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DESCRIPTION JP2016063318

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DESCRIPTION JP2016063318
Abstract: The present invention provides a sound field control system, a sound field control
method, and a signal generator for identification applied to sound field control in an outdoor
environment. SOLUTION: Weather information is acquired in an area where sounds radiated
from first and second speakers come in common by respective acoustic signals outputted from
first and second output parts. Identification signals for identifying the first and second space
transfer characteristics from the first and second speakers 130 and 130 to the area are
generated based on the weather information. First and second acoustic signals 40, 40 are
respectively acquired by the sounds radiated from the first and second speakers 130, 130
according to the identification signal. An input acoustic signal is filtered based on first and
second space transfer characteristics identified based on the first and second acoustic signals 40,
40 respectively and provided to the first and second outputs, respectively At least one of the
parameters of the first and second control filters 111 and 111 is generated. [Selected figure]
Figure 14
Sound field control system, sound field control method and signal generator for identification
[0001]
The present invention relates to a sound field control system, a sound field control method, and a
signal generator for identification.
[0002]
Outputting disaster prevention administrative radio broadcasts from a loudspeaker installed
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1
outside is being carried out.
In actual operation in this case, the area covered by one speaker is wide, and a range of about
300 m from the speaker is often assumed. Thus, in order to transmit a sound wave to a distant
place, the reproduction output by a speaker becomes large. Therefore, in the vicinity of the
speaker, the sound may be too loud, and the user may often be complained of being bothersome.
In such a case, in general, the volume of the sound output from the speaker is reduced, the
orientation of the speaker is changed, or the like, and the volume balance adjustment in the
entire area is difficult.
[0003]
Therefore, there is a need for a control technique for transmitting an appropriate volume for
every area. As a technique applicable to such control, for example, by adjusting the parameters of
the control filter and superimposing the amplitudes and phases of the sound waves output from
a plurality of speakers, in any direction (or area) of the spatial field Thus, there is known a
technique for forming a sound increase area and a sustain area, or a maintenance area and a
sound reduction area of sound pressure.
[0004]
JP, 2014-30159, A JP, 2012-156865, A JP, 2009-11, 1920 A JP, 2007-121439, A
[0005]
However, the above-described technology has been developed for indoor use, and there is a
problem that it is difficult to apply it as it is to weather conditions such as wind and outdoor
conditions where environmental noise greatly acts.
[0006]
That is, when performing sound pressure control in any direction or area by sounds output from
a plurality of speakers, it is necessary to identify the space transfer characteristic to the control
point (sound receiving point) set in any direction or area .
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In the indoor environment, the arrival time of the sound waves is fixedly determined only by the
indoor speakers, microphones, the shape of the room, and the equipment disposed.
[0007]
On the other hand, in the outdoor environment, it is necessary to consider the influence of
weather conditions.
For example, in an outdoor environment, the arrival time of sound waves is changed by the
change of apparent sound speed due to the influence of wind (wind speed, wind direction).
Therefore, for example, when the identification results of a plurality of times are compared, the
arrival times of the sound waves may not match each other, resulting in different results. In this
case, the parameters of the control filter are not stable, which makes it difficult to construct the
control filter.
[0008]
The problem to be solved by the present invention is to provide a sound field control system
applicable to sound field control in an outdoor environment, a sound field control method, and a
signal generator for identification.
[0009]
The sound field control system according to the embodiment acquires meteorological
information in an area in which sounds emitted from the first and second speakers are commonly
received by acoustic signals output from the first and second output units. Do.
Identification signals for identifying first and second space transfer characteristics from the first
and second speakers to the area, respectively, are generated based on the weather information.
First and second acoustic signals are obtained respectively from the sounds radiated from the
first and second speakers in accordance with the identification signal. First and second filter units
for filtering the input acoustic signal based on the first and second space transfer characteristics
respectively identified based on the first and second acoustic signals; At least one of the first and
second filter parameters for the two filters is generated.
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[0010]
FIG. 1 is a block diagram showing a configuration of an example of a sound field control system
according to a first example of a sound field control system. FIG. 2 is a diagram showing an
example of the arrangement of each speaker and microphone. FIG. 3 is a diagram showing an
example of filter characteristics obtained by the first example of the sound field control method.
FIG. 4 is a diagram representing an example of filter characteristics obtained by the first example
of the sound field control method in the time domain. FIG. 5 is a figure for demonstrating the
effect by the 1st example of a sound field control system. FIG. 6 is a block diagram showing a
configuration of an example of a sound field control system according to a second example of the
sound field control method. FIG. 7 is a diagram showing an example of the arrangement of each
speaker and microphone. FIG. 8 is a diagram showing an example of filter characteristics
obtained by the second example of the sound field control method. FIG. 9 is a diagram
representing an example of filter characteristics obtained by the second example of the sound
field control method in the time domain. FIG. 10 is a diagram for explaining the effect of the
second example of the sound field control method. FIG. 11 is a diagram for describing
measurement of space transfer characteristics in an outdoor environment. FIG. 12 is a diagram
for explaining measurement of space transfer characteristics in an outdoor environment. FIG. 13
is a diagram for explaining measurement of space transfer characteristics in an outdoor
environment. FIG. 14 is a block diagram showing an exemplary configuration of a sound field
control system according to the embodiment. FIG. 15 is a diagram illustrating an example of first
and second identification signals generated by the identification signal generation unit according
to the embodiment. FIG. 16 is a block diagram showing a configuration example of the
identification signal generation unit according to the embodiment. FIG. 17 is a diagram for
explaining a method of calculating an impulse response. FIG. 18 is a diagram for explaining a
method of calculating an impulse response according to the embodiment. FIG. 19 is a diagram for
explaining a method of calculating an impulse response according to the embodiment. FIG. 20 is
a diagram for explaining a method of calculating an impulse response according to the
embodiment. FIG. 21 is a diagram for explaining a method of calculating an impulse response
according to the embodiment. FIG. 22 is a diagram for explaining a method of calculating an
impulse response according to the embodiment. FIG. 23 is a diagram showing an example of an
experimental result when each filter parameter obtained by the method according to the
embodiment is applied to the first and second control filters. FIG. 24 is a flowchart illustrating an
example of a processing procedure according to the embodiment. FIG. 25 is a block diagram
showing an example of a hardware configuration of the acoustic control device applicable to the
embodiment. FIG. 26 is a block diagram showing an exemplary configuration of a sound field
control system according to a modification of the embodiment.
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FIG. 27 is a diagram schematically illustrating a sound field control system according to another
embodiment. FIG. 28 is a block diagram showing an exemplary configuration of a sound field
control system according to another embodiment. FIG. 29 is a diagram schematically illustrating
a sound field control system according to a modification of the other embodiment. FIG. 30 is a
block diagram showing an exemplary configuration of a sound field control system according to
a modification of the other embodiment.
[0011]
Hereinafter, a sound field control system, a sound field control device, and a sound field control
method according to the embodiment will be described. First, first and second examples of the
sound field control method applicable to the embodiment will be described. These first and
second examples make it possible to change the sound pressure at any point by adjusting the
amplitude, phase, and time delay amount of the sound wave emitted from two or more speakers.
It is a thing.
[0012]
(First Example of Sound Field Control Method) The first example is an example in which the
sound pressure of one control point or control area is silenced with sound waves from two
speakers. FIG. 1 shows an exemplary configuration of a sound field control system 100 according
to a first example. The sound field control system 100 includes a filter unit 110, a volume control
unit 120, speakers 130 1 and 130 2, and a microphone 150. The filter unit 110 includes a first
control filter 111 1 and a second control filter 111 2. Further, the volume adjustment unit 120
includes a first volume adjustment unit 121 1 and a second volume adjustment unit 121 2.
