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JP2015128208

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DESCRIPTION JP2015128208
An object of the present invention is to provide a speaker device that outputs a sound that causes
a virtual sound source to be perceived, and that does not impair the sense of localization even
when a sound field effect is given. The initial reflected sound adding unit adds characteristics of
the reflected sound to the audio signal input to the second sound emitting unit, and the rear
reverberation adding unit inputs the audio signal to the first sound emitting unit. Add the
characteristics of the rear reverberation to the audio signal being That is, the reflected sound
adding unit does not add the characteristics of the initial reflected sound to the sound causing
the virtual sound source to be perceived, but adds the characteristics of the initial reflected
sound to only the sound output from the second sound emitting unit. Therefore, the speaker
device prevents the change in the frequency characteristic of the sound that causes the virtual
sound source to be perceived due to the addition of the characteristic of the initial reflection
sound that has different frequency characteristics for each arrival direction. Thus, the sound that
causes the virtual sound source to be perceived maintains the frequency characteristics of the
head related transfer function. [Selected figure] Figure 2
Speaker device
[0001]
The present invention relates to a speaker device that virtually sounds an audio signal by
outputting a sound that causes a virtual sound source to be perceived.
[0002]
2. Description of the Related Art Conventionally, a speaker device is known which outputs a
sound that causes an audio signal to virtually perceive a virtual sound source and a sound having
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directivity, and that localizes an audio signal.
[0003]
For example, the array speaker apparatus shown in Patent Document 1 outputs a plurality of
directional sound beams (voice beams) by respectively delaying an audio signal and distributing
it to a plurality of speaker units.
When the listener listens to the speech beam, he perceives that the sound source is at the focal
point of the speech beam.
When the sound beam is, for example, reflected by the wall and reaches the listener, the listener
perceives that there is a sound source in the direction of the wall. Thereby, the audio signal is
localized in the direction of the wall.
[0004]
Moreover, the array speaker apparatus shown in Patent Document 1 changes the frequency
characteristic of the audio signal in order to output a sound that causes a virtual sound source to
be perceived for a channel where the sound beam can not reach the listener. More specifically,
the array speaker device shown in Patent Document 1 changes the frequency characteristic by
convoluting a head-related transfer function corresponding to the head shape of a listener into
an audio signal. The listener perceives the virtual sound source by listening to the sound whose
frequency characteristics have changed (sound causing the virtual sound source to be perceived).
Thereby, the audio signal is virtually localized.
[0005]
Patent document 1: JP 2008-227803
[0006]
The array speaker apparatus shown in Patent Document 1 virtually localizes an audio signal only
in a channel to which the audio beam can not reach, and exclusively outputs the sound that
causes the audio beam and the virtual sound source to be perceived. In order to improve the
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feeling, it is conceivable to simultaneously output both the sound beam and the sound causing
the virtual sound source to be perceived.
[0007]
Also, conventionally, it has been proposed to apply a sound field effect to the sound of content.
The sound field effect is another actual concert hall or the like while being in the room by
superimposing on the sound of the content the sound that simulates the initial reflection sound
and the rear reverberation generated in the acoustic space such as a concert hall. It gives
listeners a sense of realism as if they were in space.
[0008]
Here, the early reflection sound is a sound that is reflected by the wall of the concert hall, etc.
among the sound output from the sound source and then reaches the listener several times, and
is delayed from the direct sound that can be directly transmitted to the listener from the sound
source Reach the audience.
Since the initial reflection sound has a smaller number of reflections than the rear reverberation
sound, the reflection pattern differs depending on the arrival direction. Therefore, the initial
reflected sound has different frequency characteristics for each direction of arrival.
[0009]
The rear reverberation sound is a sound that is reflected on the inner wall of the concert hall and
the like more often than the initial reflection sound and reaches the listener, and reaches the
listener behind the initial reflection sound. Since the rear reverberation sound has a greater
number of reflections than the initial reflection sound, the reflection pattern is substantially
uniform regardless of the arrival direction. Therefore, the rear reverberation sound has
substantially the same frequency components regardless of the arrival direction. Hereinafter, a
sound simulating an actual initial reflection is simply referred to as an initial reflection, and a
sound simulating an actual rear reverberation is simply referred to as a rear reverberation.
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[0010]
However, in a speaker device that outputs both directional sound and sound causing virtual
sound source to be perceived in the same channel, when the initial reflection sound and the rear
reverberation sound are superimposed on directional sound and sound causing virtual sound
source The following problems occur.
[0011]
The sound causing the virtual sound source to be perceived is not localized because the
frequency characteristics of the head-related transfer function added for generating the virtual
sound source change when the initial reflected sound whose frequency characteristics differ for
each direction of arrival is superimposed. It becomes clear.
In addition, when a rear reverberation sound having substantially the same frequency component
is superimposed regardless of the direction of arrival, the audio signals of the directivity tend to
be similar to the audio signals of the respective channels, so that the sound images are combined,
Localization is unclear.
[0012]
Therefore, an object of the present invention is to provide a speaker device that outputs a sound
that causes a virtual sound source to be perceived and that does not impair the sense of
localization even when a sound field effect is given.
