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JP2015019150

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2015019150
The present invention provides an acoustic reproduction device capable of transmitting sound
information only in a reproduction area with a small restriction on the number and position of
applied speakers and with a light processing load. An area in which directivity of superdirective
speaker SP1 and superdirective speaker SP2 intersect is a reproduction area, and a first divided
reproduction sound is time-divisionally divided into superdirective speaker SP1, the reproduction
sound source being time division. The two divided reproduction sounds are emitted from the
superdirective speaker SP2, and the intended information is properly transmitted to the
reproduction area reproduction sound source in the crossing area. [Selected figure] Figure 1
Sound reproduction apparatus and program
[0001]
The present invention relates to a sound reproduction apparatus and program, and is applicable
to, for example, reproduction of sound information only in a specific area.
[0002]
A technology for transmitting sound information only in a specific space (area) is required to
address problems such as noise and privacy.
As a method of reproducing sound information only in the area, there is sound field control by
signal processing using a speaker array. This method is a method of eliminating the sound
03-05-2019
1
pressure on the boundary of the area by controlling the delay and frequency characteristics of
the sound output from each speaker based on the boundary sound field control theory (see
Patent Document 1).
[0003]
Also, as another method of reproducing sound information only in the area, there is also a
method of using a superdirective speaker having a sharp directivity in a specific direction. A
parametric speaker is mentioned as a typical superdirective speaker. A parametric speaker is a
speaker which forms sharp directivity by using ultrasonic waves and transmits sound without
attenuating the sound far (see Non-Patent Document 1). If such a superdirective speaker is
installed, for example, downward to the ceiling, sound information can be transmitted only to the
area directly below.
[0004]
JP, 2006-74442, A
[0005]
Tomohiro Kamakura, Shin-ichi Sakai, "Practical Application of Parametric Loudspeaker", Journal
of the Acoustical Society of Japan, Vol. 62, No. 11 (2006), pp. 791-797
[0006]
By using the above-described prior art, sound information can be transmitted only in a specific
area.
However, various problems remain when actually using it.
[0007]
The sound field control technology using a speaker array requires a huge number of speakers for
one area, requires a large amount of calculation of multi-channel filtering processing, and
requires considerable machine power to operate. Do.
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2
[0008]
Also, the method of installing the superdirective speaker on the ceiling is limited in the place
where it can be installed.
For example, in order to install outdoors, special equipment is needed, and it depends on the
shape of the ceiling indoors.
Furthermore, once installed, there is also the problem that it is difficult to move to another area.
[0009]
Therefore, there is a need for an audio reproduction apparatus and program capable of
transmitting sound information only in a specific area with a small restriction on the number and
position of the applicable speakers and with a light processing load.
[0010]
According to a first aspect of the present invention, there is provided a sound reproducing
apparatus comprising: (1) a plurality of speakers for transmitting sound by emitting sound based
on the given sound signal for the speaker, and a plurality of speakers through which the
transmitted sound passes a predetermined reproduction area And (2) from the input
reproduction sound source to be transmitted to the reproduction area, an acoustic signal for each
speaker including the information on a part of the reproduction sound source, and the acoustic
signal for all the speakers is The above-mentioned speakers formed by the speaker-by-speaker
signal forming means for forming the sound signals for the above-mentioned speakers, which can
obtain signals equivalent to the above-mentioned reproduction sound source on the assumption
of overlapping And a speaker-by-speaker signal output means for giving an acoustic signal for
each to the corresponding speaker and emitting the sound.
[0011]
The sound reproduction program according to the second aspect of the present invention emits
sound based on the given sound signal for the speaker to send out the sound, and the
transmitted sound is given to each of a plurality of speakers passing through a predetermined
reproduction area. It is an acoustic signal for each of the above-mentioned speakers including
information of a part of the reproduction sound source from the input reproduction sound
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source to be transmitted to the reproduction area from a computer mounted on a device for
forming an acoustic signal. A signal-by-speaker forming means for forming an acoustic signal for
each of the above-mentioned speakers, which can obtain a signal equivalent to the abovementioned reproduced sound source on the assumption that all the above-mentioned audio
signals for loudspeakers are superimposed; The acoustic signal for each of the speakers formed
by the per-speaker signal forming means is provided to the corresponding speaker to function as
the per-speaker signal output means for emitting sound And features.
[0012]
According to the present invention, it is possible to provide a sound reproduction apparatus and
program capable of transmitting sound information only in a specific area with a small restriction
on the number and position of applied speakers and with a light processing load. .
[0013]
It is explanatory drawing which shows the positional relationship of two superdirective speakers
and reproduction area for demonstrating the common technical thought of each embodiment
concretely.
It is explanatory drawing of the division | segmentation method of a reproduction | regeneration
sound source (acoustic signal) for distributing to two superdirective speakers of FIG.
It is a block diagram showing composition of a sound reproduction device concerning a 1st
embodiment.
It is a flowchart which shows the process of the sound reproduction apparatus which concerns
on 1st Embodiment.
It is explanatory drawing which shows the positional relationship of the superdirective speaker in
the sound reproduction apparatus concerning 2nd Embodiment, a reflection member, and
reproduction | regeneration area. It is a block diagram which shows the structure of the sound
reproduction apparatus which concerns on 2nd Embodiment. It is a block diagram which shows
the structure of the sound reproduction apparatus which concerns on 3rd Embodiment. It is a
block diagram which shows the structure of the sound reproduction apparatus concerning 4th
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Embodiment. It is a block diagram which shows the structure of the sound reproduction
apparatus which concerns on 5th Embodiment. It is explanatory drawing which shows the
example of the step-like gain which the step gain multiplication part of the sound reproduction
apparatus concerning 5th Embodiment applies. It is a block diagram which shows the structure
of the sound reproduction apparatus which concerns on 6th Embodiment. It is a block diagram
which shows the partial structure of the sound reproduction apparatus based on the modification
of 6th Embodiment.
[0014]
(A) Technical concept common to each embodiment Technical technical concept common to the
first to sixth embodiments (hereinafter referred to as "the following") before describing the first
to sixth embodiments of the sound reproduction apparatus and program according to the present
invention A brief explanation of common technical ideas).
[0015]
In the common technical concept, each superdirective speaker is installed at a different position
using a plurality of superdirective speakers in which emitted (pronounced) sound travels in a
straight line.
The directivity of each superdirective speaker is selected so as to pass through an area for
reproducing sound information (hereinafter referred to as a reproduction area). In other words,
although the sound emitted from any superdirective speaker passes through the reproduction
area, there is no area through which the sounds emitted from the plural superdirective speakers
pass together other than the reproduction area.
[0016]
Further, in the common technical concept, the signal of the sound source (reproduction sound
source) of sound information to be reproduced in the reproduction area (hereinafter simply
referred to as a reproduction sound source) is divided by the number of superdirective speakers
from a predetermined viewpoint And each divided reproduction sound source is emitted from the
corresponding superdirective speaker. Each divided reproduction sound source is obtained by
dividing the original reproduction sound source into the number of superdirective speakers.
Therefore, even if each divided reproduction sound source is listened to, the sound information
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can not be recognized or the sound information is recognized. It takes a lot of hard work. In the
common technical concept, in the reproduction area, all divided reproduction sound sources flow,
so the same state as the reproduction sound source before division flows. Therefore, when
listening in the reproduction area, the listener can recognize the sound information intended by
the reproduction sound source.
[0017]
The viewpoint for dividing the reproduction sound source is not limited to one, and it may be a
viewpoint from which the listener can recognize information when all the divided reproduction
sound sources flow in the reproduction area. For example, time division can be applied. Also, for
example, band division can be applied. Furthermore, for example, volume division can be applied.
It may be a division method combining divisions of a plurality of viewpoints. For example, a
combination of time division and band division can be applied.
[0018]
Hereinafter, a specific image of the common technical concept will be described with reference to
FIG. 1 and FIG. 2 by taking an example in which the division point of view is time division.
[0019]
FIG. 1 shows the arrangement positions of two superdirective speakers (first and second
superdirective speakers) SP1 and SP2, and the directivity of each superdirective speaker SP1 and
SP2.
The area where the directivity of the first and second superdirective speakers SP1 and SP2
intersect is the reproduction area. The reproduction sound source as shown in FIG. 2A is divided
in the time direction. The first divided reproduction sound source shown in FIG. 2 (B) including
the signal in each period of 0 to t1, t2 to t3, t4 to t5,... Is emitted from the first superdirective
speaker SP1 . On the other hand, the second split reproduction sound source shown in FIG. 2 (C)
including the signal in each period of t1 to t2, t3 to t4,... Is emitted from the second
superdirective speaker SP2.
[0020]
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For example, in the case where the reproduction sound source is "If you go up that mountain, you
can see it", time division (assuming a time division with kana characters as a unit) will be used as
a first divided reproduction sound source.? Bo ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
??????????????????????????????????
? ? ? ? ? ? ? ? ?, And are respectively emitted from the corresponding superdirective
speakers SP1 and SP2.
[0021]
At places not on the directional lines of both superdirective speakers SP1 and SP2, no
information is heard even if both superdirective speakers SP1 and SP2 are emitted.
At the location on the directional line of the first superdirective speaker SP1 excluding the
playback area, "A-A-B-B-B-B--M--R" is heard, but "A-A-B-B? ? ? ? ? ? ? ? ? ? ? ? Is
meaningless, and the original information ?If you climb up that mountain you can see the sea?
is not recognized. Similarly, ?иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии is heard at a location on
the directional line of the second superdirective speaker SP2 excluding the reproduction area?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Is meaningless, and the original information ?If you
climb up that mountain you can see it? is not recognized.
[0022]
On the other hand, in the reproduction area, the first superdirective speaker SP1 emits a sound
?A, A, B, B, M, M, I? and the second superdirective speaker SP 2 emits a sound. "? ? ? ? ?
? ? ? ? ? ? ? ? Is heard. Since one of the two types of listening sounds is a sounding
period and the other is a silent period to compensate for the silent period, the two types of
listening sounds are synthesized and listened. That is, the original reproduction sound source
"Among the mountain can be seen if you climb up" is heard, and in the reproduction area, the
information intended by the reproduction sound source is correctly transmitted.
[0023]
Hereinafter, embodiments of the sound reproducing apparatus and the program in which the
common technical concept as described above is embodied will be sequentially described.
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[0024]
(B) First Embodiment Next, a first embodiment of a sound reproduction apparatus and program
according to the present invention will be described with reference to the drawings.
[0025]
(B-1) Configuration of the First Embodiment FIG. 3 is a block diagram showing the configuration
of the sound reproduction apparatus according to the first embodiment.
The parts shown in FIG. 1 excluding superdirective speakers may be constructed by connecting
various circuits in hardware, and a general-purpose device or unit having a CPU, a ROM, a RAM,
etc. It may be constructed so as to realize the corresponding function by execution, and it can be
functionally represented in FIG. 3 even if any construction method is adopted.
[0026]
In FIG. 3, the sound reproducing apparatus 10 according to the first embodiment includes N (N is
an integer of 2 or more) superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an
acoustic signal dividing unit 12, and an acoustic signal distribution. The unit 13 includes a delay
calculation unit 14, a space coordinate data holding unit 15, a delay unit 16, and an acoustic
signal output unit 17.
[0027]
As described above, superdirective speakers SP1 to SPN are speakers that form sharp directivity
by using ultrasonic waves and transmit sound without attenuating the sound far.
The directivity of each superdirective speaker SP1 to SPN is made to pass through the
reproduction area.
In FIG. 3, the superdirective speakers SP1 to SPN appear to be arranged on a straight line, but
this arrangement is an arrangement by the convenience of the page, not an actual arrangement
(Similarly, in the block diagram described later) The placement of the superdirective speakers is
also not the actual placement).
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[0028]
In the description of the first embodiment, it is assumed that the reproduction area is fixed and
the superdirective speakers SP1 to SPN are also fixed at predetermined positions.
[0029]
However, among the plurality of reproduction areas, the same sound reproduction apparatus
may correspond to the reproduction area selected at that time.
In such a case, for example, each superdirective speaker SP1 to SPN is attached to at least one of
the horizontal angle direction and the elevation angle direction to a swing member which can
swing by a driving force such as a motor, and the selected playback According to the area, the
control unit may control the motor to change the directivity direction of the superdirective
speakers SP1 to SPN. In addition, superdirective speakers that operate in each reproduction area
are defined, and sound is emitted from a plurality of superdirective speakers determined
according to the selected reproduction area, and sound emission from other superdirective
speakers is stopped. You may do so.
