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JPH1175300

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DESCRIPTION JPH1175300
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
sound image localization apparatus, and in particular, receives an acoustic signal, performs signal
processing on the input acoustic signal, localizes a virtual sound image, and outputs a sound
image localization signal. Sound image localization apparatus.
[0002]
2. Description of the Related Art In a general stereophonic sound system conventionally used,
sound image localization is controlled using a plurality of (generally two) speakers to provide a
sense of presence in the human auditory sense of the listener. It was supposed to give. In
conventional systems, two left and right speakers located in front of the listener are usually used
to localize the sound image between the two speakers. In such a system, outside of the two
speakers, The sound image was not localized. Then, if you want to localize the sound image to the
outside of both speakers, that is, around the listener, for example, to obtain an effect that sounds
can be heard from behind the listener, in addition to the two speakers in front, you also have
speakers behind. A system to be deployed was performed.
[0003]
However, with the development of audio digitization technology and hardware such as DSP
(Digital Signal Processor), various signal processing can be easily performed, so two speakers
located in front are used. Also in the system, control has been performed to localize the sound
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image at an arbitrary position (lateral direction, rear, etc.) around the listener.
[0004]
As a sound image localization apparatus according to the prior art, Proceedings of the Meeting of
the Acoustical Society of Japan, Spring 1996, Proceedings of the Conference of Spring 1996,
p549-550, "Study on cancellation of crosstalk in acoustic control" (hereinafter referred to as
Reference 1.
There is what is described in.
[0005]
FIG. 19 is a diagram for explaining control of sound image localization. The figure a) is a figure
showing a virtually localized sound image, and the figure b) is a figure showing a system using
two speakers. Here, both the virtual localization position of the sound image and the positions of
the two speakers are assumed to be symmetrical with respect to the listener.
[0006]
In a sound image localization apparatus, direction localization processing of determining the
direction of a virtual localization position by signal processing using a head related transfer
function indicating transfer characteristics of sound from a sound source to the head or ear of a
listener And crosstalk cancellation (crosstalk cancellation) processing.
[0007]
Here, in the case of FIG. 19 b), the crosstalk signal is a signal transmitted from the left speaker to
the right ear, or from the right speaker to the left ear, and for crosstalk cancellation processing, A
crosstalk cancellation signal will be generated.
[0008]
As shown in FIG. A), in the virtual environment obtained in this system, the sound signals uL and
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uR are emitted from the left and right virtual sound image positions located behind the listener.
The sound pressures applied to the left and right ears of the listener are yL1 and yR1,
respectively.
Because of left-right symmetry, transmission from the left virtual position to the left ear and from
the right virtual position to the right ear are equal, and a head transfer function representing this
transfer characteristic is taken as TM.
Similarly, the transmission from the left virtual position to the right ear and from the right virtual
position to the left ear is represented by the same head transfer function TC. In such a virtual
environment, the relationship yL1 = TM.uL + TC.uR (1-1) yR1 = TC.uL + TM.uR (1-2) is
established for the sound pressure and the function.
[0009]
On the other hand, in the system shown in FIG. B), the acoustic signals xL and xR are emitted
from the left and right speakers 1901a and 1901b, and the sound pressures applied to the left
and right ears of the listener are respectively It is assumed that yL2 and yR2 are obtained. Also
from the left speaker position to the left ear and from the right speaker position to the right ear,
the left head position to the right ear and the right speaker position to the right ear are also
symmetrical due to left-right symmetry. The transmission to this is expressed by the same head
related transfer function SC. And about these sound pressure and a function, the relation of yL2 =
TMxLR + TCxR (2-1) yR2 = TCxL + TMxR (2-2) is materialized.
[0010]
In this system, yL1 = yL2 (3-1) yR1 = yR2 (3-2) in order to localize the sound image shown in
FIG. A) by the sounds output from the speakers 1901a and 1901b shown in FIG. From the
formulas 3-1, 1-1 and 2-1, the following formula 4-1 can be obtained, and from the formulas 3-2,
1-2 and 2-2, the following formula 4-2 can be obtained. Led.
[0011]
TM · uL + TC · uR = TM · xL + TC · xR (4-1) TC · uL + TM · uR = TC · xL + TM · xR (4-2) Then, the
equations 4-1 and 4-2 are solved for xL and xR According to one solution, assuming that the gain
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is indicated by ¦ * ¦, it can be considered as ¦ (SC / SM) ^ 2 ¦ << 1 (5), xL ˜ (FM + FC · FX) · uL +
(FC + FM.FX) .uR (6-1) xR.about. (FC + FM.FX) .uL + (FM + FC.FX) .uR (6-2) is obtained.