[0013]
The speaker device according to the present invention includes an input unit to which an audio
signal is input, a first sound emitting unit to emit a sound based on the input audio signal, and a
second sound emission to emit a sound based on the input audio signal. The audio signal input to
the input unit, the localization adding unit for performing filtering processing based on the head
related transfer function to the first sound emitting unit, and the characteristics of the initial
reflected sound to the input audio signal An initial reflection sound addition unit to be added, and
a rear reverberation sound addition unit to add characteristics of a rear reverberation sound to
the input audio signal.
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[0014]
The initial reflected sound adding unit adds the characteristic of the initial reflected sound to the
audio signal input to the second sound emitting unit, and the rear reverberation adding unit is
input to the first sound emitting unit. Add the characteristics of the rear reverberation to the
audio signal.
[0015]
The rear reverberation adding unit does not add the characteristics of the initial reflection to the
sound causing the virtual sound source to be perceived, and adds the characteristics of the initial
reflection to only the sound output from the second sound emitting unit.
Therefore, the speaker device prevents the change in the frequency characteristic of the sound
that causes the virtual sound source to be perceived due to the addition of the characteristic of
the initial reflection sound that has different frequency characteristics for each arrival direction.
Thus, the sound that causes the virtual sound source to be perceived maintains the frequency
characteristics of the head related transfer function.
[0016]
As described above, the speaker device of the present invention does not impair the localization
feeling by the sound that causes the virtual sound source to be perceived even when the sound
field effect by the early reflection sound and the rear reverberation sound is added.
[0017]
The speaker device may further include a level adjustment unit that adjusts a level ratio of the
initial reflection sound of the initial reflection sound addition unit and the rear reverberation
sound of the rear reverberation addition unit.
[0018]
This allows the level of the early reflections and the level of the rear reverberation to be in the
desired ratio of the listener.
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[0019]
The audio signal may be an audio signal of multi-channel surround sound.
[0020]
Thereby, the speaker device can impart the sound field effect while virtually localizing the audio
signal so as to surround the listener.
[0021]
Further, the first sound emitting unit may output a sound having directivity.
For example, the speaker device may output an audio beam as a directional sound in the
following configuration.
The first sound emitting unit includes a stereo speaker to which the audio signal of the
localization addition unit is input, and the second sound emitting unit delays the speaker array
and the audio signal input to the input unit. The aspect which consists of a directivity control
part distributed to the said speaker array may be sufficient.
[0022]
In this aspect, an audio beam is output as a directional sound as follows.
The speaker array composed of a plurality of speaker units emits sound based on the audio
signal delayed and distributed by the directivity control unit.
The directivity control unit delay-controls the audio signal such that the phases of sounds output
from the plurality of speaker units are aligned at a predetermined position.
As a result, the sound output from each of the plurality of speaker units reinforces each other at
a predetermined position and becomes an audio beam having directivity.
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[0023]
The localization addition unit performs filter processing so as to localize the virtual sound source
at a position at or near the position where the listener perceived the sound source by the
directional sound.
As a result, the speaker device improves the sense of localization compared to the case where
only the sound having directivity is used or the case where only the virtual sound source is used.
[0024]
The rear reverberation adding unit does not add the characteristic of the rear reverberation to
the directional sound, and adds the characteristic of the rear reverberation only to the sound that
causes the virtual sound source emitted from the first sound emitting unit to be perceived.
Therefore, since the speaker device does not add the characteristic of the rear reverberation to
the directional sound, it is prevented that the localization of the directional sound is obscured by
being pulled to the central portion of the reverberation.
[0025]
According to the present invention, even in the case of applying the sound field effect, the
speaker device does not add the characteristics of the initial reflected sound having different
frequency characteristics for each direction of arrival to the sound causing the virtual sound
source to be perceived. The frequency characteristics of the function are maintained, and
localization does not deteriorate.
[0026]
It is a figure for demonstrating the AV system 1 provided with the array speaker apparatus 2
which concerns on this embodiment.
It is a part of block diagram of the array speaker apparatus 2 and the subwoofer 3 which concern
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on this embodiment. FIG. 6 is a block diagram of an initial reflected sound processing unit 22 and
a rear reverberation processing unit 44. It is a schematic diagram which shows the example of
the impulse response measured in the concert hall. 5 is a block diagram of a localization adding
unit 42 and a correction unit 51. FIG. It is a figure for demonstrating the sound which the array
speaker apparatus 2 outputs. It is a figure for demonstrating the speaker set 2A which concerns
on the modification of the array speaker apparatus 2 which concerns on this embodiment. It is a
part of block diagram of speaker set 2A and subwoofer 3.
[0027]
An array speaker device 2 according to the present embodiment will be described using FIGS. 1
to 6. FIG. 1 is a diagram for explaining an AV system 1 provided with an array speaker device 2.
FIG. 2 is a part of a block diagram of the array speaker device 2 and the subwoofer 3. FIG. 3A is a
block diagram of the initial reflection sound processing unit 22, and FIG. 3B is a block diagram of
the rear reverberation processing unit 44. FIG. 4 is a schematic view showing an example of the
impulse response measured in the concert hall. FIG. 5A is a block diagram of the localization
addition unit 42, and FIG. 5B is a block diagram of the correction unit 51. FIG. 6 is a figure for
demonstrating the sound which the array speaker apparatus 2 outputs.
