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JPWO2013057948

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DESCRIPTION JPWO2013057948
Abstract: An acoustic rendering apparatus using a multi-channel speaker, which corresponds to a
primary wavefront propagating in a predetermined traveling direction as a sound source based
on the multi-channel speaker arrangement information, each of a plurality of speakers
constituting the multi-channel speaker The second wavefront generated by the first wavefront
based on the first delay calculation unit (501) that calculates the delay of 1 and the arrangement
information of the multichannel speaker, and the second wavefront to be wavefront-synthesized
into the disordered wavefront A second delay calculation unit (502) for calculating a
corresponding second delay, an adder (503) for calculating a total delay by adding the first delay
and the second delay, and an input sound signal Generates a multichannel audio signal for
rendering with multichannel speakers by applying a total delay to the It includes a delay filter
output to channel speaker (504), the.
Acoustic rendering apparatus and acoustic rendering method
[0001]
The present invention relates to an acoustic rendering apparatus and an acoustic rendering
method using a multi-channel speaker.
[0002]
A speaker array and a speaker matrix are rapidly spreading as acoustic devices.
09-05-2019
1
The speaker array and the speaker matrix can deliver stereophonic sound (3D audio) to the
listener and play a very important role in 3D entertainment. The speaker array and the speaker
matrix can create a new sense of hearing such as a virtual sound source existing in front of or
behind them by the principle of wavefront synthesis, so that a wide range of sweet spots
(optimum listening position) and stereo feeling can be obtained. It can be realized. Although the
following description will be made by taking the speaker array as an example, the speaker matrix
is also the same, so the description is merely omitted. That is, in the following, the description of
the speaker array also means that the speaker matrix is also described.
[0003]
Two principles of wavefront synthesis are mainly known: a method based on Rayleigh integration
and a method based on beam formation. FIG. 1A is a diagram showing the principle of wavefront
synthesis by Rayleigh integration, and FIG. 1B is a diagram showing the principle of wavefront
synthesis by beam formation.
[0004]
Rayleigh integration is used to synthesize a virtual sound source (primary sound source 11)
present behind the speaker array 10A, as shown in FIG. 1A.
[0005]
Using the Rayleigh integration, it is possible to approximate the wavefront of the primary sound
source by the distribution of the secondary sound source.
In other words, as shown in FIG. 1A, the primary sound source 11 is a virtual sound source to be
synthesized behind the speaker array 10A, and the secondary sound source is the speaker array
10A itself.
[0006]
Thus, wavefront synthesis by Rayleigh integration can be realized by simulating the amplitude
and delay of the wavefront of the primary sound source 11 (virtual sound source) reaching each
of the plurality of secondary sound sources (speaker array 10A).
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[0007]
Beamforming is also used to synthesize the virtual sound source 12 in front of the speaker array
10B, as shown in FIG. 1B.
[0008]
According to the principle of wavefront synthesis by beam forming, the virtual sound source is
applied by applying the delay and the gain to the sound signal output from each channel of the
speaker array 10B so that the sound can be maximally superimposed at the desired virtual spot.
12 can be synthesized in front of the speaker array 10B.
[0009]
However, existing content is mostly stereo sound sources.
[0010]
Therefore, development of technology for generating new hearing sensation from monaural
sound source or stereo sound source using a speaker array is actively promoted.
[0011]
For example, Patent Documents 1 to 10 disclose techniques for expanding a three-dimensional
sound image with a speaker array using reverberation.
[0012]
European Patent Application Publication No. 1225789 U.S. Patent No. 4,748,669 U.S. Patent No.
5,928,830 U.S. Patent No. 6,928,168 U.S. Patent No. 7,636,443 U.S. Patent U.S. Patent No.
7,991,176 U.S. Patent Application Publication No. 2002 U.S. Patent Application Publication No.
2008/0279401 U.S. Patent Application Publication No. 2009/0136066 U.S. Patent Application
Publication No. 2011/0190112
[0013]
However, in the above-mentioned prior art, there is a problem that the effect of the threedimensional sound image (stereo feeling, feeling of being wrapped, etc.) depends on the position
of the listener.
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[0014]
Therefore, the present invention has been made in view of such problems, and an object of the
present invention is to provide an acoustic rendering apparatus and an acoustic rendering
method capable of realizing a stereoscopic sound image having a sense of reality that does not
depend on the position of a listener.
[0015]
In order to achieve the above object, an acoustic rendering device according to an aspect of the
present invention is an acoustic rendering device using a multi-channel speaker, and the multichannel speaker is configured based on arrangement information of the multi-channel speaker. A
first delay calculating unit for calculating a first delay corresponding to a primary wavefront
propagating in a predetermined traveling direction with each of the plurality of speakers as a
sound source, and the primary wavefront based on the arrangement information of the
multichannel speaker A second delay calculating unit that calculates a second delay
corresponding to a generated second-order wavefront having a confusion wavefront, and adding
the first delay and the second delay. By adding the total delay to the input audio signal and
adding the total delay to the input audio signal. Generating a multi-channel sound signal for ring,
and a delay filter for outputting to the multichannel speaker.
[0016]
These general or specific aspects may be realized by a system, a method, an integrated circuit, a
computer program, or a recording medium such as a computer readable CD-ROM, and the
system, the method, the integrated circuit, the computer program And any combination of
recording media.