[0030]
The sound signal input unit 11 takes in a reproduction sound source (sometimes called sound
signal), and the taking method is not limited as in the example described later. Here, the acoustic
signal is not limited to the audio signal, and may be another sound signal such as an audio signal,
and in short, it may be a signal of information to be transmitted with sound to the reproduction
area. The sound signal input unit 11 may take in sound signals from various sound collection
devices in real time, and may use data files on storage media of devices provided in association
with the sound reproduction device 10. For example, an audio signal may be captured, an audio
signal may be captured from a distribution server on the Internet, or the like, and an audio signal
collected in the past and converted into a data file may be captured. When the acquired acoustic
signal is an analog signal, the acoustic signal input unit 11 also has a function of converting into
a digital signal.
[0031]
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The acoustic signal dividing unit 12 of the first embodiment divides the acoustic signal acquired
by the acoustic signal input unit 11 in the time direction. The time interval to be divided may be
constant or random, and may be determined in accordance with the characteristics of the target
acoustic signal.
[0032]
In the case of a fixed time interval, the time interval is preferably an interval which can not be
heard as a word at the longest. In addition, if the number (N) of superdirective speakers is 2, the
number of superdirective speakers to be installed is 300 milliseconds, and if the number (N) of
superdirective speakers is 3, 200 milliseconds As the number N) increases, the time interval may
be shortened. The fixed time interval to apply is not limited to one type. For example, assuming
that two types of time intervals are T1 and T2, the acoustic signal may be arbitrarily divided at
intervals of T1, T1, T2, T2, T1, T2, T1, T2, and so on.
[0033]
In the case of dividing at random intervals, for example, after obtaining a random value in the
range of 0.5 to 1.5, a predetermined fixed time is multiplied by a random value to determine a
random time interval. You may Alternatively, a plurality of different time intervals may be
determined in advance, and a random number may be used to select which one of the time
intervals is applied, and the series of time intervals to be divided may be randomly changed.
[0034]
An autocorrelation coefficient or cepstrum can be applied as a feature of an acoustic signal that
can be used to determine the time interval to be divided. The autocorrelation coefficient (the time
at which the autocorrelation becomes the largest) may be multiplied by a predetermined constant
to obtain an applied time interval. Also, prepare a table in which the range of feature quantities
such as autocorrelation coefficient and cepstrum are associated with the time interval to be
applied, and divide the time interval of the range to which the feature quantity calculated this
time belongs. The time interval may be used.
03-05-2019
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[0035]
When the acoustic signal division unit 12 divides the acoustic signal, it may divide the acoustic
signal as it is, but the cross fade (the time interval on the end side fades out and the time interval
on the new start side fades in) It is preferable to divide so as to apply The section of the cross
fade is, for example, 10 milliseconds in total before and after the division time point. By adopting
the cross fade, when the output sound (sound emission sound) from each superdirective speaker
is heard in the reproduction area, it is possible to make a natural reproduction sound source
without generating an abnormal sound.
[0036]
The acoustic signal distribution unit 13 distributes the acoustic signals time-divided by the
acoustic signal division unit 12 according to the number (N) of superdirective speakers, and
generates acoustic signals for each superdirective speaker (time-division acoustic signals or
(Sometimes called a emitted sound signal). The acoustic signal distribution unit 13 creates each
time division acoustic signal so that the section having the original acoustic signal in each time
division acoustic signal does not overlap except for the cross fade section (see FIG. 2 described
above).
[0037]
When each section of the time-divided acoustic signal is ordered from the past side as 1, 2, 3, ...
from the past side, the acoustic signal distributor 13 is, for example, an a О N + 1-th (a is an
integer of 0, 1,. Time-divided acoustic signal having an acoustic signal section) as a time-divided
acoustic signal for the first superdirective speaker SP1 and a time-divided acoustic signal having
an a О N + 2nd acoustic signal section as a second superdirective speaker The time-division
audio signals for SP2 are created similarly, and time-division audio signals for the third to N-th
superdirective speakers SP3 to SPN are created in the same manner. Also, for example, the first
to N-th acoustic signal sections are distributed to time-division acoustic signals for the first to Nth superdirective speakers SP1 to SPN using random numbers or the like, and N + 1 to 2 О N-th
acoustic signals. The signal section is distributed to time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN using random numbers and the like, and similarly,
distribution is performed using random numbers and the like to first to Nth The time-division
audio signals for the superdirective speakers SP1 to SPN may be completed.
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[0038]
The delay calculating unit 14, the space coordinate data holding unit 15, and the delay unit 16
transmit the sounds emitted by the first to N-th superdirective speakers SP1 to SPN in
accordance with the time-division acoustic signal to itself to the reproduction area. It is provided
to arrive synchronously.
[0039]
The space coordinate data holding unit 15 holds the position information of the first to Nth
superdirective speakers SP1 to SPN and other information (delay calculation information)
necessary for calculating the propagation delay time. is there.
For example, information on the direction of directivity of the first to N-th superdirective
speakers SP1 to SPN can be given as the delay calculation information. Also, for example,
position information of the reproduction area can be cited as the delay calculation information.
[0040]
The delay calculation unit 14 calculates the propagation delay time from the first to Nth
superdirective speakers SP1 to SPN to the reproduction area based on the information held in
the space coordinate data holding unit 15, and then performs the first calculation. The delay time
to be applied to the time-division audio signal for the N-th superdirective speakers SP1 to SPN is
calculated. When the delay calculation information is directional information of directivity of
each superdirective speaker SP1 to SPN, the delay calculation unit 14 reproduces from the
positional information of each superdirective speaker SP1 to SPN and the directional information
of directivity. The position of the area is calculated, and the propagation delay time from each
superdirective speaker SP1 to SPN to the reproduction area is calculated. When the delay
calculation information is position information of the reproduction area, the delay calculation
unit 14 reproduces from each superdirective speaker SP1 to SPN from the position information
of each superdirective speaker SP1 to SPN and the position information of the reproduction area.
Calculate the propagation delay time to the area. For example, the delay calculation unit 14
calculates the time difference from the minimum propagation delay time of the propagation
delay times of the superdirective speakers SP1 to SPN as the delay time while capturing the
minimum propagation delay time.
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[0041]
The delay unit 16 applies a delay to each of the time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN by the delay time calculated by the delay calculation unit 14.
[0042]
In the case where the reproduction area is fixed and superdirective speakers SP1 to SPN are also
fixedly installed, a delay time holding unit for holding the delay time is provided instead of the
configuration for calculating the delay time for each information transmission to the
reproduction area. Alternatively, the delay time held by the delay time holding unit of the delay
unit 16 may be applied to the time-division acoustic signals for the first to Nth superdirective
speakers SP1 to SPN.
[0043]
In addition, when the reproduction area is at the center of the circle and the first to Nth
superdirective speakers SP1 to SPN are disposed on the same radius of the circumference, the
difference in propagation delay time is considered to be a problem. If the sound reproduction
device is provided in a situation where it is not necessary, the delay calculation unit 14, the space
coordinate data holding unit 15, and the delay unit 16 can be omitted.
[0044]
The acoustic signal output unit 17 outputs time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN to the corresponding superdirective speakers SP1 to SPN.
In addition, if the time difference of the propagation delay time mentioned above does not pose a
problem, the acoustic signal output part 17 can also select the superdirective speaker which
outputs a time division acoustic signal at random.
[0045]
(B-2) Operation of the First Embodiment Next, the operation of the sound reproducing apparatus
10 according to the first embodiment having the above-described configuration will be described.
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FIG. 4 is a flowchart showing processing of the sound reproduction device 10 according to the
first embodiment.
[0046]
The acoustic signal to be emitted is taken into the acoustic reproduction device 10 by the
acoustic signal input unit 11 (step S1).
[0047]
The sound signal taken in by the sound signal input unit 11 is divided in the time direction so as
to be cross-faded at the boundaries of time intervals (sections) in the sound signal division unit
12 according to a predetermined division method ( Step S2).
[0048]
The acoustic signals divided in time by the acoustic signal division unit 12 are distributed
according to the number (N) of superdirective speakers in the acoustic signal distribution unit
13, and time-divided acoustic signals for each of the superdirective speakers SP1 to SPN Are
created (step S3).
[0049]
The time division acoustic signals for the superdirective speakers SP1 to SPN are respectively
delayed by the delay time calculated by the delay calculation unit 14 using the information held
in the space coordinate data holding unit 15 in the delay unit 16 Is given (step S4).
[0050]
The time-division audio signal for each superdirective speaker SP1 to SPN after delaying is given
to the corresponding superdirective speaker SP1 to SPN by the acoustic signal output unit 17,
and the directivity of the superdirective speaker SP1 to SPN is given. It is emitted in the direction
of sex (step S5).
[0051]
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Apart from the operation of the sound reproducing apparatus 10, all time-division sounds
emitted from the superdirective speakers SP1 to SPN overlap in the reproduction area, and a
listener in the reproduction area listens to all time-division sounds. be able to.
Each time-shared sound compensates for the information in the missing section even if the
information is missing, so that the listener can hear the same information as the original
playback sound source .
[0052]
Of the areas other than the reproduction area, in the area not on the direction of directivity of
any of the superdirective speakers SP1 to SPN, even one time-division sound can not be heard,
and naturally, the original reproduction is performed I can not hear the information that the
sound source has.
[0053]
In addition, in the area other than the reproduction area, in the direction of the directivity of any
one of the superdirective speakers SP1 to SPN, one time-division sound can be listened to.
However, one time-division sound contains only a very small portion of the information
possessed by the original reproduction sound source, and the listener can not recognize the
information possessed by the original reproduction sound source even after listening.
[0054]
Although in the above description, the time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN are all different, the same time-division sound signal is used
as a signal for a plurality of superdirective speakers. You may
In this case, for example, it is necessary to reduce the level of the time division acoustic signal by
the same number of reciprocals and return to the original level when mixed in the reproduction
area (fourth embodiment described later) Form reference).
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[0055]
(B-3) Effects of the First Embodiment According to the first embodiment, a plurality of
superdirective speakers are arranged so that the directivity is overlapped only in the
reproduction area, and the reproduction sound source (sound signal) is divided in time. The
sound information can be transmitted only to the reproduction area by a simple process of
distributing to each superdirective speaker and emitting the sound.
[0056]
The number of superdirective speakers for achieving such an effect may be two, and the number
of superdirective speakers can be reduced.
[0057]
Further, it is sufficient to arrange a plurality of superdirective speakers so that the directivity is
overlapped only in the reproduction area, and the position of each superdirective speaker can be
any position as long as the condition that the directivity is overlapped only in the reproduction
area is satisfied. good.
[0058]
(C) Second Embodiment Next, a second embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0059]
The sound reproduction device 10 according to the first embodiment described above performs
information transmission in one reproduction area by N (two or more) superdirective speakers
SP1 to SPN.
[0060]
The sound reproduction device 10A of the second embodiment enables information transmission
in a plurality of reproduction areas by means of N superdirective speakers SP1 to SPN of fixed
installation.
In order to enable information transmission in such a plurality of reproduction areas, the sound
03-05-2019
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reproduction device 10A of the second embodiment utilizes a reflection member that reflects the
sound traveling on a straight line in a predetermined direction.
By the way, the sound emitted from the superdirective speaker has the property of being highly
rectilinear and reflecting when it collides with the shield, and it is possible to use a reflecting
member.
[0061]
FIG. 5A is an explanatory diagram of that acoustic information can be transmitted to the three
reproduction areas AR1 to AR3 by the two superdirective speakers SP1 and SP2 by utilizing the
reflection member REF.
FIG. 5 (B) is a view for comparison with FIG. 5 (A), and shows the case where three reproduction
areas not using the reflection member REF are created (note that FIG. 5 (B) is also a book). It is an
embodiment of the invention).
In the description using FIG. 5, the sound traveling in the directivity direction is referred to as an
acoustic beam.
[0062]
The reflecting member REF divides the acoustic beam from the first superdirective speaker SP1
into two, and divides one separated acoustic beam (referred to as a first reflected acoustic beam)
clockwise from the traveling direction of the input acoustic beam Of the other separated acoustic
beam (referred to as the second reflected acoustic beam) by 135 degrees in a counterclockwise
direction from the traveling direction of the input acoustic beam. It reflects so as to have a
direction.
[0063]
The first reproduction area AR1 is an area through which both the acoustic beam from the first
superdirective speaker SP1 and the acoustic beam from the second superdirective speaker SP2
before reaching the reflection member REF pass.
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The second reproduction area AR2 is an area through which both the first reflected acoustic
beam and the acoustic beam from the second superdirective speaker SP2 pass.
The third reproduction area AR3 is an area through which the second reflected acoustic beam
and the acoustic beam from the second superdirective speaker SP2 pass.
By appropriately controlling an effective section in which the sound in the acoustic beam from
the first superdirective speaker SP1 is included, and an effective section in which the sound in
the acoustic beam from the second superdirective speaker SP2 is included Information of the
reproduction sound source can be transmitted in any of the first to third reproduction areas AR1
to AR3.