[0013]
The first control filter 111 1 and the second control filter 111 2 respectively apply filter
processing to the input sound signal 50 in accordance with filter parameters calculated as
described later. Each acoustic signal obtained by filtering the input acoustic signal by the first
control filter 111 1 and the second control filter 111 2 is input to the first volume adjustment
unit 121 1 and the second volume adjustment unit 121 2, respectively.
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[0014]
The first sound volume adjustment unit 121 1 and the second sound volume adjustment unit
121 2 are output units that perform amplification processing and sound volume adjustment
processing on the input sound signals, respectively, and output the sound signals. The acoustic
signals output from the first volume adjustment unit 121 1 and the second volume adjustment
unit 121 2 are emitted as sounds by the speakers 130 1 and 130 2.
[0015]
The sound radiated from the speaker 130 1 is collected by the microphone 150 through the path
140, converted into an acoustic signal, and output. Similarly, the sound radiated from the speaker
130 2 is collected by the microphone 150 through the path 141, converted into an acoustic
signal, and output. The sound signals output from the microphone 150 are respectively acquired
by a sound acquisition unit (not shown) and supplied to the filter calculation unit.
[0016]
In the above configuration, the speaker 130 1 is a reference sound source, and the speaker 130
2 is a control sound source. The microphone 150 is placed in any control area 160 where you
want to control the sound (in this case, you want to mute).
[0017]
The sound pressure level P of the sound arriving from the reference sound source (speaker 130
1) alone to the microphone 150 is expressed by the following equation (1). Here, it is assumed
that the space transfer characteristic from the reference sound source to the microphone 150 is
F P, and the input acoustic signal 50 input to the sound field control system 100 has an
amplitude q.
[0018]
Next, using the control sound source (speaker 130 2) with the reference sound source as it is
through reproduction, that is, without performing the filter processing by the first control filter
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111 1, the sound pressure to the microphone 150 installed in the control area 160 Consider the
case of muting
[0019]
Here, the characteristic of the first control filter 111 1 is taken as a through characteristic W 1 (=
1).
That is, since the acoustic signal output from the first control filter 111 1 is emitted from the
speaker 130 1 as a reference sound source, the characteristic is not changed.
[0020]
The space transfer characteristic from the control sound source (speaker 130 2) to the
microphone 150 is F S, and the characteristic of the second control filter 111 2 is W 2. That the
synthetic sound pressure P 'which is the sound pressure of the sound radiated from each of the
two sound sources (the reference sound source and the control sound source) is muted means
that the synthetic sound pressure P' = 0. Therefore, the following equation (2) holds.
[0021]
Therefore, the characteristic W 2 of the second control filter 111 2 for the control sound source
is expressed as the following equation (3).
[0022]
Here, as an example, it is assumed that the speakers 130 1 and 130 2 and the microphone 150
are disposed as shown in FIG.
That is, in the example of FIG. 2, the speakers 130 1 and 130 2 are arranged with the height of
3.4 m, the center part distance close to 0.5 m, and the front faces coincide with each other. Also,
the microphone 150 is arranged at a position of 20 m in the vertical direction from the front
surface of the speakers 130 1 and 130 2 and 8.5 m in the horizontal direction (in the example, in
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the direction of the speaker 130 1).
[0023]
Under such conditions, the first control filter 111 1 and the second control filter 111 2 have
through characteristics, and a predetermined identification signal is input as the input acoustic
signal 50, and the first volume adjustment unit 121 1 and the second volume After adjusting the
volume with the adjustment unit 121 2, sound is emitted from each of the speakers 130 1 and
130 2. The sound radiated from each of the speakers 130 1 and 130 2 is collected by the
microphone 150, and the space transfer characteristic F P in the path 140 and the space transfer
characteristic F S in the path 141 are based on the acoustic signal of the collected sound. Ask for
and.
[0024]
FIG. 3 shows amplitude characteristics and characteristics W 1 and W 2 of the first control filter
111 1 and the second control filter 111 2 based on the space transfer characteristics F P and F S
determined in this manner, in the frequency domain. An example of the phase characteristic is
shown. FIG. 3A shows an example of the amplitude characteristic. In FIG. 3A, the characteristic
line 200 indicates the characteristic W 1, and the characteristic line 201 indicates the
characteristic W 2. Moreover, FIG.3 (b) shows the example of a phase characteristic. In FIG. 3B,
the characteristic line 202 indicates the characteristic W 1, and the characteristic line 203
indicates the characteristic W 2.
[0025]
FIGS. 4 (a) and 4 (b) are examples in which the above-mentioned characteristics W 1 and W 2 are
inverse Fourier transformed and represented in the time domain, respectively. Parameters
corresponding to the characteristics W 1 and W 2 shown in FIGS. 4A and 4B are used as filter
parameters of the first control filter 111 1 and the second control filter 111 2, respectively. As a
result, as illustrated in FIG. 5, the muffling effect in the control area 160 can be obtained.
[0026]
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8
In FIG. 5, the characteristic line 204 shows an example of the frequency characteristic of the
sound pressure in the control area 160 when the first control filter 111 1 and the second control
filter 111 2 are not controlled, ie, in the case of the through characteristic. In addition,
characteristic line 205 is an example of the frequency characteristic of sound pressure in control
area 160 when first control filter 111 1 and second control filter 111 2 are controlled, that is,
when characteristics W 1 and W 2 are applied, respectively. Indicates It can be seen that the
sound pressure is suppressed at each frequency by the control of the first control filter 111 1
and the second control filter 111 2.
[0027]
(Second Example of Sound Field Control Method) As illustrated in FIG. 6, in the second example,
control areas (directions) in two directions are simultaneously controlled by sounds radiated
from two speakers, and This is an example of increasing the sound pressure of the second
control area 162 (control point in the area) while maintaining the sound pressure of the control
area 161 (control point in the area) of 1.
[0028]
FIG. 6 shows an exemplary configuration of the sound field control system 101 according to the
second example.
In addition, in FIG. 6, the same code | symbol is attached | subjected to the part in common with
FIG. 1 mentioned above, and detailed description is abbreviate | omitted. While the sound field
control system 100 shown in FIG. 1 described above includes one microphone 150, the sound
field control system 101 shown in FIG. 6 includes two or more microphones 151 i and 152 j. The
sound field control system according to the second example is realized by setting one or a
plurality of control points in one control area and minimizing the sum of the acoustic energy.
[0029]
Control filter that performs sound increase control by two speaker sound sources (speakers 130
1 and 130 2) when M control points are arranged in the first control area 161 and N control
points are arranged in the second control area 162. The derivation method of will be described.
[0030]
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The space transfer characteristics Z Pj and Z Sj in the paths 143 and 145 between the
microphone 151 i and the speakers 130 1 and 130 2 installed at one control point in the first
control area 161 are the space transfer characteristics Z Pj and Z Sj, respectively. I assume.
In addition, the space transfer characteristics in the paths 142 and 144 between the microphone
152 j and the speakers 130 1 and 130 2 installed at one control point in the second control area
162 are referred to as space transfer characteristics F Pi and F Si respectively. I assume.
[0031]
The sound pressure of each area after sound field control is determined by the following
equation (4) and equation (5). The sound pressure (synthetic sound pressure) P i of the i-th
control point (for example, the position of the microphone 151 i) in the first control area 161 is
given by the equation (4). Also, the sound pressure (synthetic sound pressure) Q j at the j-th
control point (for example, the position of the microphone 152 j) in the second control area 162
is given by the equation (5).
