JP2006109343

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DESCRIPTION JP2006109343
PROBLEM TO BE SOLVED: To provide a speaker array system which can freely generate an
acoustic beam having any directivity and direction, and is suitable for use in any space.
SOLUTION: A large number of speaker units SP are arranged on the outer side surface of a
cylindrical speaker array section 300. The CPU 101 selects a plurality of speaker units used for
the output of the acoustic beam based on the information specifying the directivity and direction
of the acoustic beam output from the cylindrical speaker array unit 300, and a plurality of delays
supplied to these speaker units. Calculate the delay time of the audio signal. The DSP 201
performs signal processing to obtain a plurality of delayed audio signals from a common audio
signal. [Selected figure] Figure 1
スピーカアレイシステム
[0001]
The present invention relates to a loudspeaker array system that outputs acoustic beams from a
plurality of loudspeaker units arranged in an array.
[0002]
A speaker system in which a large number of speaker units are arranged is called a "speaker
array".
In the speaker array, by controlling the delay and the gain given to the audio signal supplied to
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each speaker unit, the directivity of the speaker can be sharpened and the direction of the
acoustic beam can be controlled. When the directivity is enhanced, the same energy is emitted to
a narrower range, so that the distance attenuation of the sound pressure becomes smaller, the
sound can be clearly heard far away, and the acoustic radiation in unnecessary directions is
suppressed. be able to. In addition, since the direction of the acoustic beam can be controlled, the
speaker does not have to be directed to the listening position of the sound, so that there is an
advantage that the restriction on the installation method of the speaker is reduced. A speaker
array of this type is disclosed, for example, in Patent Document 1. Unexamined-Japanese-Patent
No. 9-233591
[0003]
By the way, the above-mentioned conventional speaker array assumes a space in which it is used,
and presets and uses a delay and a gain given to an audio signal supplied to each speaker unit so
as to obtain desirable directivity and direction. It was not suitable for use in any space.
[0004]
The present invention has been made in view of the above-described circumstances, and it is
possible to freely generate an acoustic beam having any directivity and direction, and a speaker
array system suitable for use in any space. Intended to provide.
[0005]
The present invention is an output of an acoustic beam in the speaker array based on a speaker
array including a plurality of speaker units arranged to form a convex surface, and information
specifying the directivity and direction of the acoustic beam output from the speaker array.
Calculating means for selecting a plurality of speaker units used in the circuit and calculating
delay times of a plurality of delayed audio signals supplied to the speaker units, and signal
processing for obtaining the plurality of delayed audio signals from a common audio signal And a
signal processing means for performing the processing.
According to such a speaker array system, the acoustic beam can be emitted in any direction
facing the convex surface where the speaker unit is disposed, and its directivity can be
controlled.
In a preferred embodiment, the loudspeaker array is in the form of a cylinder. If the loudspeaker
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array is a cylinder, it is possible to emit an acoustic beam in all directions 360 degrees facing the
outer surface of the cylinder. Besides cylinders, the shape of the loudspeaker array may be cones,
polyhedrons or spheres. In a preferred embodiment, when information for specifying the
directivity and direction of a plurality of types of acoustic beams generated from a plurality of
types of audio signals is given, the computing unit is configured to calculate the plurality of
delayed audios for each acoustic beam. The delay time of the signal is calculated, and the signal
processing means performs signal processing for obtaining a plurality of delayed audio signals
for outputting the respective acoustic beams from the speaker array from each of the plurality of
audio signals. According to this aspect, a plurality of types of audio signals can be emitted as a
plurality of types of acoustic beams having any directivity and direction. Further, in another
preferable aspect, the signal processing means divides the audio signal into audio signals of a
plurality of frequency bands, and a plurality of each from a plurality of audio signals of a
plurality of bands obtained by the band division means. And a windowing unit for multiplying a
plurality of audio signals of the plurality of bands by window functions according to the
respective bands. According to this aspect, since windowing processing suitable for each
frequency band is performed for each frequency band, it is possible to effectively attenuate the
entrapment sound generated outside the acoustic beam. Also, in another preferred embodiment,
the speaker array system uses a speaker unit not selected to be used for output of an acoustic
beam in the speaker array to cancel a cancellation sound that cancels out a wraparound sound
generated outside the acoustic beam. A cancellation sound generation means is provided.
According to this aspect, it is possible to suppress the generation of the wraparound sound to the
outside of the acoustic beam.