[0064]
As described above, a plurality of reproduction areas can be created by reflecting the sound
using the reflection member REF.
As apparent from the comparison of FIGS. 5A and 5B, when the same number of reproduction
areas are created, the number of superdirective speakers can be reduced by using the reflection
member.
[0065]
Here, as the reflecting member REF, any material may be used as long as it reflects the acoustic
beam.
Also, a plurality of reflecting members may be disposed, and the acoustic beam that has been
reflected once may be further reflected by another reflecting member.
By using such a reflecting member, in the space where the obstacle exists, the acoustic beam can
03-05-2019
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be made to travel while avoiding the obstacle. In the above description, the reflecting member
REF is also described as being fixed and installed in the same manner as the first and second
superdirective speakers SP1 and SP2. However, for example, the reflecting member REF can be
rotated in the horizontal angle direction As such, the positions of the second and third
reproduction areas AR2 and AR3 may be changed.
[0066]
FIG. 6 is a block diagram showing a configuration of a sound reproduction device 10A according
to the second embodiment, which installs a reflection member in addition to a plurality of
superdirective speakers and transmits a reproduction sound source to a plurality of reproduction
areas. In FIG. 6, the same reference numerals as in FIG. 3 according to the first embodiment
denote the same or corresponding parts.
[0067]
In FIG. 6, an acoustic reproduction device 10A according to the second embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. In
addition to the space coordinate data holding unit 15, the delay unit 16 and the acoustic signal
output unit 17, an acoustic signal mixing unit 18 is provided between the delay unit 16 and the
acoustic signal output unit 17.
[0068]
The sound signal input unit 11 takes in the reproduction sound sources (sound signals) SIG1 to
SIGm by the same number (m) as the number of reproduction areas.
If the acoustic signals transmitted to different reproduction areas may be the same, the number
of acquisitions of the acoustic signals may be smaller than the number of reproduction areas.
[0069]
The acoustic signal dividing unit 12 divides the acoustic signal in the time direction, as in the
first embodiment, by parallel processing on the acoustic signals SIG1 to SIGm acquired by the
acoustic signal input unit 11.
03-05-2019
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[0070]
The acoustic signal distribution unit 13 distributes the time-divided acoustic signals according to
the number (N) of superdirective speakers, as in the first embodiment, in parallel processing on
each acoustic signal after time division, An acoustic signal for each superdirective speaker is
created.
[0071]
When the acoustic signal mixing unit 18 described later mixes time-division acoustic signals for
the first to N-th superdirective speakers SP1 to SPN for each acoustic signal for each signal
emitted from the same superdirective speaker , So that the sound signal for any superdirective
speaker after mixing is substantially a time division multiplex signal, so that the division in the
time direction of the sound signal division unit 12 and the distribution of the sound signal
distribution unit 13 are performed. Just do it.
Suppose that three types of acoustic signals are A, B, and C, and they are divided into three at the
same intervals to become A1 to A3, B1 to B3, and C1 to C3.
The mixed signal for the first superdirective speaker SP1 includes A1, B2 and C3 when mixed as
described below (the delay addition to be described later is ignored here), and for the second
superdirective speaker SP2 The mixed signal includes B1, C2 and A3 and the mixed signal for the
third superdirective speaker SP3 may be distributed by the acoustic signal distribution unit 13 so
as to include C1, A2 and B3. In this case, it is possible to minimize the non-signal period in the
mixed signal.
[0072]
The space coordinate data holding unit 15 holds, for example, information capable of calculating
reproduction areas such as the positions and directivity directions of the superdirective speakers
SP1 to SPN, the positions of the reflection members, and the directions of the reflection surfaces.
The space coordinate data holding unit 15 also includes position information of the origin and
information of a reference line passing through the origin.
03-05-2019
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[0073]
The delay calculation unit 14 calculates the position of each reproduction area based on the
information held in the space coordinate data holding unit 15, and then the sound emitted from
each superdirective speaker reaches each reproduction area. Calculate the time difference of The
delay calculation unit 14 generates an acoustic signal in the reproduction area based on the
distance from the origin to each reproduction area (based on the angle formed by the reference
line and the origin and the reproduction area when the distances are the same). A number is
assigned to each acoustic signal SIG1 to SIGm acquired by the input unit 11. As mentioned in the
first embodiment, the position information of the reproduction area may be stored in the space
coordinate data holding unit 15 instead of calculating the position of the reproduction area.
Alternatively, the spatial coordinate data storage unit 15 may store the correspondence
information with the acoustic signal.
[0074]
The delay unit 16 applies delay time in parallel processing to each sound signal corresponding to
each reproduction area. When an acoustic signal for a certain reproduction area is recognized,
the delay unit 16 outputs each of the time-divided acoustic signals for the first to Nth
superdirective speakers SP1 to SPN for the acoustic signal output from the acoustic signal
distributor 13 On the other hand, a delay is given by the delay time for the corresponding
reproduction area calculated by the delay calculation unit 14.
[0075]
The acoustic signal mixing unit 18 outputs the time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN for each of the acoustic signals output from the delay unit 16
from the same superdirective speaker. It mixes every time. For example, when there are m types
of acoustic signals, there are also m time-divided acoustic signals for the first superdirective
speaker SP1 output from the delay unit 16, but the acoustic signal mixing unit 18 includes these
m first The time-division audio signals for the superdirective speaker SP1 are mixed and put
together into a signal for one first superdirective speaker SP1. The acoustic signal mixing unit 18
performs the same processing on time-division audio signals for the other second to N-th
superdirective speakers SP1 to SPN.
03-05-2019
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[0076]
The acoustic signal output unit 17 gives the time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN after the mixing processing to the corresponding
superdirective speakers SP1 to SPN, respectively, and emits the sound.
[0077]
According to the second embodiment, different reproduction sound sources can be
simultaneously transmitted to a plurality of reproduction areas, and furthermore, security of
transmission can be secured in areas other than the reproduction areas corresponding to the
reproduction sound sources.
[0078]
As modified embodiments of the second embodiment, for example, the following can be
mentioned.
[0079]
The block configuration shown in FIG. 6 can also be applied to the transmission of different
reproduction sound sources to a plurality of reproduction areas without using a reflection
member as shown in FIG. 5 (B).
However, the number of signals to be mixed, the method of distributing acoustic signals, etc. are
different from those described above.
However, since these can be easily understood, the description thereof is omitted.
[0080]
The sound reproduction device 10A of the second embodiment simultaneously transmits
different reproduction sound sources to a plurality of reproduction areas, but alternatively
transmits reproduction sound sources corresponding to the reproduction areas to each
reproduction area. You may do so.
03-05-2019
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[0081]
(D) Third Embodiment Next, a third embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0082]
In both of the sound reproducing devices of the first and second embodiments, the sound emitted
from each superdirective speaker does not make sense even if it is heard alone.
However, if the listener of the emitted sound recognizes it as some voice information and draws
attention, it may cause discomfort.
[0083]
Therefore, in the sound reproduction apparatus according to the third embodiment, reproduction
is performed by masking background noise (for example, background noise in a space where
there is a reproduction area) on sound emission sound from each superdirective speaker. It is
intended to make it hard to notice the existence of the sound emission sound for information
transmission from each superdirective speaker that was listened to outside the area.
[0084]
FIG. 7 is a block diagram showing the configuration of a sound reproduction device 10B
according to the third embodiment.
In FIG. 7, the same reference numerals as in FIG. 3 according to the first embodiment denote the
same or corresponding parts.
[0085]
In FIG. 7, an acoustic reproduction device 10B according to the third embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. In
03-05-2019
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addition to the space coordinate data holding unit 15, the delay unit 16 and the acoustic signal
output unit 17, a noise capturing microphone MIC, a background noise collection unit 19, a noise
data holding unit 20 and a noise mixing unit 21 are provided.
In the third embodiment, the number N of superdirective speakers SP1 to SPN is preferably an
even number of 2 or more.
[0086]
The noise capture microphone MIC is, for example, an omnidirectional microphone, and captures
background noise in a space including a reproduction area.
The noise capturing microphone MIC is placed at a position not in the directivity of the
superdirective speakers SP1 to SPN. Also, a plurality of noise capturing microphones MIC may be
installed, and alternatively, or background noise captured in parallel (superimposed) may be
input.
[0087]
The noise data holding unit 20 holds data of background noise. The background noise data held
by the noise data holding unit 20 may be obtained by capturing by the noise capturing
microphone MIC, or may be captured by a microphone (not shown). In other words, it may be
background noise of the space where the reproduction area exists, or may be background noise
of the space unrelated to the reproduction area.
[0088]
The background noise pickup unit 19 provides the delay unit 16 with background noise to be
superimposed (mixed) on time-division audio signals for the first to Nth superdirective speakers
SP1 to SPN. The background noise pickup unit 19 holds the background noise from the noise
capturing microphone MIC or the noise data holding unit 20 according to, for example, a
selection control signal given from the outside (such as a selection key) not shown. The
background noise data is selected and provided to the delay unit 16. In the case of selecting
03-05-2019
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background noise from the noise capturing microphone MIC, the background noise collecting
unit 19 needs to convert background noise, which is an analog signal, into a digital signal.
Although FIG. 7 shows the sound reproducing apparatus 10B provided with both the noise
capturing microphone MIC and the noise data holding unit 20, only one of the noise capturing
microphone MIC or the noise data holding unit 20 may be provided. .
[0089]
In the case of the third embodiment, the delay unit 16 adds the delay to the time-division
acoustic signal for the first to N-th superdirective speakers SP1 to SPN, and the background noise
given from the background noise collection unit 19 Add delay to The function of delaying
background noise is as follows. The delay unit 16 divides the input background noise into N
branches (N branch so as not to cause a level reduction), and for each of the branched, for the
first to Nth superdirective speakers SP1 to SPN The delay is given to the time-division acoustic
signal by the delay time to form the background noise for the first to Nth superdirective speakers
SP1 to SPN.
[0090]
The noise mixing unit 21 mixes an acoustic signal for information transmission with background
noise. The noise mixing unit 21 performs mixing so that the power of the acoustic signal for
information transmission and the background noise is equal, or the power of the background
noise is larger outside the reproduction area. In other words, the mixing ratio outside the
reproduction area is, for example, 0 dB or less in terms of the SN ratio. For example, the noise
mixing unit 21 first generates even-numbered (second, fourth,...) Superdirective speakers SP2,
SP4, among background noises for the first to Nth superdirective speakers SP1 to SPN, The
background noise for... Is inverted to form a signal of opposite phase, but the background noise
for the odd-numbered (first, third,...) Superdirective speakers SP1, SP3,. Thereafter, the timedivision acoustic signal for the same superdirective speaker and the background noise are
combined to form a time-division acoustic signal with background noise, which is applied to the
acoustic signal output unit 17.
[0091]
In the case where the number N of superdirective speakers SP1 to SPN is an odd number of 3 or
more, the even-numbered ones are phase-reversed so as to be similar to the case where mixed
background noise does not exist in the reproduction area The power of the background noise
03-05-2019
25
may be changed by applying different weighting factors to the odd-numbered ones.
[0092]
The acoustic signal output unit 17 gives time-division acoustic signals with background noise for
the first to Nth superdirective speakers SP1 to SPN to the corresponding superdirective speakers
SP1 to SPN, respectively, and emits the sound.
[0093]
All time-division sounds with background noise emitted from the superdirective speakers SP1 to
SPN overlap in the reproduction area.
The background noise in the time-division sound with background noise emitted from evennumbered superdirective speakers is the same as the background noise and the opposite phase
in the time-division sound with background noise emitted from odd-numbered superdirective
speakers Since both background noises are offset, only all time-division sounds remain, and the
listener can listen to all time-division sounds.
As a result, as described in the first embodiment, the listener can listen to the same information
as the original reproduction sound source.
[0094]
Among the areas other than the reproduction area, one time-divided sound can be listened to
together with the background noise in the area on the directionality of any one of the
superdirective speakers SP1 to SPN. Due to the presence of background noise, the listener listens
to the time-divided sound without much awareness even if the time-divided sound is strong or
weak.
[0095]
According to the third embodiment, after securing the transmission security of transmitting the
reproduction sound source only to the reproduction area, the time-division sound for that
purpose is buried in the background noise, and the listener is not good at the listener outside the
03-05-2019
26
reproduction area. It can reduce giving pleasure.
[0096]
Although the above description is based on the configuration of the first embodiment and
introduces the features of the third embodiment, it is based on the configuration of the second
embodiment and introduces the features of the third embodiment. You may do it.