[0017]
According to the present invention, it is possible to realize a rendering device and a rendering
method that can realize a realistic sound image that does not depend on the position of the
listener.
[0018]
FIG. 1A is a diagram showing the principle of wavefront synthesis by Rayleigh integration.
FIG. 1B is a diagram showing the principle of wavefront synthesis by beam formation.
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FIG. 2 is a view showing a stereo signal rendered and output by the beam forming technique.
FIG. 3A is a diagram illustrating an example of a sound source separator that separates a stereo
signal into a direct component and a diffusion component.
FIG. 3B is a diagram showing that the direct component and the diffusion component of the
stereo signal separated using the sound source separator shown in FIG. 3A are rendered and
output.
FIG. 4 is a figure for demonstrating the problem of the rendering method shown to FIG. 3B.
FIG. 5 is a block diagram showing the configuration of the acoustic rendering device of the first
embodiment.
FIG. 6A is a diagram for describing an effect when a stereo signal rendered using the acoustic
rendering device according to the first embodiment is output by a speaker array.
FIG. 6B is a diagram for describing an effect when a stereo signal rendered using the acoustic
rendering device according to the first embodiment is output by the speaker array.
FIG. 7A is a diagram showing an effect when a stereo signal rendered by the acoustic rendering
device according to the first embodiment is output by a speaker array.
FIG. 7B is a diagram showing an effect when a stereo signal rendered by the acoustic rendering
device according to the first embodiment is output by a speaker array.
FIG. 8 is a diagram showing how a stereo signal rendered by the acoustic rendering device
according to the first embodiment is reproduced by the speaker array.
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FIG. 9A shows an overview of an acoustic panel comprising a shredder diffuser. FIG. 9B is a
diagram showing depth coefficients that define the walls and indentations of the Schroeder
diffuser. FIG. 10 is a flowchart showing processing of the acoustic rendering method according to
the first embodiment. FIG. 11 is a block diagram showing the configuration of the acoustic
rendering device of the second embodiment.
[0019]
(Findings Based on the Present Invention) The inventor has found that the following problems
occur in the prior art described in the "Background Art" section.
[0020]
As stereo content is still the mainstream of existing content, development of playback technology
for creating new hearing sensations from monaural sound sources or stereo sound sources using
a speaker array is actively pursued.
Among the reproduction technologies currently being developed, since they can be used for twochannel audio equipment, there is a high expectation for the development of a technology for
expanding a three-dimensional sound image of a speaker array.
[0021]
In the following, a technology for expanding the three-dimensional sound image of the speaker
array (three-dimensional sound image enlargement technology) will be described.
[0022]
First, a simple method of reproducing a stereo signal using a speaker array will be described.
FIG. 2 is a view showing a stereo signal rendered and output by the beam forming technique.
[0023]
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That is, FIG. 2 shows a rendering method of turning two virtual spots in front of the speaker
array 10C into left and right virtual sound sources (left virtual sound source 21 and right virtual
sound source 22) by executing beam forming. There is. In this way, new hearing sensations can
be generated quickly and easily.
[0024]
However, even if a stereo signal is reproduced so as to be output from the left virtual sound
source 21 and the right virtual sound source 22 shown in FIG. 2, the listener 201 at a distance
from the center feels a narrow and unnatural sound. Problem of being
[0025]
A sound source recorded in general content, such as music data such as a CD, usually consists of
a direct component and a diffuse component.
The direct component is a component common to the left and right sound sources, and the
diffusion component is a component other than the direct component. And beamforming can
only generate directional speech. Therefore, although the listener 202 present at a position near
the center of the speaker array 10C can aurally recognize a wide natural three-dimensional
sound image, the listener 201 at a position away from the center feels a narrow and unnatural
sound. Problem of being
[0026]
Next, a rendering method different from FIG. 2 will be described using FIGS. 3A and 3B. FIG. 3A
shows an example of a sound source separator 300 that separates stereo signals into direct and
diffuse components. Further, FIG. 3B shows a state in which the direct component and the
diffusion component of the stereo signal separated using the sound source separator 300 shown
in FIG. 3A are rendered and output. Although there are many sound source separation techniques
for separating the sound source into the direct component and the diffusion component, the
detailed description of those techniques is out of the scope of the present disclosure, and thus
the description thereof is omitted.
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[0027]
The direct components (left direct component (D L) and right direct component (D R)) of the
stereo signal separated by the sound source separator 300 shown in FIG. 3A have two virtual
spots, ie, left and right virtual sound sources (left Beams are formed on the virtual sound source
31 and the right virtual sound source 32). Further, the diffusion components (the left diffusion
component (S L) and the right diffusion component (S R)) of the stereo signal separated by the
sound source separator 300 shown in FIG. 3A are rendered as plane waves. Here, the diffusion
components (the left diffusion component (S L) and the right diffusion component (S R)) are
relatively absent from the beamformed left and right virtual sound sources (the left virtual sound
source 31 and the right virtual sound source 32) Strong directivity.
[0028]
Such a rendering method can generate a more natural and wider hearing sensation for the
listener 301.
[0029]
Here, the psychoacoustic viewpoint will be described.
If the acoustic signal (voice) reaching the listener's ears is uncorrelated and has reverberation or
separation, the listener senses the acoustic signal (voice) as a spread three-dimensional sound
image.
