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JP2009188474

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DESCRIPTION JP2009188474
PROBLEM TO BE SOLVED: In an audio reproduction system equipped with a main speaker
disposed on the front of a flat-panel television receiver and a sub-speaker disposed on the back,
the distance to the wall surface when installed and the acoustic reflection characteristics of the
wall surface Even if it changes, it enables sound reproduction with less interference and
characteristic fluctuation due to the influence of the reflected sound. SOLUTION: A sound output
from a sub-speaker is compared with an audio signal supplied to the sub-speaker and an electric
signal output from the microphone by having a microphone for converting the reflected sound
into an electric signal, and an acoustic reflection characteristic is obtained. It has an analysis unit
to analyze, and corrects the phase of the audio signal supplied to the sub-speaker and the main
speaker according to the analysis result. [Selected figure] Figure 1
Audio reproduction apparatus and control method thereof
[0001]
The present invention relates to an audio reproduction apparatus that controls output
characteristics of a plurality of speakers by analyzing the acoustic characteristics of reflected
sound, and a control method thereof.
[0002]
Conventionally, there is known a speaker apparatus in which a speaker for bass reproduction is
disposed on the side and a speaker for treble reproduction is disposed on the front, utilizing that
the sound outputted from the bass reproduction speaker has relatively no directivity. There is.
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1
With such an arrangement, it is possible to realize a good bass reproduction and a speaker device
for a television receiver having a reduced width (see Patent Document 1).
[0003]
There is also known a sound field measurement apparatus which picks up a measurement signal
reproduced in a measurement sound field with a directional microphone having a plurality of
directional axes and analyzes it in each direction. As a result, it is possible to analyze the
reflection sound component of the room and evaluate the feeling of expansion, reverberation, the
localization of the sound image, and the like regarding the spatiality of the sound field (see
Patent Document 2). JP-A 06-105257 JP-A 2007-225482
[0004]
However, in the television receiver speaker of Patent Document 1, since the speaker unit is not
disposed on the back of the television receiver, it is not an acoustic system using the reflected
sound from the wall.
[0005]
In the sound field measurement device of Patent Document 2, the configuration of the
microphone is complicated because the microphone has a plurality of directional axes.
In addition, since it is necessary to place and measure the microphone at the listening position,
the wiring becomes long, and the entire apparatus becomes large, and there is a problem that the
handling becomes complicated. Although it is possible to mount the microphone on a remote
control or other listening position, in this case, it is necessary to transmit a large amount of
measured data as well as a microphone amplifier and an AD converter are disposed in the remote
control. , The circuit scale of the remote control is greatly increased. In addition, when the remote
control is placed on a flat surface such as a table, the characteristics of the microphone are
affected, and there is a problem that accurate measurement is difficult.
[0006]
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2
An object of the present invention is to provide an audio system in which a speaker is disposed
on the back side and a reflected sound from a wall is used, and an acoustic characteristic of the
reflected sound can be analyzed with a compact configuration. .
[0007]
In order to solve the above problems, an audio reproduction apparatus according to the present
invention is an audio reproduction apparatus having a first speaker and a second speaker
disposed at a position different from the first speaker, From the second speaker from the second
speaker from the second voice signal supplied to the second speaker and the electric signal
output from the microphone An analysis unit that detects a reflection time of the reflected sound
of the sound to be output; and at least one of a first sound signal and a second sound signal
supplied to the first speaker based on the reflection time. And a phase correction unit for
correcting the phase of the audio signal.
[0008]
When a flat-panel television receiver equipped with the audio reproduction apparatus of the
present invention is installed in front of a wall, interference or characteristics due to the
influence of reflected sound even if the distance to the wall or the acoustic reflection
characteristics of the wall change. Good voice reproduction with little fluctuation is possible.
[0009]
Hereinafter, the present invention will be described in detail based on its preferred embodiments
with reference to the drawings.
[0010]
FIG. 1 is a block diagram of an audio reproduction apparatus according to the present invention.
[0011]
The input audio signal input to the input unit 16 is input to the high-pass filter unit 12 and the
low-pass filter unit 13 respectively.