[0097]
(E) Fourth Embodiment Next, a fourth embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0098]
Similarly to the sound reproducing apparatus 10B of the third embodiment described above, the
sound reproducing apparatus of the fourth embodiment is not suitable for the listener who
listens to the sound emitted from each superdirective speaker outside the reproduction area. It
was intended to prevent giving pleasure.
However, the specific method for preventing giving discomfort is different from the sound
reproducing apparatus 10B of the third embodiment.
The sound reproducing apparatus according to the fourth embodiment prevents the listener from
feeling uncomfortable by embedding the level of the sound emitted from each superdirective
speaker in the background noise level outside the reproduction area.
[0099]
FIG. 8 is a block diagram showing the configuration of a sound reproduction device 10C
according to the fourth embodiment.
In FIG. 8, the same or corresponding parts as in FIG. 3 according to the first embodiment and FIG.
7 according to the third embodiment are indicated by the same reference numerals.
03-05-2019
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[0100]
In FIG. 8, an acoustic reproduction device 10C according to the fourth embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. An
acoustic signal attenuation unit 22 is provided in addition to the space coordinate data holding
unit 15, the delay unit 16, the acoustic signal output unit 17, the noise capturing microphone
MIC, and the background noise collection unit 19.
[0101]
The acoustic signal distribution unit 13 of the fourth embodiment also forms time-division
acoustic signals for the first to Nth superdirective speakers SP1 to SPN by the distribution
processing.
However, unlike the acoustic signal distribution unit 13 of the first embodiment, not all N timedivision acoustic signals are different, but the same time-division acoustic signal is associated
with a plurality of different superdirective speakers. , Forming time-divided acoustic signals for
the first to Nth superdirective speakers SP1 to SPN. For example, when N is 5, the same time
division acoustic signal is formed as the time division acoustic signals for the first and second
superdirective speakers SP1 and SP2, and the third to fifth superdirective speakers SP3 to SP3
are formed. The same time division acoustic signal is formed as a time division acoustic signal for
SP5. Here, the former time division acoustic signal and the latter time division acoustic signal are
different. For example, when the same time division acoustic signal is formed as the time division
acoustic signals for the first and second superdirective speakers SP1 and SP2, the level of the
time division acoustic signal after formation (the level of the sound interval) is It may be the
same as the level of the acoustic signal before distribution, or may be 1/2 of the level of the
acoustic signal before distribution (?2? of the denominator is the emission of the same time
division acoustic signal. It is the number of superdirective speakers to offer. The following
description will be made on the assumption that the former.
[0102]
The delay calculating unit 14, the space coordinate data holding unit 15, and the delay unit 16
are respectively similar to those of the first embodiment.
03-05-2019
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[0103]
The noise capturing microphone MIC and the background noise collecting unit 19 are
respectively similar to those of the third embodiment.
In the case of the sound reproducing apparatus 10C according to the fourth embodiment, unlike
the third embodiment, the noise data holding unit 20 is not provided. Therefore, the background
noise pickup unit 19 always operates as a noise capturing microphone. Captures background
noise captured by the MIC.
[0104]
The acoustic signal attenuation unit 18 calculates the level (for example, the sum of squares of
sample values per predetermined time) of the background noise acquired by the background
noise pickup unit 19 and is given from the delay unit 16 based on the value. The amount of
attenuation for the time-division acoustic signal for the first to Nth superdirective speakers SP1
to SPN is determined, and the time division acoustic signal for the first to Nth superdirective
speakers SP1 to SPN is attenuated. For example, when the numbers of superdirective speakers
emitting different time-division audio signals are different, the volume of each time-division audio
is adjusted to be the same when added in the reproduction area. That is, when the first and
second superdirective speakers SP1 and SP2 emit time-shared acoustic signal AA and the third to
fifth superdirective speakers SP3-SP5 emit time-shared acoustic signal BB. , The volume obtained
by adding the emitted sound from the first and second superdirective speakers SP1 and SP2 and
the volume obtained by adding the third to fifth superdirective speakers SP3 to SP5 are equal
and all It attenuates so that the S / N ratio of is less than 0 dB.
[0105]
For example, the amount of attenuation is determined by the following procedure. First,
recognize the time-divided acoustic signal with the smallest number of superdirective speakers
emitting the same time-divided acoustic signal, and estimate the attenuated level by dividing the
level of the time-divided acoustic signal by the number of loudspeakers . It is checked whether
the estimated time-divided acoustic signal level after attenuation is buried in the background
noise level (whether or not the background noise level is a predetermined multiple or less). If
buried, it is attenuated to the estimated time-divided acoustic signal level after attenuation. If not
03-05-2019
29
buried, determine the decay rate to be buried. Based on the time division acoustic signal level to
which the determined attenuation factor is applied, the emission volume level of the time division
acoustic signal in the reproduction area is calculated, and the emission volume level of the
reproduction area in the other time division acoustic signal And set the attenuation factor of the
other time division acoustic signal.
[0106]
According to the fourth embodiment, the level of the time-division acoustic signal to be emitted is
lowered and the same time-division acoustic signal is simultaneously emitted from a plurality of
superdirective speakers. While ensuring the security of transmission of transmitting only the
reproduction sound source, time-division sound for that purpose can be buried in the
background noise, and it is possible to reduce the discomfort to the listener outside the
reproduction area.
[0107]
The above description is based on the configuration of the first embodiment and introduces the
features of the fourth embodiment. However, based on the configuration of the second
embodiment, the features of the fourth embodiment are introduced. You may do it.
[0108]
In the above, the background noise level is shown to be reflected in the attenuation rate of the
time-division acoustic signal after being distributed, but instead (or in addition to this), the
acoustic signal distributor 13 The level may be given to change the number of superdirective
speakers that emit the same time-division audio signal according to the level of background
noise.
[0109]
(F) Fifth Embodiment Next, a fifth embodiment of the sound reproduction apparatus and program
according to the present invention will be described with reference to the drawings.
[0110]
The sound reproducing apparatus according to the first to fourth embodiments includes, from
the superdirective speaker, all sections including the original sound signal (reproduction sound
source) as they are (sounding section) and all the sound signal (reproduction sound source). A
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time-divided acoustic signal is emitted with two levels of level change, including a non-interval
section (silence section) in the time direction.
Although the cross fade is applied, jumping of the level change is large, and from this point of
view, there is a large possibility that the listener who listens outside the reproduction area may
feel uncomfortable.
The sound reproducing apparatus according to the fifth embodiment is intended to suppress the
jumping amount of the level change by setting the level change to three or more steps.
[0111]
FIG. 9 is a block diagram showing the configuration of a sound reproduction device 10D
according to the fifth embodiment.
In FIG. 9, the same or corresponding parts as in FIG. 3 according to the first embodiment are
indicated by the same reference numerals.
[0112]
In FIG. 9, in the sound reproducing apparatus 10D of the fifth embodiment, the sound signal
dividing unit 12 is replaced with the sound signal branching unit 23 as compared to the sound
reproducing apparatus 10 of the first embodiment, and the sound signal distributing unit 13 is
Are replaced by the step gain multiplication unit 24.
[0113]
The acoustic signal branching unit 23 branches the input acoustic signal into the number of
superdirective speakers SP1 to SPN.
The level of each branched acoustic signal may be the same as the level of the input acoustic
signal, or may be 1 / N of the level of the input acoustic signal.
03-05-2019
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The following description will be made on the assumption that the former.
[0114]
The step gain multiplication unit 24 multiplies each branched sound signal by the step gain set
for each of the superdirective speakers SP1 to SPN, and generates the first to Nth superdirective
speakers SP1 to SPN. Form an acoustic signal.
[0115]
FIG. 10 shows an example of the stepwise gain when the number N of superdirective speakers
SP1 to SPN is five.
The stepwise gain shown in FIG. 10 is repeated with a period of time T as a period, and the gain
is 0.0, 0.1, 0.2, 0.3, etc. every time T / 8 obtained by equally dividing one period into eight. It is
changed to 0.4, 0.3, 0.2, 0.1. Here, although the shapes of the stepped gains for the first to fifth
superdirective speakers SP1 to SPN are the same, the phases are different, and for the first to
fifth superdirective speakers SP1 to SPN The staged gain sum is always made to be 1.0. For
example, at the same time when the step gain for the first superdirective speaker SP1 is 0.4 of
the fifth T / 8, the step gain for the second superdirective speaker SP2 is the fourth Of the third
superdirective speaker SP3 takes 0.2 of the third T / 8, the stepped for the fourth superdirective
speaker SP4 The gain is 0.1 for the second T / 8, and the stepped gain for the fifth superdirective
speaker SP5 is 0.0 for the first T / 8. The stepwise gains for the first to fifth superdirective
speakers SP1 to SPN change while maintaining such a phase relationship that they differ by T /
8.
[0116]
The delay calculating unit 14, the space coordinate data holding unit 15, the delay unit 16 and
the acoustic signal output unit 17 are the same as those of the first embodiment.
[0117]
It is assumed that the acoustic signal for each superdirective speaker SP1 to SPN to which the
stepwise gain is added and to which a delay is added is emitted from the corresponding
superdirective speaker SP1 to SPN.
03-05-2019
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[0118]
All sounds emitted from the superdirective speakers SP1 to SPN overlap in the reproduction area,
and a listener in the reproduction area can listen to all the sounds.
Although the gains of the sounds reaching the reproduction area are different, the gains of all the
sounds are 1, so that the listener can listen to the same information as the original reproduction
sound source.
[0119]
One of the areas other than the reproduction area, in the direction of the directivity of any one of
superdirective speakers SP1 to SPN, can listen to one sound.
However, even at the maximum level, the sound to be listened to is considerably smaller than the
level that the original reproduction sound source has (0.4 in the example of FIG. 10), and
furthermore, the level changes stepwise and can not be recognized. Since it takes a period of
time, the listener can not recognize the information that the original playback sound source has
even when listening. In addition, since the level of the sound to be listened to changes stepwise,
jumping at the time of level switching is also small, and it is possible to suppress giving a listener
an unpleasant feeling.
[0120]
Although the above description is based on the configuration of the first embodiment and
introduces the features of the fifth embodiment, the fifth embodiment is based on the
configuration of the above-described embodiment other than the first embodiment. The features
of the embodiment may be introduced.
[0121]
(G) Sixth Embodiment Next, a sixth embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
03-05-2019
33
[0122]
The sound reproducing apparatuses according to the first to fourth embodiments are timedivision from the viewpoint of distributing information of the reproduction sound source (sound
signal) to a plurality of superdirective speakers, and the sound reproducing apparatus according
to the fifth embodiment The point of dividing information of reproduction sound source (sound
signal) into a plurality of superdirective speakers is that of volume division.
The sound reproducing apparatus according to the sixth embodiment is divided into bands from
the viewpoint of distributing information of a reproduction sound source (sound signal) to a
plurality of superdirective speakers.
[0123]
FIG. 11 is a block diagram showing the configuration of a sound reproduction device 10E
according to the sixth embodiment.
11, the same reference numerals as in FIG. 3 according to the first embodiment and FIG. 9
according to the fifth embodiment denote the same or corresponding parts.
[0124]
Referring to FIG. 11, in the sound reproducing apparatus 10E of the sixth embodiment, the sound
signal dividing unit 12 is replaced with the sound signal dividing unit 23 in comparison with the
sound reproducing apparatus 10 of the first embodiment. Are replaced by the acoustic band
limiting unit 25.
[0125]
The sound signal branching unit 23 branches the input sound signal into the number of
superdirective speakers SP1 to SPN as in the fifth embodiment.
In the following, the level of each branched acoustic signal will be described as being the same as
03-05-2019
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the level of the input acoustic signal.
[0126]
The sound band limiting unit 25 performs band limiting on each of the branched sound signals
for each of the superdirective speakers SP1 to SPN, and generates acoustic signals for the first to
Nth superdirective speakers SP1 to SPN. (Acoustic signal component) is formed. The acoustic
band limiting unit 25 has, for example, the same number of digital filters as the number N of
superdirective speakers SP1 to SPN (functions as any one of a low pass filter, a band pass filter,
and a high pass filter; low pass filter Or a band pass filter may be applied instead of a high pass
filter), and the first to Nth ultra high pass filters having only different band components by
passing each branched acoustic signal through a corresponding digital filter. The acoustic signals
for the directional speakers SP1 to SPN are formed. Although the bands of acoustic signals for
the first to Nth superdirective speakers SP1 to SPN are different, when all the bands of the
acoustic signals for the first to Nth superdirective speakers SP1 to SPN are combined, the original
The sound band limiting unit 25 performs band limiting processing so as to cover the entire band
of the sound signal (reproduction sound source). An analog filter may be applied to the portion of
the digital filter described above.