[0028]
The AV system 1 includes an array speaker device 2, a subwoofer 3, and a television 4. The array
speaker device 2 is connected to the subwoofer 3 and the television 4. The array speaker device
2 receives an audio signal corresponding to a video reproduced by the television 4 and an audio
signal of content from a content player (not shown). The array speaker device 2 outputs an audio
beam having directivity and a sound that causes a virtual sound source to be perceived based on
the audio signal of the input content, and further adds a sound field effect to the sound of the
content.
[0029]
First, the sound beam and the output of the initial reflected sound will be described. As shown in
FIG. 1, the array speaker device 2 includes, for example, a rectangular parallelepiped housing.
The housing of the array speaker device 2 corresponds, for example, to 16 speaker units 21A to
21P and woofers 33L and 33R (a first sound emitting unit of the present invention) on the
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surface facing the listener. And. However, the number of speaker units is not limited to sixteen,
and may be eight, for example.
[0030]
The speaker units 21A to 21P are arranged in one row. The speaker units 21A to 21P are
arranged in order from the left side when viewing the array speaker device 2 from the listener.
The woofer 33L is disposed further to the left from the speaker unit 21A. The woofer 33R is
disposed further to the right of the speaker unit 21P.
[0031]
The array speaker apparatus 2 includes a decoder 10 and a directivity control unit 20, as shown
in FIG. The set of the speaker units 21A to 21P and the directivity control unit 20 corresponds to
a second sound emitting unit of the present invention.
[0032]
The decoder 10 is connected to a DIR (Digital Audio I / F Receiver) 11, an ADC (Analog to Digital
Converter) 12, and an HDMI (High Definition Multimedia Interface) receiver 13.
[0033]
The DIR 11 receives a digital audio signal transmitted by an optical cable or a coaxial cable.
The ADC 12 converts the input analog signal into a digital signal. The HDMI receiver 13 receives
an HDMI signal conforming to the HDMI standard.
[0034]
The decoder 10 supports various data formats such as AAC (registered trademark), Dolby Digital
(registered trademark), DTS (registered trademark), MPEG-1 / 2, MPEG-2 multi-channel, or MP3.
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The decoder 10 is a multi-channel audio signal (digital audio signal of FL channel, FR channel, C
channel, SL channel, and SR channel) output from the DIR 11 and the ADC 12. Hereinafter, when
simply referred to as an audio signal, a digital audio signal shall be indicated. Convert to) and
output. The decoder 10 is an HDMI signal (a signal conforming to the HDMI standard) output by
the HDMI receiver 13. Audio data from the above to be decoded and output as an audio signal.
However, the decoder 10 can convert audio signals of various numbers of channels, such as
audio signals of seven channels, not limited to audio signals of five channels.
[0035]
The array speaker device 2 divides the band of the audio signal output from the decoder 10, and
outputs a high frequency (for example, 200 Hz or more) to the speaker units 21A to 21P, and a
low frequency (for example, less than 200 Hz) woofer 33L, 33R. And HPF 14 (14FL, 14FR, 14C,
14SR, 14SL) and LPF 15 (15FL, 15FR, 15C, 15SR, 15SL) for output to the subwoofer unit 72. The
cut-off frequencies of the HPF 14 and the LPF 15 are set to match the lower limit (200 Hz) of the
reproduction frequency of the speaker units 21A to 21P.
[0036]
The audio signal of each channel output from the decoder 10 is input to the HPF 14 and the LPF
15, respectively. The HPF 14 extracts and outputs the high frequency component (200 Hz or
more) of the input audio signal. The LPF 15 extracts and outputs the low frequency component
(less than 200 Hz) of the input audio signal.
[0037]
As shown in FIG. 2, the array speaker device 2 includes an initial reflected sound processing unit
22 in order to apply the sound field effect of the initial reflected sound to the content sound.
Each audio signal output from the HPF 14 is input to the initial reflected sound processing unit
22. The initial reflected sound processing unit 22 superimposes the audio signal of the initial
reflected sound on each input audio signal, and outputs the superimposed audio signal to the
level adjustment unit 18 (18FL, 18FR, 18C, 18SR, 18SL).
[0038]
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More specifically, as shown in FIG. 3A, the early reflection sound processing unit 22 includes a
gain adjustment unit 221, an early reflection sound generation unit 222, and a synthesis unit
223. Each audio signal input to the initial reflected sound processing unit 22 is input to the gain
adjusting unit 221 and the combining unit 223. The gain adjustment unit 221 refers to the level
of each input audio signal and the gain adjustment unit 441 (FIG. 3B) in order to adjust the level
ratio between the initial reflection sound and the rear reverberation sound. ) Adjust the level ratio
with the level of each audio signal input to each of the audio signals, and output each audio
signal after level adjustment to the initial reflected sound generation unit 222.
[0039]
The initial reflected sound generation unit 222 generates an audio signal of the initial reflected
sound based on each of the input audio signals. The audio signal of the early reflection is
generated so as to reflect the arrival direction of the actual early reflection and the delay time of
the early reflection.
[0040]
As shown in FIG. 4, the actual initial reflected sound is generated until a predetermined time (for
example, within 300 msec) elapses from the generation of the direct sound (point of time 0 in the
schematic view of FIG. 4). The actual initial reflection sound has a smaller number of reflections
than the rear reverberation sound, so the reflection pattern differs depending on the direction of
arrival. Therefore, the actual initial reflected sound has different frequency characteristics for
each direction of arrival.