[0032]
From Equations (4) and (5), the sound pressure P i of the first control area 161 is the first
speaker sound source (P) at non-control time, for example, n a times the sound pressure from the
speaker 130 1, The sound pressure Q j in the control area 162 is set to n b times the sound
pressure from the first speaker sound source (P) at the non-control time.
[0033]
First, focus on the first control area 161.
If Expression (4) is transformed, Expression (6) below is obtained, and the total sum U m of the
acoustic energy shown in Expression (7) is minimized. In Equation (6), since the value q p is a
complex amplitude, it is expressed by Equation (8).
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10
[0034]
In order to minimize the total sum U m of acoustic energy, a solution satisfying the following
equation (9) may be obtained.
[0035]
In the second control area 162, the following equations (10) to (12) are derived in the same
procedure.
[0036]
Then, a solution satisfying equation (13) is obtained such that the total sum Un of acoustic
energy is minimized.
[0037]
The solutions obtained by solving the equations (9) and (13) described above become the
following equations (14) and (15).
[0038]
Here, the values α, β i and γ i in the equations (14) and (15) are represented by the following
equations (16) to (18).
[0039]
Therefore, the control filter of the time domain obtained by inverse Fourier transforming
Equations (14) and (15) has the characteristics of the first control filter 111 1 and the second
control filter 111 2 in the configuration example of FIG. Become.
[0040]
That is, the characteristic Wp | OFF of the first control filter 111 1 at the time of non-control is
expressed by the following equation (19).
Here, since the complex amplitude q is a reference amplitude, equation (19) becomes a through
characteristic filter.
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[0041]
Further, the characteristic W p │ON of the first control filter 111 1 at the time of control is
expressed by equation (20), and the characteristic W s of the second control filter 111 2 at the
time of control is expressed by equation (21) Ru.
[0042]
Here, as an example, it is assumed that the speakers 130 1 and 130 2 and the microphones 151 i
and 152 j are arranged as shown in FIG. 7.
In the example of FIG. 7, the arrangement of the speakers 130 1 and 130 2 and the microphone
152 j is the same as the arrangement of the speakers 130 1 and 130 2 and the microphone 150
described with reference to FIG.
In FIG. 7, microphones 151 i are further arranged at a position of 20 m in the vertical direction
from the front surface of each of the speakers 130 1 and 130 2.
[0043]
Under such conditions, the sound pressure reaching the first control area 161 is increased by 6
dB (decibel) twice the amplitude, and the second control area 162 maintains the sound pressure
before and after control. .
FIG. 8 shows amplitude characteristics and phase characteristics of the characteristics of the first
control filter 111 1 and the second control filter 111 2 based on Equations (14) to (18) in this
case, in the frequency domain. An example is shown.
[0044]
FIG. 8 (a) shows an example of the amplitude characteristic, and FIG. 8 (b) shows an example of
the phase characteristic.
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In FIGS. 8A and 8B, for the first control filter 111 1, the characteristic lines 206 and 209 indicate
the non-controlled characteristic W q when the control is turned off, and the characteristic lines
207 and 210 indicate the control. Shows a characteristic W qp at the time of control with.
Further, in FIG. 8A, with respect to the second control filter 111 2, characteristic lines 208 and
211 indicate the characteristic W qs at the time of control.
[0045]
FIGS. 9 (a), 9 (b) and 9 (c) are examples in which the above-mentioned characteristics W q, W qp
and W s are inverse Fourier transformed and represented in the time domain.
Parameters corresponding to the characteristics W qL and W qpL shown in FIGS. 9A and 9B are
used as filter parameters of the first control filter 111 1. A parameter corresponding to the
characteristic W qsL shown in FIG. 9C is used as a second control filter 111 2 filter parameter.
[0046]
That is, the filter parameter of the through characteristic shown by the characteristic q L in FIG.
9A is applied to the first control filter 111 1 when it is not controlled, and it is shown by the
characteristic W qpL in FIG. Filter parameters are applied. At the time of control, the filter
parameter indicated by the characteristic W qsL is applied to the second control filter 111 2. The
second control filter 111 2 is silent when not controlled.
[0047]
FIG. 10 shows an example of the result of control by each of the above-mentioned filter
parameters by the frequency characteristic of the sound pressure level. FIG. 10A shows an
example of the control result at the control point M i in the first control area 161. A
characteristic line 212 indicates the non-control time, that is, the case where the first control
filter 111 1 has a through characteristic and the second control filter 111 2 has no sound. A
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characteristic line 213 shows the characteristic at the time of control, that is, when the first
control filter 111 1 is characteristic W qpL and the second control filter 111 2 is characteristic
W qsL. At the time of control, it can be seen that the sound pressure level is increased by
approximately 6 dB with respect to the non-control time.
[0048]
FIG. 10 (b) shows an example of the control result at the control point N j in the second control
area 162. A characteristic line 214 indicates a non-controlled characteristic, and a characteristic
line 215 indicates a controlled characteristic. It can be seen that the sound pressure level at the
non-control time is maintained even at the control time.
[0049]
Embodiment Next, an embodiment will be described. In the first example and the second example
of the sound field control method described above, the influence of the weather in the outdoor
environment, in particular, the wind is not considered. Therefore, when the first example and the
second example are applied to an outdoor environment, the identification process of the space
transfer characteristic from the speaker to an arbitrary point may be affected by the wind and
not performed correctly.
[0050]
As an example, consider the case where the speaker 132 and the microphone 153 are disposed
at a distance L in an outdoor environment as illustrated in FIG. The sound radiated from the
speaker 132 is collected by the microphone 153 and converted into an audio signal, and the
sound wave output from the speaker 132 is measured. Based on the measurement result, the
space transfer characteristic from the speaker 132 to the microphone 153 is identified.
[0051]
In the outdoor environment, the wind is often blowing, and the wind speed and direction of the
wind change instantaneously. Due to the influence of such wind, the time for the sound emitted
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from the speaker 132 to reach the control point, that is, the position of the microphone 153
changes. Therefore, every time the sound wave is measured by the microphone 153, the
excitation time of the impulse response, which is one of the indexes representing the space
transfer characteristic, fluctuates.
[0052]
FIG. 12 shows an example of the identification result of the impulse response when the distance
L from the speaker 132 to the microphone 153 in the outdoor ground is 20 m apart. In FIG. 12,
the vertical axis represents amplitude, and the horizontal axis represents tap number or time, and
characteristic lines 216 and 217 represent identification results based on the first and second
measurement results, respectively. As described above, the excitation timing (time) of the impulse
response is largely shifted between the first measurement and the second measurement although
the measurement system is the same. This is because the time for the sound wave to reach from
the speaker to the sound receiving point is changed due to instantaneous wind speed fluctuation
at the time of identification.
[0053]
The excitation timing (tap number) S at which the impulse is excited can be determined by the
following equation (22). In Expression (22), L is the distance L in FIG. 11, and indicates the
distance from the speaker 132 to the sound pressure detection unit (microphone 153). Further, c
represents the sound velocity (m / s), ff represents the wind velocity (m / s), and Fs represents
the sampling frequency (Hz).
[0054]
The sound velocity c is a specified value, and is 340 m / s at a temperature of 15 degrees. Also,
the sampling frequency Fs and the distance L are set values and are known values. Therefore, it
can be understood from equation (22) that the excitation timing S depends on the wind speed ff.
