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JP2011107084

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DESCRIPTION JP2011107084
An acoustic signal for accurately extracting a true signal sound by reducing interference noise
from a direction opposite to the signal sound direction by deforming a dipole directivity
characteristic formed by two detectors by signal processing. To provide a processing device. An
acoustic signal processing apparatus 10 performs cross spectrum processing of two acoustic
signals received by detectors 1X and 1Y with a cross spectrum computing unit 2, and an
imaginary number of phase information obtained by the cross spectrum computing unit 2. The
part is extracted by the imaginary part extraction unit 3. The adder 8 adds the phase delay θ of
the phase delay unit 6 to the extracted imaginary part and performs weighting by the weighting
unit 14, and the phase-delayed imaginary part is output from the cross spectrum computing unit
2 by the multiplication processor 4. The calculated amplitude information is successively
multiplied, and the calculated output is outputted from the output unit 5. [Selected figure] Figure
1
Acoustic signal processor
[0001]
The present invention relates to an acoustic signal processing apparatus, and in particular,
detects sound waves, vibration waves, and the like coming from a plurality of directions as
physical quantities such as displacement, vibration, pressure, etc. Audio signal processing
apparatus for extracting
[0002]
04-05-2019
1
Conventionally, when two sound detectors are arranged close to each other to measure the sound
propagation direction or size, there may be a case where the waveform limitation of the sound
source due to the detector interval or the measurement accuracy of the sound source decreases.
The
In order to prevent such a decrease in measurement accuracy, Patent Document 1 performs FFT
processing on signals received by two detectors, analyzes phase information, and in the
frequency band where the degree of correlation is high, the phase difference between the two
signals. There is disclosed a technology for calculating the sound source direction from the rate
of change with respect to the frequency of.
[0003]
In addition, as a method of measuring the propagation direction and magnitude of sound, two
nondirectional detectors are arranged close to each other to form a dipole directivity
characteristic and to measure the propagation direction and magnitude of sound. There is an
intensity law. This sound intensity method determines which sound source has arrived from
which sound source by detecting the arrival time difference of the input signals of the detectors
(microphones etc.) constituting the array on the frequency axis, and It separates frequency
components.
[0004]
Unexamined-Japanese-Patent No. 2000-266832
[0005]
However, in such a conventional sound intensity method, when the signal sound direction at the
target frequency and the interference noise from the opposite direction are mixed, an error
occurs in signal component extraction, and the accuracy of the measurement result becomes It
sometimes got worse.
[0006]
Therefore, the present invention reduces interference noise from the direction opposite to the
signal sound direction by transforming the dipole directivity characteristic formed by two
detectors by signal processing, and extracts the true signal sound with high accuracy. It is an
object of the present invention to provide an acoustic signal processing apparatus.
04-05-2019
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[0007]
In order to achieve the above object, an acoustic signal processing apparatus according to the
present invention is previously determined in an acoustic signal processing apparatus that
receives sound waves coming from a plurality of directions and extracts sound waves in a
predetermined direction. Cross spectrum calculator for calculating amplitude information and
phase information from the cross spectrum of the signal detected by each detector, and at least
two detectors arranged along the reception direction of the received sound wave A first
imaginary part extractor for extracting an imaginary part of phase information outputted from
the first phase delayer, and a first phase delayer for controlling the first phase delayer according
to a predetermined phase delay value First phase controller, a first adder for adding a phase
delay to the extracted imaginary part, a first weighter for weighting an imaginary part to which
the phase delay is added, and a weighted imaginary number The and having a first multiplier for
multiplying the amplitude information of the cross spectrum, the.
[0008]
Further, in the acoustic signal processing device according to the present invention, a plurality of
second phase delay devices and a plurality of second phase delay devices are provided in order
to form a directivity pattern in which the sensitivity in the opposite direction to the desired
direction is reduced. And the imaginary part output from the first imaginary part extractor is
branched by a predetermined number of phase delayers, and branched. A second adder for
adding a plurality of phase delays to the imaginary part, a second weighter for weighting a
plurality of imaginary parts to which each phase delay is added, and each imaginary part
superimposed is a cross spectrum And second multipliers that respectively multiply the
amplitude information.