[0041]
The audio signal of such initial reflection sound is generated by, for example, an FIR filter, and is
generated by convolving the input audio signal with a predetermined coefficient. The
predetermined coefficient is set based on, for example, sampling data of the impulse response of
the actual initial reflection sound shown in FIG. Then, the audio signal of the initial reflection
sound generated by the initial reflection sound generation unit 222 is distributed to the audio
signal of each channel and output according to the actual arrival direction of the initial reflection
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sound. Further, the initial reflection sound corresponds to the direct sound (an audio signal
directly input from the HPF 14 to the synthesizing unit 223). Are generated discretely until a
predetermined time (for example, within 300 msec) elapses from.
[0042]
Each audio signal output from the initial reflected sound generation unit 222 is input to the
synthesis unit 223. The synthesis unit 223 outputs, to the level adjustment unit 18, an audio
signal obtained by synthesizing the audio signal input from the HPF 14 and the audio signal
input from the initial reflected sound generation unit 222 for each channel. This corresponds to
direct sound (an audio signal directly input from the HPF 14 to the synthesizing unit 223). The
initial reflected sound is superimposed on. In other words, the characteristic of the early
reflection sound is added to the direct sound. The initial reflection sound is output as an audio
beam together with the direct sound.
[0043]
The level adjustment unit 18 is provided to adjust the level of the audio beam for each channel.
The level adjustment unit 18 adjusts and outputs the level of each audio signal.
[0044]
The directivity control unit 20 receives each audio signal output from the level adjustment unit
18. The directivity control unit 20 distributes the input audio signal of each channel by the
number of the speaker units 21A to 21P, and delays each of them by a predetermined delay time.
The delayed audio signal of each channel is converted into an analog audio signal by a not-shown
DAC (Digital to Analog Converter) and then input to the speaker units 21A to 21P. The speaker
units 21A to 21P emit sound based on the input audio signal of each channel.
[0045]
When the directivity control unit 20 performs delay control such that the difference between the
delay amounts provided to the audio signals input to the adjacent speaker units among the
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speaker units 21A to 21P becomes constant, the respective output from the speaker units 21A to
21P The sounds intensify their phases in the direction corresponding to the difference in the
delay amount. As a result, the sound beam is formed as a parallel wave traveling in a
predetermined direction from the speaker units 21A to 21P.
[0046]
The directivity control unit 20 can also perform delay control such that the phases of the sounds
output from the speaker units 21A to 21P are aligned at predetermined positions. In this case,
each sound output from the speaker units 21A to 21P is an audio beam focused on the
predetermined position.
[0047]
The array speaker apparatus 2 may be provided with an equalizer for each channel before or
after the directivity control unit 20 to adjust the frequency characteristics of each audio signal.
[0048]
The audio signal output from the LPF 15 is input to the woofer 33L or 33R and the subwoofer
unit 72.
[0049]
The array speaker device 2 further divides an audio signal (less than 200 Hz) other than the
band of the sound beam into a band (for example, 100 Hz or more) for the woofer 33L, 33R and
a band (for example, less than 100 Hz) for the subwoofer unit 72. , The HPF 30 (30LL, 30R) and
the LPF 31 (31L, 31R).
The cut-off frequencies of the HPF 30 and the LPF 31 are respectively set to match the upper
limit (100 Hz) of the reproduction frequency of the subwoofer unit 72.
[0050]
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The audio signal (less than 200 Hz) output from the LPF 15 (15FL, 15C, 15SL) is added by the
adding unit 16.
The audio signal added by the adding unit 16 is input to the HPF 30L and the LPF 31L. The HPF
30L extracts and outputs a high frequency component (100 Hz or more) of the input audio
signal. The LPF 31L extracts and outputs the low frequency component (less than 100 Hz) of the
input audio signal. The audio signal output from the HPF 30L is input to the woofer 33L via the
level adjustment unit 34L, the addition unit 32L, and a not-shown DAC. The audio signal output
from the LPF 31L is input to the subwoofer unit 72 of the subwoofer 3 via the level adjustment
unit 70F, the addition unit 71, and a not-shown DAC. The level adjusters 34 L and 70 F adjust the
level of the input audio signal in order to adjust the level ratio of the sound beam, the sound
output from the woofer 33 L, and the sound output from the subwoofer unit 72. Adjust and
output.
[0051]
The audio signals output from the LPF 15 (15FR, 15C, 15SR) are added by the adding unit 17.
The audio signal added by the adding unit 17 is input to the HPF 30R and the LPF 31R. The HPF
30R extracts and outputs the high frequency component (100 Hz or more) of the input audio
signal. The LPF 31R extracts and outputs the low frequency component (less than 100 Hz) of the
input audio signal. The audio signal output from the HPF 30R is input to the woofer 33R via the
level adjustment unit 34R, the addition unit 32R, and a DAC (not shown). The audio signal output
from the LPF 31R is input to the subwoofer unit 72 via the level adjustment unit 70G, the
addition unit 71, and a not-shown DAC. The level adjustment unit 34R and the level adjustment
unit 70G adjust the level ratio of the audio signal, the sound output from the woofer 33R, and the
sound output from the subwoofer unit 72 by adjusting the level of the input audio signal. Adjust
and output.
[0052]
As described above, the array speaker device 2 outputs the audio beam on which the initial
reflected sound is superimposed from the speaker units 21A to 21P for each channel, and
woofers (less than 200 Hz) for the sounds other than the audio beam band as woofers 33L and
33R. And the subwoofer unit 72.