[0127]
In the above, although the thing which forms the acoustic signal (acoustic signal component) for
the 1st-N-th superdirective speakers SP1-SPN from which a zone | band in charge differs is
shown using a band limiting filter, it showed by another method It is also possible to form
acoustic signals for the first to Nth superdirective speakers SP1 to SPN having different assigned
bands. For example, the FFT (Fast Fourier Transform) may be used to form acoustic signals for
first to Nth superdirective speakers SP1 to SPN having different assigned bands.
[0128]
FIG. 12 is a block diagram showing a partial configuration of a sound reproduction device
according to a modification using FFT (Fast Fourier Transform). FIG. 12 shows the configuration
from the acoustic signal input unit 11 to the delay unit 16. The configuration after the delay unit
16 is the same as that of FIG.
03-05-2019
35
[0129]
The sound reproduction device 10F illustrated in FIG. 12 includes an FFT processing unit 26, an
FFT point distribution unit 27, and an inverse FFT processing unit 28 between the sound signal
input unit 11 and the delay unit 16.
[0130]
The FFT processing unit 26 converts the input acoustic signal (reproduction sound source) into a
signal on the frequency axis (hereinafter referred to as an FFT signal) by FFT.
Here, for example, the number of FFT points of the FFT signal is preferably an integral multiple
of the number N of the first to N-th superdirective speakers SP1 to SPN.
[0131]
The FFT point distribution unit 27 distributes all points of the FFT signal to N to form FFT signals
for the first to Nth superdirective speakers SP1 to SPN. For example, when the number of points
of the FFT signal obtained by the FFT processing unit 26 is p О N, the FFT point distribution unit
27 determines the first superdirective speaker SP1 according to the information of p points
extracted from the p О N points. The FFT signal for the second superdirective speaker SP1 is
formed by the information of p points extracted from the remaining p О (N?1) points, and the
same applies in the same manner. The FFT signals for the third to Nth superdirective speakers
SP3 to SPN are formed. Here, the p points to be extracted may be continuous p points or may be
a total of p points by skipping.
[0132]
The inverse FFT processing unit 28 performs inverse FFT processing on each of the FFT signals
for the first to Nth superdirective speakers SP1 to SPN, and outputs the first to Nth
superdirective speakers SP1 to SPN. Acoustic signal (acoustic signal component) for the
[0133]
The delay calculating unit 14, the space coordinate data holding unit 15, the delay unit 16 and
the acoustic signal output unit 17 are the same as those of the first embodiment.
03-05-2019
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[0134]
It is assumed that the acoustic signals for the superdirective speakers SP1 to SPN which are
band-limited and to which a delay is added are emitted from the corresponding superdirective
speakers SP1 to SPN.
[0135]
All band-limited sounds emitted from each superdirective speaker SP1 to SPN overlap in the
reproduction area, and a listener in the reproduction area can listen to all band-limited sounds.
Each band of sound reached the playback area has a different band, but the band combining all
the sounds is the same as the band of the original playback source, so that the listener The same
information can be heard.
[0136]
One of the areas other than the reproduction area, in the direction of the directivity of any one of
superdirective speakers SP1 to SPN, can listen to one sound.
However, since the sound to be listened to comprises only a part of the band, the listener can not
recognize the information that the original playback sound source has even if the user listens.
[0137]
Although the above description is based on the configuration of the first embodiment and
introduces the features of the sixth embodiment, the sixth embodiment is based on the
configuration of the above-described embodiment other than the first embodiment. The features
of the embodiment may be introduced.
[0138]
(H) Other Embodiments In the description of each of the above embodiments, various modified
embodiments are mentioned, but further, modified embodiments as exemplified below can be
03-05-2019
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mentioned.
[0139]
In each of the above embodiments, the division method for forming an acoustic signal to the
superdirective speaker is one of time division, volume division, and band division. However, two
or more of these three types of division methods may be used. A division method to be combined
may be applied.
For example, N superdirective speakers are divided into two groups, acoustic signals of each
group are respectively formed by time division, and acoustic signals for superdirective speakers
in the group are formed by volume division or band division. You may do so.
[0140]
In each of the above embodiments, no processing is performed on the acoustic beam that has
passed through the reproduction area (the acoustic beam that has passed through the last
reproduction area in the case of acoustic beams that pass through a plurality of reproduction
areas). The sound absorbing member may be made to collide with the acoustic beam to prevent
unnecessary reflection.
[0141]
Although the above-mentioned each embodiment showed what applied the superdirective
speaker to all the speakers, the speaker to apply is not limited to a superdirective speaker.
For example, an omnidirectional general speaker can be applied.
Here, all the speakers may be general speakers, or a superdirective speaker and a general
speaker may be mixed.
In the latter case, the distribution ratio of the transmitted information may be different between
the superdirective speaker and the general speaker. For example, in time division distribution in
03-05-2019
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the case of one superdirective speaker and one general speaker, the total time of distribution
may be set to 2: 1 by the superdirective speaker and the general speaker. good.
[0142]
In each of the above-described embodiments, although the case of the application for
transmitting information to the person (listener) in the reproduction area has been described, the
acoustic signal may be reproduced in the reproduction area for other purposes. For example, in
order to apply, as a reproduction sound source, a thing that a human being (or another animal)
feels uncomfortable and does not hold up, and to move a human being in a reproduction area, a
human who has entered a reproduction area, etc. to another area The sound reproduction
apparatus of the present invention may be applied.
[0143]
SP1 to SPN: super-directional speaker, MIC: microphone for noise capture, 10, 10A to 10E: sound
reproduction device, 11: acoustic signal input unit, 12: acoustic signal division unit, 13: acoustic
signal distribution unit, 14: delay Calculation unit 15 Space coordinate data holding unit 16
Delay device 17 Acoustic signal output unit 18 Acoustic signal mixing unit 19 Background noise
pickup unit 20 Noise data holding unit 21 Noise mixing unit 22, audio signal attenuating unit 23,
acoustic signal branching unit 24, step gain multiplying unit 25, acoustic band limiting unit 26,
FFT processing unit 27, FFT point distribution unit 28, inverse FFT processing unit.
03-05-2019
39
"the following") before describing the first
to sixth embodiments of the sound reproduction apparatus and program according to the present
invention A brief explanation of common technical ideas).
[0015]
In the common technical concept, each superdirective speaker is installed at a different position
using a plurality of superdirective speakers in which emitted (pronounced) sound travels in a
straight line.
The directivity of each superdirective speaker is selected so as to pass through an area for
reproducing sound information (hereinafter referred to as a reproduction area). In other words,
although the sound emitted from any superdirective speaker passes through the reproduction
area, there is no area through which the sounds emitted from the plural superdirective speakers
pass together other than the reproduction area.
[0016]
Further, in the common technical concept, the signal of the sound source (reproduction sound
source) of sound information to be reproduced in the reproduction area (hereinafter simply
referred to as a reproduction sound source) is divided by the number of superdirective speakers
from a predetermined viewpoint And each divided reproduction sound source is emitted from the
corresponding superdirective speaker. Each divided reproduction sound source is obtained by
dividing the original reproduction sound source into the number of superdirective speakers.
Therefore, even if each divided reproduction sound source is listened to, the sound information
03-05-2019
5
can not be recognized or the sound information is recognized. It takes a lot of hard work. In the
common technical concept, in the reproduction area, all divided reproduction sound sources flow,
so the same state as the reproduction sound source before division flows. Therefore, when
listening in the reproduction area, the listener can recognize the sound information intended by
the reproduction sound source.
[0017]
The viewpoint for dividing the reproduction sound source is not limited to one, and it may be a
viewpoint from which the listener can recognize information when all the divided reproduction
sound sources flow in the reproduction area. For example, time division can be applied. Also, for
example, band division can be applied. Furthermore, for example, volume division can be applied.
It may be a division method combining divisions of a plurality of viewpoints. For example, a
combination of time division and band division can be applied.
[0018]
Hereinafter, a specific image of the common technical concept will be described with reference to
FIG. 1 and FIG. 2 by taking an example in which the division point of view is time division.
[0019]
FIG. 1 shows the arrangement positions of two superdirective speakers (first and second
superdirective speakers) SP1 and SP2, and the directivity of each superdirective speaker SP1 and
SP2.
The area where the directivity of the first and second superdirective speakers SP1 and SP2
intersect is the reproduction area. The reproduction sound source as shown in FIG. 2A is divided
in the time direction. The first divided reproduction sound source shown in FIG. 2 (B) including
the signal in each period of 0 to t1, t2 to t3, t4 to t5,... Is emitted from the first superdirective
speaker SP1 . On the other hand, the second split reproduction sound source shown in FIG. 2 (C)
including the signal in each period of t1 to t2, t3 to t4,... Is emitted from the second
superdirective speaker SP2.
[0020]
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6
For example, in the case where the reproduction sound source is "If you go up that mountain, you
can see it", time division (assuming a time division with kana characters as a unit) will be used as
a first divided reproduction sound source.? Bo ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
??????????????????????????????????
? ? ? ? ? ? ? ? ?, And are respectively emitted from the corresponding superdirective
speakers SP1 and SP2.
[0021]
At places not on the directional lines of both superdirective speakers SP1 and SP2, no
information is heard even if both superdirective speakers SP1 and SP2 are emitted.
At the location on the directional line of the first superdirective speaker SP1 excluding the
playback area, "A-A-B-B-B-B--M--R" is heard, but "A-A-B-B? ? ? ? ? ? ? ? ? ? ? ? Is
meaningless, and the original information ?If you climb up that mountain you can see the sea?
is not recognized. Similarly, ?иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии is heard at a location on
the directional line of the second superdirective speaker SP2 excluding the reproduction area?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Is meaningless, and the original information ?If you
climb up that mountain you can see it? is not recognized.
[0022]
On the other hand, in the reproduction area, the first superdirective speaker SP1 emits a sound
?A, A, B, B, M, M, I? and the second superdirective speaker SP 2 emits a sound. "? ? ? ? ?
? ? ? ? ? ? ? ? Is heard. Since one of the two types of listening sounds is a sounding
period and the other is a silent period to compensate for the silent period, the two types of
listening sounds are synthesized and listened. That is, the original reproduction sound source
"Among the mountain can be seen if you climb up" is heard, and in the reproduction area, the
information intended by the reproduction sound source is correctly transmitted.
[0023]
Hereinafter, embodiments of the sound reproducing apparatus and the program in which the
common technical concept as described above is embodied will be sequentially described.
03-05-2019
7
[0024]
(B) First Embodiment Next, a first embodiment of a sound reproduction apparatus and program
according to the present invention will be described with reference to the drawings.
[0025]
(B-1) Configuration of the First Embodiment FIG. 3 is a block diagram showing the configuration
of the sound reproduction apparatus according to the first embodiment.
The parts shown in FIG. 1 excluding superdirective speakers may be constructed by connecting
various circuits in hardware, and a general-purpose device or unit having a CPU, a ROM, a RAM,
etc. It may be constructed so as to realize the corresponding function by execution, and it can be
functionally represented in FIG. 3 even if any construction method is adopted.
[0026]
In FIG. 3, the sound reproducing apparatus 10 according to the first embodiment includes N (N is
an integer of 2 or more) superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an
acoustic signal dividing unit 12, and an acoustic signal distribution. The unit 13 includes a delay
calculation unit 14, a space coordinate data holding unit 15, a delay unit 16, and an acoustic
signal output unit 17.
[0027]
As described above, superdirective speakers SP1 to SPN are speakers that form sharp directivity
by using ultrasonic waves and transmit sound without attenuating the sound far.
The directivity of each superdirective speaker SP1 to SPN is made to pass through the
reproduction area.
In FIG. 3, the superdirective speakers SP1 to SPN appear to be arranged on a straight line, but
this arrangement is an arrangement by the convenience of the page, not an actual arrangement
(Similarly, in the block diagram described later) The placement of the superdirective speakers is
also not the actual placement).
03-05-2019
8
[0028]
In the description of the first embodiment, it is assumed that the reproduction area is fixed and
the superdirective speakers SP1 to SPN are also fixed at predetermined positions.
[0029]
However, among the plurality of reproduction areas, the same sound reproduction apparatus
may correspond to the reproduction area selected at that time.
In such a case, for example, each superdirective speaker SP1 to SPN is attached to at least one of
the horizontal angle direction and the elevation angle direction to a swing member which can
swing by a driving force such as a motor, and the selected playback According to the area, the
control unit may control the motor to change the directivity direction of the superdirective
speakers SP1 to SPN. In addition, superdirective speakers that operate in each reproduction area
are defined, and sound is emitted from a plurality of superdirective speakers determined
according to the selected reproduction area, and sound emission from other superdirective
speakers is stopped. You may do so.