However, FM, FC, and FX in a formula are FM = TM / SM (7-1) FC = TC / SM (7-2) FX = -SC / SM
(7-3)
[0012]
It is also possible to use another solution to obtain xL = FM · uL + FC · uR + FX · xR (8-1) x R = FC ·
uL + FM · uR + FX · xL (8-2). Here, in Equations 8-1 and 8-2, the first term and the second term
on the right side indicate the direction of the sound image (localize the direction), and the third
term on the right side cancels the crosstalk component. It is.
[0013]
The configuration of a conventional sound image localization apparatus for controlling sound
image localization using the above relationship is shown in a functional block diagram of FIG.
17a). As shown in the figure, the sound image localization apparatus according to the prior art
comprises crosstalk cancellation means 1701, direction localization means 1702a and 1702b,
and adders 1703a and 1703b, and an input terminal 1704a, And 1704 b, and outputs signals
obtained as a result of signal processing from output terminals 1705 a and 1705 b.
[0014]
Direction localization means 1702a and 1702b generate signals indicating the direction of the
sound image position by arithmetic processing on the sound signals input from the input
terminals 1704a and 1704b. The adders 1703a and 1703b perform addition processing on the
input signal. The crosstalk cancellation unit 1701 removes crosstalk components from the input
signal.
[0015]
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FIG. 6 b) is a diagram showing a first example of a detailed configuration of a sound image
localization apparatus according to the prior art. The crosstalk cancellation means 1701 shown
in FIG. 6A includes the crosstalk cancellation signal generation filters 1706a and 1706b shown
in FIG. 6B, and adders 1703c and 1703d. The direction localization means 1702a and 1702b
shown in FIG. 14A are composed of main pass filters 1707a and 1707b and crosstalk pass filters
1708a and 1708b. The main pass filter and the crosstalk pass filter may be collectively referred
to as a direction localization filter.
[0016]
The sound image localization apparatus according to the prior art configured as described above
generates the outputs xL and xR according to the above equations 6-1 and 6-2, and the operation
thereof will be described below. Left and right input acoustic signals are input from the input
terminals 1704a and 1704b, respectively. In FIG. 17 b), the first input acoustic signal input from
the input terminal 1704a is input to the main pass filter 1707a and the crosstalk pass filter
1708a. In the main pass filter 1707a, an operation processing is performed by multiplying the
coefficient shown in the above equation 7-1 and in the crosstalk pass filter 1708a the coefficient
shown in the equation 7-2, and the output of the main pass filter 1707a is an adder. The output
of the crosstalk pass filter 1708a is input to the adder 1703b at 1703a.
[0017]
Similarly, the second input acoustic signal input from the input terminal 1704b is input to the
main pass filter 1707b and the crosstalk pass filter 1708b, and is shown in the above-described
Equation 7-1 and Equation 7-2, respectively. Arithmetic processing for multiplying the
coefficients is executed, and the output of the main pass filter 1707 b is input to the adder 1703
b, and the output of the crosstalk pass filter 1708 b is input to the adder 1703 a.
[0018]
The adders 1703a and 1703b respectively perform addition processing on the input signals, and
the adder 1703a outputs the addition result to the adder 1703c and the crosstalk cancellation
signal generation filter 1706a.
The crosstalk cancellation signal generation filter 1706 a generates a crosstalk cancellation
signal and outputs the crosstalk cancellation signal to the adder 1703 d by executing arithmetic
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processing of multiplying the coefficient shown in the above-mentioned equation 7-3.
[0019]
Similarly, the adder 1703 b outputs the addition result to the adder 1703 d and the crosstalk
cancellation signal generation filter 1706 b. The crosstalk cancellation signal generation filter
1706 b performs operation processing of multiplying the coefficient shown in the equation 7-3
described above to generate a crosstalk cancellation signal, and outputs the crosstalk
cancellation signal to the adder 1703 c.
[0020]
In the adders 1703 c and 1703 d, the addition result of the adder 1703 a and the adder 1703 b
and the crosstalk cancellation signal having substantially the same phase as the inverted phase of
the addition result are subjected to addition processing, At the output terminals 1705a and
1705b, the signals from which the crosstalk components have been removed, which are
represented by the equations 6-1 and 6-2, are output.
[0021]
In the sound image localization apparatus having the configuration shown in FIG. 17 b), the
output of the crosstalk cancellation signal generation filter (for example, 1706 a) in one channel
is on the output side of the other channel (the adder 1703 d located on the output terminal 1705
b side) Because it is output, it is called a feedforward type.