[0009]
Further, in the acoustic signal processing device according to the present invention, the first or
second phase controller is characterized in that the angle of the directivity pattern can be
arbitrarily changed by changing the phase delay.
Since the directivity pattern angle changes according to the frequency of the signal of interest, it
is preferable to set a phase delay according to the frequency of the signal.
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[0010]
Further, in the acoustic signal processing device according to the present invention, the
directivity width narrower than the directivity width before multiplication is formed by
multiplying a plurality of directivity patterns respectively changed in an arbitrary angular
direction.
Specifically, a directivity pattern formed by combining a plurality of phase delays is used to form
a plurality of directivity patterns rotated to a desired azimuth angle, and multiplication is
performed to obtain an azimuth angle and a directivity width. It can be set arbitrarily.
[0011]
In the acoustic signal processing apparatus according to the present invention, three-dimensional
control of three-dimensional directivity is enabled by arranging at least four detectors in a threedimensional manner.
With such a configuration, directivity can be narrowed as compared with the conventional type
by arbitrarily setting the azimuth angle and the directivity width while being a detector used in
the acoustic intensity method.
[0012]
In the acoustic signal processing apparatus according to the present invention, the medium at the
installation site of the detector can be applied to any medium regardless of whether it is air or
liquid.
In particular, it can also be applied to the propagation of solids in water, in air, in the ground and
in mechanical structures.
[0013]
By using the acoustic signal processing apparatus according to the present invention, it is
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possible to deform the dipole directivity characteristic usually used in the acoustic intensity
method by signal processing, and reduce disturbance noise from the direction opposite to the
signal sound direction. There is an effect that it becomes possible.
[0014]
FIG. 1 is a block diagram showing a basic configuration of an acoustic signal processing device
according to the present invention.
It is a block diagram showing composition of an acoustic signal processing device used as
reference in understanding the present invention.
It is a related figure showing the relation between two detectors and a signal arrival direction. It
is a pattern figure of the general dipole directivity characteristic formed of two detectors. It is a
block diagram showing an example of an acoustic signal processing device concerning the
present invention. In the acoustic signal processing apparatus of FIG. 5, it is a directivity pattern
figure in, when phase delay is changed. In the acoustic signal processing apparatus of FIG. 5, it is
a directivity pattern figure in, when phase delay is changed. FIG. 7 is a pattern diagram showing a
change in directivity pattern near a phase delay of 54 degrees in FIG. 6. It is a characteristic view
which shows the relationship between the phase delay and the frequency of a sound wave in this
embodiment. FIG. 6 is a directivity pattern diagram using two phase delayers in the acoustic
signal processing device of FIG. 5; FIG. 6 is a directivity pattern diagram using two phase
delayers in the acoustic signal processing device of FIG. 5; FIG. 6 is a directivity pattern diagram
using two phase delayers in the acoustic signal processing device of FIG. 5; FIG. 6 is a directivity
pattern diagram using three phase delayers in the acoustic signal processing device of FIG. 5; FIG.
6 is a directivity pattern diagram using three phase delayers in the acoustic signal processing
device of FIG. 5; FIG. 6 is a directivity pattern diagram using four phase delayers in the acoustic
signal processing device of FIG. 5; It is a block diagram which shows the other example of the
acoustic signal processing apparatus which concerns on this invention. FIG. 17 is a block diagram
of an integrated processor of the audio signal processing device of FIG. 16; FIG. 17 is a directivity
pattern diagram when the central azimuth of a beam and the directional azimuth width
(directional width) from the beam center are changed in the acoustic signal processing device of
FIG. 16; It is a directional pattern figure at the time of narrowing a directional bearing width |
variety by multiplying three directional pattern of FIG. 18 together. In the acoustic signal
processing apparatus of FIG. 16, it is a directivity pattern figure at the time of swinging the
center direction of a beam 90 degrees. It is a directional pattern figure at the time of narrowing a
directional width by multiplying three directional patterns of FIG. 20 together.