[0030]
The sound signal input unit 11 takes in a reproduction sound source (sometimes called sound
signal), and the taking method is not limited as in the example described later. Here, the acoustic
signal is not limited to the audio signal, and may be another sound signal such as an audio signal,
and in short, it may be a signal of information to be transmitted with sound to the reproduction
area. The sound signal input unit 11 may take in sound signals from various sound collection
devices in real time, and may use data files on storage media of devices provided in association
with the sound reproduction device 10. For example, an audio signal may be captured, an audio
signal may be captured from a distribution server on the Internet, or the like, and an audio signal
collected in the past and converted into a data file may be captured. When the acquired acoustic
signal is an analog signal, the acoustic signal input unit 11 also has a function of converting into
a digital signal.
[0031]
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9
The acoustic signal dividing unit 12 of the first embodiment divides the acoustic signal acquired
by the acoustic signal input unit 11 in the time direction. The time interval to be divided may be
constant or random, and may be determined in accordance with the characteristics of the target
acoustic signal.
[0032]
In the case of a fixed time interval, the time interval is preferably an interval which can not be
heard as a word at the longest. In addition, if the number (N) of superdirective speakers is 2, the
number of superdirective speakers to be installed is 300 milliseconds, and if the number (N) of
superdirective speakers is 3, 200 milliseconds As the number N) increases, the time interval may
be shortened. The fixed time interval to apply is not limited to one type. For example, assuming
that two types of time intervals are T1 and T2, the acoustic signal may be arbitrarily divided at
intervals of T1, T1, T2, T2, T1, T2, T1, T2, and so on.
[0033]
In the case of dividing at random intervals, for example, after obtaining a random value in the
range of 0.5 to 1.5, a predetermined fixed time is multiplied by a random value to determine a
random time interval. You may Alternatively, a plurality of different time intervals may be
determined in advance, and a random number may be used to select which one of the time
intervals is applied, and the series of time intervals to be divided may be randomly changed.
[0034]
An autocorrelation coefficient or cepstrum can be applied as a feature of an acoustic signal that
can be used to determine the time interval to be divided. The autocorrelation coefficient (the time
at which the autocorrelation becomes the largest) may be multiplied by a predetermined constant
to obtain an applied time interval. Also, prepare a table in which the range of feature quantities
such as autocorrelation coefficient and cepstrum are associated with the time interval to be
applied, and divide the time interval of the range to which the feature quantity calculated this
time belongs. The time interval may be used.
03-05-2019
10
[0035]
When the acoustic signal division unit 12 divides the acoustic signal, it may divide the acoustic
signal as it is, but the cross fade (the time interval on the end side fades out and the time interval
on the new start side fades in) It is preferable to divide so as to apply The section of the cross
fade is, for example, 10 milliseconds in total before and after the division time point. By adopting
the cross fade, when the output sound (sound emission sound) from each superdirective speaker
is heard in the reproduction area, it is possible to make a natural reproduction sound source
without generating an abnormal sound.
[0036]
The acoustic signal distribution unit 13 distributes the acoustic signals time-divided by the
acoustic signal division unit 12 according to the number (N) of superdirective speakers, and
generates acoustic signals for each superdirective speaker (time-division acoustic signals or
(Sometimes called a emitted sound signal). The acoustic signal distribution unit 13 creates each
time division acoustic signal so that the section having the original acoustic signal in each time
division acoustic signal does not overlap except for the cross fade section (see FIG. 2 described
above).
[0037]
When each section of the time-divided acoustic signal is ordered from the past side as 1, 2, 3, ...
from the past side, the acoustic signal distributor 13 is, for example, an a О N + 1-th (a is an
integer of 0, 1,. Time-divided acoustic signal having an acoustic signal section) as a time-divided
acoustic signal for the first superdirective speaker SP1 and a time-divided acoustic signal having
an a О N + 2nd acoustic signal section as a second superdirective speaker The time-division
audio signals for SP2 are created similarly, and time-division audio signals for the third to N-th
superdirective speakers SP3 to SPN are created in the same manner. Also, for example, the first
to N-th acoustic signal sections are distributed to time-division acoustic signals for the first to Nth superdirective speakers SP1 to SPN using random numbers or the like, and N + 1 to 2 О N-th
acoustic signals. The signal section is distributed to time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN using random numbers and the like, and similarly,
distribution is performed using random numbers and the like to first to Nth The time-division
audio signals for the superdirective speakers SP1 to SPN may be completed.
03-05-2019
11
[0038]
The delay calculating unit 14, the space coordinate data holding unit 15, and the delay unit 16
transmit the sounds emitted by the first to N-th superdirective speakers SP1 to SPN in
accordance with the time-division acoustic signal to itself to the reproduction area. It is provided
to arrive synchronously.
[0039]
The space coordinate data holding unit 15 holds the position information of the first to Nth
superdirective speakers SP1 to SPN and other information (delay calculation information)
necessary for calculating the propagation delay time. is there.
For example, information on the direction of directivity of the first to N-th superdirective
speakers SP1 to SPN can be given as the delay calculation information. Also, for example,
position information of the reproduction area can be cited as the delay calculation information.
[0040]
The delay calculation unit 14 calculates the propagation delay time from the first to Nth
superdirective speakers SP1 to SPN to the reproduction area based on the information held in
the space coordinate data holding unit 15, and then performs the first calculation. The delay time
to be applied to the time-division audio signal for the N-th superdirective speakers SP1 to SPN is
calculated. When the delay calculation information is directional information of directivity of
each superdirective speaker SP1 to SPN, the delay calculation unit 14 reproduces from the
positional information of each superdirective speaker SP1 to SPN and the directional information
of directivity. The position of the area is calculated, and the propagation delay time from each
superdirective speaker SP1 to SPN to the reproduction area is calculated. When the delay
calculation information is position information of the reproduction area, the delay calculation
unit 14 reproduces from each superdirective speaker SP1 to SPN from the position information
of each superdirective speaker SP1 to SPN and the position information of the reproduction area.
Calculate the propagation delay time to the area. For example, the delay calculation unit 14
calculates the time difference from the minimum propagation delay time of the propagation
delay times of the superdirective speakers SP1 to SPN as the delay time while capturing the
minimum propagation delay time.
03-05-2019
12
[0041]
The delay unit 16 applies a delay to each of the time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN by the delay time calculated by the delay calculation unit 14.
[0042]
In the case where the reproduction area is fixed and superdirective speakers SP1 to SPN are also
fixedly installed, a delay time holding unit for holding the delay time is provided instead of the
configuration for calculating the delay time for each information transmission to the
reproduction area. Alternatively, the delay time held by the delay time holding unit of the delay
unit 16 may be applied to the time-division acoustic signals for the first to Nth superdirective
speakers SP1 to SPN.
[0043]
In addition, when the reproduction area is at the center of the circle and the first to Nth
superdirective speakers SP1 to SPN are disposed on the same radius of the circumference, the
difference in propagation delay time is considered to be a problem. If the sound reproduction
device is provided in a situation where it is not necessary, the delay calculation unit 14, the space
coordinate data holding unit 15, and the delay unit 16 can be omitted.
[0044]
The acoustic signal output unit 17 outputs time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN to the corresponding superdirective speakers SP1 to SPN.
In addition, if the time difference of the propagation delay time mentioned above does not pose a
problem, the acoustic signal output part 17 can also select the superdirective speaker which
outputs a time division acoustic signal at random.
[0045]
(B-2) Operation of the First Embodiment Next, the operation of the sound reproducing apparatus
10 according to the first embodiment having the above-described configuration will be described.
03-05-2019
13
FIG. 4 is a flowchart showing processing of the sound reproduction device 10 according to the
first embodiment.
[0046]
The acoustic signal to be emitted is taken into the acoustic reproduction device 10 by the
acoustic signal input unit 11 (step S1).
[0047]
The sound signal taken in by the sound signal input unit 11 is divided in the time direction so as
to be cross-faded at the boundaries of time intervals (sections) in the sound signal division unit
12 according to a predetermined division method ( Step S2).
[0048]
The acoustic signals divided in time by the acoustic signal division unit 12 are distributed
according to the number (N) of superdirective speakers in the acoustic signal distribution unit
13, and time-divided acoustic signals for each of the superdirective speakers SP1 to SPN Are
created (step S3).
[0049]
The time division acoustic signals for the superdirective speakers SP1 to SPN are respectively
delayed by the delay time calculated by the delay calculation unit 14 using the information held
in the space coordinate data holding unit 15 in the delay unit 16 Is given (step S4).
[0050]
The time-division audio signal for each superdirective speaker SP1 to SPN after delaying is given
to the corresponding superdirective speaker SP1 to SPN by the acoustic signal output unit 17,
and the directivity of the superdirective speaker SP1 to SPN is given. It is emitted in the direction
of sex (step S5).
[0051]
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14
Apart from the operation of the sound reproducing apparatus 10, all time-division sounds
emitted from the superdirective speakers SP1 to SPN overlap in the reproduction area, and a
listener in the reproduction area listens to all time-division sounds. be able to.
Each time-shared sound compensates for the information in the missing section even if the
information is missing, so that the listener can hear the same information as the original
playback sound source .
[0052]
Of the areas other than the reproduction area, in the area not on the direction of directivity of
any of the superdirective speakers SP1 to SPN, even one time-division sound can not be heard,
and naturally, the original reproduction is performed I can not hear the information that the
sound source has.
[0053]
In addition, in the area other than the reproduction area, in the direction of the directivity of any
one of the superdirective speakers SP1 to SPN, one time-division sound can be listened to.
However, one time-division sound contains only a very small portion of the information
possessed by the original reproduction sound source, and the listener can not recognize the
information possessed by the original reproduction sound source even after listening.
[0054]
Although in the above description, the time-division audio signals for the first to Nth
superdirective speakers SP1 to SPN are all different, the same time-division sound signal is used
as a signal for a plurality of superdirective speakers. You may
In this case, for example, it is necessary to reduce the level of the time division acoustic signal by
the same number of reciprocals and return to the original level when mixed in the reproduction
area (fourth embodiment described later) Form reference).
03-05-2019
15
[0055]
(B-3) Effects of the First Embodiment According to the first embodiment, a plurality of
superdirective speakers are arranged so that the directivity is overlapped only in the
reproduction area, and the reproduction sound source (sound signal) is divided in time. The
sound information can be transmitted only to the reproduction area by a simple process of
distributing to each superdirective speaker and emitting the sound.
[0056]
The number of superdirective speakers for achieving such an effect may be two, and the number
of superdirective speakers can be reduced.
[0057]
Further, it is sufficient to arrange a plurality of superdirective speakers so that the directivity is
overlapped only in the reproduction area, and the position of each superdirective speaker can be
any position as long as the condition that the directivity is overlapped only in the reproduction
area is satisfied. good.
[0058]
(C) Second Embodiment Next, a second embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0059]
The sound reproduction device 10 according to the first embodiment described above performs
information transmission in one reproduction area by N (two or more) superdirective speakers
SP1 to SPN.
[0060]
The sound reproduction device 10A of the second embodiment enables information transmission
in a plurality of reproduction areas by means of N superdirective speakers SP1 to SPN of fixed
installation.
In order to enable information transmission in such a plurality of reproduction areas, the sound
03-05-2019
16
reproduction device 10A of the second embodiment utilizes a reflection member that reflects the
sound traveling on a straight line in a predetermined direction.
By the way, the sound emitted from the superdirective speaker has the property of being highly
rectilinear and reflecting when it collides with the shield, and it is possible to use a reflecting
member.
[0061]
FIG. 5A is an explanatory diagram of that acoustic information can be transmitted to the three
reproduction areas AR1 to AR3 by the two superdirective speakers SP1 and SP2 by utilizing the
reflection member REF.
FIG. 5 (B) is a view for comparison with FIG. 5 (A), and shows the case where three reproduction
areas not using the reflection member REF are created (note that FIG. 5 (B) is also a book). It is an
embodiment of the invention).
In the description using FIG. 5, the sound traveling in the directivity direction is referred to as an
acoustic beam.
[0062]
The reflecting member REF divides the acoustic beam from the first superdirective speaker SP1
into two, and divides one separated acoustic beam (referred to as a first reflected acoustic beam)
clockwise from the traveling direction of the input acoustic beam Of the other separated acoustic
beam (referred to as the second reflected acoustic beam) by 135 degrees in a counterclockwise
direction from the traveling direction of the input acoustic beam. It reflects so as to have a
direction.
[0063]
The first reproduction area AR1 is an area through which both the acoustic beam from the first
superdirective speaker SP1 and the acoustic beam from the second superdirective speaker SP2
before reaching the reflection member REF pass.
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17
The second reproduction area AR2 is an area through which both the first reflected acoustic
beam and the acoustic beam from the second superdirective speaker SP2 pass.
The third reproduction area AR3 is an area through which the second reflected acoustic beam
and the acoustic beam from the second superdirective speaker SP2 pass.