[0055]
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15
In indoor environments, the identification of spatial transfer characteristics by multiple speakers
can be determined geometrically according to the arrangement of each speaker and microphone.
FIG. 13 shows an example of the arrangement of a microphone and a plurality of speakers. In
FIG. 13, microphones 154 are arranged at an interval of a distance L from the speaker 133 1 in
front of the speaker 133 1 with respect to the speakers 133 1 and 133 2 which are disposed at
an interval of a distance D. ing. In this case, in the distance between the speaker 133 1 and the
speaker 133 2, a distance difference ds according to the distance D exists in the distance to the
microphone 154.
[0056]
In an indoor environment not affected by wind, the space transfer characteristic F p from the
speaker 133 1 to the microphone 154 and the space transfer characteristic F s from the speaker
133 2 to the microphone 154 are strictly determined using this distance difference ds. It is
possible to ask. On the other hand, in the outdoor environment, due to the influence of wind, the
difference between the space transfer characteristic F p and the space transfer characteristic F s
is not only due to this distance difference ds. Therefore, in a sound field control system where
phase interference adjustment of control points from a plurality of speakers must be strictly
performed using the distance difference ds, the control law does not hold, and a desired effect
may not be obtained. is there.
[0057]
As this solution, it is difficult to eliminate the influence of wind in an outdoor environment, so in
the identification of space transfer characteristics with multiple speakers, it is recommended to
make the wind influence uniform for the sound radiated from the multiple speakers. Just do it.
[0058]
Therefore, in the embodiment, in the identification work of the space transfer characteristic
(spatial path) from each speaker to one control point, a short time test sound is cyclically
radiated from a plurality of speakers to each control point. Collects the sound emitted from the
speaker.
Thereby, each space transfer characteristic concerning each speaker can be identified in the state
which received the wind influence to the sound radiated from a plurality of speakers
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substantially uniformly.
[0059]
FIG. 14 shows an exemplary configuration of a sound field control system according to the
embodiment. In FIG. 14, the same reference numerals are given to the parts common to those in
FIG. 1 and FIG. 6 described above, and the detailed description will be omitted.
[0060]
In FIG. 14, the sound field control system 10a includes the sound field control unit 11a, the
control filter calculation unit 23, the amplitude adjustment unit 26, two or more microphones 24
1 and 24 2, and the microphones 24 1 and 24 2. It includes two or more corresponding weather
information acquisition units 21 1 and 21 2, and speakers 130 1 and 130 2.
[0061]
The sound field control system 10a shown in FIG. 14 corresponds to the second example of the
sound field control method described above.
In the system corresponding to the first example of the sound field control method, one
microphone and one weather information acquisition device may be provided.
[0062]
The microphones 24 1 and 24 2 are respectively installed in the first control area and the second
control area to be controlled, and pick up the sound emitted from the speakers 130 1 and 130 2,
convert it into an acoustic signal, and output it Do.
[0063]
The weather information acquisition units 21 1 and 21 2 are installed near the microphones 24
1 and 24 2, respectively, acquire information on surrounding weather, and output the
information as weather information data 40 1 and 40 2, respectively.
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The weather information acquisition units 21 1 and 21 2 acquire at least wind information as
weather information. The wind information here includes the wind speed and the wind direction.
The weather information acquisition units 21 1 and 21 2 may further acquire other weather
information such as temperature, humidity, and barometric pressure.
[0064]
The sound field control unit 11 a includes an identification signal generation unit 20, a filter unit
110, and a volume adjustment unit 120. The filter unit 110 and the volume adjustment unit 120
are similar to the filter unit 110 and the volume adjustment unit 120 described with reference to
FIGS. 1 and 6. That is, the filter unit 110 includes the first control filter 111 1 and the second
control filter 111 2 whose characteristics are determined by filter parameters set from the
outside, as described above. The sound volume adjustment unit 120 has a function of an output
unit that adjusts the sound volume of the sound signal output from the first control filter 111 1
and the second control filter 111 2 and outputs the sound signal to the speakers 130 1 and 130
2.
[0065]
The identification signal generation unit 20 is an identification signal according to the
embodiment based on the weather information data 40 1 and 40 2 outputted from the weather
information acquisition units 21 1 and 21 2 and the setting data inputted from the outside, for
example. Generate Although the details will be described later, the identification signal
generation unit 20 repeatedly distributes one identification signal into a first identification signal
and a second identification signal every predetermined time and outputs it. The first
identification signal and the second identification signal are output as the output signals 42 1
and 42 2 of the identification signal generation unit 20 respectively via the first control filter
111 1 and the second control filter 111 2. The signal is supplied to the adjustment unit 121 1
and the second volume adjustment unit 121 2.
[0066]
As an original identification signal to be distributed by the identification signal generation unit
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20, a signal generally used for identification processing such as white noise or TSP (Time
Stretched Pulse) signal can be applied. The identification signal generation unit 20 may internally
generate this original identification signal or may be supplied as an input acoustic signal.
[0067]
FIG. 15 shows an example of first and second identification signals generated by the
identification signal generator 20 according to the embodiment. The identification signal
generation unit 20 repeatedly distributes the original identification signal into a first
identification signal 300 and a second identification signal 301 for each predetermined
reproduction time width.
[0068]
For example, the identification signal generation unit 20 outputs the original identification signal
as the first identification signal 300 1 for the reproduction time width, and then outputs the
original identification signal as the second identification signal 301 1. Do. Next, the identification
signal generation unit 20 outputs the original identification signal as the first identification signal
300 2, and then outputs the identification signal as the second identification signal 301 2. The
identification signal generation unit 20 repeatedly performs this operation, and the first
identification signal 300 3, the second identification signal 301 3, the first identification signal
300 4, the second identification signal 301 4, As described above, the first identification signal
300 and the second identification signal 301 are cyclically output with a predetermined
reproduction time width.
[0069]
Preferably, the first identification signal 300 and the second identification signal 301 for each
predetermined reproduction time width are continuously output so that the interval does not
open at the time of distribution.
[0070]
In addition, it is desirable that the reproduction time width be as short as possible because it can
respond to instantaneous changes in the wind.
11-04-2019
19
The minimum time width T, which is the lowest value of the reproduction time width, is the
desired filter length TAP of the impulse response (spatial transfer characteristic) used when the
control filter calculation unit 23 described later calculates the filter parameters, and the
excitation timing of the impulse response Based on S and S, it can be determined by the following
equation (23). In Equation (23), N represents the average number of times when the control filter
calculation unit 23 described later determines the impulse response, and Fs represents the
sampling frequency.
[0071]
Here, in the equation (23), the filter length TAP, the averaging number N, and the sampling
frequency Fs can be considered as fixed values, and are input from the outside as input data 41
and set in the identification signal generation unit 20, for example. . The present invention is not
limited to this, and the filter length TAP, the number of averaging times N, and the sampling
frequency Fs may be acquired from the control filter calculation unit 23 or the like. The filter
length TAP is, in other words, the cutout width (window width) of the input signal when
performing the fast Fourier transform. The number of extractions of the input signal is the
average number N.
[0072]
On the other hand, in the equation (23), the excitation timing S is a value depending on the wind
speed ff in accordance with the equation (22) described above. Therefore, the minimum time
width T depends on the wind speed ff.
[0073]
FIG. 16 shows a configuration example of the identification signal generation unit 20 according
to the embodiment. FIG. 16 (a) is a configuration example in the case of supplying the original
identification signal as the input acoustic signal 50 from the outside, and FIG. 16 (b) is an
identification signal incorporating a sound source generation unit for generating the
identification signal. It is an example of composition of generation part 20 '.
