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JP2007110455

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DESCRIPTION JP2007110455
PROBLEM TO BE SOLVED: To provide an acoustic reproduction system capable of forming a
virtual sound source by an acoustic beam and making a range in which an effect as a virtual
sound source appears can be wider than before. SOLUTION: A sound processing unit 100
performs at least a delay process on an audio signal to generate a plurality of delayed audio
signals for causing a direct sound beam BD directly reaching a designated focal point F to be
output from the speaker array 1. A plurality of delayed audio signals for causing the speaker
array 1 to output the reflected sound beams BL and BR arriving at the same focal point F via the
reflection by the wall WL or WR generate a plurality of speakers SP-k (k = 1 to n). [Selected
figure] Figure 1
Sound reproduction system
[0001]
The present invention relates to a sound reproduction system using a speaker array.
[0002]
The speaker array is formed by arranging a plurality of speakers in a line or matrix.
By providing a common audio signal to each of the speakers constituting this speaker array, and
by appropriately adjusting the phase of the audio signal supplied to each speaker at that time, an
arbitrary point in front of the speaker array is focused. An acoustic beam can be output. When
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such an acoustic beam is generated, a virtual sound source appears at the focal point of the
acoustic beam, and the listener receives an impression as if a sound is emitted from the virtual
sound source. Therefore, various types of sound reproduction systems have been proposed
which provide a listener with music and the like by forming a virtual sound source with a speaker
array. In addition, the technique which forms a virtual sound source with a speaker array is
disclosed by the nonpatent literature 1 and patent document 1, for example. “Threedimensional sound reproduction using a speaker array”, NHK Science and Technical Research
Laboratories Shigehiro Nakayama, Hiroyuki Okubo, Kei Watanabe, Takeshi Komiya, Journal of
VMA Research Society Issue No. 9 12-17 pages, July 12, 2002 JP, 2005-64746, A
[0003]
By the way, when a virtual sound source is formed by an acoustic beam output from the speaker
array, the area where the effect as a virtual sound source is expressed is narrow, and a range
sandwiched by extension lines of two straight lines drawn from both ends of the speaker array
toward the focal point If it is not inside, it is difficult to listen to the sound of the virtual sound
source. For this reason, there has been a problem that the sound reproduction system using the
conventional speaker array is not suitable for applications where a wide range of listeners can
listen to music.
[0004]
The present invention has been made in view of the above-described circumstances, and it is an
acoustic reproduction system capable of forming a virtual sound source by an acoustic beam and
making the range of the effect as a virtual sound source wider than before. The purpose is to
provide.
[0005]
According to the present invention, there is provided a speaker array in which a plurality of
speakers are arranged in a line or in a matrix, and a means for performing delay processing on
an audio signal at least and generating a plurality of delayed audio signals for driving the
plurality of speakers in the speaker array. A direct sound beam signal processing unit for
generating a plurality of delayed audio signals for causing the speaker array to output a direct
sound beam directly arriving at a designated focal point; and a reflected sound arriving at the
same focal point via reflection by a wall And a signal processing unit including a plurality of
reflected sound beam signal processing units for generating a plurality of delayed audio signals
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for outputting a beam from the speaker array.
According to the invention, multiple types of acoustic beams representing the same audio signal
reach a common focus from a wide range of directions. Therefore, the area | region which the
effect as a virtual sound source formed in a focus can express can be made wide.
[0006]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. First Embodiment FIG. 1 is a diagram showing an overall configuration of a sound
reproduction system according to a first embodiment of the present invention. The sound
reproduction system includes a speaker array 1 and a sound processing unit 100. Here, the
speaker array 1 is a device in which a plurality of speakers SP-k (k = 1 to n) are arranged in a line
or matrix, and is fixed to a front wall WF of a room. Further, the sound processing unit 100
drives the speakers SP-k (k = 1 to n) on the basis of an audio signal obtained from a sound source
(not shown in FIG. 1), and three kinds of sounds having a common focus F. The beam is output
from the speaker array 1. That is, a direct sound beam BD directly coming from the speaker array
1 to the focal point F, a reflected sound beam BL emitted from the speaker array 1 and then
reflected by the left wall WL to reach the focal point F, and emitted from the speaker array 1
After that, it is a reflected sound beam BR that is reflected by the right wall WR and reaches the
focal point F. The feature of the present embodiment lies in the aspect of generation of an
acoustic beam performed under the control of the acoustic processing unit 100.