[0012]
Under the control of the control unit 9, the high-pass filter 12 of the input voice signal filters the
high band and the low-pass filter 13 outputs the low band.
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[0013]
The phase correction unit 11 corrects the phase of the output of the high-pass filter unit 12
based on the control of the control unit 9.
The phase correction unit 11 may be configured to correct the phase of the output of the low
pass filter unit 13 or may correct the phase of both outputs.
[0014]
The first volume adjustment unit 7 adjusts the output amplitude of the phase correction unit 11
based on the control of the control unit 9.
[0015]
The second volume adjuster 8 adjusts the output amplitude of the low pass filter 13 based on the
control of the controller 9.
[0016]
The first amplification unit 4 amplifies the output of the first volume adjustment unit 7 to an
output level at which the main speaker 1 (corresponding to the first speaker) can drive.
[0017]
The second amplification unit 5 amplifies the output of the second volume adjustment unit 8 to
an output level at which the sub-speaker 2 (corresponding to the second speaker) can drive.
[0018]
The third amplification unit 6 amplifies the output of the microphone 3 to an output level that
can be analyzed by the analysis unit 10.
[0019]
The main speaker 1 converts a high frequency audio signal (corresponding to a first audio signal)
output from the first amplification unit 4 into an audible sound.
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[0020]
The sub-speaker 2 converts the low frequency audio signal (corresponding to the second audio
signal) output from the second amplification unit 5 into an audible sound.
[0021]
The microphone 3 receives the sound output from the sub-speaker 2 and the reflected sound
thereof and converts the sound into an electrical signal.
[0022]
The analysis unit 10 compares the output of the third amplification unit 6 with the output of the
second amplification unit 5, and analyzes the distance from the position of the sub-speaker to the
object reflecting the output sound of the sub-speaker and the acoustic reflection characteristics
Do.
[0023]
The control unit 9 adjusts the frequency characteristic, phase characteristic, and amplitude
characteristic of the sound output from the main speaker 1 and the sub-speaker 2 according to
the analysis result of the analysis unit 10.
[0024]
Hereinafter, the operation of the audio reproduction device will be described in detail using the
process flow diagram of the audio reproduction device of the present invention shown in FIG.
[0025]
When the process is started by turning on the power, the output adjustment value of the second
volume adjustment unit 8 is set to a specific value (S1).
As a result, the low-pass filtered signal of the input signal is amplified by the second
amplification unit 5 and output from the sub-speaker 2.
[0026]
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The low frequency sound output from the sub-speaker 2 is reflected to the surroundings to
become a reflected sound.
The reflected sound converted to an electrical signal by the microphone 3 is compared with the
low-pass filtered signal output by the second amplification unit 5 by the analysis unit 10 to
calculate the reflection time (S2).
[0027]
The control unit controls the phase correction unit 11 so that the output signal of the main
speaker 1 directly reaching the listener and the output signal of the sub-speaker 2 reaching as a
reflected sound do not interfere due to the phase difference based on the reflection time. Set the
characteristics of (S3).
[0028]
Furthermore, the analysis unit 10 compares the output signal of the microphone 3 with the lowpass filtered signal output from the second amplification unit 5 to analyze the sound pressure
level and the amplitude frequency characteristic of the reflected sound (S4).
[0029]
According to the sound pressure level and the amplitude frequency characteristic, when the
sound pressure level of the reflected sound is high or the low frequency component is large, the
control unit 9 performs the second volume adjustment unit 8 in order to prevent excessive bass.
Decrease the setting volume of (S5).
Furthermore, when there are many specific frequency components in the reflected sound, the
cut-off frequencies of the high-pass filter 12 and the low-pass filter 13 are adjusted to prevent
the frequency from becoming excessive (S6).
By the above processing, the output characteristics of the main speaker 1 and the sub speaker 2
are properly adjusted.
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[0030]
FIG. 3 is a block diagram of the case where the audio reproduction apparatus of the present
invention is applied to a television receiver.
The microphone 3 is disposed in the vicinity of the sub-speaker 2 in order to efficiently convert
the reflected sound of the signal output from the sub-speaker 2 into an electrical signal.