[0053]
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The cutoff frequencies of the HPF 40 FL, HPF 40 FR, HPF 40 C, HPF 40 SL, and HPF 40 SR may
be the same as the cutoff frequencies of the HPF 14 FL, HPF 14 FR, HPF 14 C, HPF 14 SL, and
HPF 14 SR.
Further, the low-frequency band may not be output to the subwoofer 3 as an aspect in which
only the HPF 40FL, HPF 40FR, HPF 40C, HPF 40SL, and HPF 40SR is provided at the front stage
of the reverberation processing unit 44.
[0054]
Next, localization of the virtual sound source and output of the rear reverberation will be
described. As shown in FIG. 2, the array speaker device 2 includes a rear reverberation
processing unit 44, a localization adding unit 42, a crosstalk cancellation processing unit 50, and
delay processing units 60L and 60R.
[0055]
The array speaker device 2 divides the band of the audio signal output from the decoder 10,
outputs a high frequency (for example, 100 Hz or more) to the woofer 33L, 33R, and outputs a
low frequency (for example, less than 100 Hz) to the subwoofer unit 72 In order to do this, HPF
40 (40FL, 40FR, 40C, 40SR, 40SL) and LPF 41 (41FL, 41FR, 41C, 41SR, 41SL) are provided. The
cutoff frequencies of the HPF 40 and the LPF 41 are set so as to match the upper limit (100 Hz)
of the reproduction frequency of the subwoofer unit 72.
[0056]
The audio signal of each channel output from the decoder 10 is input to the HPF 40 and the LPF
41, respectively. The HPF 40 extracts and outputs a high frequency component (100 Hz or more)
of the input audio signal. The LPF 41 extracts and outputs the low frequency component (less
than 100 Hz) of the input audio signal.
[0057]
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The array speaker device 2 includes level adjustment units 70A to 70E in order to adjust the
level ratio between the sound output from the woofer 33L, 33R and the sound output from the
subwoofer unit 72.
[0058]
The level adjustment units 70A to 70E adjust the level of each audio signal output from the LPF
41.
The audio signals whose levels are adjusted by the level adjustment units 70A to 70E are added
by the addition unit 71, respectively. The audio signal added by the adding unit 71 is input to the
subwoofer unit 72 via a DAC (not shown).
[0059]
Each audio signal output from the HPF 40 is input to the rear reverberation processing unit 44.
The rear reverberation processing unit 44 superimposes the audio signal of the rear
reverberation on each input audio signal and outputs the superimposed audio signal to the level
adjustment unit 43 (43FL, 43FR, 43C, 43SR, 43SL).
[0060]
More specifically, the rear reverberation processing unit 44 includes a gain adjustment unit 441,
a rear reverberation generation unit 442, and a synthesis unit 443 as shown in FIG. 3 (B). Each
audio signal input to the rear reverberation processing unit 44 is input to the gain adjustment
unit 441 and the combining unit 443. The gain adjustment unit 441 adjusts the level ratio of the
initial reflection sound to the rear reverberation sound by adjusting the level of each input audio
signal and each audio input to the gain adjustment unit 221 of the initial reflection sound
processing unit 22. The level ratio to the level of the signal is adjusted, and each audio signal
after level adjustment is output to the rear reverberation generation unit 442.
[0061]
The rear reverberation generation unit 442 generates an audio signal of rear reverberation based
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on each input audio signal.
[0062]
As shown in FIG. 4, the actual rear reverberation occurs for a predetermined time (for example, 2
seconds) after the initial reflection.
Since the actual rear reverberation sound has a greater number of reflections than the initial
reflection sound, the reflection pattern is substantially uniform regardless of the arrival direction.
Therefore, the rear reverberation sound has substantially the same frequency components
regardless of the arrival direction.
[0063]
The rear reverberation generation unit 442 includes, for each channel, a configuration in which,
for example, a comb filter and an all pass filter cyclic filter (IIR filter) are combined in multiple
stages in order to generate such a rear reverberation. The coefficients of each filter are set to be
the characteristics of the actual rear reverberation (the delay time from the direct sound, the
length of the rear reverberation, and the attenuation with respect to the length of the rear
reverberation). For example, the rear reverberation sound is generated so as to occur after the
generation time of the initial reflection sound generated by the initial reflection sound generation
unit 222 (300 msec from the generation of the direct sound). Thus, the rear reverberation
generation unit 442 generates, for each channel, an audio signal of the rear reverberation for
each channel after 300 msec from direct sound generation and until 2,000 msec elapses, and
outputs the audio signal to the synthesizer 443. Although the example in which the rear
reverberation generation unit 442 is realized by an IIR filter is shown, it can be realized by using
an FIR filter.
[0064]
The audio signals output from the rear reverberation generation unit 442 are input to the
synthesis unit 443. The synthesizing unit 443 synthesizes each audio signal input from the rear
reverberation generating unit 442 with each audio signal input from the HPF 40 as shown in FIG.
2 and FIG. The signal is output to the level adjustment unit 43. Thus, direct sound (corresponding
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to an audio signal directly input from the HPF 40 to the synthesizing unit 443). The rear
reverberation is superimposed on. In other words, the characteristic of the rear reverberation is
added to the direct sound. The rear reverberation sound is output from the woofer 33L, 33R
together with the sound that causes the virtual sound source to be perceived.