[0007]
FIG. 2 is a block diagram showing the configuration of the sound processing unit 100. As shown
in FIG. The sound processing unit 100 receives an audio signal in digital form from the sound
source 101. The direct sound beam signal processing unit 111 generates n delayed audio signals
for causing the direct sound beam BD to be output from the speaker array 1 based on the input
audio signal. Also, the reflected sound beam signal processing units 112 and 113 are configured
to output n delayed audio signals for outputting the reflected sound beam BL from the speaker
array 1 and n pieces for outputting the reflected sound beam BR from the speaker array 1. Each
generates a delayed audio signal. The n delayed audio signals generated by each signal
processing unit are respectively associated with n speakers SP-k (k = 1 to n). The adders 121-k (k
= 1 to n) add the delayed audio signals obtained from the signal processing units corresponding
to the same speaker and output the result. The D / A converter 122-k (k = 1 to n) converts each
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of the delayed audio signals output from the adder 121-k (k = 1 to n) into an analog format, and
outputs the speaker SP-k (k = 1 to n).
[0008]
In the audio signal input from the sound source 101, focal position data indicating the position of
the common focal point F of the three acoustic beams is multiplexed. The distance calculating
unit 131 and the parameter calculating unit 132 constitute means for controlling the direct
sound beam signal processing unit 111 and the reflected sound beam signal processing units
112 and 113 based on the focal position data.
[0009]
FIG. 3 shows the contents of processing performed by the distance calculation unit 131 and the
parameter calculation unit 132. First, the distance calculation unit 131 stores information on the
arrangement of walls in the room where the speaker array 1 is installed, and the positional
relationship between the wall and the speaker array 1. When the distance calculation unit 131
receives the focus position data, the distance DD-k (k =) until each sound wave constituting the
acoustic beam BD emitted from the speaker SP-k (k = 1 to n) directly reaches the focal point F. 1
to n) and the distance DL-k (k = 1 to k) to reach the focal point F through the reflection by the
wall WL and the sound waves constituting the acoustic beam BL respectively emitted from the
speakers SP-k (k = 1 to n) n) and distances DR-k (k = 1 to n) from the sound waves constituting
the acoustic beam BR respectively emitted from the speakers SP-k (k = 1 to n) to reflection on the
wall WR to reach the focal point F And are calculated respectively.
[0010]
The parameter calculator 132 calculates differences ΔDD-k (k = 1 to n), ΔDL-k (k = 1 to n), and
ΔDR between the distances calculated by the distance calculator 131 and the longest distance
among them. Calculate -k (k = 1 to n). In the example shown in FIG. 1, the distance DL-n of the
path from the speaker SP-n to the focal point F via the reflection by the left wall WL in the path
of the acoustic beam BL is the longest. Therefore, in the parameter calculation unit 132, the
difference between each distance calculated by the distance calculation unit 131 and the longest
distance DL-n is calculated. Next, the parameter calculation unit 132 calculates the differences
ΔDD-k (k = 1 to n), ΔDL-k (k = 1 to n), and ΔDR-k (k = 1 to n) of the distances thus obtained. Is
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divided by the velocity of sound to calculate delay amounts TD-k (k = 1 to n), TL-k (k = 1 to n)
and TR-k (k = 1 to n) for obtaining a delayed audio signal. . Then, the parameter operation unit
132 sends the delay amount TD-k (k = 1 to n) to the direct sound beam signal processing unit
111, and the delay amount TL-k (k = 1 to n) and TR-k (k = k). 1 to n) are set in the reflected
sound beam signal processing units 112 and 113, respectively. Further, the parameter
calculation unit 132 sets window function values used for windowing processing to suppress the
occurrence of side lobes in the respective signal processing units 111, 112, and 113.
[0011]
The direct sound beam signal processing unit 111 delays the input audio signals from the sound
source 101 by TD-k (k = 1 to n), respectively, and generates n delayed audio signals by
multiplying them by the window function value. . Also, the reflected sound beam signal
processing units 112 and 113 respectively delay the same input audio signal by TL-k (k = 1 to n)
and multiply the window function values by n delayed audio signals, and The same input audio
signals are each delayed by TR-k (k = 1 to n), and n delayed audio signals are generated by
multiplying them by the window function value. As described above, these delayed audio signals
are added to those corresponding to the same speaker, and the addition results are respectively
supplied to the corresponding speakers.
[0012]
According to the above configuration, three types of acoustic beams BD, BL and BR are outputted
by the speaker array 1, and the acoustic beams BD, BL and BR reach the common focal point F in
the same phase. Therefore, the sound pressure locally increases at the focal point F, and a virtual
sound source is formed at the focal point F. In this case, a region obtained by extending the three
sound beams BD, BL and BR is a region where the sound of the virtual sound source can be
heard. Therefore, the effect of the virtual sound source can be expressed in a wider range
compared to the prior art.