[0030]
That is, the spread of the three-dimensional sound image can also be improved by adding
reverberation to the stereo signal. The reverberation gives rise to the illusion of distance,
allowing the listener to hear the stereo sound source even further away. As a result, wider stereo
separation occurs and the listener perceives as a wider stereo image. The reverberation also
enhances the feeling of envelope. Note that reverberation is produced when uncorrelated signals
given various kinds of delays reach the listener's ears.
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[0031]
The three-dimensional sound image enlargement technology based on reverberation is disclosed
in the above-mentioned Patent Documents 1 to 7. In addition, in the three-dimensional sound
image enlargement technique based on reverberation, in addition to the above-described
techniques, as described in the above-mentioned Patent Documents 1 to 7, use of a filter for
performing delay insertion and polarization inversion, and decorrelation of signals. And,
techniques that use crosstalk are included.
[0032]
(Formula 1)
[0033]
Here, in Equation 1, L and R indicate that the original stereo signal, L ′ and R ′ indicate an
extended stereo signal, and reverb () indicates that reverberation is to be performed.
[0034]
Furthermore, a technique called head shadow modeling is known which is a further improvement
of the above-described three-dimensional sound image enlargement technique.
The head shadow modeling technique is a technique used for simulation of a 3D sound source,
and is a technique in which a three-dimensional sound image enlargement technique is improved
in combination with reverberation as described in Patent Documents 8 to 10 above.
Specifically, the head shadow modeling technology is a technology for moving the stereo sound
source away from the listener by adding a delay between the listeners' ears and further
increasing the illusion of the distance created by the addition of reverberation.
[0035]
In addition, there is also another three-dimensional sound image enlargement technique in which
a stereo sensation is generated by multiple reflection by generating a plurality of wavefronts in
different directions for the purpose of generating a stereo sensation by multiple reflection.
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[0036]
However, in the above-mentioned prior art, there is a problem that the effect of the threedimensional sound image (stereo feeling) depends on the position of the listener.
This will be described below.
[0037]
For example, the rendering method shown in FIG. 3B produces a wider auditory image as
compared to the rendering method shown in FIG. 2, but the stereo image (stereo feeling) is still
narrow. This will be described with reference to FIG. FIG. 4 is a figure for demonstrating the
problem of the rendering method shown to FIG. 3B.
[0038]
As shown in FIG. 4, the listener 401 present near the center of the speaker array 10E can sense
different acoustic signals with both ears, so it can sense a good three-dimensional sound image
(stereo sense). On the other hand, since the listener 402 present at a position away from the
center senses substantially the same voice with both ears, the stereophonic sound image (stereo
feeling) is impaired and the stereophonic sound image (stereo feeling) is sufficiently sensed. Can
not.
[0039]
There is also a problem that the three-dimensional sound image enlargement technology based
on reverberation or the improved three-dimensional sound image enlargement technology based
on reverberation using head shadow modeling can not be applied to a speaker array. The reason
is that the speaker array is intended to play a sound in a narrow sweet spot.
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10
[0040]
However, if pre-processing to add reverberation to the acoustic signal can be performed, the
listener 401 present at a position near the center of the speaker array 10E can sense a more
extensive three-dimensional sound image by the rendering method shown in FIG. 3B. it can.
[0041]
However, since the listener 402 existing at a position away from the center hears a similar sound
image with both ears, the problem that the three-dimensional sound image (stereo feeling) is lost
and the sufficient three-dimensional sound image can not be detected is the same. is there.
[0042]
Also, as another solid sound image enlargement method, there is a method of generating a
plurality of wavefronts using echoes, but this method is not a reliable method because it is
premised on the presence of acoustic reflection in the surroundings.
[0043]
Therefore, an aspect of the present invention is made in view of such problems, and it is an
object of the present invention to provide an acoustic rendering device and an acoustic rendering
method capable of realizing a three-dimensional sound image having a spread independent of the
position of a listener. .
[0044]
In order to solve the above-mentioned problem, an acoustic rendering device according to an
aspect of the present invention is an acoustic rendering device using a multi-channel speaker,
and the multi-channel speaker is configured based on arrangement information of the multichannel speaker. A first delay calculating unit for calculating a first delay corresponding to a
primary wavefront propagating in a predetermined traveling direction with each of the plurality
of speakers as a sound source, and the primary wavefront based on the arrangement information
of the multichannel speaker A second delay calculating unit that calculates a second delay
corresponding to a generated second-order wavefront having a confusion wavefront, and adding
the first delay and the second delay. By adding the total delay to the input audio signal and
adding the total delay to the input audio signal. Generating a multi-channel sound signal for ring,
and a delay filter for outputting to the multichannel speaker.
[0045]
With this configuration, it is possible to realize a stereo feeling that does not depend on the
09-05-2019
11
position of the listener.
[0046]
Furthermore, by generating (rendering) a multi-channel sound signal from the input sound signal
in this way, not only it is possible to enhance the stereo feeling to the listener when reproduced
by the multi-channel speaker, but also the envelope feeling ( Feeling of being wrapped can also
be enhanced.
[0047]
Also, for example, the first delay calculating unit may calculate the first delay so that the primary
wavefront is a plane wave or a circular wave.
[0048]
Also, for example, the input acoustic signal is a stereo signal, and the first delay calculating unit is
configured to set the first wavefront so as to propagate in different traveling directions in the
signals of the two channels of the stereo signal. The delay of may be calculated.
[0049]
Also, for example, the second delay calculation unit may calculate the second delay using a
random number value.
