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JP2006109344

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DESCRIPTION JP2006109344
PROBLEM TO BE SOLVED: To efficiently diffuse and reflect a radiation sound from a sound
emitting means such as a speaker. SOLUTION: An acoustic reflector r that reflects a sound flux,
and an array speaker ASP that emits a sound flux from the sound flux radiation surface P to the
acoustic reflector r, and the reflection surface rs of the acoustic reflector r is smooth Is formed in
a convex shape, and protrudes toward the direction in which the sound flux is emitted. With such
a configuration, the sound flux is efficiently diffused in the front-rear direction of the acoustic
reflector r. [Selected figure] Figure 5
Acoustic reflection system
[0001]
The present invention relates to a technology for listening to voices and musical tones in an
acoustic space such as a hall or a theater.
[0002]
In an acoustic space such as a hall or a theater, generally, a plurality of speakers are dispersedly
disposed on a wall surface or a ceiling.
If sound is emitted simultaneously from these multiple speakers, stereo effects and special effects
can be produced. However, since it is necessary to install a number of loudspeakers according to
the size of the acoustic space, in addition to the considerable cost, complicated operations such
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as wiring around each loudspeaker are required.
[0003]
In Patent Documents 1 and 2, an array speaker in which a plurality of speaker units are arranged
in a row direction or in a plane is installed on a ceiling or the like, and an acoustic beam B
emitted from the array speaker is reflected on a wall surface to localize a sound image. (Japanese
Patent Application Laid-Open No. 2000-101118), or the array speaker is rotated to localize the
sound image in all directions of 360 ° as viewed from the listener (Japanese Patent Application
Laid-Open No. 2004-101501). The array speaker used here is a speaker system in which a
plurality of speaker units are arranged in a row direction or in a plane, and the directivity is
controlled by appropriately controlling the delay time of the audio signal supplied to each
speaker unit. A sound wave (hereinafter referred to as an acoustic beam) can be emitted in a
desired direction. Therefore, also in Patent Document 1, the acoustic beam B can be emitted in a
plurality of directions by installing the array speaker at one place, and the wiring work to the
speaker can be significantly reduced. However, on a flat wall such as a hole, usually only specular
reflection occurs, so the sound can only reach in one direction corresponding to the reflection
angle, and it is not possible to obtain the sound spread from the reflection surface. JP-A-9233591 JP-A-9-233588 JP
[0004]
As described above, even if the devices shown in Patent Documents 1 and 2 are used, the spread
of sound can not be obtained from the reflection surface, so if it is intended to obtain a wide
sound, it will eventually be I had to install a speaker.
[0005]
The present invention has been made in view of the above-mentioned circumstances, and it is
possible to obtain a spread reflected sound even when using a sound emitting means such as an
array speaker capable of emitting a beam of sound flux. Aims to provide an acoustic reflection
system that can
[0006]
In order to solve the problems described above, the present invention includes an acoustic
reflector that reflects a sound flux, and a sound flux output unit that emits the sound flux from
the sound flux emission surface to the acoustic reflector. The reflecting surface of the acoustic
reflector is formed in a smooth convex shape, and protrudes in the direction in which the sound
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flux is emitted.
[0007]
In this case, the sound flux may be a parallel beam, and the convex shape is formed such that the
outer edge of the cross section of the acoustic reflector is a parabola, and the sound flux is set
parallel to the axis of the parabola. It is suitable.
[0008]
Further, the acoustic reflector may have an elliptical cross-sectional shape, and the sound flux
may be a convergent beam that converges to a focal point far from the sound flux radiation
surface among two focal points of the ellipse.
[0009]
Further, the surface of the acoustic reflector may be a hyperbola at the outer edge of the cross
section, and the sound flux may be a sound flux emitted toward the reflection surface from a
focal point other than the reflector side among the focal points of the hyperbola.