11-04-2019
20
[0074]
In FIG. 16A, the identification signal generation unit 20 includes an operation unit 2000, a
selector 2001, and a switch (SW) unit 2002. The selector 2001 selects which of the weather
information data 40 1 and 40 2 output from the weather information acquisition units 211 and
212 is to be used. Arithmetic unit 2000 is based on the data selected by selector 2001 among
weather information data 40 1 and 40 2, filter length TAP input as input data 41, averaging
number N, sampling frequency Fs, and distance L. , The minimum time width T is calculated. The
minimum time width T can be calculated using the equations (22) and (23) described above.
[0075]
The SW unit 2002 controls the connection between the input sound signal 50 and the outputs
42 1 and 42 2 in accordance with the control signal 44 output from the computing unit 2000.
[0076]
For example, the operation unit 2000 receives the original identification signal as the input
acoustic signal 50, and the identification signal generation unit 20 outputs the first identification
signal 300 and the second identification signal as the outputs 42 1 and 42 2. In the case of
outputting 301, the control signal 44 which switches the outputs 42 1 and 42 2 for each
calculated minimum time width T is output.
As a result, the original identification signal input as the input acoustic signal 50 is repeatedly
distributed to the first identification signal 300 and the second identification signal 301 for each
minimum time width T, and the outputs 42 1 and 42 are output. Output as 2
[0077]
In addition, when the identification signal generation unit 20 does not output the first
identification signal 300 and the second identification signal 301, the arithmetic unit 2000
shares, for example, the input acoustic signal 50 with the outputs 42 1 and 42 2. Output a
control signal 44. As a result, the input sound signal 50 is subjected to filter processing by the
first control filter 111 1 and the second control filter 111 2, respectively, and supplied to the
11-04-2019
21
first volume adjusters 121 1 and 121 2, and the speakers 130 1 and 130 2. Is emitted as sound
from
[0078]
In FIG. 16B, the identification signal generation unit 20 'includes an operation unit 2000', a
selector 2001, a SW unit 2002 ', and a test sound source generation unit 2003. The test sound
source generation unit 2003 generates the first identification signal 300 and the second
identification signal 301 which are alternately repeated at predetermined time intervals as
described with reference to FIG. 15 according to the control of the operation unit 2000 ′. . The
first identification signal 300 and the second identification signal 301 generated by the test
sound source generation unit 2003 are input to the SW unit 2002 '. The SW unit 2002 ′ is
externally supplied with the first identification signal 300 and the second identification signal
301 input from the test sound source generation unit 2003 according to the control signal 44
supplied from the operation unit 2000 ′. From the input acoustic signal 50, the signals to be
output as the outputs 42 1 and 42 2 are selected.
[0079]
The acoustic signals output from the microphones 24 1 and 24 2 are adjusted in amplitude by
the amplitude adjustment unit 26 and supplied to the control filter calculation unit 23. Further,
distribution information indicating processing for distributing the identification signal into the
first identification signal 300 and the second identification signal 301 is supplied from the
identification signal generation unit 20 to the control filter calculation unit 23. As the
distribution information, for example, information indicating the timing of distributing the
identification signal into the first identification signal 300 and the second identification signal
301 can be used.
[0080]
The control filter calculating unit 23 functions as a filter calculating unit that calculates filter
parameters to be set in the first control filter 111 1 and the second control filter 111 2. Further,
the control filter calculation unit 23 is supplied with the acoustic signal whose amplitude has
been adjusted by the amplitude adjustment unit 26. In other words, the control filter calculation
unit 23 also functions as a sound acquisition unit that acquires the acoustic signal output from
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the amplitude adjustment unit 26. At this time, based on the distribution information supplied
from the identification signal generation unit 20, the control filter calculation unit 23 generates
acoustic signals acquired from the amplitude adjustment unit 26 into first identification signals
300 1, 300 2,. The corresponding part and the part corresponding to the second identification
signals 301 1, 301 2,... Are extracted, and an impulse response is obtained for each extracted
part.
[0081]
Basically, as illustrated in FIG. 17, the control filter calculation unit 23 performs Fourier
transform on data in the window while shifting the window with a predetermined tap width by a
fixed shift amount, and The impulse response, that is, the space transfer characteristic is
determined by averaging the values obtained in the above in a predetermined number of times
for each tap number.
[0082]
The sounds based on the first identification signals 300 1, 300 2,... And the second identification
signals 301 1, 301 2,... Output from the identification signal generator 20 are speakers 130 1
and 130 2. It is regenerated and emitted.
The control filter calculation unit 23 collects the reproduced sound of the first identification
signals 300 1, 300 2,... And the second identification signals 301 1, 301 2,... By the microphones
24 1 and 24 2. The space transfer characteristic from each of the speakers 130 1 and 130 2 to
each of the microphones 24 1 and 24 2 (a first control area and a second control area) is
determined based on the acoustic signal obtained as described above. Then, the control filter
calculation unit 23 calculates each filter parameter for the first control filter 111 1 and the
second control filter 111 2 based on the determined space transfer characteristic, and the first
control filter 111 1 and the second control filter 111. Set to 2
[0083]
During the identification process of the space transfer characteristic, the control filter calculation
unit 23 sets the filter parameter of the through characteristic to the first control filter 111 1 and
the second control filter 111 2. Alternatively, the control filter calculation unit 23 bypasses the
first control filter 111 1 and the second control filter 111 2 during the identification process of
11-04-2019
23
the space transfer characteristic.
[0084]
A method of calculating an impulse response to the first identification signal 300 and the second
identification signal 301 according to the embodiment will be described with reference to FIGS.
18 to 22. FIG. 18 shows an example of a method of calculating an impulse response using each
identification signal according to the embodiment. Taking the first identification signal 300 as an
example, since the first identification signals 300 1, 300 2,... Are distributed to every minimum
time width T, the time width of data is short, and the impulse response, that is, the space transfer
characteristic The amount of time shift (the number of averaging) at the time of calculating?
[0085]
Therefore, the control filter calculation unit 23 calculates the impulse response of the first
identification signal 300 by the following two steps. In the first step, the control filter calculation
unit 23 shifts the window of the tap width as one of the first identification signal 300 1 as the
windows 303 1, 303 2,. Do. The control filter calculation unit 23 obtains the impulse response in
the first identification signal 300 1 by averaging the calculated impulse responses for each tap
number in the first identification signal 300 1. The control filter calculation unit 23 executes this
process a plurality of times such as first identification signals 300 2, 300 3, and so on.
[0086]
In the second step, the control filter calculation unit 23 further averages each of the impulse
responses obtained in the plurality of impulse response calculation processes as a whole. Then,
the control filter calculation unit 23 obtains an impulse response obtained by averaging, as an
impulse response in the entire first identification signal 300, that is, as a space transfer
characteristic. As described above, it is expected that the S / N can be improved by further
averaging the averages of the impulse responses obtained respectively for the first identification
signals 300 1, 300 2,.
[0087]
11-04-2019
24
FIG. 19 and FIG. 20 show examples of impulse response selection methods according to the
embodiment. Furthermore, as exemplified in FIG. 19, the control filter calculation unit 23 further
generates one first identification signal 300 n (n is 1, 2,..., X) and a second signal, which are
continuously reproduced. A set consisting of the identification signal 301 n is one loop Loop # n.