[0006]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. First Embodiment FIG. 1 is a block diagram showing an electrical configuration of a
speaker array system according to a first embodiment of the present invention. As shown in this
figure, the speaker array system is composed of a CPU board 100, a DSP board 200, and a
cylindrical speaker array unit 300.
[0007]
FIG. 2 is a plan view of the cylindrical speaker array unit 300, and FIG. 3 is a side view of the
cylindrical speaker array unit 300. As shown in these figures, the cylindrical speaker array unit
300 is formed by arranging a large number of speaker units SP on the outer wall of a cylindrical
body having a hollow portion. More specifically, the cylindrical speaker array unit 300 includes a
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plurality of line array units LU each having a plurality of speaker units SP. Each line array unit LU
is a boundary between a first plate portion 301 forming a part of the outer wall of the cylindrical
speaker array portion 300 and an adjacent line array unit LU (next to the left in the example
shown in FIG. 2) And a second plate portion 302 which is a wall. Here, the first plate portion 301
is a long plate member, and a plurality of speaker units SP are arranged here to form one line.
The arrangement direction (line direction) of the speaker units SP is parallel to the direction of
the axis of the cylindrical speaker array unit 300. The angle formed by the first plate portion 301
and the second plate portion 302 is determined by the number of line array units LU constituting
the cylindrical speaker array portion 300.
[0008]
The second board 302 in each line array unit LU includes an interface board 310 and each
speaker unit for one line as a means for driving the speaker unit SP for one line provided in the
line array unit LU. A plurality of digital amplifier boards 320 corresponding to the SP are
attached. The cylindrical speaker array unit 300 includes a power supply 330 for supplying
power to the circuits mounted on each digital amplifier board 320, the CPU board 100 and the
DSP board 200 in FIG. 1 (both not shown in FIG. 2). ) Is fixed.
[0009]
In the present embodiment, the cylindrical speaker array unit 300 is provided as a means for
generating an acoustic beam having any directivity and direction. Here, with reference to FIG. 4
to FIG. 9, the generation principle of the acoustic beam in the present embodiment will be
described. Of these drawings, FIGS. 4, 6 and 8 show the cylindrical speaker array unit 300 as
viewed from above, and FIGS. 5, 7 and 9 show cylindrical speaker array units. A state in which
300 is viewed from the side is shown.
[0010]
In the example shown in FIG. 4 and FIG. 5, the convergent acoustic beam is generated so that the
sound pressure is locally high at the position P apart from the cylindrical speaker array unit 300.
Assuming that a plurality of sound waves having the same waveform and the same phase are
simultaneously output from a plurality of virtual sound source positions on a spherical surface of
radius r centered at the position P, the sound waves are added in the same phase at the position
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P. The sound pressure at P increases locally. In the example shown in FIG. 4 and FIG. 5, this is
used to generate an acoustic beam locally increasing the sound pressure at the position P by the
cylindrical speaker array unit 300. That is, it is as follows.
[0011]
First, in the present embodiment, a plurality of suitable speaker units SP are selected from the
cylindrical speaker array unit 300. In this selection process, for example, a plurality of speaker
units SP which may be considered to be capable of causing effective radiation sound to reach the
position P, such as the speaker unit SP within a predetermined range centered on the speaker
unit SP closest to the position P It is selected.
[0012]
Next, for each of the selected speaker units SP, the distance between the speaker unit SP and the
position P is determined, and the time required for the sound to propagate is determined for the
difference r between the radius r and this distance. Then, a plurality of types of delay processing
for delaying the signal by each required time determined for each speaker unit SP are applied to
the same audio signal to generate a plurality of delayed audio signals, and the speaker units
respectively corresponding to the respective delayed audio signals It supplies to SP. In this way,
the sound emitted from each speaker unit SP is added in the same phase at the position P as
described above.
[0013]
The examples shown in FIGS. 6 and 7 generate parallel acoustic beams that have neither
convergence nor divergence. In order to generate such parallel acoustic beams, the following
processing is performed in this embodiment. First, a speaker unit SP whose direction of
propagation of the acoustic beam is directly in front is determined, and a plurality of speaker
units SP within a predetermined range around this are selected as speaker units to be operated
for output of the acoustic beam. Here, the size of the range of the speaker unit SP to be selected
may be determined in accordance with the size W of the radiation range of the acoustic beam in
the horizontal direction. Next, behind the selected speaker units SP, a virtual plane orthogonal to
the propagation direction of the acoustic beam is assumed. Next, for each speaker unit SP, the
distance ΔL from the speaker unit SP to the virtual plane is determined, and the time required
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for the sound to propagate is determined for each of the distances ΔL. Then, a plurality of
delayed audio signals in which the original audio signal is delayed by the required time
determined for each speaker unit SP are generated and supplied to the speaker units SP.
