and sounds coming from unspecified directions
are mixed, the usefulness under noise is considered to be poor.
[0003]
In addition, as a sound source tracking device using a microphone array for selectively
emphasizing sound coming from any direction, a portable sound source tracking device (Patent
Document 3) or a car-mounted sound source that a searcher carries and uses A search device
(Patent Document 4) has been proposed. However, it may be difficult for vehicles to approach a
search site in an actual disaster area. In addition, it may be difficult for the searcher to continue
on-site investigations due to sunset, bad weather, and the risk of secondary disaster occurrence.
[0004]
JP-A-11-192318 JP-A-2000-131455 JP-A-2007-180953 JP-A-2007-180942
[0005]
In the affected areas of natural disasters such as earthquakes and typhoons, and large accident
occurrence sites, it is required to quickly find survivors.
At this time, the voices and sounds emitted by the survivors are important clues. Sound is the
best clue, especially when the field of view is limited by obstacles such as rubble. Therefore, there
is a means to amplify the sound collected by a unidirectional microphone or nondirectional
microphone and let the searcher hear it by headphones etc. However, in the case of a
unidirectional microphone, only one direction can be searched at a time. ineffective. In the case
of an omnidirectional microphone, signals coming from unspecified directions are mixed, so the
influence of extraneous noise is strong.
04-05-2019
2
[0006]
By using a microphone array, it is possible to form sharp directivity or focus in any direction by
signal processing, so there is a high possibility of finding a minute signal even under noise.
Moreover, since a plurality of independent directivity can be formed simultaneously, a wide area
can be efficiently searched.
[0007]
The object of the present invention is to provide a microphone array having the above
advantages on a deformable material so that it can be installed according to the topography of
the site, even while the searcher's on-site investigation is interrupted. The purpose is to make it
possible to continue measuring the acoustic signal.
[0008]
The sound source tracking device according to the present invention is a microphone comprising
a plurality of microphones and an AD converter for converting sound signals of a plurality of
channels into digital signals on a curtain-like, net-like, string-like or wire-like material whose
shape can be freely deformed. A signal input unit provided with an array and means for
determining a relative positional relationship of the plurality of microphones provided in the
signal input unit; A sound source tracking device comprising a signal processing unit that
controls directivity and that combines signals of a plurality of channels, and a signal output unit
that converts a signal combined by the signal processing unit into an analog signal and outputs
the signal acoustically .
[0009]
The sound source tracking device according to the present invention may be provided with a
function of creating image information by signal processing from signals of a plurality of
channels in the signal processing unit, and a video output unit for outputting this image.
[0010]
The signal input unit may be subjected to waterproof processing or water repellent processing
for protecting the microphones so that the plurality of microphones provided in the signal input
unit are not immersed in the liquid.
04-05-2019
3
[0011]
A plurality of microphones provided in the signal input unit can be covered with a windscreen for
suppressing the generation of wind noise.
[0012]
According to the present invention, a sound source search device which can be arranged
according to the topography of a search site is provided, and sound measurement can be
continued even in a situation where it is difficult for the searcher to continue investigation on the
site due to the risk of secondary disaster occurrence etc. It becomes.
[0013]
By using the microphone array technology, it is possible to generate sharp directivity in any
direction, which makes it easy to detect a weak signal emitted under a noise environment.
In addition, in the microphone array, since multiple directivity can be controlled independently, it
is possible to search in multiple directions simultaneously.
[0014]
Furthermore, it is possible to use wireless technology etc. to transmit signals from the signal
input unit to the signal processing unit, and the observer observes the sound of the search target
area while being in a place where the risk of secondary disasters is small. It is possible to
continue.
That is, even if the searcher's investigation of the site is interrupted due to sunset or bad weather,
the observer in a safe place can be synthesized by the signal processing unit by installing the
sound source search apparatus according to the present invention on the site. It becomes
possible to continue monitoring the sound and the image, and the search activity by the sound
source search can be continued regardless of day and night without spending valuable time.