[0013]
Second Embodiment FIG. 4 is a diagram showing an overall configuration of a sound
reproduction system according to a second embodiment of the present invention. This sound
reproduction system uses the speaker array 1 as a main speaker array, and additionally has sub
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speaker arrays 2 and 3. The main speaker array 1 is fixed to the front wall WF of the room, as in
the first embodiment. Further, sub-speaker arrays 2 and 3 have n speakers in the same manner
as main speaker array 1, and are fixed to regions where sound beams from main speaker array 1
are not emitted on walls WL and WR, respectively. There is.
[0014]
In the present embodiment, the main speaker array 1 and the sub speaker arrays 2 and 3 each
output the next acoustic beam. a. Main speaker array 1-Direct sound beam B-1-D directly
reaching focal point F-Reflected sound beam B--1-L reaching focal point F via reflection by wall
WL-Reflected sound reaching focal point F via reflection by wall WR Beam B-1-R b. Sub-speaker
array 2-Direct sound beam B-2-D directly reaching focal point F-Reflected sound beam B-2-M
reaching focal point F via reflection by wall WF-Reflected sound reaching focal point F via
reflection by wall WR Beam B-2-R c. Sub-speaker array 3-Direct sound beam B-3-D directly
reaching focal point F-Reflected sound beam B-3-L reaching focal point F via reflection by wall
WL-Reflected sound arriving at focal point F via reflection by wall WF Beam B-3-M
[0015]
FIG. 5 is a block diagram showing a configuration of the sound processing unit 150 that
performs drive control of the speaker arrays 1 to 3 to output the above-described sound beam.
As shown, the sound processing unit 150 has nine types of signal processing units 151 to 159
that respectively generate n delayed audio signals for obtaining the nine types of sound beams.
As in the first embodiment, the n delayed audio signals output from each signal processing unit
are respectively associated with the n speakers constituting the speaker array. The n delayed
audio signals output from the signal processing units 151 to 153 are synchronously added by
adders 161-k (k = 1 to n) corresponding to the same speaker, and each addition result is D It is
converted into an analog form by the / A converter 164-k (k = 1 to n) and supplied to each
speaker of the speaker array 1. Adders 162-k (k = 1 to n) and D / A converters 165-k (k = 1 to n)
that play similar roles also between the group of signal processing units 154 to 156 and the sub
speaker array 2 ), And the adder 163-k (k = 1 to n) and the D / A converter 166-that also play a
similar role between the group of signal processing units 157 to 159 and the sub speaker array
3. k (k = 1 to n) is provided. As in the first embodiment, the distance calculation unit 171 and the
parameter calculation unit 172 each signal processing unit 151 so that nine types of acoustic
beams reach the common focus F in the same phase based on the focus position data Generate
the delay amount and window function value set to -159.
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[0016]
According to the present embodiment, more acoustic beams reach the common focal point F
from a wider range of directions as compared with the first embodiment. Therefore, compared to
the first embodiment, the effect of the virtual sound source can be expressed in a wider range.
[0017]
<Other Embodiments> The first and second embodiments of the present invention have been
described above, but other embodiments can be considered in the present invention. For
example: (1) In the first and second embodiments, the focus position data is multiplexed to the
audio signal supplied from the sound source, and the directivity control of the acoustic beam is
performed according to the focus position data. Focus position data may be input by operating a
pointing device such as a mouse or the like to form a direct sound beam and a reflected sound
beam having a focus indicated by the focus position data. (2) In the first and second
embodiments, all signal processing units are always operated, but a plurality of signal processing
units are selected according to the selection operation performed by the user or the selection
information multiplexed into the audio signal. A control unit that operates selectively may be
provided in the sound processing unit, and one or more sound beams may be selected and output
from a plurality of types of sound beams that can be output. This aspect has an advantage that it
is possible to freely switch the area in which the effect of the virtual sound source is developed.
[0018]
BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the whole structure of the
sound reproduction system which is 1st Embodiment of this invention. It is a block diagram
which shows the structure of the sound processing unit in the embodiment. It is a block diagram
which shows the processing content of the distance calculating part and the parameter
calculating part in the embodiment. It is a figure which shows the whole structure of the sound
reproduction system which is 2nd Embodiment of this invention. It is a block diagram which
shows the structure of the sound processing unit in the embodiment.
Explanation of sign
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[0019]
1 to 3 ... speaker array, WF, WL, WR ... wall, 111 to 113, 151 to 159 ... signal processing unit,
131, 171 ... distance calculation unit, 132, 172 ... parameter calculation unit, SP − k (k = 1 to n)
... speaker, 121-k (k = 1 to n), 161-k (k = 1 to n), 162-k (k = 1 to n), 163-k (k = 1 to n ... Adder,
122-k (k = 1 to n), 164-k (k = 1 to n), 165-k (k = 1 to n), 166-k (k = 1) ~ N) ... D / A converter.
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