[0014]
The example shown in FIGS. 8 and 9 is the reverse of the example shown in FIGS. 4 and 5. In this
example, a divergent acoustic beam is generated from each of the speaker units SP so as to widen
the radiation surface as it propagates, and the effect of making it sound as if there is a sound
source position at the position P is realized. In order to realize this effect, in the present
embodiment, based on the radiation direction of the acoustic beam, a plurality of speaker units
SP suitable for radiation in such radiation direction is first selected. Next, an imaginary spherical
surface of radius r centered on the position P is assumed behind the selected speaker units SP.
Next, for each speaker unit SP, the distance ΔL from the speaker unit SP to the virtual spherical
surface is determined, and the required time required for sound to propagate is determined for
each of the distances ΔL. Then, a plurality of delayed audio signals in which the original audio
signal is delayed by the required time determined for each speaker unit SP are generated and
supplied to the speaker units SP. The above is the generation principle of the acoustic beam in
this embodiment.
[0015]
In FIG. 1, a CPU 101 and a non-volatile memory 102 are mounted on a CPU board 100. The CPU
101 has a communication function for communicating with a device connected via a USB
interface, a device connected via Ethernet (registered trademark), a device connected via a MIDI
cable, and a host computer. ing. With this communication function, the CPU 101 receives
information indicating the directivity and direction of the acoustic beam from the host computer
etc., and outputs the acoustic beam having such directivity and direction according to the above
principle. The DSP board 200 calculates parameters necessary for controlling the directivity and
direction of the acoustic beam, such as the range of speaker units SP to be operated for the
output of S, and the delay time for obtaining delayed audio signals for each speaker unit. Supply.
The details of the arithmetic processing performed by the CPU 101 will be clarified in the
description of the operation of the present embodiment in order to avoid redundant description.
[0016]
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The nonvolatile memory 102 stores the ID of the CPU 101. Such an ID is stored, as one of the
embodiments of the present invention, because there can be a mode in which a plurality of
speaker array systems shown in FIG. 1 are connected to a host computer in charge of overall
control. Note that a DIP switch may be provided instead of the non-volatile memory 102. FIG. 10
shows an example in which a plurality of speaker array systems shown in FIG. 1 are connected.
In this example, cylindrical speaker array units 300 of a plurality of speaker array systems are
vertically stacked to constitute a cylindrical speaker array unit long in the axial direction, and
CPU 101 of each speaker array system operates as a host computer via Ethernet. It is connected.
This configuration is advantageous in that the directivity can be sharpened or controlled to the
low range because the line array unit having a long line length is configured. In this aspect, in
order to communicate with the CPU 101 of a certain system, the host computer transmits the ID
of the other party of communication. Each CPU 101 compares the ID transmitted from the host
computer with the ID stored in the non-volatile memory 102, and communicates with the host
computer if they match.
[0017]
In FIG. 1, a DSP 201, a DIR (digital interface receiver) 202, a format conversion unit 203, a
plurality of drivers 204, and a driver 205 are mounted on the DSP board 200. The DSP 201
receives digital audio signals via the DIR 202 and processes these digital audio signals under the
control of the CPU 101. The signal processing performed by the DSP 201 includes windowing
processing in addition to the generation of the above-described delayed audio signal. The DSP
201 executes these processes to generate and output digital audio signals addressed to the
plurality of speaker units SP operating for the output of the acoustic beam. The details of the
signal processing performed by the DSP 201 will also be clarified in the description of the
operation of the present embodiment in order to avoid redundant description.
[0018]
The plurality of drivers 204 are respectively associated with the plurality of speaker units SP
provided in the cylindrical speaker array unit 300. The digital audio signal addressed to the
specific speaker unit SP output from the DSP 201 is converted into a format suitable for
transmission by the format conversion unit 203, and the one corresponding to the speaker unit
SP which is the destination among the plurality of drivers 204 is selected. It is supplied to the
interface board 310 via the interface board.
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[0019]
The DIR 202 generates a synchronization signal such as a clock based on the input digital audio
signal. The generated synchronization signal is input to the DSP 201 and the format conversion
unit 203 and supplied to all the interface boards 310 in the cylindrical speaker array unit 300
via the driver 205.