[0065]
The level adjustment unit 43 adjusts the level of each input audio signal and outputs it to the
localization addition unit 42 in order to adjust the level of the sound causing the virtual sound
source to be perceived for each channel.
[0066]
The localization adding unit 42 performs processing to localize each input audio signal to a
virtual sound source position.
In order to localize an audio signal to a virtual sound source position, a head-related transfer
function (hereinafter referred to as HRTF) indicating a transfer function between a
predetermined position and a listener's ear. Use).
[0067]
The HRTF is an impulse response that expresses the magnitude, arrival time, frequency
characteristics, and the like of sounds from the virtual speakers installed at a certain position to
the left and right ears. By attaching the HRTF to the audio signal and emitting the sound from the
woofer 33L (or the woofer 33R), the listener perceives as being emitted from the virtual speaker.
[0068]
As shown in FIG. 5A, the localization addition unit 42 includes filters 421L to 425L and filters
421R to 425R for convoluting HRTF impulse responses for each channel.
[0069]
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The audio signal of the FL channel (the audio signal output from the HPF 40FL) is input to the
filters 421L and 421R.
The filter 421L is a virtual sound source VSFL on the left front of the listener on the audio signal
of the FL channel (see FIG. 6). The HRTF of the route from the position of) to the left ear is given.
The filter 421R adds the HRTF of the path from the position of the virtual sound source VSFL to
the right ear to the audio signal of the FL channel.
[0070]
The filter 422L applies the HRTF of the path from the position of the virtual sound source VSFR
in front of the listener's right front to the listener's left ear to the audio signal of the FR channel.
The filter 422R applies the HRTF of the path from the position of the virtual sound source VSFR
to the right ear to the audio signal of the FR channel.
[0071]
The filters 423L to 425L apply HRTFs of the route from the position of the virtual sound sources
VSC, VSSL, and VSSR corresponding to the C, SL, and SR channels to the left ear of the listener to
the audio signals of the C, SL, and SR channels. The filters 423R to 425R apply HRTFs of the
route from the position of the virtual sound sources VSC, VSSL, and VSSR according to the C, SL,
and SR channels to the right ear of the listener to the audio signals of the C, SL, and SR channels.
[0072]
Then, the addition unit 426L synthesizes the audio signals output from the filters 421L to 425L,
and outputs the synthesized audio signal as the audio signal VL to the crosstalk cancellation
processing unit 50. The adding unit 426R synthesizes the audio signals output from the filters
421R to 425R, and outputs the synthesized audio signal to the crosstalk cancellation processing
unit 50 as an audio signal VR.
[0073]
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The crosstalk cancellation processing unit 50 cancels the crosstalk emitted from the woofer 33L
to the right ear, and the woofer 33L and the woofer 33R so that the direct sound emitted from
the woofer 33L to the left ear can be heard flat. Change the frequency characteristics of each
input audio signal. Similarly, the crosstalk cancellation processing unit 50 cancels the crosstalk
emitted from the woofer 33R to the left ear, and the woofer 33L and the woofer 33L so that the
direct sound emitted from the woofer 33R to the right ear can be heard flat. The frequency
characteristics of each audio signal input to the woofer 33R are changed.
[0074]
More specifically, the crosstalk cancellation processing unit 50 performs processing using the
correction unit 51 and the combining units 52L and 52R.
[0075]
As shown in FIG. 5B, the correction unit 51 includes direct correction units 511L and 511R and
cross correction units 512L and 512R.
The audio signal VL is input to the direct correction unit 511L and the cross correction unit
512L. The audio signal VR is input to the direct correction unit 511R and the cross correction
unit 512R.
[0076]
The direct correction unit 511L performs a process of causing the listener to perceive the sound
emitted from the woofer 33L as if emitted near the left ear. In the direct correction unit 511L, a
filter coefficient is set so that the sound output from the woofer 33L can be heard flat at the
position of the left ear. The direct correction unit 511L corrects the input audio signal VL and
outputs an audio signal VLD.
[0077]
The cross correction unit 512R, together with the synthesis unit 52L, outputs from the woofer
03-05-2019
20
33L a sound in reverse phase of the sound that wraps around to the left ear from the woofer
33R, and cancels the sound pressure at the position of the left ear, Suppress what you hear in
your left ear. In addition, the cross correction unit 512R performs a process of causing the
listener to perceive that the sound emitted from the woofer 33L is emitted near the left ear. In
the cross correction unit 512R, a filter coefficient is set such that the sound output from the
woofer 33R can not be heard at the position of the left ear. The cross correction unit 512R
corrects the input audio signal VR and outputs an audio signal VRC.
[0078]
The combining unit 52L combines the audio signal VRC with the audio signal VLD in reverse
phase.
[0079]
The direct correction unit 511R performs a process of causing the listener to perceive the sound
emitted from the woofer 33R as if emitted near the right ear.
In the direct correction unit 511R, a filter coefficient is set such that the sound output from the
woofer 33R sounds flat at the position of the right ear. The direct correction unit 511R corrects
the input audio signal VR and outputs an audio signal VRD.