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[0015]
Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an
embodiment) will be described according to the drawings.
[0016]
First, an example of the acoustic signal processing apparatus according to the present
embodiment will be outlined using the block diagram of FIG.
A characteristic matter in the present invention is to form a desired directivity pattern by adding
time delay or phase delay to one of the two detectors in accordance with the frequency of the
sound wave to be extracted. For this purpose, the acoustic signal processing apparatus 10 of FIG.
1 has a phase delay unit 6, a phase controller 7 for controlling each phase delay amount of the
phase delay unit 6, and weighting for multiplying the amplitude by the signal added with the
phase delay. And a multiplier 4 for multiplying the multiplied signals. The details will be
described after the basic configuration is described.
[0017]
FIG. 2 shows a reference configuration of the acoustic signal processing apparatus 20 which is a
reference for understanding the present invention. FIG. 2 shows an acoustic signal processing
apparatus 20 used for general acoustic intensity measurement, in which detectors 1X and 1Y for
receiving sound waves, and cross spectrum processing of two acoustic signals received by the
detectors 1X and 1Y Cross spectrum calculator 2, an imaginary part extractor 3 for extracting an
imaginary part of the phase information obtained by the cross spectrum calculator 2, an
imaginary part obtained by the imaginary part extractor 3, and an amplitude of the cross
spectrum calculator 2. It has a multiplication processor 4 for multiplying information and an
output unit 5 for outputting various displays and the like. The multiplication processor 4
performs multiplication by the medium density and frequency in the measurement environment
(underwater, air, etc.) in which the detectors are installed, and the interval between two
detectors. Next, the arrangement of the detectors will be described.
[0018]
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FIG. 3 shows the relationship between the two detectors 1X, 1Y and the signal arrival direction.
The detectors 1X and 1Y are nondirectional microphones, and the distance between the
detectors 1X and 1Y is Δr. Also, the measurement orientation is set with reference to a line
passing through the detectors 1X and 1Y. Here, assuming that the signal arrival direction is φ,
the time difference between the signals arriving at each detector is τ, and the sound velocity c of
the medium, the distance due to the time difference τ is τ · c. Detectors 1X and 1Y are
nondirectional detectors, but the time relationship of arrival of the acoustic signal is that when φ
<± 90 degrees, detector 1Y receives the acoustic signal before 1X, and φ = ± At 90 degrees,
the reception times of the acoustic signals of the detectors 1Y and 1X are simultaneous, and
when φ> ± 90 degrees, 1X receives the acoustic signal before 1Y. The time difference τ at
which the detector 1X and the detector 1Y capture an acoustic signal from the signal arrival
direction φ can be expressed by the following equation: τ = Δr · cos (φ) / c Equation (1)
[0019]
Also, the directivity pattern formed by the two detectors (1X, 1Y) is as shown in FIG. The
circumferential direction in FIG. 4 indicates the azimuth φ (degree) in which signals and noise
arrive, and the direction extending radially from the central part of the directivity pattern
indicates the level (dB) indicating the strength of the signal. Become. The sensitivity in the
azimuth near 0 degrees and 180 degrees in Fig. 4 is high, and conversely, in the azimuths near
90 degrees and 270 degrees, the dipole directivity characteristic in which the signals of the two
detectors interfere and the sensitivity decreases and approaches zero. It shows. Also, the
directivity pattern is vertically and horizontally symmetrical on the paper. Here, in order to
change the directivity pattern arbitrarily, it is necessary to set the phase difference between the
detectors 1X and 1Y in order to control signal interference.