[0020]
One interface board 310 is provided for each of a plurality of line array units LU constituting the
cylindrical speaker array unit 300. The interface board 310 provided in each line array unit LU is
provided with a plurality of receivers 311 for receiving digital audio signals addressed to a
plurality of speaker units SP provided in the line array unit.
[0021]
Further, each line array unit LU is provided with a plurality of digital amplifier boards 320
mounted with circuits for driving a plurality of speaker units SP provided in the line array unit. A
digital amplifier board 320 corresponding to one speaker unit SP receives a digital audio signal
addressed to the speaker unit SP from the corresponding receiver 311 and converts it into an
analog audio signal, and this analog audio signal And an amplifier 322 for amplifying the signal
and sending it to the speaker unit SP. The above is the details of the configuration of the speaker
array system according to the present embodiment.
[0022]
Next, the operation of this embodiment will be described. In the following, for convenience of
explanation, a cylindrical speaker is specified by an index j specifying the position in the
alignment direction of the line array unit LU and an index i specifying the position in the
alignment direction of the speaker units SP in the line array unit LU. The individual speaker units
SPij provided in the array unit 300 are specified. Also, as shown in FIGS. 2 and 3, the cylindrical
speaker array unit 300 has 36 line array units LU, and each line array unit LU has 12 speaker
units SP. All the speaker units constituting the cylindrical speaker array unit 300 are represented
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by SPij (i = 1 to 12, j = 1 to 36).
[0023]
FIG. 11 is a diagram for explaining the processing content of the CPU 101. The CPU 101 receives
information indicating the directivity and direction of the acoustic beam to be generated from a
host computer or the like. When generating an acoustic beam as shown in FIG. 4 and FIG. 5, the
information indicating directivity and direction includes information indicating the coordinates of
the position P that locally increases the sound pressure. Also, in the case of generating parallel
acoustic beams as shown in FIGS. 6 and 7, the information indicating directivity and direction
includes information indicating the propagation direction of the acoustic beam and the radiation
width W thereof. Further, as shown in FIG. 8 and FIG. 9, when generating an acoustic beam to be
heard so that the virtual sound source position is at the position P, the information indicating the
directivity and direction is the information indicating the coordinates of the virtual sound source
position P including. When receiving information indicating such directivity and direction, the
CPU 101 selects a speaker unit SP to be operated for generation of the acoustic beam. As shown
in FIG. 11, when generating an acoustic beam that locally increases the sound pressure at a
position P outside the cylindrical speaker array unit 300, the position P is located directly in
front in the selection process of the speaker unit SP. The index jm of the line array unit LU is
determined, and predetermined ranges ja (= jm−Δj) to jb (= jm + Δj) centering on the jm are
determined. Then, the speaker units SPij (i = 1 to 12, j = ja to jb) are used as the speaker units
operated to generate an acoustic beam.
[0024]
As already described with reference to FIGS. 4 to 9, in this embodiment, in addition to generating
an acoustic beam that raises the sound pressure at a specific position P, a parallel acoustic beam
is generated (FIGS. 6 and 7). 7) Generate an acoustic beam that sounds as if the sound source
position is at a specific position P (FIGS. 8 and 9). An example of the method of selecting the
speaker unit SP to be operated to generate each acoustic beam has already been described with
reference to FIGS. 4 to 9, and thus the description thereof is omitted here. Regardless of which
acoustic beam is generated, in the selection process of the speaker unit SP, the range ja to jb of
the index j of the speaker unit SPij to be operated for the generation of the acoustic beam is
determined.
[0025]
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When the speaker units SPij (i = 1 to 12, j = ja to jb) to be operated for generating the acoustic
beam are determined, the CPU 101 determines the delay time Dij (i = 1) of the delayed audio
signal supplied to these speaker units. 〜1212, j = ja to jb) are respectively calculated. This
calculation method is as already described with reference to FIGS. 4 to 9.
[0026]
Next, the CPU 101 executes four window function values WAij (i = 1 to 12, j = ja to jb), WBij (i = 1
to 12, j = ja to jb), and WCij (i = 1 to 12, j). = Ja to jb) and WDij (i = 1 to 12, j = ja to jb), delay
times Dij (i = 1 to 12, j = ja to jb), and speaker units SPij (to which they should be applied) The
information indicating i = 1 to 12 and j = ja to jb) is associated and supplied to the DSP 201.