Then, the control filter calculation unit 23 compares the first identification signal 300 n with the
second identification signal 301 n for each loop Loop # n, and the first identification signal 300 n
with the second identification signal 300 n. The time difference ds n of the impulse excitation
time of the identifying signal 301 n is determined.
[0088]
In the example of FIG. 19, the first identification signal 300 1 and the second identification signal
301 1 reproduced immediately after the first identification signal 300 1 form one set of loop
Loop # 1. Ru. The first identification signal 300 2 reproduced immediately after the second
identification signal 301 1 and the second identification signal 301 2 reproduced immediately
after the first identification signal 300 2 are 1 It is referred to as a loop Loop # 2.
[0089]
In this way, for the loop Loop #n of X set of the first identification signal 300 n and the second
identification signal 301 n reproduced immediately after the first identification signal 300 n. The
time difference ds n of the impulse excitation time is determined respectively.
[0090]
FIG. 20 shows the time differences ds 1, ds 2 and ds 3 of the impulse excitations of the first
identification signal 300 n and the second identification signal 301 n for each loop Loop # 1, # 2
and # 3. An example is shown.
FIG. 20A shows the impulse response (characteristic line 222 1 and characteristic line 223 1) of
the reproduced sound of each of the first identification signal 300 1 and the second identification
signal 301 1 of the loop Loop # 1. . FIG. 20B shows impulse responses (characteristic line 222 2
and characteristic line 223 2) of the reproduced sound of the first identification signal 300 2 and
the second identification signal 301 2 of the loop Loop # 2. . FIG. 20C shows the impulse
response (characteristic line 222 3 and characteristic line 2233) by the reproduction sound of
11-04-2019
25
the first identification signal 300 3 and the second identification signal 301 3 of the loop Loop #
3. .
[0091]
The control filter calculation unit 23 compares the time differences ds 1, ds 2,..., Ds X for X
groups thus calculated, and these time differences ds 1, ds 2,. It is determined whether or not For
example, the control filter calculation unit 23 selects one of the time differences ds 1, ds 2,..., Ds x
and calculates the difference between the selected time difference and another time difference.
The control filter calculation unit 23 determines that the time difference ds m (m is 1, 2,..., X)
where this difference deviates from the predetermined range as the time difference which
deviates from the constant value. Then, the control filter calculation unit 23 excludes each
impulse response by the reproduction sound of each of the first identification signal 300 m and
the second identification signal 301 m corresponding to the time difference ds m determined to
be out of the constant value. Then, as described above, the impulse response is averaged.
[0092]
That is, it may be considered that the reproduced sound of the first identification signal 300 n
and the second identification signal 301 n corresponding to the time difference ds n deviated
from the fixed value is, for example, affected by the instantaneous wind. it can.
[0093]
Since it is necessary to calculate the difference of each time difference ds n as described above,
the number of repetitions X of the loop Loop # X described above, that is, each of the first
identification signal 300 n and the second identification signal 301 n Each number of outputs is
at least two.
[0094]
21 and 22, for example, for the first identification signal 300, excluding the impulse response
due to the reproduced sound of the first identification signal 300 m corresponding to the time
difference ds m which deviates from the constant value as described above. An example of
obtaining an average of the first identification signals 300 1, 300 2,..., 300 n will be shown.
11-04-2019
26
Here, the first identification signals 300 1, 300 2 and 300 3 will be described as an example.
[0095]
In FIG. 21, characteristic lines 218, 219 and 220 indicate examples of impulse responses by the
reproduction sound of the first identification signal 3001, the first identification signal 3002 and
the first identification signal 3003, respectively. Show.
Thus, it can be seen that each impulse response has a difference within a predetermined range.
FIG. 22 shows an example of the result of calculating the average of each impulse response by
the reproduction sound of each of the first identification signal 300 2 and the first identification
signal 300 3 (characteristic line 221). It can be seen that the characteristic line 221 shows a
shape very similar to the characteristic lines 218 to 220 in FIG.
[0096]
The control filter calculation unit 23 obtains an impulse response (spatial transfer characteristic)
from each of the first identification signals 300 1, 300 2,..., 300 X as described above, and based
on the obtained impulse response, The filter parameters to be applied to the first control filter
111 1 are calculated according to (4) to equation (21) (or equation (1) to equation (3)). Similarly,
the control filter calculation unit 23 obtains an impulse response (spatial transfer characteristic)
from each of the second identification signals 301 1, 301 2,..., 301 X, and a second control filter
based on the obtained impulse response. Calculate the filter parameters to be applied to 111 2.
[0097]
FIG. 23 shows an example of experimental results in the case where each filter parameter
obtained as described above according to the embodiment is applied to the first control filter 111
1 and the second control filter 111 2. The arrangement of the speakers 130 1 and 130 2 and the
microphones 24 1 and 24 2 is different from the arrangement described with reference to FIG. 7
from the speakers 130 1 and 130 2 to the microphones 151 i (microphones 24 1) It is assumed
that the distance L up to is 60 m. Further, in this example, the sound pressure reaching the first
control area, ie, the position of the microphone 24 1 is increased by 9.4 dB by three times the
amplitude, and the sound pressure before and after control is increased at the second control
11-04-2019
27
area, ie, the position of the microphone 24 2 Shall be maintained.
[0098]
FIG. 23 (a) shows an example of the experimental result at the front, ie at the position of the
microphone 24 1. A characteristic line 224 shows an example of the result when the control by
each of the first control filter 111 1 and the second control filter 111 2 is not being controlled,
and a characteristic line 225 shows an example of the result at the control time. FIG. 23 (b)
shows an example of the experimental result at the position of 8.5 m on the left, that is, the
microphone 24 2. A characteristic line 224 'shows an example of the result when the control by
each of the first control filter 111 1 and the second control filter 111 2 is not controlled, and a
characteristic line 225' shows an example of the result at the control time.
[0099]
As shown in FIGS. 23 (a) and 23 (b), a space with few errors due to wind from the two speakers
130 1 and 130 2 to the control points of the first control area and the second control area,
respectively. It can be understood that the desired effect can be realized even in an outdoor
environment by using the transfer characteristic.
[0100]
FIG. 24 is a flowchart illustrating an example of the processing procedure according to the
above-described embodiment.
Note that, prior to the processing of this flowchart, the control filter calculation unit 23 sets the
first control filter 1111 and the second control filter 1112 to the through characteristic or the
bypass, respectively. The identification signal generation unit 20 is assumed to have the
configuration shown in FIG.
[0101]
In step S10, the identification signal generation unit 20 acquires wind speed information based
on the weather information data 40 1 and 40 2 output from the weather information acquisition
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28
units 21 1 and 21 2. In step S11, the identification signal generation unit 20 calculates an output
parameter of the identification signal. More specifically, the identification signal generation unit
20 is based on the wind speed information (wind speed ff) acquired in step S10 and the distance
L, the sound speed C, the sampling frequency Fs, the filter length TAP and the average number N
previously input. The minimum time width T is calculated as an output parameter in accordance
with the equations (22) and (23) described above.
[0102]
In the next step S12, the identification signal generation unit 20 performs the first identification
signals 300 1 300 2... And the second identification signals 301 1 301 2 according to the
minimum time width T calculated in step S12. And generate and output. That is, the identification
signal generation unit 20 generates an original identification signal (white noise or TSP signal)
for the test sound source generation unit 2003, and repeatedly generates the generated original
identification signal with the minimum time width T. It controls to distribute to the identification
signal 300 n and the second identification signal 301 n for output.
[0103]
In addition, the identification signal generation unit 20 turns off the output of the input acoustic
signal 50 for the SW unit 2002, and the first identification signal 300 n and the second
identification signal output from the test sound source generation unit 2003. It is controlled to
output 301 n as the outputs 421 and 422.