[0010]
Further, when the bundle of virtual parallel lines is drawn from the sound flux radiation surface
to the reflection surface, the convex shape extends from an arbitrary position orthogonal to the
virtual parallel line to the tip of the convex shape. The distance of the virtual parallel line may be
the shortest, and the distance of the virtual parallel line from the position to the reflection
surface may be sequentially increased as the distance from the tip portion increases.
[0011]
Further, the acoustic reflector may be set at a position where the tip of the convex shape reaches
the sound bundle most quickly.
[0012]
According to the present invention, the sound flux strikes the convex shape of the acoustic
reflector and is diffused.
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In this case, since the acoustic reflector protrudes in the direction of emission of the sound flux,
the sound flux can be efficiently diffused.
In addition, by changing the position at which the sound bundle of the acoustic reflector is
reflected, it is possible to change the position and size of the area to which the reflected sound
reaches.
[0013]
(1) Principle of Array Speaker Before entering into the details of the embodiment of the present
invention, first, the principle of the array speaker used in this embodiment will be briefly
described.
[0014]
FIG. 1 is a diagram showing an electrical configuration of an array speaker ASP configured by
two speaker units SP1 and SP2.
In FIG. 1, the central axes Y1 and Y2 of the speaker units SP1 and SP2 are parallel to each other,
and the cones (diaphragms) of the speaker units SP1 and SP2 are disposed at the same position
in the direction of the central axes Y1 and Y2 It shall be done.
Further, the distance between the central axis Y1 and the central axis Y2 is "a", and the angle
from the central axes Y1 and Y2 to the radiation directions Y11 and Y22 (hereinafter referred to
as radiation angle) is "θ".
Assuming that the listening area is sufficiently far, the path difference between the sound wave
emitted from the speaker unit SP1 in the direction of the radiation direction Y11 and the sound
wave emitted from the speaker unit SP2 in the direction of the emission direction Y22 is “a · sin
θ It becomes ".
[0015]
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The audio signal input from the input terminal Tin is branched into two paths.
The audio signal of one of the paths is supplied to the speaker unit SP1 via the delay circuit DL1,
and the audio signal of the other path is supplied to the speaker unit SP2 via the delay circuit
DL2.
The audio signal is a signal indicating various sounds such as human voice and musical
instrument performance sound.
The delay circuits DL1 and DL2 respectively delay the supplied audio signal by time D1 and D2
(D2 ≧ D1) and output the delayed signal.
Therefore, a time difference (D2-D1) occurs between the sound wave emitted from the speaker
unit SP1 and the sound wave emitted from the speaker unit SP2.
[0016]
Since there is a path difference between the radiation axis Y11 and the radiation axis Y22 as
described above in addition to the time difference between the two sound waves as described
above, both sound waves depend on the position (hearing point) where each sound wave reaches
in the acoustic space R The phase relationship of is different. For example, at a certain position,
both sound waves are in phase and added, and the volume is doubled. Also, at other positions,
both sound waves have an opposite phase and are offset, and the volume becomes zero.
Therefore, by appropriately controlling the delay amount in each of the delay circuits DL1 and
DL2, it is possible to make the sound waves emitted from the array speaker ASP have the desired
directivity. Of course, the principle is the same even if the number of speaker units is further
increased.
[0017]
Although the number of channels of the audio signal is one in FIG. 1, the number of channels
may be more. Also, after delay processing is performed on the audio signal of each channel with
an appropriate delay amount, the audio signal subjected to the delay processing is added and
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emitted from each speaker unit, whereby an acoustic beam for each channel is separately
provided. It is possible to emit in different directions. For example, it is possible to emit different
musical tones as different acoustic beams or to emit speech of different languages and dubbed
speech of movies as different acoustic beams.