Hereinafter, these pieces of information will be collectively referred to as acoustic beam
configuration parameters.
[0027]
The window function values WAij (i = 1 to 12, j = ja to jb), etc. are to be multiplied by the delayed
audio signal to suppress the side lobes leaking out of the radiation range of the intended acoustic
beam, and the acoustic beam Among the speaker units SPij (i = 1 to 12, j = ja to jb) operated to
generate the value of the delay audio signal, values are determined so as to suppress the level of
the delayed audio signal supplied to the speaker unit in the peripheral portion. In the present
embodiment, in view of the fact that the window function effective for side lobe suppression
depends on the band of the audio signal, four types of window functions WA, WB, WC and
corresponding to each band obtained by dividing the audio frequency band into four. WD is
available. In the present embodiment, a plurality of acoustic beams may be generated by the
cylindrical speaker array unit 300 based on a plurality of digital audio signals. In that case,
information specifying the directivity and direction of each acoustic beam is given to the CPU
101 from, for example, a host computer. At this time, the CPU 101 obtains the above-mentioned
acoustic beam configuration parameters for each of the plurality of acoustic beams, and sends
the parameters to the DSP 201.
[0028]
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Further, in the present embodiment, information indicating the directivity and direction of a
certain acoustic beam may change over time. In that case, the CPU 101 obtains an acoustic beam
configuration parameter corresponding to the newly designated directivity and direction every
time the designated directivity and direction change, and sends it to the DSP 201.
[0029]
As an aspect of changing the information indicating the directivity and direction of the acoustic
beam with the passage of time, time-series information indicating the directivity and direction of
the acoustic beam is recorded on, for example, a recording medium, and this is There may be an
aspect in which the data is read and supplied to the CPU 101. As an aspect other than this, the
aspect which instruct ¦ indicates the direction of an acoustic beam to CPU101 by operation of a
joystick, a rotary encoder, 3D input device etc. can be considered.
[0030]
FIG. 12 is a block diagram showing the signal processing performed by the DSP 201 in a
hardware manner. In the example shown in FIG. 12, the DSP 201 is provided with arithmetic
processing means for generating delayed audio signals for generating acoustic beams for each of
the five types of digital audio signals S1 to S5. Five types of digital audio signals S1 to S5 are
supplied via the DIR 202.
[0031]
Hereinafter, among the processing means corresponding to the digital audio signals S1 to S5
among the five types, the processing means corresponding to the illustrated digital audio signal
S1 will be described, but the other digital audio signals S2 to S5 will be described. Arithmetic
processing means corresponding to are also similar to this.
[0032]
The DSP 201 performs delay processing 2011 for time alignment on the input digital audio S1.
This is processing for adjusting the phase relationship between the digital audio signals S1 to S5.
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The delay time in the delay processing 2011 is designated by the CPU 101.
[0033]
Next, the DSP 201 performs an LPF process 2012A for selecting the signal of the lowest band
among the four bands obtained by dividing the audio frequency band, a first BPF process 2012B
for selecting the signal of the second band, and a third band. The 2BPF processing 2012C and
the HPF processing 2012D for selecting the signal in the highest band are applied to the digital
audio signal that has undergone the delay processing 2011, respectively.
[0034]
Next, the DSP 201 performs an oversampling process 2013 on each digital audio signal that has
undergone the LPF process 2012A, the first BPF process 2012B, the second BPF process 2012C,
and the HPF process 2012D, and then performs a delay process 2014, respectively.
The oversampling processing 2013 is performed to increase the resolution of the delay time in
the delay processing 2014.
[0035]
Each delay processing 2014 refers to the information on the delay time in the acoustic beam
configuration parameters given from the CPU 101 for the digital audio signal S1, and delays the
oversampled digital audio signal by the delay time Dij (i = 1 to 12). , J = ja to jb) to generate a
plurality of delayed digital audio signals delayed. These are delayed digital audio signals
corresponding to the speaker units SPij (i = 1 to 12, j = ja to jb).
[0036]
Next, the DSP 201 applies windowing processing 2015A, 2015B, 2015C and 2015D to the
delayed digital audio signal obtained by each delay processing 2014 respectively. Here, in the
windowing process 2015A, window function values WAij (i = 1 to 12, j = ja to jb) are extracted
from the acoustic beam configuration parameters given from the CPU 101 for the digital audio
signal S1. The window function values WAij (i = 1 to 12, j = ja to jb) are respectively multiplied to
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the delayed digital audio signals corresponding to the speaker units SPij (i = 1 to 12, j = ja to jb).