[0022]
Further, Japanese Patent Application No. 8-41665 (hereinafter referred to as Reference 2) is
taken as a second example for realizing the conventional sound image localization apparatus
shown in FIG. 17a).
There is one described in.
FIG. 18 is a diagram showing a second example of the detailed configuration of the sound image
localization apparatus according to the prior art. In the configuration shown in FIG. 17A, the
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crosstalk cancellation means 1701 in FIG. 17A includes crosstalk cancellation signal generation
filters 1806a and 1806b, and adders 1803a and 1803b. The direction localization means 1702a
and 1702b shown in FIG. 17a) are made up of main pass filters 1807a and 1807b, and crosstalk
pass filters 1808a and 1808b. The adders 1803a and 1803b are also part of the crosstalk
cancellation means 1701 in FIG. 17a) as described above, and are also adders 1703a and 1703b
shown in the figure.
[0023]
Here, the sound image localization apparatus shown in FIG. 18 generates the outputs xL and xR
according to the above-mentioned equations 8-1 and 8-2, which differs from the configuration
shown in FIG. Since the output of the crosstalk cancellation signal generation filter (for example,
1806a) in is output to the input side (the adder 1803b on the output terminal 1704b side) of the
other channel, it is called a feedback type. The operation of the sound image localization
apparatus configured as described above will be described below.
[0024]
Left and right input acoustic signals are input from input terminals 1804 a and 1804 b,
respectively. The first input acoustic signal input from the input terminal 1804a is input to the
main path filter 1807a and the crosstalk path filter 1808a, and the main path filter 1807a
determines the coefficient shown in the above equation 7-1, In the crosstalk pass filter 1808a,
operation processing of multiplying the coefficient shown in equation 7-2 is executed, the output
of the main pass filter 1807a is inputted to the adder 1803a, and the output of the crosstalk pass
filter 1808a is inputted to the adder 1803b. Similarly, the second input acoustic signal input
from the input terminal 1804b is input to the main pass filter 1807b and the crosstalk pass filter
1808b, and the coefficients shown in the above-described Equation 7-1 and Equation 7-2,
respectively. And the outputs of the main pass filter 1807 b and the crosstalk pass filter 1808 b
are input to the adders 1803 b and 1803 a, respectively.
[0025]
The adders 1803a and 1803b respectively perform addition processing on the input signals, and
the adder 1803a outputs the addition result to the crosstalk cancellation signal generation filter
1806a. The crosstalk cancellation signal generation filter 1806a generates a crosstalk
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cancellation signal and outputs the crosstalk cancellation signal to the adder 1803b by executing
arithmetic processing of multiplying the coefficient shown in the above-mentioned equation 7-3.
Similarly, the adder 1803b outputs the addition result to the crosstalk cancellation signal
generation filter 1806b, and the crosstalk cancellation signal generation filter 1806b performs
the arithmetic processing of multiplying the coefficient shown in the above-mentioned equation
7-3. A talk cancellation signal is generated and output to the adder 1803a.
[0026]
In the adders 1803a and 1803b, the crosstalk component is obtained by adding the addition
result of the output from the direction localization filter and the crosstalk cancellation signal
having substantially the same phase as the inverted phase of the addition result. Is removed.
Therefore, the signals represented by equations 8-1 and 8-2 are output to the output terminals
1805a and 1805b.
[0027]
In the feedback-type sound image localization apparatus configured as described above, it is
possible to perform multiple cancellation processing in which generation of a crosstalk
cancellation signal and crosstalk cancellation processing using the generated signal are repeated,
as shown in FIG. Compared to the feedforward type device of the first example, the influence of
diffraction due to the low band portion of the acoustic signal is reduced, so that the low band
characteristics can be improved.
[0028]
SUMMARY OF THE INVENTION In the sound image localization apparatus according to the prior
art, as described above, the sound processing for obtaining the virtual localization position of the
sound image and the calculation processing for compensating for the crosstalk component are
performed. It enables localization.
However, when such a sound image localization apparatus is to be realized in a computer system
using a CPU or DSP, some problems described below occur.
[0029]
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The first problem is that the memory used for temporary storage for arithmetic processing is that
the amount and performance of the memory provided in the computer system become the limits
for arithmetic processing. The main restrictions on this memory are (A) restriction by memory
amount used for storing acoustic signal data (B) restriction by memory amount used to store
filter coefficients (C) restriction by memory access time .
[0030]
Here, the problem of (A) and (B) is that when the number of words indicating the amount of
memory is small, this limits the number of taps indicating the order of the filter, and the number
of taps is sufficient By not being able to obtain, it leads to the accuracy of arithmetic processing
falling.