[0018]
Next, embodiments of the present invention will be described in detail. (2) Overall configuration
of sound system
[0019]
FIG. 2 is a plan view showing the configuration of the acoustic system according to the
embodiment. The sound space R is a hall where concerts and events are held, and a stage ST
where lectures, performances, singing and the like are performed, and a passenger seat SE where
an appreciator (listener) is located are provided. Near the ceiling of the rear wall WL1 of the
passenger seat SE, an array speaker ASP is provided. The array speaker ASP is a sound emitting
means for emitting a directional sound wave (acoustic beam). In addition, the acoustic reflectors
r1 to r6 are provided on the side wall surfaces WL2 and WL3 of the acoustic space R. Each of the
acoustic reflectors r1 to r6 has an acoustic reflection surface, and reflects the acoustic beam
emitted from the array speaker ASP toward the inside of the acoustic space R by the acoustic
reflection surface. In FIG. 2, arrows B1 to B6 extending from the position of the array speaker
ASP in the direction of the respective acoustic reflectors r1 to r6 indicate acoustic beams.
Further, dotted lines extending concentrically from the positions of the acoustic reflectors r1 to
r6 illustrate how the reflected acoustic beam travels (scatters) while diffusing in the acoustic
space R. In the side wall surfaces WL2 and WL3, on the wall surface portions other than the
portions where the acoustic reflectors r1 to r6 are provided, an acoustic sound absorber such as
a sound absorption panel is provided for the purpose of preventing flutter echo and the like. .
[0020]
FIG. 3 is a block diagram showing the electrical configuration of the array speaker ASP and its
peripheral devices. The array speaker ASP is composed of eight speaker units SP1 to SP8
arranged in a line in the horizontal direction. The main control unit CU includes a CPU and a
memory m as a storage unit. The audio signal supplied from the main control unit CU to the
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input terminal Tin is supplied to the speaker units SP1 to SP8 via the delay circuits DL1 to DL8
and the level control circuits W1 to W8. The delay circuits DL1 to DL8 delay the input audio
signal. The level control circuits W1 to W8 attenuate or amplify the level of the input audio
signal. The operation parameters of the delay circuits DL1 to DL8 and the level control circuits
W1 to W8 are designated by the control signal supplied from the main control unit CU. The user
interface unit UI includes an operation unit including various switches and keys, and a display
unit such as a liquid crystal display. The operator can give various instructions to the main
control unit CU by operating the operation unit while referring to the information displayed on
the display unit.
[0021]
Here, FIG. 4 is a perspective view of the acoustic space R viewed from the position of the rear
wall surface WL1. As shown in FIG. 3, the acoustic reflectors r1 to r6 are provided at
predetermined heights of the side wall surfaces WL2 and WL3. The acoustic beam emitted by the
array speaker ASP is reflected by the acoustic reflectors r1 to r6 to reach the listener of the
audience SE.
[0022]
Next, the shapes of the acoustic reflectors r1 to r6 will be described. The acoustic reflectors r1 to
r6 are formed as pillars (see FIG. 5B) having a cross section which is convex toward the array
speaker ASP. And as shown in FIG. 2, it is the cross-sectional shape of the shape which the
acoustic reflector r2 protruded more than the acoustic reflector r1, and becomes the crosssectional shape which the acoustic reflector r3 protruded more than the acoustic reflector r2 ing.
In addition, the acoustic reflectors r1, r2 and r3 and the acoustic reflectors r4, r5 and r6 are
formed symmetrically with respect to the array speaker ASP, and all the acoustic reflectors r1 to
r6 are in the direction of the array speaker ASP. Protruding. Note that the acoustic reflectors r1
to r6 all have substantially the same configuration, and therefore, when it is not necessary to
distinguish them from one another, they are collectively referred to as "acoustic reflector r". The
same applies to the acoustic beams B1 to B6.
[0023]
Next, the shape of the reflecting surface rs of the acoustic reflector r will be described in detail.