The other windowing processing is the same, but in windowing processing 2015B, the window
function values WBij (i = 1 to 12, j = ja to jb) in the acoustic beam configuration parameters are
window function values in windowing processing 2015C. WCij (i = 1 to 12, j = ja to jb) is used,
and windowing processing 2015D uses window function values WDij (i = 1 to 12, j = ja to jb).
[0037]
The DSP 201 performs a plurality of additions for combining a plurality of digital audio signals to
be supplied to all the speaker units SPij (i = 1 to 12, j = 1 to 36) of the cylindrical speaker array
unit 300 in parallel with the above processing. Process 2017 is executed in parallel. Then, the
DSP 201 executes a mapping process 2016 for handing over the delayed digital audio signals to
be sent to the respective speaker units SPij obtained by the windowing process to the addition
process 2017 for those speaker units SPij.
[0038]
The results of the plurality of addition processes 2017 corresponding to the speaker units SPij (i
= 1 to 12, j = 1 to 36) are output from the DSP 201 through the plurality of addition processes
2018, and the format conversion unit 203 in FIG. 204 are supplied to the digital amplifier board
320 via the receiver 311. As a result, an acoustic beam having designated directivity and
direction is generated by the cylindrical speaker array unit 300.
[0039]
Next, signal processing performed in the DSP 201 to temporally change the directivity and
direction of the acoustic beam will be described. As described above, when the information
indicating the directivity and direction of an acoustic beam changes with the passage of time, the
CPU 101 causes the newly instructed directivity to be changed whenever the instructed
directivity and direction change. The acoustic beam configuration parameters corresponding to
the and directions are determined and sent to the DSP 201. In order to cope with such switching
of acoustic beam configuration parameters, the DSP 201 more specifically performs delay
processing 2014, windowing processing 2015A, and mapping processing 2016 shown in FIG. 12
by methods as shown in FIGS. 13 and 14, for example. Is running. Although only the part related
to the windowing process 2015A is shown in FIG. 13 as an example, the parts related to other
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windowing processes have the same process content.
[0040]
First, the DSP 201 selects one of the register arrays RAij (i = 1 to 12, j = 1 to 36) and the register
arrays RBij (i = 1 to 12, j = 1 to 36). A switch SW is provided. Here, each signal stored in each
register of the register array selected by the switch SW is used to drive the speaker unit SPij (i =
1 to 12, j = 1 to 36).
[0041]
Then, for example, the delay time DAij (i = 1 to 12, j = ja to jb), the window function value WAAij
(i = 1 to 12, j = ja to jb) and the speaker unit according to the acoustic beam configuration
parameters currently given. It is assumed that SPij (i = 1 to 12, j = ja to jb) is specified. In this
case, the DSP 201 generates a plurality of delayed digital audio signals having delay times DAij (i
= 1 to 12, j = ja to jb) from the oversampled signal S1, respectively, and adds them to the window
function value WAAij ( i = 1 to 12, j = ja to jb) are multiplied respectively. Then, the plurality of
windowed delayed digital signals obtained by the multiplication are, for example, the registers
RAij (i = 1 to 12, j = ja to jb in the register array RAij (i = 1 to 12, j = 1 to 36). Write to). While this
operation is being performed, the switch SW selects the register array RAij (i = 1 to 12, j = 1 to
36), and the signal stored therein is the speaker unit SPij (i = 1 to 12, j = 1 to 36) (RAij mapping
in FIG. 14).
[0042]
Thereafter, a new acoustic beam configuration parameter is generated by the CPU 101, and delay
time DBij (i = 1 to 12, j = ja 'to jb') and window function value WBAij (i = 1 to 12) are generated
by this acoustic beam configuration parameter. It is assumed that j = ja 'to jb') and speaker units
SPij (i = 1 to 12, j = ja 'to jb') are specified.
[0043]
In this case, while continuing signal processing using the old acoustic beam configuration
parameters, delay processing and windowing processing using the new acoustic beam
configuration parameters are performed, and the windowed delayed digital audio signal obtained
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as a result is obtained. The data is written to the registers RBij (i = 1 to 12, j = ja 'to jb') in the
other register array RBij (i = 1 to 12, j = 1 to 36).