[0020]
Thus, the flow of signals in the basic configuration of the present invention will be described. The
acoustic signal processing apparatus 10 of FIG. 1 performs cross spectrum processing of the two
acoustic signals received by the detectors 1X and 1Y with the cross spectrum computing unit 2,
and the imaginary part of the phase information obtained by the cross spectrum computing unit
2 The imaginary part extraction unit 3 extracts the imaginary part. The adder 8 adds the phase
delay θ of the phase delay unit 6 to the extracted imaginary part and performs weighting by the
weighting unit 14, and the phase-delayed imaginary part is output from the cross spectrum
04-05-2019
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computing unit 2 by the multiplication processor 4. The calculated amplitude information is
successively multiplied, and the calculated output is outputted from the output unit 5.
[0021]
The phase delay unit 6 is controlled by the phase control unit 7, and the adder 8 applies a phase
delay to the extracted imaginary part and outputs it to the weighting unit 14. The weighting
device 14 changes directivity by deforming the dipole directivity. The multiplication processor 4
includes cross spectrum amplitude information, a signal with phase delay weighted, frequency f
(Hz) of acoustic signal, medium density ((kg / m <3>), inter-detector distance Δr (m), etc. The
physical quantities of are multiplied and output to the output unit 5.
[0022]
Here, when the phase delay added to the acoustic signal of the detector 1X by the phase delay
unit 6 is determined as the delay time t, the delay θ (degrees) instructed from the phase
controller and the frequency f of the acoustic signal It can be expressed as (Equation 2) t = θ /
(360 f) Equation (2) In the above equation, the time relationship between the acoustic signals of
the detector 1X and the detector 1Y is time = 0 and time = τ + t, respectively. The inter-detector
distance Δt, which is a parameter of the embodiment, is, for example, Δr = 0.045 m within 3 dB
of measurement tolerance within a frequency bandwidth from f = 100 Hz to 10 kHz according to
acoustic intensity theory in water. Of c was 1480 m / s.
[0023]
6 to 7 show pattern changes of directivity formation results when the phase delay θ is changed
by the phase controller 7 of the acoustic signal processing device 30 of FIG. First, the phase delay
θ was set for the purpose of enhancing the sensitivity of the signal arriving from the azimuth of
0 ° and reducing the sensitivity of the signal from the azimuth of 180 ° where the disturbance
sound such as the reflected wave arrives. 6A shows the directivity pattern when the phase delay
θ = 18 degrees, FIG. 6B shows θ = 36 degrees, and FIG. 6C shows θ = 54 degrees. When the
phase delay θ is added, the vertical asymmetry is lost as viewed on the paper, but the left-right
symmetry is maintained, and the lower sensitivity decreases as the angle θ is increased.
Comparing the general directivity pattern shown in FIG. 4 with the directivity pattern in FIG. 6,
the sensitivity above hardly changes, and at 0 degrees <azimuth <90 degrees and 270 degrees
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<azimuth <360 degrees It almost matches. From this, it is understood that the downward
interference noise can be reduced by the directivity pattern at θ = 54 degrees.
[0024]
Next, the phase delay θ was set for the purpose of enhancing the sensitivity of the signal
arriving from the azimuth 180 ° and reducing the sensitivity of the signal from the azimuth 0 °
at which the disturbance sound such as the reflected wave arrives. FIG. 7D shows directivity
patterns when the phase delay θ = 162 degrees, (e) is θ = 144 degrees, and (f) is θ = 126
degrees. As shown in FIG. 7, the upper and lower objects are broken as viewed on the paper, but
the left-right symmetry is maintained. Similarly, comparing the general directivity pattern shown
in FIG. 4 with the directivity pattern in FIG. 7, the lower sensitivity hardly changes, and 90
degrees <azimuth angle <180 degrees and 180 degrees <azimuth angle <270 The degrees almost
match. From this, it is understood that the upward interference noise can be reduced by the
directivity pattern at the phase delay θ = 126 degrees. In other words, it means that the
insensitive direction can be arbitrarily changed by the phase controller 7. However, since it was
unclear whether or not the phase delay of 54 degrees and 126 degrees was optimal, it was
determined by simulation that the change in directivity pattern in the vicinity of the phase delay
of 54 degrees.