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FIG. 5A is a view showing details of the cross-sectional shape of the acoustic reflector r. In this
figure, the positional relationship between the reflective surface rs of one acoustic reflector r
provided on the side wall surface WL and the array speaker ASP is shown. Virtual parallel lines s,
s, s, s... Shown in FIG. 5A are virtual parallel lines drawn from the sound flux emission surface P
of the array speaker ASP toward the reflection surface rs of the acoustic reflector r. The sound
flux emitting surface P is a portion of the front surface of the speakers SP1 to SP8 or the surface
of the baffle plate to which the speakers SP1 to SP8 are attached, which emits a sound flux for
the acoustic reflector r. The imaginary straight line L is a straight line orthogonal to the parallel
lines s, s... And drawn at an arbitrary position. Here, the cross-sectional shape of the reflection
surface of the acoustic reflector r is a smooth convex shape, and the tip of the projection has a
convex parallel line s, s ... between the virtual straight line L and the reflection surface rs. And is
formed to be gradually longer as it goes away from the tip.
[0024]
When the reflecting surface is configured as described above, when the parallel acoustic beam B
is emitted from the array speaker ASP, this parallel acoustic beam B is diffused around the
acoustic reflector r. That is, when the virtual parallel line s shown in FIG. 5A is replaced with a
sound bundle indicating the parallel acoustic beam B, the reflected sound is diffused in all
directions in the acoustic space R as shown by a broken line in the figure. .
[0025]
In the configuration described above, when the array speaker ASP outputs parallel acoustic
beams B1 to B6 toward the respective acoustic reflectors r1 to r6, the acoustic beams B1 to B6
are diffused around the respective acoustic reflectors r1 to r6. Ru. At this time, the sound image
of the diffused sound is localized at the positions of the acoustic reflectors r1 to r6. From the
viewpoint of the listener, it feels as if there are speakers at the positions of the acoustic reflectors
r1 to r6. become.
[0026]
By the way, in the acoustic system according to the present embodiment, when the acoustic beam
B is applied to the acoustic reflector r, the entire surface of the reflective surface of the acoustic
reflector r may not be applied. It is possible to apply an acoustic beam according to the area to be
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reflected.
[0027]
In this case, in the array speaker ASP, the radiation direction can be changed or the width of the
acoustic beam B can be changed by controlling the delay amount in each of the speaker units
SP1 to SP8. Here, the width of the acoustic beam means the thickness of the acoustic beam in the
direction orthogonal to the traveling direction (radial direction) of the acoustic beam. Reducing
the width of the acoustic beam B corresponds to increasing the directivity, and increasing the
width of the acoustic beam B corresponds to reducing the directivity. FIGS. 6-8 is a figure which
showed a mode that the radiation direction of the acoustic beam B was changed according to the
position of the listening area. As shown in FIG. 6, when the acoustic beam B is emitted toward the
reflecting surface rp1 relatively close to the array speaker ASP side among the reflecting surfaces
rs, the acoustic beam B is reflected in the direction approaching the array speaker ASP It will be
done. Therefore, the acoustic beam B can reach the listening area LA located behind the acoustic
reflector r. In FIG. 6, “forward” is a direction approaching the stage ST, and “backward”
means a direction away from the stage ST (direction approaching the rear wall surface WL1) (the
same applies in the following description).
[0028]
On the other hand, as shown in FIG. 8, when the acoustic beam B is emitted toward the reflecting
surface rp2 relatively far from the array speaker ASP among the reflecting surfaces rs, the
acoustic beam B is directed in the direction away from the array speaker ASP It will be reflected.
Accordingly, the acoustic beam B can reach the listening area LA located in front of the acoustic
reflector r. Then, as shown in FIG. 7, when the acoustic beam B is emitted toward the reflection
surface rp3 located in the middle of the reflection surface rp1 of FIG. 6 and the reflection surface
rp2 of FIG. The position of is also near the middle of the listening area of FIG. 6 and the listening
area of FIG. That is, the acoustic beam B can be made to reach the listening area LA located
approximately to the side of the acoustic reflector r.