Then, when this writing is completed, the switch SW is switched to the side of the register array
RBij (i = 1 to 12, j = 1 to 36). Thus, the signals stored in the register array RBij (i = 1 to 12, j = 1
to 36) are used to drive the speaker units SPij (i = 1 to 12, j = 1 to 36) (in FIG. 14). RBij mapping).
[0044]
Thereafter, the same applies to the case where a new acoustic beam configuration parameter is
generated by the CPU 101, and signal processing using the register array RBij (i = 1 to 12, j = 1
to 36) currently in use is continued, The results of signal processing based on the new acoustic
beam configuration parameters are written to the register array RAij (i = 1 to 12, j = 1 to 36), and
then the register array is switched. By repeating the operation as described above, signal
processing corresponding to the time-varying acoustic beam configuration parameter is
advanced, and an acoustic beam whose directivity and direction change with time is generated.
[0045]
The operation of the DSP 201 has been described above using the digital audio signal S1 as an
example, but the same processing is performed for the other digital audio signals S2 to S5. Then,
the result of the signal processing of each of the digital audio signals S1 to S5 is added in the
addition processing 2018 for each of the speaker units SPij, and used for driving the cylindrical
speaker array unit 300. Here, the CPU 101 in this embodiment generates an acoustic beam
configuration parameter for each of the digital audio signals S1 to S5 and supplies it to the DSP
201, and the DSP 201 applies signal processing of the digital audio signals S1 to S5 for each of
them. Run using the specified acoustic beam configuration parameters. Therefore, according to
the present embodiment, five types of acoustic beams with different directivity and direction can
be generated by the cylindrical speaker array unit 300. Moreover, in the present embodiment,
since the cylindrical speaker array unit 300 is configured as illustrated in FIG. 2 and FIG. 3, the
directivity and direction of the acoustic beam can be arbitrarily set within the 360 ° all azimuth
range. In addition, the directivity and direction of the acoustic beam can be changed in the axial
direction of the cylindrical speaker array unit 300.
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[0046]
Second Embodiment In the first embodiment, from the speaker units SP of the cylindrical speaker
array unit 300, a part of the speaker units SP that are likely to be useful for generation of the
designated acoustic beam are selected. , Only those speaker units SP were operated. In the
speaker array system according to the second embodiment of the present invention, the speaker
unit SP which has not been selected for generation of the acoustic beam is operated as a means
for canceling the wraparound sound. The configuration of this speaker array system is basically
the same as that of the first embodiment. The difference from the first embodiment is that the
CPU 101 not only performs the process of generating the acoustic beam configuration
parameters but also generates a sound that cancels out with the speaker unit SP not selected for
the generation of the acoustic beam. Control of the DSP 201 to make the
[0047]
FIG. 15 shows an operation example of the speaker array system according to the second
embodiment of the present invention. In this example, a speaker unit SP within the range
indicated by the arrow Y1 is used to emit an acoustic beam that causes the sound source to be
heard at the position P into the area AR. As described in the first embodiment, if the delay time of
the audio signal supplied to each speaker unit SP is adjusted and appropriate windowing
processing is performed, the radiation of the sound wave to the outside of the area AR can be
suppressed to some extent. it can. However, since the sound output from the speaker unit SP
propagates in a relatively wide range, it inevitably reaches the area BR outside the area AR as a
wrap around sound. Therefore, in the present embodiment, using the speaker unit SP within the
range indicated by the arrow Y2 which is not selected as the speaker unit SP for generating an
acoustic beam, the cancellation sound that cancels out with the wraparound sound in the area BR
is the area BR Radiate inside. There are the following three methods for generating this offset
sound.
[0048]
a. First cancellation sound generation method In this method, the output sound of a speaker
unit SP (hereinafter referred to as a wrap around sound generation speaker unit) within the
range of the arrow Y1 turns into a wrap around sound and a position within the area BR
(hereinafter wrap around) When it is known that the sound reaches the sound arrival position Q),
the cancellation sound is generated as follows. That is, as shown in FIG. 16, the delay time of the
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delayed audio signal supplied to the speaker unit SP in the arrow Y2 is adjusted so that the
cancellation sound of the opposite phase to the wraparound sound arrives at the wraparound
sound arrival position Q. The CPU 101 generates a cancellation tone parameter necessary to
obtain such a delayed audio signal, and sends it to the DSP 201.