[0050]
Also, for example, the multi-channel speaker may consist of a speaker array.
[0051]
Also, for example, the second delay calculation unit may be configured by taking a channel index
obtained by squaring the arrangement number of each speaker from one end of the speaker
array in the plurality of speakers constituting the speaker array according to a prime number
method. The second delay may be calculated by using the result of the remainder calculation.
[0052]
Also, for example, the multi-channel speaker may be made of a speaker matrix.
09-05-2019
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[0053]
Also, for example, the second delay calculation unit calculates the product of the arrangement
row number and the arrangement column number of the speakers in the plurality of matrix-like
speakers constituting the speaker matrix, and the calculated product is a prime number law The
second delay may be calculated by using the result of the remainder calculation at.
[0054]
Further, for example, the arrangement information may include an interval between each of the
plurality of speakers.
[0055]
Further, for example, the arrangement information may include the number of the plurality of
speakers.
[0056]
Further, in order to solve the above problems, an acoustic rendering device according to an
aspect of the present invention is an acoustic rendering device using a multi-channel speaker,
and is a sound source separation that separates an input acoustic signal into a direct component
and a diffusion component. And a direct component rendering unit that renders the direct
component and generates a direct component for rendering using a multi-channel speaker, and
configures the multi-channel speaker based on arrangement information of the multi-channel
speaker A first delay calculating unit that calculates a first delay corresponding to a primary
wavefront propagating in a predetermined traveling direction with each of a plurality of speakers
as a sound source, and generated by the primary wavefront based on arrangement information of
the multichannel speaker Secondary wave which is a secondary wave front that is combined with
the complex wave front A second delay calculation unit that calculates a second delay
corresponding to the first delay unit, a first addition unit that calculates a total delay by adding
the first delay and the second delay, and the spread component A multi-channel signal for
rendering by the multi-channel speaker is generated by adding a delay filter applying the total
delay, an output from the direct component rendering unit and an output from the delay filter,
and And a second addition unit for outputting to a multi-channel speaker.
[0057]
Note that these general or specific aspects may be realized by a system, a method, an integrated
circuit, a computer program, or a recording medium such as a computer readable CD-ROM, a
system, a method, an integrated circuit, a computer program Or it may be realized by any
combination of recording media.
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[0058]
Hereinafter, an acoustic rendering device and an acoustic rendering method according to an
aspect of the present invention will be specifically described with reference to the drawings.
[0059]
Each embodiment described below shows one specific example of the present invention.
Numerical values, shapes, materials, components, arrangement positions and connection forms of
components, steps, order of steps, and the like shown in the following embodiments are merely
examples, and the present invention is not limited thereto.
Further, among the components in the following embodiments, components not described in the
independent claim indicating the highest concept are described as arbitrary components.
[0060]
(First Embodiment) FIG. 5 is a block diagram showing a configuration of an acoustic rendering
apparatus according to a first embodiment.
FIGS. 6A and 6B are diagrams for explaining the effect when a stereo signal rendered using the
acoustic rendering device according to the first embodiment is output by a speaker array.
7A and 7B are diagrams showing an effect when a stereo signal rendered by the acoustic
rendering device according to the first embodiment is output by a speaker array.
FIG. 8 is a diagram showing a state in which a stereo signal rendered by the acoustic rendering
device shown in FIG. 5 is reproduced by the speaker array.
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[0061]
The acoustic rendering device 50 shown in FIG. 5 is an acoustic rendering device using the
speaker array 500, and includes a first delay calculating unit 501, a second delay calculating unit
502, an adder 503, and a delay filter 504. Equipped with
[0062]
The speaker array 500 is an example of a multi-channel speaker, for example.
As mentioned above, the multi-channel speakers may be not only a speaker array but also a
speaker matrix.
That is, FIG. 5 only shows the speaker array 500 as an example.
[0063]
The first delay calculation unit 501 corresponds to a primary wavefront propagating in a
traveling direction in a predetermined direction with each of a plurality of speakers constituting
the speaker array 500 as a sound source based on arrangement information (speaker array
information) of the speaker array 500. Calculate the first delay.
[0064]
Specifically, the first delay calculating unit 501 transmits a primary wavefront (basic wavefront)
propagating in a predetermined traveling direction as the primary wavefront 601A (basic
wavefront) shown in FIG. 6A and the primary wavefront 601B shown in FIG. 6B. The delay (first
delay) for generating (wavefront synthesis) is calculated.
[0065]
More specifically, the first delay calculation unit 501 calculates a first delay D 1 (c) with respect
to the c-th speaker in the plurality of speakers constituting the speaker array 500.
Here, the c-th means an ordinal number based on one end of the speaker array 500 in the
09-05-2019
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plurality of speakers constituting the speaker array 500.
In the case where the first delay calculating unit 501 is a speaker matrix in which the multichannel speakers are not the speaker array 500 but the speaker matrix of R rows and C columns,
the first delay calculation unit 501 performs a first delay on the r row and c column speakers
Calculate D 1 (r, c).
[0066]
Here, for example, the first delay calculating unit 501 calculates the first delay so that the
primary wavefront (basic wavefront) becomes a plane wave or a circular wave.
[0067]
More specifically, when the multi-channel speaker is the speaker array 500, the first delay
calculating unit 501 uses, for example, the first equation 2 to cause the plane wave to be emitted
from the c-th speaker of the speaker array 500. Calculate the delay D 1 (c).