[0029]
Furthermore, as can be understood by comparing FIGS. 5 and 6 described above, if the width wd
of the acoustic beam B is increased even if the positions on the reflective surface rs of the
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radiation center axis WO are almost the same (FIG. In the case, the reflected acoustic beam B will
travel in a wider direction. That is, the diffusion effect of the acoustic beam B by reflection is
increased, and the listening area LA can be enlarged. Conversely, if the width wd of the acoustic
beam B is reduced (in the case of FIG. 6), the direction in which the acoustic beam B is reflected
is limited to a certain direction, so the listening area LA becomes smaller.
[0030]
Next, an aspect of the shape of the reflective surface rs will be described. As shown in FIG. 9,
when the curved diameter of the reflecting surface rs is relatively small, most of the acoustic
beam B is reflected in the direction away from the array speaker ASP. That is, a reflection
phenomenon similar to specular reflection that occurs on a planar wall surface is occurring. In
this case, as shown in FIG. 9, the acoustic beam B can reach the listening area LA located in front
of the acoustic reflector r. Next, as shown in FIG. 10, if the radius of curvature of the reflecting
surface rs is made larger than in the case of FIG. 9, the direction of the reflected acoustic beam B
will be less biased. That is, as viewed from the position of the acoustic reflector r, the acoustic
beam B can reach the relatively wide listening area LA from the front to the rear. Further, as
shown in FIG. 11, when the curved diameter of the reflecting surface rs is further increased, the
acoustic beam B is reflected in the direction approaching the array speaker ASP. Therefore, the
acoustic beam B can reach the listening area LA located behind the acoustic reflector r.
[0031]
As described above, the shape of the reflecting surface rs is formed into a smooth convex shape,
and the acoustic beam B is emitted by projecting toward the direction in which the acoustic beam
B is emitted (the direction in which the sound flux is emitted). Can be efficiently diffused in the
front-rear direction of the reflector, and the reflection state can be appropriately set by changing
the curvature. Further, the method of forming the convex shape is not limited to the forming
method shown in FIG. 5A, and the convex shape may be formed smoothly and in the direction in
which the sound flux is emitted. Furthermore, the position of the tip of the convex shape may be
set to a position where the sound flux reaches the earliest.
[0032]
The present invention can be implemented in various forms as follows. (1) As a cross-sectional
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shape of the reflecting surface rs, an ellipse, a parabola, or a hyperbola may be used as follows.
For example, FIG. 12 is an example in the case of making the cross-sectional shape of the
acoustic reflector r elliptical. In this example, the acoustic beam B may be a parallel beam, but as
shown in FIG. 12, it is assumed that the acoustic beam B converges to the focal point F2 farther
from the array speaker ASP among the two focal points F1 and F2 of the ellipse. Since the sound
reflected by the acoustic reflector r travels along a straight line passing through the focal point
F1 closer to the array speaker ASP, the sound image position of the reflected sound sounds as if
it were at the focal point F1. In this figure, the side wall surface WL is indicated by a dashed
dotted line, but the portion below the dashed dotted line does not have to be formed as an
acoustic reflector r, and may be formed only above the dashed dotted line .
[0033]
Also, the acoustic reflector r may be not only a cylinder having a cross-sectional ellipse but also
an ellipsoid that can be rotated about the x-axis. In this case, the sound image of the reflected
sound is recognized as a point source diffused from the focal point F1 in four directions.
[0034]
FIG. 13 shows an example in which the outer edge of the cross-sectional shape of the acoustic
reflector r is a parabola. In this example, the acoustic beam is a parallel beam parallel to a line
connecting the apex of the parabola and the focal point. According to such a configuration, since
the reflected sound reflected by the acoustic reflector travels along a straight line passing
through the focal point F of the parabola, the sound image of the reflected sound sounds as if it
were at the focal point F. In this figure, the side wall surface WL is indicated by a dashed dotted
line, but the portion below the dashed dotted line does not have to be formed as an acoustic
reflector r, and may be formed only above the dashed dotted line . Also, the acoustic reflector r
may be formed not only as a column but also as a solid that can be formed by rotating a parabola
about a line connecting its apex and the focal point F as an axis. In this case, the reflected sound
is recognized as a sound emitted with the focal point F as a point sound source.