[0025]
FIG. 8 shows the result of simulation of directivity patterns of the acoustic signal at a frequency
of 10 kHz from θ = 50 degrees to θ = 57 degrees in steps of one degree. As a condition of the
preferred directivity pattern, a pattern in which the sensitivity at an azimuth angle of 180
degrees in the opposite direction to the azimuth angle of 0 degree is the smallest is set as a good
pattern. In FIG. 8, the sensitivity (−26 dB) at an azimuth angle of 180 degrees gradually
decreased as the phase delay was increased from θ = 50 degrees by 1 degree, and became 0 at
θ = 54 degrees. As the phase delay is further increased, the sensitivity at an azimuth angle of
180 degrees increases at θ = 55 degrees, and the sensitivity becomes −26 dB at θ = 57
degrees. The same result was obtained at θ = 124 °. From this it has been found that a phase
delay of 54 degrees and 126 degrees is preferred at a frequency of 10 kHz.
[0026]
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In addition, since the directivity pattern is also influenced by the frequency of the acoustic signal,
the optimum phase delay with respect to the frequency is calculated by simulation. FIG. 9 shows
the relationship of the degree of phase delay when the frequency of the sound wave is changed
from 1 kHz to 10 kHz. In FIG. 9, when the frequency is increased from 1 kHz to 1 kHz, the phase
delay is increased, but the increase rate is reduced when the frequency exceeds 5 kHz, and the
phase delay becomes 57 degrees at a frequency of 8 kHz. From this, it was found that when the
frequency is 10 kHz, the phase delay θ = 54 degrees is preferable, and for example, at the
frequency 5 kHz, the phase delay θ = 47 degrees is preferable.
[0027]
By appropriately setting the relationship between the frequency (for example, 10 kHz) of the
acoustic signal and the phase delay (for example, θ = 54 degrees) from the above-mentioned
simulation, a preferable directivity pattern can be obtained even by adding only one phase delay.
. However, for example, even in the case of θ = 54 degrees, although the sensitivity difference of
20 dB can be secured near azimuth angle = 150 degrees and 210 degrees, it has some sensitivity.
So we made an acoustic signal controller that can investigate combinations of two to four phase
delays.
[0028]
The acoustic signal processing device 30 of FIG. 5 can set a combination of a plurality of phase
delays by the phase controller 7 in order to facilitate directivity formation by a plurality of phase
delay devices. The acoustic signal processing device 30 extracts the imaginary part from the
phase information φ (12) obtained by the cross spectrum calculator 2 by the sin (φ) calculation
of the imaginary part extractor 3, and then extracts n phase delayers 6. It is branched and a
plurality of phase delays are added by the adder 8 to the imaginary part. Further, after the sound
signal processing device 30 performs a weighting operation of sin <2> (sin (φ) + θ) with a
plurality of weighting devices 14 on the added imaginary part, the multiplication processor 4
calculates the cross spectrum. The configuration is such that the imaginary part weighted by the
amplitude information (11) is multiplied.
[0029]
First, using the acoustic signal processing device 30 of FIG. 5, changes in directivity patterns
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were investigated using two (two series) phase delayers. 10 to 12 show directivity patterns using
two phase delay units (6a, 6b) in the acoustic signal processing device 30 of FIG. The phase delay
is made 0 degrees and 36 degrees in FIG. 10 (a1) by such two series of phase delay devices. In
the directivity pattern of FIG. 10 (b1), although the sensitivity at an azimuth angle of 90 degrees
and 270 degrees is lowered, the sensitivity at an azimuth angle of 180 degrees is not lowered,
and preferable characteristics can not be obtained.