[0068]
(Formula 2)
[0069]
Here, α and β are predetermined values.
The same applies to the following.
[0070]
Similarly, when the multi-channel speaker is a speaker matrix, the first delay calculating unit 501
uses, for example, Equation 3 to generate a first delay D in order to cause a plane wave to be
emitted from the R row C column speaker of the speaker matrix. Calculate 1 (r, c).
[0071]
(Equation 3)
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[0072]
Here, not only α and β but also γ is a predetermined value.
[0073]
In addition, when the multi-channel speaker is the speaker array 500, the first delay calculation
unit 501 uses, for example, the equation 4 to generate the first delay D 1 to cause the c-th
speaker of the speaker array 500 to emit a circular wave. Calculate (c).
[0074]
(Equation 4)
[0075]
Here, as described above, α and β are predetermined values.
[0076]
Similarly, when the multi-channel speaker is a speaker matrix, the first delay calculating unit 501
uses, for example, the first delay to generate a circular wave from the R row C column speaker of
the speaker matrix. Calculate
[0077]
(Equation 5)
[0078]
Here, not only α and β but also δ and γ are predetermined values.
[0079]
The second delay calculation unit 502 is a secondary wavefront generated by the propagating
primary wavefront based on the arrangement information (speaker array information) of the
speaker array 500, and corresponds to a second wavefront having a confusion wavefront.
Calculate the delay of
09-05-2019
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[0080]
Specifically, the second delay calculating unit 502 generates a second wavefront having a
confusion wavefront, such as the second wavefront 602A shown in FIG. 6A and the second
wavefront 602B shown in FIG. 6B (second delay Calculate).
[0081]
More specifically, the second delay calculating unit 502 calculates a second delay D 2 (c) for the
c-th speaker of the speaker array 500.
[0082]
When the multi-channel speaker is a speaker matrix including the R row C column speakers
instead of the speaker array 500, the second delay calculation unit 502 performs the second
delay calculation unit 502 for the second row r column c speaker Calculate the delay D 2 (r, c) of
[0083]
Here, for example, the second delay calculation unit 502 calculates a second delay using random
number values in order to simulate the convexo-concave of the confusion wavefront.
Hereinafter, a method of calculating a second delay using a random number will be described.
[0084]
When the multi-channel speaker is the speaker array 500, the second delay calculating unit 502
uses, for example, the equation 6 to generate a confusion wavefront in which the c-th speaker of
the speaker array 500 is used as a sound source to generate a wave front. Calculate the second
delay D 2 (c).
[0085]
(Equation 6)
[0086]
Here, rand () is a random number generator, and α and β are predetermined values.
09-05-2019
18
[0087]
Similarly, in the case where the multi-channel speaker is a speaker matrix, the second delay
calculating unit 502 generates, for example, the equation 7 in order to generate a confusion
wavefront in which the speakers in R row and C column of the speaker matrix are used as a
sound source. The second delay D 2 (r, c) is calculated using this.
[0088]
(Equation 7)
[0089]
Here, as described above, rand () is a random number generator, and α and β are
predetermined values.
[0090]
Note that the method of calculating the second delay for generating the secondary wavefront
that is the scattered wavefront is not limited to the case where the second delay calculation unit
502 uses the above-described random number.
For example, the second delay calculating unit 502 may calculate the second delay using a
Schrader diffuser to simulate the convexo-concave surface of the confusion wavefront.
The method will be described below.
[0091]
Schrader diffusers are physical diffusers with multiple "dents" with different "depth coefficients",
intended to scatter incident waves into multiple reflective wavelets.
It is known that when Schroeder diffusers are used for sound processing, the sound can be
spread equally in all directions.
09-05-2019
19
Therefore, it is often used for acoustic processing to generate a pleasing sound to the ear.
[0092]
FIG. 9A is a diagram showing an overview of an acoustic panel provided with a Schroeder
diffuser, and FIG. 9B is a diagram showing a depth coefficient that defines a recess and a wall of
the Schroeder diffuser.
[0093]
The depth coefficient S m of the recess of the Schroeder diffuser can be calculated as a square
residue series as shown in Equation 8.
[0094]
(Equation 8)
[0095]
Here, m is a continuous natural number 0, 1, 2, 3, 4, etc., and p is a prime number.
Also, mod indicates a remainder operator.
[0096]
One way to calculate the second delay using the Schrader diffuser to simulate the concavity and
convexity of the confusion wavefront is to set the second delay to be proportional to the depth
coefficient S m of the Schrader diffuser How to
For example, the second delay can be set by replacing the arrangement number c of the c-th
speaker in the plurality of speakers constituting the speaker array 500 with the above natural
number m.
09-05-2019
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[0097]
That is, when the multi-channel speaker is the speaker array 500, the second delay calculation
unit 502 uses Expression 9 to calculate the second delay D 2 (c c) for the c-th (arrangement
number c) speaker of the speaker array 500. Can be calculated.
[0098]
(Equation 9)
[0099]
Here, α and β are predetermined values.
[0100]
Similarly, when the multi-channel speaker is a speaker matrix, the second delay calculation unit
502 uses the depth coefficient of the recess shown in equation 10, S r, c, and equation 11 to
determine R row C column The second delay D 2 (r, c) for the speaker of
[0101]
(Equation 10)
[0102]
(Equation 11)
[0103]
Here, as described above, α and β are predetermined values.