By appropriately controlling an effective section in which the sound in the acoustic beam from
the first superdirective speaker SP1 is included, and an effective section in which the sound in
the acoustic beam from the second superdirective speaker SP2 is included Information of the
reproduction sound source can be transmitted in any of the first to third reproduction areas AR1
to AR3.
[0064]
As described above, a plurality of reproduction areas can be created by reflecting the sound
using the reflection member REF.
As apparent from the comparison of FIGS. 5A and 5B, when the same number of reproduction
areas are created, the number of superdirective speakers can be reduced by using the reflection
member.
[0065]
Here, as the reflecting member REF, any material may be used as long as it reflects the acoustic
beam.
Also, a plurality of reflecting members may be disposed, and the acoustic beam that has been
reflected once may be further reflected by another reflecting member.
By using such a reflecting member, in the space where the obstacle exists, the acoustic beam can
03-05-2019
18
be made to travel while avoiding the obstacle. In the above description, the reflecting member
REF is also described as being fixed and installed in the same manner as the first and second
superdirective speakers SP1 and SP2. However, for example, the reflecting member REF can be
rotated in the horizontal angle direction As such, the positions of the second and third
reproduction areas AR2 and AR3 may be changed.
[0066]
FIG. 6 is a block diagram showing a configuration of a sound reproduction device 10A according
to the second embodiment, which installs a reflection member in addition to a plurality of
superdirective speakers and transmits a reproduction sound source to a plurality of reproduction
areas. In FIG. 6, the same reference numerals as in FIG. 3 according to the first embodiment
denote the same or corresponding parts.
[0067]
In FIG. 6, an acoustic reproduction device 10A according to the second embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. In
addition to the space coordinate data holding unit 15, the delay unit 16 and the acoustic signal
output unit 17, an acoustic signal mixing unit 18 is provided between the delay unit 16 and the
acoustic signal output unit 17.
[0068]
The sound signal input unit 11 takes in the reproduction sound sources (sound signals) SIG1 to
SIGm by the same number (m) as the number of reproduction areas.
If the acoustic signals transmitted to different reproduction areas may be the same, the number
of acquisitions of the acoustic signals may be smaller than the number of reproduction areas.
[0069]
The acoustic signal dividing unit 12 divides the acoustic signal in the time direction, as in the
first embodiment, by parallel processing on the acoustic signals SIG1 to SIGm acquired by the
acoustic signal input unit 11.
03-05-2019
19
[0070]
The acoustic signal distribution unit 13 distributes the time-divided acoustic signals according to
the number (N) of superdirective speakers, as in the first embodiment, in parallel processing on
each acoustic signal after time division, An acoustic signal for each superdirective speaker is
created.
[0071]
When the acoustic signal mixing unit 18 described later mixes time-division acoustic signals for
the first to N-th superdirective speakers SP1 to SPN for each acoustic signal for each signal
emitted from the same superdirective speaker , So that the sound signal for any superdirective
speaker after mixing is substantially a time division multiplex signal, so that the division in the
time direction of the sound signal division unit 12 and the distribution of the sound signal
distribution unit 13 are performed. Just do it.
Suppose that three types of acoustic signals are A, B, and C, and they are divided into three at the
same intervals to become A1 to A3, B1 to B3, and C1 to C3.
The mixed signal for the first superdirective speaker SP1 includes A1, B2 and C3 when mixed as
described below (the delay addition to be described later is ignored here), and for the second
superdirective speaker SP2 The mixed signal includes B1, C2 and A3 and the mixed signal for the
third superdirective speaker SP3 may be distributed by the acoustic signal distribution unit 13 so
as to include C1, A2 and B3. In this case, it is possible to minimize the non-signal period in the
mixed signal.
[0072]
The space coordinate data holding unit 15 holds, for example, information capable of calculating
reproduction areas such as the positions and directivity directions of the superdirective speakers
SP1 to SPN, the positions of the reflection members, and the directions of the reflection surfaces.
The space coordinate data holding unit 15 also includes position information of the origin and
information of a reference line passing through the origin.
03-05-2019
20
[0073]
The delay calculation unit 14 calculates the position of each reproduction area based on the
information held in the space coordinate data holding unit 15, and then the sound emitted from
each superdirective speaker reaches each reproduction area. Calculate the time difference of The
delay calculation unit 14 generates an acoustic signal in the reproduction area based on the
distance from the origin to each reproduction area (based on the angle formed by the reference
line and the origin and the reproduction area when the distances are the same). A number is
assigned to each acoustic signal SIG1 to SIGm acquired by the input unit 11. As mentioned in the
first embodiment, the position information of the reproduction area may be stored in the space
coordinate data holding unit 15 instead of calculating the position of the reproduction area.
Alternatively, the spatial coordinate data storage unit 15 may store the correspondence
information with the acoustic signal.
[0074]
The delay unit 16 applies delay time in parallel processing to each sound signal corresponding to
each reproduction area. When an acoustic signal for a certain reproduction area is recognized,
the delay unit 16 outputs each of the time-divided acoustic signals for the first to Nth
superdirective speakers SP1 to SPN for the acoustic signal output from the acoustic signal
distributor 13 On the other hand, a delay is given by the delay time for the corresponding
reproduction area calculated by the delay calculation unit 14.
[0075]
The acoustic signal mixing unit 18 outputs the time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN for each of the acoustic signals output from the delay unit 16
from the same superdirective speaker. It mixes every time. For example, when there are m types
of acoustic signals, there are also m time-divided acoustic signals for the first superdirective
speaker SP1 output from the delay unit 16, but the acoustic signal mixing unit 18 includes these
m first The time-division audio signals for the superdirective speaker SP1 are mixed and put
together into a signal for one first superdirective speaker SP1. The acoustic signal mixing unit 18
performs the same processing on time-division audio signals for the other second to N-th
superdirective speakers SP1 to SPN.
03-05-2019
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[0076]
The acoustic signal output unit 17 gives the time-division acoustic signals for the first to Nth
superdirective speakers SP1 to SPN after the mixing processing to the corresponding
superdirective speakers SP1 to SPN, respectively, and emits the sound.
[0077]
According to the second embodiment, different reproduction sound sources can be
simultaneously transmitted to a plurality of reproduction areas, and furthermore, security of
transmission can be secured in areas other than the reproduction areas corresponding to the
reproduction sound sources.
[0078]
As modified embodiments of the second embodiment, for example, the following can be
mentioned.
[0079]
The block configuration shown in FIG. 6 can also be applied to the transmission of different
reproduction sound sources to a plurality of reproduction areas without using a reflection
member as shown in FIG. 5 (B).
However, the number of signals to be mixed, the method of distributing acoustic signals, etc. are
different from those described above.
However, since these can be easily understood, the description thereof is omitted.
[0080]
The sound reproduction device 10A of the second embodiment simultaneously transmits
different reproduction sound sources to a plurality of reproduction areas, but alternatively
transmits reproduction sound sources corresponding to the reproduction areas to each
reproduction area. You may do so.
03-05-2019
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[0081]
(D) Third Embodiment Next, a third embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0082]
In both of the sound reproducing devices of the first and second embodiments, the sound emitted
from each superdirective speaker does not make sense even if it is heard alone.
However, if the listener of the emitted sound recognizes it as some voice information and draws
attention, it may cause discomfort.
[0083]
Therefore, in the sound reproduction apparatus according to the third embodiment, reproduction
is performed by masking background noise (for example, background noise in a space where
there is a reproduction area) on sound emission sound from each superdirective speaker. It is
intended to make it hard to notice the existence of the sound emission sound for information
transmission from each superdirective speaker that was listened to outside the area.
[0084]
FIG. 7 is a block diagram showing the configuration of a sound reproduction device 10B
according to the third embodiment.
In FIG. 7, the same reference numerals as in FIG. 3 according to the first embodiment denote the
same or corresponding parts.
[0085]
In FIG. 7, an acoustic reproduction device 10B according to the third embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. In
03-05-2019
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addition to the space coordinate data holding unit 15, the delay unit 16 and the acoustic signal
output unit 17, a noise capturing microphone MIC, a background noise collection unit 19, a noise
data holding unit 20 and a noise mixing unit 21 are provided.
In the third embodiment, the number N of superdirective speakers SP1 to SPN is preferably an
even number of 2 or more.
[0086]
The noise capture microphone MIC is, for example, an omnidirectional microphone, and captures
background noise in a space including a reproduction area.
The noise capturing microphone MIC is placed at a position not in the directivity of the
superdirective speakers SP1 to SPN. Also, a plurality of noise capturing microphones MIC may be
installed, and alternatively, or background noise captured in parallel (superimposed) may be
input.
[0087]
The noise data holding unit 20 holds data of background noise. The background noise data held
by the noise data holding unit 20 may be obtained by capturing by the noise capturing
microphone MIC, or may be captured by a microphone (not shown). In other words, it may be
background noise of the space where the reproduction area exists, or may be background noise
of the space unrelated to the reproduction area.
[0088]
The background noise pickup unit 19 provides the delay unit 16 with background noise to be
superimposed (mixed) on time-division audio signals for the first to Nth superdirective speakers
SP1 to SPN. The background noise pickup unit 19 holds the background noise from the noise
capturing microphone MIC or the noise data holding unit 20 according to, for example, a
selection control signal given from the outside (such as a selection key) not shown. The
background noise data is selected and provided to the delay unit 16. In the case of selecting
03-05-2019
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background noise from the noise capturing microphone MIC, the background noise collecting
unit 19 needs to convert background noise, which is an analog signal, into a digital signal.
Although FIG. 7 shows the sound reproducing apparatus 10B provided with both the noise
capturing microphone MIC and the noise data holding unit 20, only one of the noise capturing
microphone MIC or the noise data holding unit 20 may be provided. .
[0089]
In the case of the third embodiment, the delay unit 16 adds the delay to the time-division
acoustic signal for the first to N-th superdirective speakers SP1 to SPN, and the background noise
given from the background noise collection unit 19 Add delay to The function of delaying
background noise is as follows. The delay unit 16 divides the input background noise into N
branches (N branch so as not to cause a level reduction), and for each of the branched, for the
first to Nth superdirective speakers SP1 to SPN The delay is given to the time-division acoustic
signal by the delay time to form the background noise for the first to Nth superdirective speakers
SP1 to SPN.
[0090]
The noise mixing unit 21 mixes an acoustic signal for information transmission with background
noise. The noise mixing unit 21 performs mixing so that the power of the acoustic signal for
information transmission and the background noise is equal, or the power of the background
noise is larger outside the reproduction area. In other words, the mixing ratio outside the
reproduction area is, for example, 0 dB or less in terms of the SN ratio. For example, the noise
mixing unit 21 first generates even-numbered (second, fourth,...) Superdirective speakers SP2,
SP4, among background noises for the first to Nth superdirective speakers SP1 to SPN, The
background noise for... Is inverted to form a signal of opposite phase, but the background noise
for the odd-numbered (first, third,...) Superdirective speakers SP1, SP3,. Thereafter, the timedivision acoustic signal for the same superdirective speaker and the background noise are
combined to form a time-division acoustic signal with background noise, which is applied to the
acoustic signal output unit 17.
[0091]
In the case where the number N of superdirective speakers SP1 to SPN is an odd number of 3 or
more, the even-numbered ones are phase-reversed so as to be similar to the case where mixed
background noise does not exist in the reproduction area The power of the background noise
03-05-2019
25
may be changed by applying different weighting factors to the odd-numbered ones.
[0092]
The acoustic signal output unit 17 gives time-division acoustic signals with background noise for
the first to Nth superdirective speakers SP1 to SPN to the corresponding superdirective speakers
SP1 to SPN, respectively, and emits the sound.
[0093]
All time-division sounds with background noise emitted from the superdirective speakers SP1 to
SPN overlap in the reproduction area.
The background noise in the time-division sound with background noise emitted from evennumbered superdirective speakers is the same as the background noise and the opposite phase
in the time-division sound with background noise emitted from odd-numbered superdirective
speakers Since both background noises are offset, only all time-division sounds remain, and the
listener can listen to all time-division sounds.
As a result, as described in the first embodiment, the listener can listen to the same information
as the original reproduction sound source.
[0094]
Among the areas other than the reproduction area, one time-divided sound can be listened to
together with the background noise in the area on the directionality of any one of the
superdirective speakers SP1 to SPN. Due to the presence of background noise, the listener listens
to the time-divided sound without much awareness even if the time-divided sound is strong or
weak.
[0095]
According to the third embodiment, after securing the transmission security of transmitting the
reproduction sound source only to the reproduction area, the time-division sound for that
purpose is buried in the background noise, and the listener is not good at the listener outside the
03-05-2019
26
reproduction area. It can reduce giving pleasure.