[0031]
In addition, when there is a limit to the amount of high-speed internal memory provided in the
computer system, a relatively low-speed external memory (RAM) is used to ensure the accuracy
of necessary arithmetic processing (C Problems are obstacles.
That is, in the arithmetic processing for realizing the digital filter used for the direction
localization processing and the crosstalk cancellation processing as described above, since
frequent memory access is required, an external memory with a low access speed is simply used.
It was difficult to solve the limitation of memory size.
[0032]
The second problem is about a control device such as a DSP provided in the computer system,
and the processing speed is a limit for arithmetic processing. That is, when a sufficient
processing speed can not be obtained, the order of the digital filter is limited, which leads to a
decrease in the accuracy of the arithmetic processing.
[0033]
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As a third problem, in the sound image localization apparatus according to the prior art, there is
a point that it is not always easy to cope with the setting change of the sound system using the
sound image localization apparatus. The sound image localization apparatus (feedback type) of
the second example of the prior art shown in FIG. 18 improves the low-range reproducibility as
compared with the feedforward type as described above. However, when the speaker provided in
the sound system using such a sound image localization apparatus has a small aperture,
distortion of the sound may occur due to the large energy of the low band. In order to improve
this point, it is conceivable to use a filter that cuts the low band, but the addition of the filter
leads to an increase in circuit size and an increase in cost.
[0034]
Furthermore, when the arrangement of the speakers in the sound system is changed and the
opening angles of the speakers are different, in the sound image localization apparatus according
to the related art, the entire parameter of the filter FX has been changed. Therefore, in order to
cope with the setting change of the sound system, it is necessary to hold the parameters for each
setting, and the memory requirement increases for storing the parameters.
[0035]
As indicated by the above three problems, the sound image localization apparatus according to
the prior art requires high-speed memory capacity and processing speed when implemented in a
computer system, and the accuracy of control of sound image localization is required. The
problem is that it is difficult to simultaneously achieve the reduction of the cost of the computer
system.
[0036]
The present invention has been made in view of such circumstances, and it is an object of the
present invention to provide a sound image localization apparatus capable of realizing sound
image localization with high accuracy while restricting an increase in circuit size due to a
necessary amount of memory. Do.
[0037]
Another object of the present invention is to provide a sound image localization apparatus
capable of realizing sound image localization with high accuracy by using an external memory
even when the capacity of a high-speed internal memory is limited.
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[0038]
Another object of the present invention is to provide a sound image localization apparatus
capable of realizing sound image localization with high accuracy even in a computer system not
equipped with a high-performance DSP or the like by simplifying arithmetic processing.
[0039]
Another object of the present invention is to provide a sound image localization apparatus that
can flexibly cope with a change in setting in an acoustic system without increasing the circuit
size.
[0040]
SUMMARY OF THE INVENTION In order to achieve the above object, a sound image localization
apparatus according to claim 1 of the present invention receives an acoustic signal, performs
signal processing on the input acoustic signal, and generates a virtual image. Sound image
localization apparatus for localizing a typical sound image and outputting a sound image
localization signal, generating crosstalk cancellation signals, and performing crosstalk
cancellation processing using the generated crosstalk cancellation signals; A directional
localization means for localizing the direction of a virtual sound source position with respect to
the signal subjected to the crosstalk cancellation processing in the talk cancellation means is
provided.
Thus, crosstalk cancellation processing is first performed on the input audio signal, and then
sound image localization processing is performed.
[0041]
The sound image localization apparatus according to claim 2 is the apparatus according to claim
1, wherein the crosstalk cancellation means comprises first and second crosstalk cancellation
signal generating filters, and first and second adders. And the first adder adds the first acoustic
signal and the signal generated by the second crosstalk cancellation signal generation filter, and
the second adder adds the second acoustic signal and the second acoustic signal to the second
adder. The addition processing is performed on the signal generated by the crosstalk cancellation
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signal generation filter of No. 1 and the direction localization means includes the first and second
main pass filters and the first and second crosstalk pass filters. And first and second adders, in
the first adder, the signal processed in the first main pass filter and the second crosstalk pass
filter There is added processing and signal processing, in the second adder, a signal processed in
the second main-pass filter, is to addition processing and processing the signal in the first
crosstalk-pass filter.
Thus, crosstalk cancellation processing is performed on an input audio signal using a signal
generated by the crosstalk cancellation signal generation filter, and then sound image localization
processing using the main pass filter and the crosstalk pass filter is performed.
[0042]
A sound image localization apparatus according to claim 3 receives an acoustic signal, performs
signal processing on the input acoustic signal, localizes a virtual sound image, and outputs a
sound image localization signal. Crosstalk cancellation means for generating a crosstalk
cancellation signal by using a comb filter and performing crosstalk cancellation processing using
the generated crosstalk cancellation signal, and direction localization for localizing the direction
of a virtual sound source position And means.