[0104]
Note that the first delay calculation unit 501 and the second delay calculation unit 502 both have
speaker array information including the positional relationship such as the number and interval
of the plurality of speakers constituting the speaker array, directivity pattern, etc. It needs the
placement information of multi-channel speakers (speaker array or matrix).
[0105]
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The adder 503 is an example of an addition unit or a first addition unit, and calculates a total
delay by adding the first delay and the second delay.
[0106]
Specifically, as shown in Equation 12, the adder 503 calculates the first delay D 1 (c) calculated
by the first delay calculation unit 501 and the second delay calculation unit 502 The delay D 2
(c) of 2 is added to calculate the total delay D total (c) for the c-th speaker of the speaker array
500.
[0107]
(Expression 12)
[0108]
In the case where the adder 503 is a speaker matrix in which the multi-channel speaker is not
the speaker array 500 but a speaker matrix consisting of R row C column speakers, it is
calculated by the first delay calculation unit 501 as shown in Equation 13. The first delay D 1 (r,
c) and the second delay D 2 (r, c) calculated by the second delay calculation unit 502 are added
to obtain the total delay for the r row c column speaker Calculate D total (r, c).
[0109]
(Equation 13)
[0110]
The delay filter 504 applies the total delay calculated by the adder 503 to the input sound signal
to generate a multi-channel sound signal for rendering by the speaker array 500, and outputs the
multi-channel sound signal to the speaker array 500.
[0111]
Specifically, the delay filter 504 is, for example, an integer delay filter, and the total delay D total
(c) calculated by the adder 503 is input to the input acoustic signal x (n) as shown in equation
14. Applying generates a multi-channel signal y c (n) for rendering to the c-th speaker.
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Here, n is a sample index.
[0112]
(Equation 14)
[0113]
When delay filter 504 is a speaker matrix in which the multi-channel speakers are not speaker
array 500 but a speaker matrix composed of R row C column speakers, the total delay D total
calculated by adder 503 as shown in equation 15. By applying (r, c) to the input acoustic signal x
(n), a multi-channel signal yr, c (n) for rendering is generated.
[0114]
(Equation 15)
[0115]
A stereo signal (multi-channel signal) rendered using the acoustic rendering device 50 configured
as described above is output to the speaker array 500.
Thereby, each speaker (sound source) of the speaker array 500 can reproduce an acoustic signal
(multi-channel signal) in which the primary wavefront and the confusion wavefront (primary
wavefront) are combined as shown in FIG. 7A or 7B. it can.
[0116]
The effects when the stereo signal rendered using the acoustic rendering device 50 is reproduced
by the speaker array 500 will be specifically described below with reference to FIGS. 6A, 6B, and
8.
In the following, the input sound signal will be described as a stereo signal.
09-05-2019
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[0117]
First, as shown in FIGS. 6A and 6B, the speaker array 500 reproduces stereo signals (left and
right signals) by generating (wavefront synthesis) a primary wavefront 601A and a primary
wavefront 601B directed in a predetermined direction.
That is, as shown in FIG. 6A, for example, the speaker array 500 reproduces the left signal that is
wavefront synthesized so as to guide the primary wavefront 601A slightly to the right.
In addition, the speaker array 500 reproduces a right signal that is wavefront synthesized so as
to guide the primary wavefront 601A slightly to the left as shown in FIG. 6A.
[0118]
In such a primary wavefront (basic wavefront), as described above, the first delay appropriately
calculated for each speaker (each channel) configuring the speaker array 500 is assigned to each
speaker (each channel) Is generated by being applied to the input acoustic signal.
[0119]
As a result, as shown in FIG. 8, even the listener 601 located far from the center (sweet spot) of
the speaker array 500 can sense both the left and right signals, ie sense a stereo sense.
[0120]
Further, the speaker array 500 reproduces a stereo signal so as to combine the confusion
wavefront as a secondary wavefront.
That is, the speaker array 500 reproduces the left signal on which wavefront synthesis is
performed such that the secondary wavefront 602A as shown in FIG. 6A becomes a disordered
wavefront, and the secondary wavefront 602B as shown in FIG. 6B becomes a disordered
wavefront To reproduce the right signal that is wavefront synthesized.
[0121]
09-05-2019
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Such a secondary wave front (confusion wave front) is generated by applying the second delay
appropriately calculated as described above to the input acoustic signal assigned to each channel.
[0122]
As a result, a large number of crowded and delayed right and left signal reproduction sounds
reach the listener's 601 ears.
When these reach both ears, it gives a pleasant sense of stereo and reverberation.
[0123]
For example, by calculating the second delay using a random number value, the listener 601 can
sense high density jams and a large number of sounds resembling reverberation.
That is, the presence of the listener 601 can be enhanced without depending on the position of
the listener.
Also, by calculating the second delay using, for example, the mathematical properties of the
Schroeder spreader, more even speech spreading can be realized for the listener 601.
That is, it is possible to provide the listener 601 with a three-dimensional sound image with a
sense of expansion, without depending on the position of the listener.
[0124]
As described above, the acoustic rendering device 50 has a high density due to the influence of
the first wavefront transmitted in the predetermined traveling direction determined by the first
delay and the second delay, and a large number of delayed acoustic signals are generated. A
multi-channel acoustic signal can be generated that is rendered into a secondary wavefront that
09-05-2019
25
results in a disturbing wavefront such as that included.