[0031]
The operation of the television receiver will be described with reference to the flowchart of FIG. 2
again.
The flat panel television receiver is installed with a wall on the back, and the main speaker 1 is
disposed on the front side of the flat panel television and the sub-speaker 2 is disposed on the
back side.
[0032]
In the signal output process (S1), the sound outputted from the sub-speaker 2 is reflected on the
wall surface on the back of the rear of the television receiver to become a reflected sound, and is
inputted to the microphone 3.
As for the reflected sound, a reflection time analysis process (S2) calculates the length of the
reflected sound arrival path 25 which changes according to the distance from the wall surface.
The control unit 9 stores a path length difference table for calculating the difference between the
direct arrival path 26 and the path length of the reflected arrival path 27 according to the length
of the reflected sound arrival path 25.
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[0033]
Using the path length difference table, the output sound of the main speaker 1 directly reaching
the listener and the output sound of the sub speaker 2 reflected and arriving do not cause
interference due to the phase difference due to the difference in path length , The phase of the
output speech is adjusted (S3).
[0034]
Specifically, as shown in FIG. 4A, when the direct arrival path 26 and the reflected arrival path 27
interfere so that the voice is canceled out, as shown in FIG. 4B, The phase of the output sound of
the main speaker 1 is corrected so as to be in phase with each other.
[0035]
Next, in the reflection frequency characteristic analysis process (S4), the sound pressure level
and the frequency characteristic of the reflected sound are analyzed according to the acoustic
reflectance of the wall surface, the reflection frequency characteristic, and the relationship
between the sub-speaker 2 and the wall surface Ru.
[0036]
FIG. 5 is an example of reproduction characteristics of sound set by the volume adjustment
control processing (S5) and the filtering characteristic control processing (S6) according to the
analysis result of the reflection frequency characteristic analysis processing (S4).
[0037]
As shown in FIG. 5A, when the reflection level of voice is hardly dependent on frequency, the
signal levels of the sub speaker and the main speaker are equalized, and the crossover level is set
to an intermediate value.
[0038]
As shown in FIG. 5 (b), when there are a lot of low frequency components of the reflected sound
or when the sound pressure level is high, the second volume adjusting unit 8 sets the low
frequency audio signal so that the bass does not become excessive. Modulate the input signal to
reduce the signal level.
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As shown in FIG. 5C, when there are many specific frequency components in the reflected sound,
the control unit 9 cuts the high-pass filtering unit 12 and the low-pass filtering unit 13 so that
the voice of that frequency is not excessive. Adjust the off frequency.
As a result, the crossover level of the frequency characteristic of the high band audio signal and
the low band audio signal is modulated to the low level side.
[0039]
The above is the processing of only the right channel in the stereo configuration.
The left main channel, the second sub speaker 22, and the second microphone 28 perform
similar processing independently of the right channel.
Since the left and right channels are processed independently, as shown in FIG. 6, the present
invention can be easily applied even when the television receiver is arranged not parallel to the
wall surface.
[0040]
Further, it is also possible to correct with higher accuracy by calculating the angle with the wall
surface from the difference in the length of the reflected sound microphone arrival path 25 in the
left and right channels.
[0041]
Hereinafter, a second embodiment according to the present invention will be described.
[0042]
FIG. 7 is a block diagram of an audio reproduction apparatus according to a second embodiment
of the present invention.
[0043]
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Based on the control of the reference signal generating unit 14 for outputting a reference signal
used for measurement and the control unit 9, one of the low-pass filtering unit 13 and the
reference signal generating unit 14 is selected to output a low-pass audio signal. It is
characterized by having a selection unit 15 for outputting.
The operations other than the operation relating to the selection unit 15 are the same as in the
first embodiment.
[0044]
When the power is turned on, the control unit 9 controls the selection unit 15 to select the
output of the reference signal generation unit 14.
Thereafter, using the reference signal, correction processing according to the flowchart of FIG. 2
is performed in the same manner as in the first embodiment.
After the correction processing is completed, the control unit 9 controls the selection unit 15 to
switch the reference signal to the output signal of the low pass filter unit 13.