Thus, the crosstalk cancellation processing is performed using the signal generated by the
crosstalk cancellation signal generation filter using the comb filter having the same coefficient.
[0043]
A sound image localization apparatus according to a fourth aspect of the present invention is a
sound image localization apparatus that receives an acoustic signal, performs signal processing
on the input acoustic signal, localizes a virtual sound image, and outputs a sound image
localization signal. Hold the crosstalk cancellation signal generated at a certain time, hold a
plurality of signals generated by delaying the held signal, and hold a predetermined coefficient
for a specific one of the held plurality of signals Crosstalk cancellation means for generating a
crosstalk cancellation signal at a time subsequent to the certain time using the signal obtained by
multiplication and performing crosstalk cancellation processing using the generated crosstalk
cancellation signal; And a directional localization means for localizing the direction of the sound
source position.
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Thereby, the crosstalk cancellation processing is performed using the signal generated by the
crosstalk cancellation signal generation filter using the comb filter alternative circuit for reducing
the operation processing load.
[0044]
A sound image localization apparatus according to claim 5 is the apparatus according to any one
of claims 3 or 4, further comprising a low pass filter for processing an input signal or an output
signal to the crosstalk cancellation means. .
Thus, the crosstalk cancellation processing is performed on the signal from which the highfrequency component has been removed, using the signal generated by the crosstalk cancellation
signal generation filter using the comb filter or the comb filter alternative circuit.
[0045]
A sound image localization apparatus according to claim 6 receives a sound signal, performs
signal processing on the input sound signal, localizes a virtual sound image, and outputs a sound
image localization signal. And a crosstalk cancellation signal generation filter for generating a
crosstalk cancellation signal and a crosstalk cancellation signal generated by the crosstalk
cancellation filter to an input side of the crosstalk cancellation signal generation filter for
crosstalk cancellation processing. A crosstalk cancel means having a switch for switching
whether to use or output to the output side to use for crosstalk cancellation processing, and a
direction localization means to localize the direction of a virtual sound source position is there.
Thereby, feedback type processing and feed forward perform switching between multiple
processing.
[0046]
A sound image localization apparatus according to claim 7 receives a sound signal, performs
signal processing on the input sound signal, localizes a virtual sound image, and outputs a sound
image localization signal. Crosstalk cancellation comprising a crosstalk cancellation signal
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generation filter for generating the crosstalk cancellation signal, and delay means for processing
an input signal or an output signal to the crosstalk cancellation signal generation filter, the delay
time being variable Means, and direction localization means for localizing the direction of the
virtual sound source position. As a result, processing is performed by switching the amount of
initial delay in crosstalk cancellation processing.
[0047]
The sound image localization apparatus according to claim 8 can input an input sound signal to
be localized in the first direction and an input sound signal to be localized in the second
direction, and the input sound A sound image localization apparatus for performing signal
processing on a signal, localizing a virtual sound image, and outputting a sound image
localization signal, comprising a first and a second filter, wherein the first filter is crossed A first
mode used as a talk cancellation signal generation filter, and a second mode using the first filter
as a filter for localization in the second direction and using the second filter as a crosstalk
cancellation signal generation filter Comprising: a crosstalk cancellation means having a
changeover switch for switching between the following modes; and a direction localization means
for localizing the direction of a virtual sound source position A. As a result, processing is
performed by switching between crosstalk cancellation signal generation filters used for
processing for localizing a sound image to be localized in the first direction and processing for
localizing a sound image to be localized in the second direction.
[0048]
DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment The sound image
localization apparatus according to the first embodiment of the present invention reduces the
required memory amount by performing direction localization processing on the signal subjected
to the crosstalk cancellation processing.
[0049]
FIG. 1a) is a block diagram showing the configuration of the sound image localization apparatus
according to the first embodiment. As shown, the sound image localization apparatus according
to the first embodiment includes the crosstalk cancellation means 101, direction localization
means 102a and 102b, and adders 103a and 103b, and the input terminal 104a, And 104b, and
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outputs signals obtained as a result of signal processing from the output terminals 105a and
105b.
[0050]
The crosstalk cancellation means 101 removes crosstalk components from the signals input from
the input terminals 104a and 104b. The direction localization means 102a and 102b generate a
signal indicating the direction of the sound image position by arithmetic processing on the input
sound signal. The adders 103a and 103b perform addition processing on the input signal.