[0080]
The cross correction unit 512L, together with the synthesis unit 52R, outputs from the woofer
33R a sound in the reverse phase of the sound that wraps around from the woofer 33L to the
right ear, and cancels the sound pressure at the position of the right ear. Suppress what you hear
in your right ear. In addition, the cross correction unit 512L performs a process of causing the
listener to perceive that the sound emitted from the woofer 33R is emitted near the right ear. The
cross correction unit 512L is set with a filter coefficient such that the sound output from the
woofer 33L can not be heard at the position of the right ear. The cross correction unit 512L
corrects the input audio signal VL and outputs an audio signal VLC.
[0081]
The synthesis unit 52R reverses the audio signal VLC and synthesizes the audio signal VRD.
03-05-2019
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[0082]
The audio signal output from the combining unit 52L is input to the delay processing unit 60L.
The audio signal is delayed for a predetermined time by the delay processing unit 60L and input
to the level adjustment unit 61L. The audio signal output from the combining unit 52R is input to
the delay processing unit 60R. The delay processing unit 60R delays the audio signal with the
same delay time as the delay processing unit 60L.
[0083]
The delay time by the delay processing units 60L and 60R is set so that the sound beam and the
sound causing the virtual sound source to be perceived are not output at the same timing. This
makes the formation of the sound beam less likely to be disturbed by the perceived sound of the
virtual source. In addition, the array speaker apparatus 2 is provided with a delay processing unit
for each channel downstream of the directivity control unit 20, and delays the sound beam so
that the sound beam does not interfere with the sound that causes the virtual sound source to be
perceived. It does not matter.
[0084]
Level adjusters 61L and 61R are provided to collectively adjust the levels of sounds that cause
virtual sound sources of all channels to be perceived. The level adjusters 61L and 61R adjust the
levels of the audio signals delayed by the delay processors 60L and 60R. The audio signals whose
levels are adjusted by the level adjustment units 61L and 61R are input to the woofers 33L and
33R via the addition units 32L and 32R.
[0085]
Since the audio signals out of the band (less than 200 Hz) of the sound beam output from the
speaker units 21A to 21P are input to the adding units 32L and 32R, the sound outside the band
of the sound beam and the sound for localizing the virtual sound source Is output by the woofer
33L, 33R.
03-05-2019
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[0086]
As described above, the array speaker device 2 localizes the audio signal of each channel on
which the audio signal of the rear reverberation is superimposed to a virtual sound source
position.
[0087]
Next, a sound field generated by the array speaker device 2 will be described with reference to
FIG.
In FIG. 6, the outline arrows indicate the paths of the sound beam output from the array speaker
device 2, and the plurality of arcs indicate sounds perceiving the virtual sound source output
from the array speaker device 2.
Also, in FIG. 6, the asterisk indicates the position of the sound source generated by the sound
beam and the position of the virtual sound source.
[0088]
As shown in FIG. 6, the array speaker apparatus 2 outputs five audio beams in accordance with
the number of channels of the input audio signal. The audio signal of C channel is delaycontrolled so that the focal position is set to the rear of the array speaker apparatus 2, for
example. Then, the listener perceives that the sound source SC of the C channel audio signal is in
front of the listener.
[0089]
The audio signals of the FL and FR channels are delay-controlled so that, for example, the sound
beam is focused on the wall on the left front of the listener and the wall on the right front of the
listener. Each sound beam based on the audio signals of the FL and FR channels is reflected once
by the wall of the room R to reach the position of the listener. Then, the listener perceives that
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the sound sources SFL and SFR of the audio signal of the FL and FR channels are on the wall on
the left front and the wall on the right front of the listener.
[0090]
The audio signals of the SL and SR channels are delay-controlled so that, for example, the sound
beam is directed to the left side wall and the right side wall of the listener. Each sound beam
based on the audio signals of the SL and SR channels is reflected on the wall of the room R and
reaches the wall on the left rear of the listener and the wall on the right rear of the listener. Each
sound beam is reflected again on the left rear wall of the listener and on the right rear wall of the
listener to reach the position of the listener respectively. Then, the listener perceives that the
sound sources VSSL and VSSR of the audio signal of the SL and SR channels are on the wall on
the left rear of the listener and the wall on the right rear of the listener.
[0091]
The filters 421L to 425L and the filters 421R to 425R of the localization addition unit 42 are set
such that the positions of the virtual speakers are substantially the same as the positions of the
sound sources SFL, SFR, SC, SSL, and SSR. Then, as shown in FIG. 6, the listener perceives the
virtual sound sources VSC, VSFL, VSFR, VSSL, and VSSR at substantially the same positions as the
positions of the sound sources SFL, SFR, SC, SSL, and SSR.
[0092]
Thereby, the array speaker apparatus 2 improves the sense of localization compared to the case
where only the sound beam is used or the case where only the virtual sound source is used.
[0093]
Here, as shown in FIG. 6, the array speaker apparatus 2 superimposes an initial reflected sound
on each sound beam.
Since the sound that causes the virtual sound source to be perceived does not have an initial
reflection sound that differs in frequency characteristics for each direction of arrival, the
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frequency characteristics of the head-related transfer function are maintained. Also, since the
sound causing the virtual sound source to be perceived imparts a sense of localization due to the
difference in frequency characteristics between the two ears, the difference in arrival time of the
sound, and the volume difference, the rear reverberation sound with uniform frequency
characteristics is superimposed on each channel. Even if it does, the frequency characteristic of
the head related transfer function is not affected and there is no change in the sense of
localization.