[0015]
04-05-2019
4
Since the sound source tracking device of the present invention is deformable, it can be folded or
rounded when not in use.
Therefore, the vehicle can be brought to a place where it can not approach.
When using it, it will be used by expanding it to the size or length according to the topography of
the site.
[0016]
An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a configuration example of a sound source tracking device according to the present
invention.
In the figure, the signal input unit 1 comprises a microphone array comprising a plurality of
microphones and amplifiers disposed on a deformable material and an AD converter. Since the
signal input unit is deformable, it can be installed in the search target area according to the
topography of the site. The shape of the deformable material may be a curtain like a vinyl sheet,
a net shape, a string shape or a wire shape. Although the material is not limited, it is desirable
that the sound source tracking device of the present invention be strong and have excellent
water resistance so as to withstand use under severe conditions. In addition, since exposure to
strong wind is also assumed, it is desirable to devise measures to suppress the generation of wind
noise as much as possible.
[0017]
An acoustic signal received by a plurality of microphones in the signal input unit 1 is converted
into a digital signal by an AD converter, and is sent to the signal processing unit 2. At this time,
by transmitting using wireless communication as shown, the observer can continue to observe
the sound of the search target area while being in a place where the risk of secondary disaster is
small, but the present invention It is also possible to use other communication means, such as
04-05-2019
5
wired. The signal processing unit 2 delays and adds signals of a plurality of channels
corresponding to a plurality of microphones to give directivity to the signal input unit in an
arbitrary direction. As a result, the sound coming from any direction is selectively emphasized
and presented from the signal output unit 3. The directivity of the signal input unit is generated
by signal processing and can be freely set in the direction desired by the observer.
[0018]
The signal processing unit 2 performs delay-and-sum combining in all directions in the search
target area, creates an image that expresses the difference in the level of the obtained signal as
the difference in color, lightness, etc. can do. The observer can look at this image to deduce in
which direction the sound is present.
[0019]
FIG. 2 shows an embodiment in which the microphone array is arranged on a string-like or wirelike deformable material. Since the signal processing unit and the like are the same as in FIG. 1,
they are omitted. Since the signal input unit 1 is deformable, it can be inserted into a narrow
space having a complicated shape.
[0020]
Here, the directivity can be formed in an arbitrary direction by the delay-sum combination when
the time difference required for the sound arriving from that direction to reach each microphone
is known. Since the signal input unit of the present invention has an indefinite shape and changes
according to the topography of the site, it is necessary to determine the relative positional
relationship between the microphones by some method in order to know the arrival time
difference of sound. The method of determining the positional relationship between the
microphones is not limited to a specific method, and a gyro technology, a GPS position sensor, or
a technology combining them may be used.
[0021]
04-05-2019
6
In addition, since the microphone is a sensor that receives sound, means for using the sound to
determine the positional relationship between the microphones can be considered. A method of
determining the position of the microphone using sound will be described with reference to FIGS.
3 and 4.
[0022]
FIG. 3 shows an example of the configuration of the signal input unit in the case of including
means for determining the position of the microphone using sound. Here, the signal input unit 1
includes a signal sound generator A for generating a signal sound, a signal sound generator B,
and a signal sound generator C. These sound generators are speakers or tweeters, or ultrasonic
transmitters, etc., which are installed at the search site at a spatially sufficient distance to
generate an audio signal or an ultrasonic signal. The signal to be generated is preferably a pulselike signal of short duration. The generated signal propagates in the air at the speed of sound c
(m / s) and is received by the individual microphones. Therefore, when the signals generated
from the tone generator reach the individual microphones, a time difference occurs depending on
the distance from the tone generator to each microphone. Using the difference in arrival time as
a clue, it is possible to determine the positional relationship of each microphone with respect to
the signal sound generator.