[0051]
The arithmetic processing performed by the sound image localization apparatus according to the
first embodiment configured as described above will be described below. First, in addition to the
formulas 1-1 to 8-2 shown in the prior art, vL and vR which satisfy the following formula are
defined.
[0052]
xL = FM.vL + FC.vR (9-1) xR = FC.vL + FM.vR (9-2) Substituting the equation 9-1 into the equation
8-1, substituting the equation 9-2 into the equation 8-2 The following equation is obtained by
[0053]
FM · vL + FC · vR = FM · uL + FC · uR + FX (FC · vL + FM · vR) (10-1) FC · vL + FM · vR = FC · uL +
FM · uR + FX · (FM · vL + FC · vR) (10-2) formula 10 From -1 and Formula 10-2, FM and FC can
be eliminated, and the following formula is obtained.
[0054]
vL = uL + FX.vR (11-1) vR = uR + FX.vL (11-2) And, in the equations 11-1 and 11-2, the crosstalk
cancellation means is provided on the input side as the equation 9 above. The -1 and 9-2 mean
that a direction localization means is provided on the output side.
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Therefore, as shown in FIG. 1a), the sound image localization apparatus of the first embodiment
is provided with the crosstalk cancellation means 101 on the input side and the direction
localization means 102a and 102b on the output side.
[0055]
Further, FIG. 6 b) is a diagram showing a first example of a detailed configuration of the sound
image localization apparatus according to the first embodiment.
The crosstalk cancellation means 101 shown in FIG. 6A includes the crosstalk cancellation signal
generation filters 106a and 106b shown in FIG. 7B, and adders 103c and 103d. Also, the
direction localization means 102a and 102b shown in FIG. 11 a) are made up of main pass filters
107a and 107b and crosstalk pass filters 108a and 108b. The operation of the first example of
the sound image localization apparatus according to the first embodiment configured as
described above will be described below.
[0056]
Left and right input acoustic signals uL and uR are respectively input from the input terminals
104a and 104b. In FIG. 1 b), the first input sound signal uL input from the input terminal 104a is
input to the adder 103c, and the second input sound signal uR input from the input terminal
104b is input to the adder 103d. Immediately after the processing in the sound image
localization apparatus according to the first embodiment starts, the crosstalk cancellation signal
generation filters 106a and 106b do not generate signals, and thus signals from the respective
adders 103c and 103d are generated. There is no output, and the adders 103c and 103d output
the input signals uL and uR as they are, and the signal uL is output as the signal vL to the
crosstalk cancellation signal generation filter 106a and the signal uR is output as the signal vR
for crosstalk cancellation. It is input to the signal generation filter 106b.
[0057]
The crosstalk cancellation signal generation filter 106 a generates a crosstalk cancellation signal
and outputs the crosstalk cancellation signal to the adder 103 d by executing an operation
process of multiplying the coefficient shown in the above-mentioned equation 7-3. The crosstalk
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cancellation signal generation filter 106 b performs the same arithmetic processing to generate a
crosstalk cancellation signal and outputs the crosstalk cancellation signal to the adder 103 c.
[0058]
In the adder 103c, the crosstalk cancellation process is performed by adding the input acoustic
signal uL and the crosstalk cancellation signal, and the signal vL shown in Expression 11-1 is
generated. The generated signal vL is input to the main pass filter 107a and the crosstalk pass
filter 108a. Similarly, from the adder 103d, a signal vR shown in Equation 11-2 is generated, and
is input to the main pass filter 107b and the crosstalk pass filter 108b.
[0059]
In the main pass filter 107a, an operation processing is performed to multiply the coefficient
shown in the above equation 7-1 and the coefficient shown in the equation 7-2 in the crosstalk
pass filter 108a, and the output of the main pass filter 107a is an adder. The output of the
crosstalk pass filter 108a is input to the adder 103b at 103a. Here, the output of the main pass
filter 107a is the first term on the right side of Expression 9-1, and the output of the crosstalk
pass filter 108a is the second term on the right side of Expression 9-2.
[0060]
Similarly, in the adder 103 d, crosstalk cancellation processing is performed in which the
crosstalk cancellation signal is added to the input acoustic signal uR, and the obtained signal vR
is the main path filter 107 b and the crosstalk path filter 108 b. Are respectively input and
multiplied by the coefficients shown in Equations 7-1 and 7-2. The output of the main path filter
107b is output to the adder 103b and the output from the crosstalk path filter 108b is output. It
is input to the adder 103a. The output of the main pass filter 107b is the first term on the right
side of Expression 9-2, and the output of the crosstalk pass filter 108b is the second term on the
right side of Expression 9-1.