[0045]
As the reference signal, it is possible to use a signal whose signal level is not dependent on
frequency or a signal whose signal level is proportional to the frequency, at a signal level which
is constant in time.
[0046]
In the present embodiment, the correction processing is performed using the reference signal
with a stable signal level, so that the correction with higher accuracy is possible.
[0047]
Hereinafter, a third embodiment according to the present invention will be described.
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[0048]
FIG. 8 is a block diagram of an audio reproduction apparatus according to a third embodiment of
the present invention.
[0049]
FIG. 9 is a block diagram of the case where the audio reproduction device in the third
embodiment is applied to a television receiver.
[0050]
This is a 2.1 channel configuration having a first input unit 16 and a second input unit 22
corresponding to the left and right channels of the stereo signal.
The sub-speaker 2 is a subwoofer that reproduces the low band of both channel inputs. The first
main speaker 1 reproduces the high band of the right channel input, and the second main
speaker 17 reproduces the high band of the left channel input.
[0051]
When the reference signal output is selected by the selection unit 15, the signal output process
(S1) and the reflection time analysis process (S2) are performed as in the second embodiment,
and the length of the reflected sound microphone arrival path 25 is recognized. After that, the
direct arrival path 26 and the reflection arrival path 27 are calculated by the control unit 9.
After phase control processing (S3) according to the calculation result, reflection frequency
characteristic analysis processing (S4), volume adjustment control processing (S5), and filtering
characteristic control processing (S6) are performed.
[0052]
The audio signals input from the first input unit 16 and the second input unit 22 are converted
by the low pass filtering unit 13 into monaural low pass signals.
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The low pass filtered signal output process (S7) outputs the left and right low pass signals from
the sub-speaker 2.
The sense of direction of sound is insensitive to lower frequencies, so even monophonic
reproduction has less influence on the separation of auditory stereos and is reproduced.
[0053]
Further, the sub-speaker 2 and the microphone 3 can be respectively configured one by one, and
by performing a series of processing once, stereo sound reproduction with less interference and
characteristic fluctuation due to the influence of the reflected sound can be performed.
[0054]
Hereinafter, a fourth embodiment according to the present invention will be described.
[0055]
FIG. 10 is a block diagram of an audio reproduction apparatus according to a fourth embodiment
of the present invention.
[0056]
FIG. 11 is a block diagram of the case where the audio reproduction device in the fourth
embodiment is applied to a television receiver.
[0057]
The second sub-speaker 22 is disposed at a position different from the first sub-speaker 2.
According to the control of the control unit 9, it has a second selection unit 23 which selects one
of the first sub-speaker 2 and the second sub-speaker 22 and supplies the output of the second
amplification unit 5. It features.
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[0058]
When the reference signal output is selected by the first selection unit 15, as in the second
embodiment, the operation is performed according to the flowchart shown in FIG.
As a result of the reflection time analysis process (S2), when it is detected that the reflection time
is within a predetermined time or as a result of the reflection frequency characteristic analysis
process (S4), the control unit 9 detects that the reflection level is out of the predetermined range.
It is determined that the television receiver is being used in a wall-mounted state.
At this time, the second selection unit 23 selects the second sub-speaker 22.
Furthermore, the characteristics of the phase correction unit 11, the volume of the second
volume adjustment unit 8, and the cutoff frequencies of the high-pass filter unit 12 and the lowpass filter unit 13 are switched to settings suitable for the characteristics of the second subspeaker 22. Be
[0059]
At this time, since the sense of direction of the sound is insensitive to lower frequencies,
reproduction in monaural has less influence on separation of aural stereo.
[0060]
By the above processing, even if the television receiver is used in a wall-mounted state, the audio
signal correction is appropriately performed by the output of the second sub-speaker 22.
When used in a state where there is a certain distance between the wall surface and the subspeaker 2, even if the distance or the acoustic reflection characteristics of the wall surface
change, voice reproduction with little interference or characteristic fluctuation due to the
influence of the reflected sound Is possible.
[0061]
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Hereinafter, a fifth embodiment according to the present invention will be described.
[0062]
FIG. 12 is a block diagram of an audio reproduction apparatus according to a fifth embodiment of
the present invention.