[0094]
Further, the array speaker device 2 does not superimpose the rear reverberation sound on each
sound beam, but superimposes the rear reverberation sound on the sound causing the virtual
sound source to be perceived. Therefore, since the array speaker apparatus 2 does not
superimpose the rear reverberation sound having substantially the same frequency component
regardless of the arrival direction on each sound beam, the audio signals of the sound beams are
similar and the sound images are combined. Absent. Thereby, the array speaker apparatus 2
prevents the localization feeling of each sound beam from being unclear. Also, since the sound
beam causes localization to be perceived by the sound pressure from the arrival direction, there
is no change in the sense of localization even if the initial reflected sound with different
frequency characteristics is superimposed for each arrival direction and the frequency
characteristics change. .
[0095]
As described above, the array speaker device 2 applies the sound field effect to the sound of the
content by the initial reflection sound and the rear reverberation sound without impairing the
effect of localization of the sound that causes each sound beam and the virtual sound source to
be perceived. Can.
[0096]
Moreover, the array speaker apparatus 2 can change the level ratio of an initial reflection sound
and a back reverberation to a listener's desired ratio by providing the group with the gain
adjustment part 221 and the gain adjustment part 441.
[0097]
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Further, the array speaker device 2 outputs an audio beam and a sound for perceiving a virtual
sound source, and gives a sound field effect, to an audio signal of multi-channel surround sound.
Therefore, the array speaker apparatus 2 can impart a sound field effect to the sound of the
content while giving a sense of localization so as to surround the listener.
[0098]
In the above example, the rear reverberation generated by the rear reverberation generation unit
442 is output from the woofer 33L, 33R after being superimposed on the sound causing the
virtual sound source to be perceived, but the sound causing the virtual sound source to be
perceived It does not have to be superimposed.
For example, the audio signal of the rear reverberation sound generated by the rear
reverberation generation unit 442 may be input to the woofer 33L, 33R through the level
adjustment units 34L, 34R without passing through the localization addition unit 42.
[0099]
Next, a speaker set 2A according to a modification of the array speaker device 2 will be described
with reference to the drawings. FIG. 7 is a diagram for explaining the speaker set 2A. FIG. 8 is a
part of a block diagram of the speaker set 2A and the subwoofer 3. However, the arrow in FIG. 7
indicates the path of sound having directivity in the interior 900 of the car.
[0100]
The speaker set 2A is different from the array speaker device 2 in that the directional speaker
unit 21 (21Q, 21R, 21S, 21T, 21U) outputs a sound having directivity. The description of the
configuration overlapping with the array speaker device 2 is omitted.
[0101]
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26
Each directional speaker unit 21 is arranged according to the channel. That is, the directional
speaker unit 21S corresponding to the C channel is disposed in front of the listener. The
directional speaker unit 21Q corresponding to the FL channel is disposed in front of and to the
left of the listener. The directional speaker unit 21R corresponding to the FR channel is disposed
in front of and to the right of the listener. The directional speaker unit 21T corresponding to the
SL channel is disposed behind and to the left of the listener. The directional speaker unit 21U
corresponding to the SR channel is disposed behind and to the right of the listener.
[0102]
Each audio signal output from the level adjustment unit 18 is input to the delay processing unit
23 (23FL, 23FR, 23C, 23SR, 23SL) as shown in FIG. The delay processing unit 23 performs a
delay process according to the path length from each directional speaker unit 21 to the listener
so that the phases of the sound having directivity in the vicinity of the listener are aligned.
[0103]
Each audio signal output from the delay processing unit 23 is input to each directional speaker
unit 21. Even with such a configuration, the speaker set 2A can superimpose the initial reflection
sound on the sound having directivity corresponding to each channel and deliver it to the
listener.
[0104]
In this modification, the delay times of the delay processing unit 60 and the delay processing unit
23 are respectively set so that sounds having directivity and sounds that cause a virtual sound
source to be perceived are not output at the same timing.
[0105]
DESCRIPTION OF SYMBOLS 1 ... AV system 2, 2A ... Array speaker apparatus 3 ... Sub woofer 4 ...
Television 10 ... Decoder 11 ... DIR12 ... ADC13 ... HDMI receiver 14FL, FR, C, SR, SL ... HPF15FL,
FR, C, SR, SL ... LPF16, 17 ... addition unit 18 ... level adjustment unit 20 ... directivity control units
21A to 21P ... speaker units 21Q, 21R, 21S, 21U, 21T ... directional speaker unit 22 ... initial
reflected sound processing unit 221 ... gain adjustment unit 222 ... initial stage Reflected sound
generation unit 223 ... synthesis unit 30L, 30R ... HPF 31L, 31R ... LPF 32L, 32R ... addition unit
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33L, 33R ... woofer 40FL, FR, C, SR, SL ... HPF 41FL, FR, C, SR, SL ... LPF42 ... localization Addition
unit 43 ... Level adjustment unit 44 ... Rear reverberation processing unit 441 ... Ge Adjustment
unit 442 ... rear reverberation generation unit 443 ... synthesis unit 50 ... crosstalk cancellation
processing unit 51 ... correction unit 52L, 52R ... synthesis unit 60L, 60R ... delay processing unit
61L, 61R ... level adjustment units 70A to 70E, 70F , 70 G ... Level adjustment unit 71 ... Addition
unit 72 ... Subwoofer unit
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