[0061]
The apparatus of the sound image localization apparatus according to the first example of the
first embodiment is that the signals respectively input in the adders 103a and 103b are added,
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and the result of the addition is output to the output terminals 105a and 105b. As the output, the
signals xL and xR subjected to the sound image localization processing, which are represented by
the equations 9-1 and 9-2, are output.
[0062]
As described above, in the sound image localization apparatus according to the first embodiment,
the crosstalk cancellation signal generation is performed as shown in FIG. 1 b) by performing the
direction localization processing on the signal subjected to the crosstalk cancellation processing.
The filter (FX) and the direction localization filters (FM and FC) are such that vL and vR serving
as filter inputs are common signals.
Therefore, for filtering, it is sufficient to hold these two types of signals, and a sound image
localization apparatus according to the prior art which is required to hold four types of signals as
shown in FIG. In comparison, it is possible to reduce the capacity of the memory necessary for
holding the acoustic signal described in (A) of the first problem of the prior art.
[0063]
Here, in order to explain the necessary amount of memory in the device of the first embodiment,
the configuration of each filter used for crosstalk cancellation processing and direction
localization processing is shown below.
[0064]
The filters include an FIR (Finite Impulse Response) filter that performs product-sum operation
on an input signal, and an IIR (Infinite Impulse Response) filter that performs product-sum
operation on an output signal in addition to the input signal. Although the sound image
localization apparatus of the first embodiment can be realized as one using any filter.
FIG. 2 shows that the crosstalk cancellation signal generation filters 106a and 106b and the
direction localization filters 107a, 107b, 108a and 108b included in the device of the first
example of the first embodiment (FIG. 1b) are configured using FIR filters. It is a figure which
shows the example which was done. FIG. 3 is a diagram showing an example in which each filter
shown in FIG. 1 b) is configured by connecting an FIR filter and an IIR filter in cascade.
08-05-2019
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[0065]
In the example shown in FIG. 2, the crosstalk cancellation signal generation filter 106a included
in the sound image localization apparatus of the first example (FIG. 1b) of the first embodiment
includes delay units 111a and 111c to 111f and multipliers 110x1 to 110x5. And an adder 103i.
The crosstalk cancellation signal generation filter 106b is composed of delay units 111b, 111g to
111j, multipliers 110x6 to 110x10, and an adder 103j. In FIG. 2, the portions represented by
dotted lines such as multipliers 110 x 1 to 110 x 5 and delay devices 111 c to 111 f indicate that
the number of multipliers, delay devices, etc. is variable.
[0066]
The main pass filter 107a includes delay devices 111c to 111f, multipliers 110m1 to 110m5,
and an adder 103e. The main pass filter 107b includes delay devices 111g to 111j, multipliers
110m6 to 110m10, and an adder 103f. The crosstalk path filter 108a includes delay devices
111c to 111f and 111n to 111p, multipliers 110c1 to 110c5, and an adder 103g. The crosstalk
path filter 107b is configured by delay units 111g to 111j and 111k to 111m, multipliers 110c6
to 110c10, and an adder 103h.
[0067]
Further, the multipliers 110a1 and 110a2 in FIG. 2 function as attenuators provided to prevent
an overflow from occurring when performing fixed-point arithmetic. The delay units 111k to
111p are provided to realize the time difference between both ears.
[0068]
In the filter configuration shown in FIG. 2, by providing the delay units 111c to 111j, as the
signals vL and vR shown in FIG. 1b, the input to the crosstalk cancellation signal generation filter
and the input to the direction localization filter are These delay devices are shared and held.
Therefore, the required amount of memory for holding can be reduced as compared with the
case of holding the input to each filter.
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19
[0069]
FIG. 3 shows a configuration example using an IIR filter as described above. As shown, in this
example, the IIR filters FXI 112a and 112b that configure the crosstalk cancellation signal
generation filter, the IIR filters FMI 113a and 113b that configure the main path filter, and the
IIR filter FCI that configures the crosstalk path filter It comprises the 114a and 114b, and these
IIR filters and the FIR filter shown in FIG. 2 are cascaded.
[0070]
Thus, assuming that the portions formed by the main pass filter, the crosstalk pass filter, and the
FIR filter of the crosstalk cancellation signal generation filter are FMF, FCF, and FXF, the FMs
shown in equations 7-1 to 7-3, FC and FX are such that FM = FMF · FMI (12-1) FC = FCF · FCI
(12-2) FX = FXF · FXI (12-3).
[0071]
Also in this case, as in the case of the configuration shown in FIG. 2, the input of the part of the
FIR filter can be shared, and the memory requirement can be similarly reduced.
However, a remarkable reduction effect can not be obtained as in the case of using only an FIR
filter.