[0104]
The identification signal generation unit 20 may set the time for distributing the original
identification signal to the first identification signal 300 n and the second identification signal
301 n as a time longer than the minimum time width T.
[0105]
In the next step S13, the control filter calculation unit 23 acquires the outputs of the
microphones 24 1 and 24 2 via the amplitude adjustment unit 26.
In step S14, the control filter calculation unit 23 uses the outputs of the microphones 24 1 and
11-04-2019
29
24 2 acquired in step S13 to transmit the microphones 24 1 and 24 2 from the speakers 130 1
and 130 2 as described above. The space transfer characteristic (impulse response) up to is
calculated.
[0106]
In step S15, the control filter calculation unit 23 calculates filter parameters to be set in the first
control filter 111 1 and the second control filter 111 2 using the space transfer characteristic
calculated in step S14.
Then, in the next step S16, the control filter calculation unit 23 sets each of the calculated filter
parameters in the first control filter 111 1 and the second control filter 111 2.
[0107]
At this time, the identification signal generation unit 20 turns off the outputs of the first
identification signal 300 1 and the second identification signal 301 1 output from the test sound
source generation unit 2003, and outputs the input acoustic signal 50. Control to output as 42 1
and 42 2. The input sound signal 50 is supplied to the first sound volume adjustment unit 121 1
and the second sound volume adjustment unit 121 2 via the first control filter 111 1 and the
second control filter 111 2, and the speakers 130 1 and 130 2 are supplied. It is output. As a
result, in the first control area and the second control area, a sound based on the input acoustic
signal 50 arrives at a desired sound pressure.
[0108]
Preferably, the first volume adjustment unit 121 1 and the second volume control unit 121 2
have substantially the same characteristics. Furthermore, it is desirable that the first volume
adjustment unit 121 1 and the second volume control unit 121 2 have substantially the same
volume setting. Here, with the same volume setting, the same acoustic signal is input The settings
are such that the amplitudes of the output sound signals of the two cases are substantially the
same.
11-04-2019
30
[0109]
(Hardware Configuration Applicable to Embodiment) FIG. 25 shows an example of the hardware
configuration of the acoustic control apparatus applicable to the embodiment. In FIG. 25, the
sound control apparatus 1000 includes a central processing unit (CPU) 1002, a read only
memory (ROM) 1003, a random access memory (RAM) 1004, a user input unit 1005, a display
1006, and a communication interface ( I / F 1007, data I / F 1010, and audio I / F 1011. The
acoustic control device 1000 further includes a test sound source output unit 1012, an
identification signal switching unit 1013, a switching unit 1014, filters 1015 1 and 1015 2, and
amplifier units 1016 1 and 1016 2. These units are communicably connected to one another via
a bus 1001. The communication path between the audio I / F 1011 and the bus 1001 is omitted
in FIG.
[0110]
The CPU 1002 controls the overall operation of the acoustic control device 1000 using the RAM
1004 as a work memory in accordance with, for example, a program stored in advance in the
ROM 1003. For example, the ROM 1003 includes a sound control program for causing the CPU
1002 to execute the function of the identification signal generation unit 20 and the function of
the control filter calculation unit 23 as well as a program of overall control.
[0111]
The user input unit 1005 includes various operators such as a switch for receiving a user input
and a dial. The user input unit 1005 is not limited to this, and may be a keyboard or a touch
panel integrally configured with a display 1006 described later. The display 1006 performs
display based on a display control signal generated by the CPU 1002 according to a program.
The communication I / F 1007 communicates with an external device by wire or wirelessly.
[0112]
The data I / F 1010 is an interface that performs data communication with an external device,
and can use, for example, Universal Serial Bus (USB). For example, the weather information data
40 1 and 40 2 output from the weather information acquisition units 21 1 and 21 2 are input
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31
from the data I / F 1010 and passed to the CPU 1002.
[0113]
The audio I / F 1011 is an interface of an acoustic signal supplied from the outside. When the
acoustic signal supplied from the outside is an analog signal, the audio I / F 1011 performs A / D
conversion on the analog acoustic signal based on a predetermined sampling frequency to obtain
a digital acoustic signal. For example, acoustic signals output from the microphones 24 1 and 24
2 are input from the audio I / F 1011 and are passed to the CPU 1002 as digital acoustic signals.
In addition, an input acoustic signal 50 used for actual reproduction is also input to the audio I /
F 1011.
[0114]
Note that the weather information data 40 1 and 40 2 output from the weather information
acquisition units 21 1 and 21 2 are not limited to being input from the data I / F 1010. For
example, the weather information data 401 and 402 output from the weather information
acquisition units 21 1 and 21 2 may be transmitted by wireless communication such as a
wireless LAN (Local Area Network) and received by the communication I / F 1007. Good.
Similarly, the acoustic signals output from the microphones 24 1 and 24 2 are not limited to
being input from the audio I / F 1011, and can be transmitted by wireless communication such
as wireless LAN and can be received by the communication I / F 1007. .
[0115]
The test sound source output unit 1012 generates white noise and a TSP signal according to an
instruction of the CPU 1002, and outputs the generated signal as an original identification signal.
According to the function of the identification signal generation unit 20 realized by the program
operated by the CPU 1002, the identification signal switching unit 1013 has, for example, the
first identification signal 300 n and the first identification signal 300 n with the minimum time
width T. The signal is repeatedly distributed to the second identification signal 301 n and output.
[0116]
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32
The switching unit 1014 outputs the first identification signal 300 n and the second
identification signal 301 n output from the identification signal switching unit 1013 and the
acoustic signal supplied from the audio I / F 1011 as Switching between the filters 1015 1 and
1015 2 and the bus 1001 is performed according to the instruction of the CPU 1002.
[0117]
The filters 1015 1 and 1015 2 respectively correspond to the first control filter 111 1 and the
second control filter 111 2 described above.
That is, in the filters 1015 1 and 1015 2, each filter parameter calculated according to the
function of the control filter calculation unit 23 realized by the program operated by the CPU
1001 is set, and according to the set filter parameter, the input acoustic signal is Apply filter
processing.
[0118]
The amplifier units 1016 1 and 1016 2 respectively correspond to the first volume adjustment
unit 121 1 and the second volume adjustment unit 121 2 described above. That is, the amplifier
units 1016 1 and 1016 2 perform volume adjustment (amplitude adjustment) on the input sound
signals according to the instruction of the CPU 1002. The acoustic signals output from the
amplifier units 1016 1 and 1016 2 are supplied to, for example, the speakers 130 1 and 130 2.
Note that the amplification units that perform power amplification for reproducing the sound
signal as sound by the speakers 130 1 and 130 2 may be built in each of the amplifier units
1016 1 and 1016 2, and this sound control device It may be an external configuration of 1000.
[0119]
In the above description, the test sound source output unit 1012, the identification signal
switching unit 1013, the switching unit 1014, and the filters 1015 1 and 1015 2 are described
as being configured by hardware independent of one another. It is not limited to this example.
For example, some or all of the test sound source output unit 1012, the identification signal
switching unit 1013, the switching unit 1014, and the filters 1015 1 and 1015 2 may be
configured by a program operated by the CPU 1002. You may comprise using the integrated
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33
circuit of 1 chip.
[0120]
The above-described sound control program is stored in advance in the ROM 1003 and provided.
Not limited to this, the sound control program may be supplied from an external device via the
communication I / F 1007 or the data I / F 1010.