[0030]
In FIG. 11 (a2), the phase delay is set to 0 degrees and 54 degrees. In the directivity pattern of
FIG. 11 (b2), the sensitivity from the lower side of the paper surface is further lowered than that
of the directivity pattern of FIG. 10, and the sensitivity is 0 at an azimuth angle of 180 degrees.
There is no decrease in sensitivity near and 255 degrees. Therefore, as shown in FIG. 12 (a3), the
phase delay is set to 36 degrees and 54 degrees. In the directivity pattern of FIG. 12 (b3), the
sensitivity at the lower side on the paper surface is significantly reduced, and the sensitivity
difference of 30 dB can be secured even at azimuth angles of 120 degrees, 150 degrees, 210
degrees and 240 degrees. From this, it was found that the phase delay is preferably 36 degrees
and 54 degrees in the two series of phase delay devices.
[0031]
Next, using the acoustic signal device 30 of FIG. 5, changes in directivity patterns were
investigated using three (three series) phase delayers. FIGS. 13 to 14 show directivity using three
phase delayers in the acoustic signal processing device 30 of FIG. The phase delay is set to 0
degree, 18 degrees and 36 degrees in FIG. 13 (a1) by such three series of phase delay devices. In
the directivity pattern of FIG. 13 (b1), although the sensitivity from the lower side on the paper
surface is lowered, a preferable characteristic can not be obtained. Therefore, in FIG. 14 (a2), the
phase delays are set to 18 degrees, 36 degrees and 54 degrees. In the directivity pattern of FIG.
14 (b2), the sensitivity at the lower side on the paper surface is significantly reduced, and the
sensitivity is reduced even at around 150 degrees and 210 degrees, and a sensitivity difference
of 35 dB can be secured. From this, it was found that the phase delay of 18 degrees, 36 degrees
and 54 degrees is preferable in the three series of phase delay devices.
[0032]
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FIG. 15 shows directivity patterns in which four phase delayers are used in the acoustic signal
processing device 30 of FIG. When phase delay is set to 0 degree, 18 degrees, 36 degrees, and
54 degrees in FIG. 15A by such four series of phase delay devices, it is almost the same as the
directivity of the three series in FIG. Although the characteristic was obtained, in the directivity
pattern of FIG. 15 (b), since the signal of phase delay of 0 degree was used, the sensitivity at
azimuth angle of 90 degrees and 270 degrees becomes 0, and comparison with FIG. 14 (b2)
Thus, suitable characteristics with further reduced directivity were obtained. From this, it is
possible to create a pattern as the number of sequences to be multiplied is finer, but on the other
hand, it is not efficient such as an increase in the amount of equipment and an increase in
arithmetic processing. As a result of investigation, the value of the series n is preferably in the
range of n = 2 to 4.
[0033]
Although the series of investigations described above has made it possible to form a directivity
pattern in which the sensitivity in the opposite direction to the desired direction is reduced, it is
possible to form a beam-like directivity with a narrowed directivity width (directed azimuth
width) I decided to investigate further.
[0034]
16 and 17 show an acoustic signal processing apparatus 40 capable of forming beam-like
directivity.
The acoustic signal processing device 40 of FIG. 16 has detectors 1X and 1Y, three integrated
processors 17, three beam controllers 16, a multiplier 4 and an output device 5. Further, details
of the integration processor 17 are shown in FIG. The integration processor 17 is substantially
the same as the configuration of FIG. 5, but since the phase controller 7 has a beam input
terminal, an offset can be added to the phase delay inherent to the phase delayer. The beam
controller 16 can further input the central azimuth φc of the beam and the directional azimuth
width φw of the beam to the integration processor 17 having a three-sequence phase delay unit.
[0035]
Specifically, the beam controller 16a outputs φ-φc + φw, the beam controller 16b outputs φφc, and the beam controller 16c outputs φ-φc-φw to each integrated processor. Furthermore,
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by changing φc and φw, the directivity pattern rotates in a similar shape.