[0096]
Although the above description is based on the configuration of the first embodiment and
introduces the features of the third embodiment, it is based on the configuration of the second
embodiment and introduces the features of the third embodiment. You may do it.
[0097]
(E) Fourth Embodiment Next, a fourth embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
[0098]
Similarly to the sound reproducing apparatus 10B of the third embodiment described above, the
sound reproducing apparatus of the fourth embodiment is not suitable for the listener who
listens to the sound emitted from each superdirective speaker outside the reproduction area. It
was intended to prevent giving pleasure.
However, the specific method for preventing giving discomfort is different from the sound
reproducing apparatus 10B of the third embodiment.
The sound reproducing apparatus according to the fourth embodiment prevents the listener from
feeling uncomfortable by embedding the level of the sound emitted from each superdirective
speaker in the background noise level outside the reproduction area.
[0099]
FIG. 8 is a block diagram showing the configuration of a sound reproduction device 10C
according to the fourth embodiment.
In FIG. 8, the same or corresponding parts as in FIG. 3 according to the first embodiment and FIG.
7 according to the third embodiment are indicated by the same reference numerals.
03-05-2019
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[0100]
In FIG. 8, an acoustic reproduction device 10C according to the fourth embodiment includes N
superdirective speakers SP1 to SPN, an acoustic signal input unit 11, an acoustic signal division
unit 12, an acoustic signal distribution unit 13, a delay calculation unit 14, and the like. An
acoustic signal attenuation unit 22 is provided in addition to the space coordinate data holding
unit 15, the delay unit 16, the acoustic signal output unit 17, the noise capturing microphone
MIC, and the background noise collection unit 19.
[0101]
The acoustic signal distribution unit 13 of the fourth embodiment also forms time-division
acoustic signals for the first to Nth superdirective speakers SP1 to SPN by the distribution
processing.
However, unlike the acoustic signal distribution unit 13 of the first embodiment, not all N timedivision acoustic signals are different, but the same time-division acoustic signal is associated
with a plurality of different superdirective speakers. , Forming time-divided acoustic signals for
the first to Nth superdirective speakers SP1 to SPN. For example, when N is 5, the same time
division acoustic signal is formed as the time division acoustic signals for the first and second
superdirective speakers SP1 and SP2, and the third to fifth superdirective speakers SP3 to SP3
are formed. The same time division acoustic signal is formed as a time division acoustic signal for
SP5. Here, the former time division acoustic signal and the latter time division acoustic signal are
different. For example, when the same time division acoustic signal is formed as the time division
acoustic signals for the first and second superdirective speakers SP1 and SP2, the level of the
time division acoustic signal after formation (the level of the sound interval) is It may be the
same as the level of the acoustic signal before distribution, or may be 1/2 of the level of the
acoustic signal before distribution (?2? of the denominator is the emission of the same time
division acoustic signal. It is the number of superdirective speakers to offer. The following
description will be made on the assumption that the former.
[0102]
The delay calculating unit 14, the space coordinate data holding unit 15, and the delay unit 16
are respectively similar to those of the first embodiment.
03-05-2019
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[0103]
The noise capturing microphone MIC and the background noise collecting unit 19 are
respectively similar to those of the third embodiment.
In the case of the sound reproducing apparatus 10C according to the fourth embodiment, unlike
the third embodiment, the noise data holding unit 20 is not provided. Therefore, the background
noise pickup unit 19 always operates as a noise capturing microphone. Captures background
noise captured by the MIC.
[0104]
The acoustic signal attenuation unit 18 calculates the level (for example, the sum of squares of
sample values per predetermined time) of the background noise acquired by the background
noise pickup unit 19 and is given from the delay unit 16 based on the value. The amount of
attenuation for the time-division acoustic signal for the first to Nth superdirective speakers SP1
to SPN is determined, and the time division acoustic signal for the first to Nth superdirective
speakers SP1 to SPN is attenuated. For example, when the numbers of superdirective speakers
emitting different time-division audio signals are different, the volume of each time-division audio
is adjusted to be the same when added in the reproduction area. That is, when the first and
second superdirective speakers SP1 and SP2 emit time-shared acoustic signal AA and the third to
fifth superdirective speakers SP3-SP5 emit time-shared acoustic signal BB. , The volume obtained
by adding the emitted sound from the first and second superdirective speakers SP1 and SP2 and
the volume obtained by adding the third to fifth superdirective speakers SP3 to SP5 are equal
and all It attenuates so that the S / N ratio of is less than 0 dB.
[0105]
For example, the amount of attenuation is determined by the following procedure. First,
recognize the time-divided acoustic signal with the smallest number of superdirective speakers
emitting the same time-divided acoustic signal, and estimate the attenuated level by dividing the
level of the time-divided acoustic signal by the number of loudspeakers . It is checked whether
the estimated time-divided acoustic signal level after attenuation is buried in the background
noise level (whether or not the background noise level is a predetermined multiple or less). If
buried, it is attenuated to the estimated time-divided acoustic signal level after attenuation. If not
03-05-2019
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buried, determine the decay rate to be buried. Based on the time division acoustic signal level to
which the determined attenuation factor is applied, the emission volume level of the time division
acoustic signal in the reproduction area is calculated, and the emission volume level of the
reproduction area in the other time division acoustic signal And set the attenuation factor of the
other time division acoustic signal.
[0106]
According to the fourth embodiment, the level of the time-division acoustic signal to be emitted is
lowered and the same time-division acoustic signal is simultaneously emitted from a plurality of
superdirective speakers. While ensuring the security of transmission of transmitting only the
reproduction sound source, time-division sound for that purpose can be buried in the
background noise, and it is possible to reduce the discomfort to the listener outside the
reproduction area.
[0107]
The above description is based on the configuration of the first embodiment and introduces the
features of the fourth embodiment. However, based on the configuration of the second
embodiment, the features of the fourth embodiment are introduced. You may do it.
[0108]
In the above, the background noise level is shown to be reflected in the attenuation rate of the
time-division acoustic signal after being distributed, but instead (or in addition to this), the
acoustic signal distributor 13 The level may be given to change the number of superdirective
speakers that emit the same time-division audio signal according to the level of background
noise.
[0109]
(F) Fifth Embodiment Next, a fifth embodiment of the sound reproduction apparatus and program
according to the present invention will be described with reference to the drawings.
[0110]
The sound reproducing apparatus according to the first to fourth embodiments includes, from
the superdirective speaker, all sections including the original sound signal (reproduction sound
source) as they are (sounding section) and all the sound signal (reproduction sound source). A
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time-divided acoustic signal is emitted with two levels of level change, including a non-interval
section (silence section) in the time direction.
Although the cross fade is applied, jumping of the level change is large, and from this point of
view, there is a large possibility that the listener who listens outside the reproduction area may
feel uncomfortable.
The sound reproducing apparatus according to the fifth embodiment is intended to suppress the
jumping amount of the level change by setting the level change to three or more steps.
[0111]
FIG. 9 is a block diagram showing the configuration of a sound reproduction device 10D
according to the fifth embodiment.
In FIG. 9, the same or corresponding parts as in FIG. 3 according to the first embodiment are
indicated by the same reference numerals.
[0112]
In FIG. 9, in the sound reproducing apparatus 10D of the fifth embodiment, the sound signal
dividing unit 12 is replaced with the sound signal branching unit 23 as compared to the sound
reproducing apparatus 10 of the first embodiment, and the sound signal distributing unit 13 is
Are replaced by the step gain multiplication unit 24.
[0113]
The acoustic signal branching unit 23 branches the input acoustic signal into the number of
superdirective speakers SP1 to SPN.
The level of each branched acoustic signal may be the same as the level of the input acoustic
signal, or may be 1 / N of the level of the input acoustic signal.
03-05-2019
31
The following description will be made on the assumption that the former.
[0114]
The step gain multiplication unit 24 multiplies each branched sound signal by the step gain set
for each of the superdirective speakers SP1 to SPN, and generates the first to Nth superdirective
speakers SP1 to SPN. Form an acoustic signal.
[0115]
FIG. 10 shows an example of the stepwise gain when the number N of superdirective speakers
SP1 to SPN is five.
The stepwise gain shown in FIG. 10 is repeated with a period of time T as a period, and the gain
is 0.0, 0.1, 0.2, 0.3, etc. every time T / 8 obtained by equally dividing one period into eight. It is
changed to 0.4, 0.3, 0.2, 0.1. Here, although the shapes of the stepped gains for the first to fifth
superdirective speakers SP1 to SPN are the same, the phases are different, and for the first to
fifth superdirective speakers SP1 to SPN The staged gain sum is always made to be 1.0. For
example, at the same time when the step gain for the first superdirective speaker SP1 is 0.4 of
the fifth T / 8, the step gain for the second superdirective speaker SP2 is the fourth Of the third
superdirective speaker SP3 takes 0.2 of the third T / 8, the stepped for the fourth superdirective
speaker SP4 The gain is 0.1 for the second T / 8, and the stepped gain for the fifth superdirective
speaker SP5 is 0.0 for the first T / 8. The stepwise gains for the first to fifth superdirective
speakers SP1 to SPN change while maintaining such a phase relationship that they differ by T /
8.
[0116]
The delay calculating unit 14, the space coordinate data holding unit 15, the delay unit 16 and
the acoustic signal output unit 17 are the same as those of the first embodiment.
[0117]
It is assumed that the acoustic signal for each superdirective speaker SP1 to SPN to which the
stepwise gain is added and to which a delay is added is emitted from the corresponding
superdirective speaker SP1 to SPN.
03-05-2019
32
[0118]
All sounds emitted from the superdirective speakers SP1 to SPN overlap in the reproduction area,
and a listener in the reproduction area can listen to all the sounds.
Although the gains of the sounds reaching the reproduction area are different, the gains of all the
sounds are 1, so that the listener can listen to the same information as the original reproduction
sound source.
[0119]
One of the areas other than the reproduction area, in the direction of the directivity of any one of
superdirective speakers SP1 to SPN, can listen to one sound.
However, even at the maximum level, the sound to be listened to is considerably smaller than the
level that the original reproduction sound source has (0.4 in the example of FIG. 10), and
furthermore, the level changes stepwise and can not be recognized. Since it takes a period of
time, the listener can not recognize the information that the original playback sound source has
even when listening. In addition, since the level of the sound to be listened to changes stepwise,
jumping at the time of level switching is also small, and it is possible to suppress giving a listener
an unpleasant feeling.
[0120]
Although the above description is based on the configuration of the first embodiment and
introduces the features of the fifth embodiment, the fifth embodiment is based on the
configuration of the above-described embodiment other than the first embodiment. The features
of the embodiment may be introduced.
[0121]
(G) Sixth Embodiment Next, a sixth embodiment of the sound reproduction apparatus and
program according to the present invention will be described with reference to the drawings.
03-05-2019
33
[0122]
The sound reproducing apparatuses according to the first to fourth embodiments are timedivision from the viewpoint of distributing information of the reproduction sound source (sound
signal) to a plurality of superdirective speakers, and the sound reproducing apparatus according
to the fifth embodiment The point of dividing information of reproduction sound source (sound
signal) into a plurality of superdirective speakers is that of volume division.
The sound reproducing apparatus according to the sixth embodiment is divided into bands from
the viewpoint of distributing information of a reproduction sound source (sound signal) to a
plurality of superdirective speakers.
[0123]
FIG. 11 is a block diagram showing the configuration of a sound reproduction device 10E
according to the sixth embodiment.
11, the same reference numerals as in FIG. 3 according to the first embodiment and FIG. 9
according to the fifth embodiment denote the same or corresponding parts.
[0124]
Referring to FIG. 11, in the sound reproducing apparatus 10E of the sixth embodiment, the sound
signal dividing unit 12 is replaced with the sound signal dividing unit 23 in comparison with the
sound reproducing apparatus 10 of the first embodiment. Are replaced by the acoustic band
limiting unit 25.
[0125]
The sound signal branching unit 23 branches the input sound signal into the number of
superdirective speakers SP1 to SPN as in the fifth embodiment.
In the following, the level of each branched acoustic signal will be described as being the same as
03-05-2019
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the level of the input acoustic signal.
[0126]
The sound band limiting unit 25 performs band limiting on each of the branched sound signals
for each of the superdirective speakers SP1 to SPN, and generates acoustic signals for the first to
Nth superdirective speakers SP1 to SPN. (Acoustic signal component) is formed. The acoustic
band limiting unit 25 has, for example, the same number of digital filters as the number N of
superdirective speakers SP1 to SPN (functions as any one of a low pass filter, a band pass filter,
and a high pass filter; low pass filter Or a band pass filter may be applied instead of a high pass
filter), and the first to Nth ultra high pass filters having on
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