[0023]
FIG. 4 schematically shows a method of obtaining the position of the microphone from the arrival
time of the signal sound. Assuming that it takes da seconds for the signal output from the tone
generator A to reach an arbitrary microphone x, and db seconds for the signal output from the
tone generator B to reach the same microphone x, the microphone x is centered on the signal
sound generator A and is on the spherical surface of radius Ra, and is also centered on the signal
sound generator B and on the spherical surface of radius Rb. That is, the microphone x will be on
the circumference ab shown in the figure. Here, the radii Ra and Rb are the product of the speed
of sound and the arrival time, that is, Ra = c × da Rb = c × db. Furthermore, although not shown
in FIG. 4, if there is a third tone generator (tone generator C), the time taken for the signal output
from this tone generator C to reach the microphone x is taken. Assuming that it is dc, the position
of the microphone x is located at the intersection of the spherical surface of radius Rc = c × dc
and the above-mentioned circumference ab with the signal sound generator C at the center.
There are two intersection points at the maximum unless the signal sound generators A, B and C
are arranged in a straight line, and the position of the microphone x is narrowed to two points by
using three signal sound generators. become. In this way, it is possible to determine the relative
04-05-2019
7
positional relationship of the microphones from the difference in time for the signal sounds
outputted from the plurality of signal sound generators to reach the individual microphones. At
this time, although position estimation becomes difficult when signals output from a plurality of
signal sound generators interfere with each other, interference can be avoided by shifting the
timings and frequency bands of the signal sounds generated from the respective signal sound
generators. it can. If the positional relationship of a plurality of microphones is known by the
method as described above, the directivity of the signal input unit can be controlled by the
method described below.
[0024]
Next, a method of generating directivity in an arbitrary direction using a microphone array will
be described using FIG. The example of FIG. 5 is a two-channel microphone array, and a direction
indicated by an angle α in the drawing is a target direction. In the figure, the time difference
between sounds arriving from the target direction reaching the two microphones is the
difference between the distances r × cos α divided by the speed of sound c, ie, the time
difference of arrival = (r × cos α) / c. As shown in the left view of FIG. 5, the sound arriving
from the target direction first reaches the microphone 1 and reaches the microphone 2 with a
delay of (r × cos α) / c (seconds). Here, as shown in the right figure of Fig. 5, if the path of
channel 1 is delayed by (r × cos α) / c (seconds) and then the signals of both channels are
synthesized, the timing of the sound coming from the target direction is Since the channels are
aligned, the maximum addition effect can be obtained, while the interchannel time difference
exists for sounds coming from other than the target direction, so the maximum addition effect
can not be obtained. As a result, the sound coming from the target direction is selectively
emphasized. In the signal processing unit of the present invention, strong directivity is generated
in an arbitrary direction by so-called delay-sum combining in which signals of all channels are
synthesized after controlling delays of individual channel paths.
[0025]
Note that FIGS. 3 and 4 show an example of a method of determining the positional relationship
of a plurality of microphones, and any other method may be used if the relative positional
relationship between the microphones can be determined.
[0026]
The sound source tracking device according to the present invention can be widely used for
sound source search applications, and survivor search in a disaster stricken area is an example of
the application.
04-05-2019
8
[0027]
The basic embodiments of the present invention have been described above, but the present
invention is not limited to these embodiments.
Appropriate modifications can be made without departing from the scope of the present
invention.
[0028]
The structural example of the sound source search apparatus of this invention.
The schematic diagram of the sound source search apparatus which has a string-like or wire-like
signal input part by this invention. The structural example of the signal input part provided with
a means to obtain | require the position of a microphone using a sound. The schematic diagram
explaining the method of calculating | requiring the position of a microphone using a sound. The
schematic diagram explaining the method to produce | generate the directivity of a microphone
array by delay sum synthetic | combination.
Explanation of sign
[0029]
1 signal input unit 2 signal processing unit 3 signal output unit 4 video output unit
04-05-2019
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