[0036]
FIG. 18 shows directivity patterns in the case where the central direction of the beam and the
distance from the beam center or the azimuth angle are changed in the acoustic signal
processing device 30 of FIG. 5, and phase control of FIG. The phase control in FIG. 18 (b) is φc =
0 ° and φw = 0 °, and the phase control in FIG. 18 (c) is φc = 0 ° and φw = −60 °. is there.
FIG. 19 shows a directivity pattern when the directivity width is narrowed by multiplying the
three directivity patterns of FIG. By multiplying, if there is an azimuth whose sensitivity is low in
any one of the three directivity patterns, the azimuth decreases its sensitivity by multiplication
processing, and as a result, the beam width narrows. As shown in FIG. 19, the beam width of the
directivity pattern multiplied as compared with a single directivity pattern is reduced, and it
becomes possible to form a pattern having directivity of 60 degrees width near the azimuth angle
of 0 degrees.
[0037]
Next, the formation of a directivity pattern in which the central azimuth angle φc of the beam is
rotated to an azimuth angle of 90 degrees will be described. By controlling three sets of three
series of phase delay devices 6 using the phase controller 7 of FIG. 5, a pattern having a central
azimuth φc of 90 degrees and a directional azimuth width φw of 60 degrees was formed. .
[0038]
FIG. 20 shows directivity patterns when the central direction of the beam and the distance from
the beam center or the direction of the beam are changed in the acoustic signal processing
device 30 of FIG. The phase control of FIG. 20 (a) is φc = −90 degrees, φw = 60 degrees, and
the phase control of FIG. 20 (b) is φc = −90 degrees, φw = 0 degrees, and FIG. 20 (c) The phase
control is φc = −90 degrees and φw = −60 degrees. FIG. 21 shows a directivity pattern in the
case where the directivity width is narrowed by multiplying the three directivity patterns of FIG.
As shown in FIG. 19, the beam width is reduced, and it becomes possible to form a pattern having
directivity of 60 degrees in the vicinity of 60 degrees of azimuth.
04-05-2019
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[0039]
On the other hand, in the prior art, in order to obtain a directivity pattern as shown in FIG. 21, a
large number of detectors are linearly arranged at an interval of wavelength / 2 (wavelength =
sound velocity / frequency) to narrow the directivity by the addition effect. Although it was
necessary and required many detectors, by using the acoustic signal processing device according
to the present invention, the directivity width can be narrowed by performing signal processing
using at least two detectors. As a result, it is possible to easily remove the noise from the
direction other than the beam direction and to easily make the direction characteristic of the
signal source.
[0040]
Furthermore, by using the acoustic signal processing device according to the present invention,
even in three-dimensional measurement, it is possible to arrange detectors in the central portion
and in the XYZ axes, and to measure using a total of four detectors.
[0041]
As described above, by using the acoustic signal processing device according to the present
embodiment, it is possible to deform the dipole directivity characteristic usually used in the
acoustic intensity method by signal processing, and it is possible to reverse the signal sound
direction. It is possible to reduce disturbance noise from the direction.
In the present embodiment, the delay angle is controlled by the phase delay unit. However, the
present invention is not limited to this, and in consideration of conversion calculation of time
delay and phase delay, calculation with less control by time delay In some cases, the delay time
may be controlled by a time delay unit.
Furthermore, since the numerical values described in the present embodiment are merely
examples, and are affected by the directivity pattern of the detector itself, for example, it is
preferable to add a directivity pattern correction unit separately. It's too late.
[0042]
1X, 1Y detector, 2 cross spectrum calculator, 3, 13 imaginary part extractor, 4 multiplier, 5
outputs, 6 phase delay, 7 phase controller, 8 adder, 10, 20, 30, 40 Acoustic signal processor, 11
amplitude information, 12 phase information, 14 weighter, 16 beam controller, 17 integrated
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processor.
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