[0035]
FIG. 14 is an example in which the outer edge of the cross-sectional shape of the acoustic
reflector is hyperbolic. In this example, the acoustic beam is an acoustic beam that is diffused
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from one focal point F1 of the hyperbolic curve toward the acoustic reflector r. According to such
a configuration, since the reflected sound reflected by the acoustic reflector r travels along a
straight line passing through the other focal point F2 of the hyperbola, the sound image of the
reflected sound sounds as if it were at the focal point F2. In this figure, the side wall WL2 is
indicated by an alternate long and short dash line, but the portion below the alternate long and
short dash line need not be formed as an acoustic reflector r, and may be formed only above the
alternate long and short dash line. The acoustic reflector r may not only be formed as a cylinder,
but may be formed as a solid that can be formed by rotating a hyperbola about a line connecting
the focal point F1 and the focal point F2. In this case, the reflected sound is recognized as a
sound emitted with the focal point F2 as a point sound source.
[0036]
(2) The acoustic space to which the acoustic system according to the embodiment is applied is
applied to any facility indoors or outdoors, for example, a church, an opera house, a conference
room, or a competition venue such as synchronized swimming or figure skating. Is possible. In
the case of outdoor application, an array speaker or acoustic reflector may be installed on a
dedicated pole or column. It may be suspended from a ceiling or installed on a balloon floating in
the air. In the embodiment, an array speaker having a single-row configuration has been
described. However, the present invention is not limited to this. For example, an array speaker
may be configured by a total of m × n speaker units, with m speaker units having an n-row
configuration. Good. When only the reflection surface of the acoustic reflector is changed to cope
with the change in the listening area, it is not necessary to use the array speaker, and it is
directed to emit a directional sound wave toward the acoustic reflection surface. It is possible to
substitute a sex speaker (for example, a horn speaker).
[0037]
It is a figure explaining the principle for an array speaker to emit a directional sound wave. It is a
schematic diagram which shows the whole structure of the sound system which concerns on one
Embodiment of this invention. It is a block diagram which shows the electrical configuration of
the array speaker and its peripheral device in the same system. It is a perspective view which
shows the acoustic space to which the acoustic system which concerns on the embodiment is
applied. It is a figure which shows a mode that an acoustic beam is reflected by the acoustic
reflective surface. It is a figure which shows the relationship between an acoustic reflector and a
listening area. It is a figure which shows the relationship between an acoustic reflector and a
listening area. It is a figure which shows the relationship between an acoustic reflector and a
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listening area. It is a figure which shows the relationship between an acoustic reflector and a
listening area. It is a figure which shows the relationship between an acoustic reflector and a
listening area. It is a figure which shows the relationship between an acoustic reflector and a
listening area. It is a figure which shows the path | route of the reflected sound at the time of
making the cross-sectional shape of an acoustic reflector into an ellipse. It is a figure which
shows the path | route of a reflected sound at the time of making the outer edge of the cross
section of an acoustic reflector into a parabola. It is a figure which shows the path | route of a
reflected sound at the time of making the outer edge of the cross section of an acoustic reflector
into a hyperbola.
Explanation of sign
[0038]
R: acoustic space, ASP: array speaker, SP1 to SP8: speaker unit, W1 to W8: level control circuit,
DL1 to DL8: delay circuit, CU: main control unit, UI: user interface unit, r1 to r6: acoustic
reflector, B1 to B6: acoustic beam, rs: acoustic reflection surface, LA: listening area.
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