Thereby, the multi-channel speaker can reproduce an audio signal with enhanced stereo feeling
to the listener by the generated multi-channel audio signal.
Furthermore, the feeling of envelope can be enhanced.
[0125]
The primary wavefront and the secondary wavefront (confused wavefront) may be dynamically
changed with time.
In that case, smoothing may be applied to either the delay value or the multi-channel acoustic
signal so as to allow a smooth transition from one wavefront to another.
[0126]
Also, since the equations described above can be generalized without departing from the content
of the present invention, the loudspeakers that make up the multi-channel loudspeaker are
arranged, for example, to be fixed or move on a plane or on a three-dimensional surface It may
be done.
[0127]
Also, in the above-mentioned equation, the constant may be zero.
In that case, a plane wave parallel to the speaker array 500 is generated.
If the input sound signal is monaural, the same effect is obtained, and this case is also included in
the contents of the present invention.
09-05-2019
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[0128]
Also, in the above, by generating a primary wavefront on which sound propagates so that a plane
wave or a circular wave is emitted, an acoustic signal can be guided to a listener at a distance
from the center of the multichannel speaker. Although explained, it is not limited to it.
It may be used in combination with another rendered uncorrelated audio signal to create a
position independent stereo sensation.
[0129]
The present embodiment may be realized not only as an apparatus but also as a method in which
processing means constituting the apparatus are steps.
Below, it will be briefly described.
[0130]
FIG. 10 is a flowchart showing processing of the acoustic rendering method according to the first
embodiment.
[0131]
The acoustic rendering device 50 according to the present embodiment first, based on the
arrangement information of the multichannel speakers, corresponds to a first wavefront that
propagates in a predetermined traveling direction with each of the plurality of speakers
constituting the multichannel speaker as a sound source. The delay of is calculated (S101).
[0132]
For example, a first delay corresponding to a primary wavefront for propagating left and right
signals of a stereo signal in a predetermined direction is calculated.
09-05-2019
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That is, the first delay for each channel (each speaker) of the speaker array or the speaker matrix
is calculated, and the calculated first delay is executed (reproduced) on each corresponding
channel (each speaker). Can generate a first order wavefront.
[0133]
Next, based on the arrangement information of the multi-channel speaker, a second delay
corresponding to a secondary wavefront generated by the propagating primary wavefront and
having a disordered wavefront is calculated (S102).
[0134]
For example, by applying the second delay calculated in S102 to the input acoustic signal
assigned to each channel (each speaker) of the speaker array or the speaker matrix, it is possible
to generate a secondary wavefront that is a confusion wavefront. it can.
[0135]
Next, the total delay is calculated by adding the calculated first delay and second delay (S103).
[0136]
Next, a total delay is applied to the input sound signal to generate a multi-channel sound signal
for rendering with a multi-channel speaker (S104).
Then, the generated multichannel audio signal is output to the multichannel speaker.
[0137]
According to the above method, the sense of stereo and the sense of envelopment of the sound
signal to be reproduced can be enhanced, so that the listener can sense the sense of diffusion and
the sense of reverberation without depending on the position.
[0138]
Second Embodiment In the second embodiment, the case where the input sound source is
directly separated into the signal and the diffusion component and applied to the acoustic
rendering device of the first embodiment will be described.
09-05-2019
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[0139]
FIG. 11 is a block diagram showing the configuration of the acoustic rendering device of the
second embodiment.
[0140]
The acoustic rendering device 80 shown in FIG. 11 further includes the configuration of a sound
source separator 805, a direct component rendering unit 806, and an adder 807 in addition to
the acoustic rendering device 50a corresponding to the first embodiment.
[0141]
The sound source separator 805 separates the input sound signal into a direct component and a
diffuse component.
[0142]
Here, the input sound signal will be described below as a stereo signal.
[0143]
First, stereo signals can be modeled as, for example, Equation 16 and Equation 17.
[0144]
(Equation 16)
[0145]
(Equation 17)
[0146]
Here, n indicates the number of samples, L (n) indicates the left signal of the stereo signal, and R
(n) indicates the right signal of stereo.
09-05-2019
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Also, d represents a delay, and α represents the gain of the coefficient of the stereo left input
signal.
D (nd) indicates the direct component of the left signal of the stereo signal, and D (n) indicates
the direct component of the right signal of the stereo signal.
S l (n) and S r (n) indicate the diffuse components of both the left and right signals, respectively.
[0147]
Then, the sound source separator 805 formulates an error function based on the parameters of
the stereo signal modeled as described above, and minimizes the error function to simultaneously
process all the parameters α, d, D (n−d). ), D (n), S l (n), S r (n).
In this way, the sound source separator 805 can estimate the direct component and the diffusion
component with the solved parameters.
[0148]
That is, the sound source separator 805 separates the input sound signal into the direct
component and the diffusion component by solving the parameters of the stereo signal modeled
as described above.
[0149]
Note that the method of sound source separation by the sound source separator 805 is not
limited to the above-described sound source separation method.
The sound source separator 805 may be any method as long as it can generate mutually
uncorrelated diffused components due to the nature of the input acoustic signal to be used.
[0150]
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Here, the operations of the first delay calculation unit 501, the second delay calculation unit 502,
the adder 503, and the delay filter 504a are the same as those described in the first embodiment,
and thus the description thereof is omitted.
The difference from the first embodiment is that the input signal input to the delay filter 504 a is
a diffusion component of the input acoustic signal output from the sound source separator 805.