[0049]
b. Second cancellation sound generation method In this method, it is known that the output
sound of a wraparound sound generation speaker unit within the range of the arrow Y1 reaches
a wraparound sound arrival position Q in the area BR as a wraparound sound. Generate a
cancellation sound as follows. First, a transfer function G1 of a path until the audio signal
becomes a wraparound sound via the wraparound sound generation speaker unit and reaches a
position in the area BR is previously obtained. Next, a speaker unit SP within a range indicated by
the arrow Y2 is selected as a cancellation sound speaker unit, and a transfer function G2 from
the cancellation sound speaker unit to the wraparound sound arrival position Q is obtained in
advance. Then, when emitting an acoustic beam into the area AR based on an audio signal, as
shown in FIG. 17, the audio signal is subjected to a filter process corresponding to the transfer
function G1, and the looped sound at the looped sound arrival position is An audio signal
corresponding to V. is generated, the phase of this audio signal is inverted, and filtering
processing equivalent to the inverse function G2 <-1> of the transfer function G2 is performed
and supplied to the cancellation sound speaker unit. By performing such processing, it is possible
to supply the cancellation sound of the wraparound sound and the reverse phase to the arrival
position of the wraparound sound and cancel the wraparound sound.
[0050]
c. Third cancellation sound generation method In this method, it is known that the output
sound of a wraparound sound generation speaker unit within the range of arrow Y1 reaches a
wraparound sound arrival position Q in area BR as a wraparound sound. A sensor for detecting
the wraparound sound is disposed at the wraparound sound arrival position Q in FIG. Further, a
speaker unit SP within the range indicated by the arrow Y2 is selected as the cancellation sound
speaker unit. Then, when an acoustic beam is emitted into the area AR based on an audio signal,
as shown in FIG. 18, the audio is controlled so that the level of the looping sound at the looping
sound arrival position Q detected by the sensor becomes a minimum value. The signal is
subjected to adaptive filter processing and supplied to the cancellation sound speaker unit. By
performing such processing, it is possible to suppress the level of the looping sound at the
looping sound arrival position Q low.
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[0051]
The cancellation sound generation method described above is particularly effective for canceling
the sneak noise in the low range. Therefore, the above-mentioned cancellation sound generation
method may be implemented by limiting only to the low frequency component.
[0052]
<Other Embodiments> In addition to the above-described embodiments, for example, the
following embodiments can be considered in the present invention. (1) In each of the above
embodiments, a cylindrical speaker array is used. However, the shape of the loudspeaker array
may, for example, be a cone, a polyhedron or a sphere. (2) As shown in FIG. 19, the cylindrical
speaker array unit 300 is divided into two, for example, and the processing of generating the
delayed digital audio signal to be provided to the speaker unit SP in the divided area is shared by
two DSPs 201A and 201B. You may By doing this, the load on each DSP can be alleviated, and
the processing speed can be increased.
[0053]
It is a block diagram showing composition of a speaker array system which is a 1st embodiment
of this invention. It is a top view which shows the structure of the cylindrical speaker array part
in the same speaker array system. It is a side view which shows the structure of the cylindricaltype speaker array part. It is a figure explaining the generation ¦ occurrence ¦ production
principle of the acoustic beam in the embodiment. It is a figure explaining the generation ¦
occurrence ¦ production principle of the acoustic beam in the embodiment. It is a figure
explaining the generation ¦ occurrence ¦ production principle of the acoustic beam in the
embodiment. It is a figure explaining the generation ¦ occurrence ¦ production principle of the
acoustic beam in the embodiment. It is a figure explaining the generation ¦ occurrence ¦
production principle of the acoustic beam in the embodiment. It is a figure explaining the
generation ¦ occurrence ¦ production principle of the acoustic beam in the embodiment. It is a
figure which shows the example of the system which used two or more same spare array
systems. It is a figure explaining the processing content of CPU in the embodiment. It is a figure
explaining the processing content of DSP in the embodiment. It is a figure explaining the
processing content of DSP in the embodiment. It is a figure explaining the processing content of
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DSP in the embodiment. It is a figure which shows operation ¦ movement of the speaker array
system which is 2nd Embodiment of this invention. It is a figure which shows the 1st example of
the cancellation sound generation method in the embodiment. It is a figure which shows the 1st
example of the cancellation sound generation method in the embodiment. It is a figure which
shows the 1st example of the cancellation sound generation method in the embodiment. It is a
figure which shows other embodiment of this invention.
Explanation of sign
[0054]
101 ... CPU, 201 ... DSP, 300 ... cylindrical speaker array part.
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