[0063]
FIG. 13 is a block diagram of the case where the audio reproduction device in the fifth
embodiment is applied to a television receiver.
[0064]
As in the fourth embodiment, the second sub-speaker 22 is disposed at a position different from
the first sub-speaker 2.
In place of the selection unit 23, a balance adjustment unit 24 for adjusting the output balance of
the second amplification unit 5 is provided.
[0065]
Similar to the fourth embodiment, the correction process is performed according to the flowchart
of FIG.
[0066]
As the result of the reflection time analysis process (S2), as the reflection time is longer or as the
result of the reflection frequency characteristic analysis process (S4), the lower the reflection
level, is it difficult for the control section 9 to reproduce using wall reflection? Or judge that
there is no wall.
At this time, the reproduction level of the second sub-speaker 22 is increased.
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The sense of direction of sound is insensitive to lower frequencies, so even monophonic
reproduction has less influence on the separation of auditory stereos and is reproduced.
[0067]
Also, according to the reproduction level of the second sub-speaker 22, adjust the characteristics
of the phase correction unit 11, the setting volume of the second volume adjustment unit 8, and
the cutoff frequency of the high-pass filter 12 and the low-pass filter 13. You may
[0068]
By the above processing, even if the television receiver is used in a state where reproduction
using the reflection of the wall surface by the sub-speaker 2 is difficult, the output of the second
sub-speaker 22 corrects.
When used in a state where there is a wall with a certain degree of reflection characteristic
behind the sub-speaker 2, even if the distance or the acoustic reflection characteristic of the wall
changes, voice reproduction with less interference and characteristic fluctuation due to the
influence of reflected sound Is possible.
[0069]
FIG. 1 is a block diagram of an audio reproduction device according to a first embodiment of the
present invention.
It is a processing flow figure of the audio reproduction device concerning a 1st embodiment of
the present invention.
FIG. 1 is a schematic view of a television receiver equipped with an audio reproduction device
according to a first embodiment of the present invention.
It is explanatory drawing for demonstrating the phase of the output audio ¦ voice of this
invention.
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It is an explanatory view for explaining an example of reproduction characteristics of an audio
reproduction device concerning one embodiment of the present invention.
It is a schematic diagram at the time of arrange ¦ positioning in the state which is not parallel to a
wall surface the television receiver carrying the audio reproduction apparatus which concerns on
one Embodiment of this invention.
It is a block diagram of the audio reproduction apparatus concerning a 2nd embodiment of the
present invention.
It is a block diagram of the audio reproduction apparatus concerning a 3rd embodiment of the
present invention.
It is a schematic diagram of the television receiver carrying the audio reproduction apparatus
which concerns on the 3rd Embodiment of this invention.
It is a block diagram of the audio reproduction apparatus concerning a 4th embodiment of the
present invention.
It is a schematic diagram of the television receiver carrying the audio reproduction apparatus
which concerns on the 4th Embodiment of this invention.
It is a block diagram of the audio reproduction apparatus concerning a 5th embodiment of the
present invention.
It is a schematic diagram of the television receiver carrying the audio reproduction apparatus
which concerns on the 5th Embodiment of this invention.
Explanation of sign
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[0070]
Reference Signs List 1 main speaker 2 sub speaker 3 microphone 4 first amplification unit 5
second amplification unit 6 third amplification unit 7 first volume adjustment unit 8 second
volume adjustment unit 9 control unit 10 analysis unit 11 phase correction unit 12 high-pass
filtering unit 13 low-pass filtering unit 14 reference signal generating unit 15 selection unit 16
input unit 17 second main speaker 18 fourth amplification unit 19 third volume adjustment unit
20 second high-pass filtering unit 21 first 2 input section 22 second sub-speaker 23 second
selection section 24 balance adjustment section 25 reflected sound microphone arrival path 26
direct arrival path 27 reflection arrival path 28 second microphone S1 signal output processing
S2 reflection time analysis processing S3 phase Control processing S4 reflection frequency
characteristic analysis processing S5 volume adjustment control processing S6 filtering
characteristic control processing S7 low-pass filtering signal output processing
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