[0151]
That is, the delay filter 504 a applies the total delay to the spread component of the input
acoustic signal output by the sound source separator 805.
[0152]
The direct component rendering unit 806 renders the direct component and generates a direct
component for rendering using a multi-channel speaker.
[0153]
That is, the direct component rendering unit 806 renders the direct component of the input
acoustic signal output by the sound source separator 805.
In addition, since the method to render can be performed based on the above-mentioned beam
formation or Rayleigh integration, description is abbreviate ¦ omitted.
[0154]
The adder 807 is an example of a first addition unit, and adds the output from the direct
component rendering unit 806 and the output from the delay filter 504 to generate a multichannel signal for rendering with a multi-channel speaker. And output to a multichannel speaker.
[0155]
Specifically, the adder 807 adds the output of the direct component rendering unit 806 and the
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output of the delay filter 504 to generate a multi-channel signal to be output to the speaker array
500.
[0156]
According to the acoustic rendering device 80 configured as described above, the primary
wavefront and the confusion wavefront can be generated by using mutually uncorrelated
diffused components, so that the stereo feeling and the wrapping feeling can be further
enhanced. Can.
[0157]
The present embodiment teaches how to combine the sound rendering device of the first
embodiment and the sound source separator.
Specifically, in the present embodiment, rendering is performed only on the diffusion component
of the sound source separator.
As a result, since the sound source separators can generate mutually uncorrelated diffused
components, it is possible to significantly enhance the detection of a three-dimensional sound
image (stereo feeling, feeling of being wrapped).
[0158]
In the present embodiment, the present invention can be applied to an arbitrary number of direct
components and diffusion components.
Specifically, the direct component and the diffusion component may be extracted from the subset
of the multichannel acoustic signal.
For example, for a 5.1 channel source, the source separator 805 may process only the front
channel to produce a direct component and a diffuse component, etc.
09-05-2019
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[0159]
Further, as a modification of the present embodiment, an input sound signal in which all direct
components and diffusion components are preprocessed may be input without using the sound
source separator 805.
Here, examples of applicable pretreatments are given below, all of which are within the scope of
the present invention.
[0160]
(1) The diffusion component may be preprocessed by a reverberation filter, a polarity inverter or
the like.
Also, the reverberation filter may be changed for each channel.
This cancels out the comb filter effect at a particular listening location.
(2) Furthermore, in order to reduce the comb filter effect, the spectrum region where comb
filtering is likely to occur may be adjusted.
(3) It may be possible to increase the frequency to compensate for the amount of high frequency
attenuation faster than the propagation distance when compared to the low frequency.
[0161]
As described above, according to the present invention, it is possible to realize an acoustic
rendering device and an acoustic rendering method capable of realizing stereo feeling
independent of the position of a listener.
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For example, when a multi-channel audio signal obtained by rendering an audio signal using the
audio rendering apparatus and audio rendering method of the present invention is reproduced
by a speaker array or a speaker matrix, the stereo feeling and envelope feeling (wrapped feeling)
are enhanced. It is possible to realize stereo feeling and envelope feeling (wrapped feeling)
independent of the position of the listener.
[0162]
In the above embodiments, each component may be configured by dedicated hardware or may be
realized by executing a software program suitable for each component.
Each component may be realized by a program execution unit such as a CPU or a processor
reading and executing a software program recorded in a recording medium such as a hard disk
or a semiconductor memory.
Here, software for realizing the image decoding apparatus and the like according to each of the
above-described embodiments is the following program.
[0163]
That is, this program causes the computer to generate a first delay corresponding to a primary
wavefront propagating in a predetermined traveling direction with each of a plurality of speakers
constituting the multi-channel speaker as a sound source based on arrangement information of
the multi-channel speaker And a second delay corresponding to a secondary wavefront generated
by the primary wavefront based on the arrangement information of the multi-channel speaker,
the second wavefront being wavefront synthesized to the disordered wavefront. Calculating the
total delay by adding the first delay and the second delay, and applying the total delay to the
input audio signal, Generate a multi-channel audio signal for rendering with a channel speaker,
said multi-channel A total delay applied step of outputting the manufacturers to perform the
acoustic rendering method comprising.
[0164]
The acoustic rendering device, the acoustic rendering method, and the like according to one or
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more aspects of the present invention have been described above based on the embodiments, but
the present invention is not limited to the embodiments.
Without departing from the spirit of the present invention, various modifications as may occur to
those skilled in the art may be applied to this embodiment, or a configuration constructed by
combining components in different embodiments may be one or more of the present invention. It
may be included within the scope of the embodiments.
[0165]
Does the invention use a multi-channel speaker array / matrix, such as a sound bar with
integrated speaker array / matrix, attachable speaker array / matrix accessories, etc., television,
personal computer, mobile phone, tablet type device etc. It can be used for a wide range of
applications.
[0166]
10A, 10B, 10C, 10D, 500 Speaker Array 11 Primary Sound Source 12 Virtual Sound Source 21,
31 Left Virtual Sound Source 22, 32 Right Virtual Sound Source 50, 50a, 80 Sound Rendering
Device 201, 202, 301, 401, 402, 601, 602 Listener 300, 805 Source separator 501 First delay
calculation unit 502 Second delay calculation unit 503, 807 Adder 504, 504a Delay filter 601A,
601B Primary wavefront 602A, 602B Secondary wavefront 806 Direct component rendering unit
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