[0121]
For example, the acoustic control program according to the embodiment has a module
configuration including the identification signal generation unit 20 and the control filter
calculation unit 23. As an actual hardware, the CPU 1002 performs the acoustic control program
from the storage 1003, for example. The above-described units are loaded onto the RAM 1004
by reading and execution, and the identification signal generating unit 20 and the control filter
calculating unit 23 are generated on the RAM 1004.
[0122]
(Modification of the Embodiment) In the above, in order for the sound field control system 10a to
control the sound pressure of the two control areas, the weather information acquisition units 21
1 and 21 2, the microphone 24 1 and the two control areas, respectively. Although 24 2 is
arranged, this is not limited to this example.
That is, as exemplified in FIG. 26, the weather information acquisition units 21 1, 21 2,..., 21 N
and the microphones 24 1, 24 2,. And the sound pressure of the N control areas can be
controlled.
[0123]
In this case, as exemplified in FIG. 26 as a sound field control system 10b, the sound field control
unit 11b includes a filter unit 110 ′ including N control filters and a sound volume adjustment
unit 120 including N sound adjustment units. Have '. The filter unit 110 ′ includes a first
control filter 111 1, a second control filter 111 2,..., An Nth control filter 111 N. Also, the volume
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34
adjuster 120 'includes a first volume adjuster 1211, a second volume adjuster 1212, ..., and an
Nth volume adjuster 121N. The first volume adjuster 121 1, the second volume adjuster 121 2,...,
And the Nth volume adjuster 121 N output an acoustic signal to each of the N speakers 130 1,
130 2,.
[0124]
In this case, for example, with the speaker 130 1 as a reference sound source and the other
speakers 130 2 to 130 N as control sound sources, the reference sound source and each control
sound source are paired, for each set of reference sound source and one control sound source.
And execute the processing according to the above-described embodiment. At this time, the
identification signal generation unit 20 ′ generates a first identification signal, a second
identification signal,..., N for reproduction by the respective speakers 130 1, 130 2,. The
identification signals of N identification signals are cyclically distributed for each minimum time
width T, and repeatedly output as outputs 42 1, 42 2,..., 42 N.
[0125]
Other Embodiments Next, other embodiments will be described. Another embodiment is an
example in which a sound according to an identification signal is emitted from the control area
side, and the emitted sound is collected by the reference sound source and the control sound
source. FIG. 27 is a diagram schematically illustrating a sound field control system according to
another embodiment.
[0126]
That is, since the reciprocity theorem holds for the space transfer characteristics, appropriate
space transfer characteristics should be obtained even if the mounting conditions of the speaker
for emitting the sound by the identification signal and the microphone for collecting the sound
are reversed. Can. That is, as illustrated in FIG. 27, the speakers 30 are disposed at the position of
the control area, and the microphones 25 1 and 25 2 are respectively provided near the speaker
130 1 of the reference sound source and near the speaker 130 2 of the control sound source.
Place. The speaker 30 emits a sound based on an identification signal such as white noise or a
TSP signal, and the emitted sound is collected by the microphones 25 1 and 25 2 respectively.
11-04-2019
35
[0127]
According to this configuration, it is possible to simultaneously measure the spatial transfer
functions of multiple paths from the speaker 30 to the microphones 251 and 252. As a result,
the microphones 251 and 252 receive the same wind effect, and therefore, it is not necessary to
repeatedly output the identification signal in the identification signal generation unit 20
according to the above-described embodiment, and identification can be performed even with
only one monaural reproduction. Become.
[0128]
FIG. 28 shows an exemplary configuration of a sound field control system according to another
embodiment. In FIG. 28, in the sound field control system 10 c, the acoustic signals output from
the microphones 25 1 and 25 2 are supplied to the control filter calculation unit 23 ′ via the
amplitude adjustment unit 26. The speaker 30 is also supplied with an identification signal input
as the input acoustic signal 50. When controlling the sound pressure of the first control area and
the second control area, the speakers 30 are disposed in the first control area and the second
control area, respectively, and the identification signal is transmitted to the two speakers 30.
Switch to supply.
[0129]
When the control area is one, the control filter calculation unit 23 'uses the acoustic signal
supplied from each of the microphones 25 1 and 25 2 according to the above equations (1) and
(2) to perform the first control filter. The filter parameters of 111 1 and second control filter 111
2 are calculated respectively. Further, in the case where there are two control areas, the control
filter calculation unit 23 'uses the acoustic signals supplied from the respective microphones 25
1 and 25 2 according to the above-mentioned formulas (4) to (21). The filter parameters of the
control filter 111 1 and the second control filter 111 2 are respectively calculated.
[0130]
Modification of Another Embodiment A modification of the other embodiment will be described.
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As well known, when a speaker receives sound pressure, an acoustic signal is output by back
electromotive force and can be used as a microphone. In a modification of the other embodiment,
the back electromotive force of the speaker is used. FIG. 29 is a diagram schematically
illustrating a sound field control system according to a modification of the other embodiment.
[0131]
As exemplified in FIG. 29, in a modification of the other embodiment, the microphones 25 1 and
25 2 used in the other embodiment described above are a speaker 130 1 ′ which is a reference
sound source and a speaker 130 2 which is a control sound source. And replaced with '. The
speakers 130 1 ′ and 130 2 ′ output acoustic signals 32 1 and 32 2, respectively, by receiving
sound pressure.
[0132]
Also in this configuration, as in the other embodiments described above, it is possible to
simultaneously measure the spatial transfer functions of a plurality of paths from the speakers
30 to the respective speakers 130 1 ′ and 130 2 ′ as microphones. As a result, since the
speakers 130 1 ′ and 130 2 ′ receive the same wind effect, repeated output of the
identification signal in the identification signal generation unit 20 according to the abovedescribed embodiment is not necessary, and one system of monaural reproduction is provided. It
is possible to identify it alone.
[0133]
FIG. 30 shows a configuration of an example of a sound field control system according to a
modification of the other embodiment. In FIG. 28, in the sound field control system 10d, the
acoustic signals output from the speakers 1301 'and 1302' are supplied to the control filter
calculation unit 23 'via the amplitude adjustment unit 26'. The speaker 30 is also supplied with
an identification signal input as the input acoustic signal 50. The other configuration is the same
as that of the sound field control system 10c according to the other embodiment described in
FIG. 28, and thus the detailed description will be omitted.
[0134]
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37
The present invention is not limited to the above embodiments as it is, and at the implementation
stage, the constituent elements can be modified and embodied without departing from the scope
of the invention. In addition, various inventions can be formed by appropriate combinations of a
plurality of components disclosed in the above-described embodiments. For example, some
components may be deleted from all the components shown in each embodiment. Furthermore,
components in different embodiments may be combined as appropriate.
[0135]
10a, 10b, 10c, 10d, 100 sound field control system 20 identification signal generation unit 23,
23 'control filter calculation unit 30, 1301, 1301', 1302, 1302 'speaker 50 input acoustic signal
21 1,, 21 2, 21 N Weather information acquisition unit 24 1, 24 2, 24 N, 150, 151 i, 152 j
Microphone 110, 110 ′ Filter unit 111 1 First control filter 111 2 Second control filter 111 N
Nth control filter 120 volume adjustment unit 121 1 first volume adjustment unit 121 2 second
volume adjustment unit 121 N Nth volume adjustment unit 160, 161, 162 control area 300, 300
1, 300 2, 300 3, 300 n for first identification Signals 301, 301 1, 301 2, 302 3, 302 n second
identification signals
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38
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