[0072]
FIG. 4 is a diagram showing a second example of the detailed configuration of the sound image
localization apparatus of the first embodiment shown in FIG. 1a). As shown in the figure, the
sound image localization apparatus of the second example includes adders 103a to 103d,
crosstalk cancellation signal generation filters 106a and 106b, main pass filters 107a and 107b,
and crosstalk pass filter 108a, And 108b, the high pass main pass filters 117a and 117b, the
band division circuits 115a and 115b, and the band synthesis circuits 116a and 116b. Also in
this example, as in the first example shown in FIG. 1 b), input acoustic signals are input from the
input terminals 104 a and 104 b and signals obtained as a result of signal processing are output
08-05-2019
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from the output terminals 105 a and 105 b. .
[0073]
The band division circuits 115a and 115b perform predetermined division processing on the
input signal to generate a low band component and a high band component. The band combining
circuits 116a and 116b perform predetermined combining processing on the input signals to
generate combined signals. The high pass main path filters 117a and 117b perform the same
arithmetic processing as the main pass filters 107a and 107b. The adders 103a to 103d, the
crosstalk cancellation signal generation filters 106a and 106b, the main pass filters 107a and
107b, and the crosstalk pass filters 108a and 108b are the same as in the first example.
[0074]
The operation of the sound image localization apparatus according to the second example of
Embodiment 1 configured as described above will be described below. Left and right input
acoustic signals are respectively input from the input terminals 104a and 104b. The first input
acoustic signal input from the input terminal 104a is input to the band division circuit 115a, and
the band division circuit 115a divides the first input acoustic signal into a high band component
and a low band component by division processing. Do. Then, the band dividing circuit 115a
outputs the high frequency component to the high frequency main path filter 117a and the low
frequency component to the adder 103c. Also, the band division circuit 115b operates in the
same manner.
[0075]
The high-pass main path filters 117a and 117b respectively perform operation processing of
multiplying the input high-pass component by the coefficient shown in Equation 7-1 and output
the generated signal to the band combining circuits 116a and 116b. Do.
[0076]
The crosstalk cancellation process and the direction localization process are performed on the
low frequency component of the input acoustic signal as in the first example, and the generated
signal is input to the band synthesis circuits 115a and 115b.
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21
The band synthesis circuits 115a and 115b perform synthesis processing on the signal derived
from the high band component processed by the high band filter and the signal derived from the
low band component subjected to the direction localization processing after the crosstalk
cancellation processing. , And outputs the generated combined signal to the output terminals
105a and 105b.
[0077]
As described above, in the sound image localization apparatus according to the second example,
processing in which the crosstalk component is considered is performed only on the low
frequency component of the input signal. In general, in the case of an audio signal, the influence
of a slight positional deviation of the listener of the audio system is large for the high-frequency
component, and the individual difference is also large. Therefore, by performing crosstalk
cancellation processing Since the effect is small, in the sound image localization apparatus of the
second example, only the process using the main pass filter is executed for the high frequency
component. Therefore, since only low frequency components are targeted in the crosstalk
cancellation processing, the sampling frequency can be lowered, and the circuit scale of the filter
configured as shown in FIG. 2 and FIG. 3 can be further reduced. This is possible without
reducing the accuracy of the
[0078]
Thus, according to the sound image localization apparatus of the first embodiment, as shown in
FIG. 1a), the crosstalk cancellation means 101 is provided on the input side, and the direction
localization means 102a and 102b are provided on the output side. The respective filters
included in the crosstalk cancellation means 101 and the direction localization means 102a and
102b are shared by using delay devices as shown in FIG. 2 and FIG. It is possible to perform good
sound image localization with a small amount of memory.
[0079]
Second Embodiment
The sound image localization apparatus according to the second embodiment of the present
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22
invention uses a comb filter. FIG. 5 is a block diagram showing the configuration of a first
example of the sound image localization apparatus of the second embodiment. The schematic
configuration of the sound image localization apparatus according to the second embodiment is
similar to that of the feedback type according to the prior art shown in FIG. As shown in FIG. 5, in
the sound image localization apparatus according to the second embodiment, adders 503a, 503b,
503e, and 503f, main path filters 507a and 507b, crosstalk path filters 508a and 508b, and
delays are provided. , And multipliers 510x1 to 510x10, and an input sound signal is input from
the input terminals 504a and 504b, and signals obtained as a result of signal processing are
output from the output terminals 505a and 505b. Output. As in FIG. 2 and the like, dotted lines
in the arrangement of delay devices and multipliers in the drawing indicate that the number is
arbitrary.
[0080]
In the figure, delay units 511a, 511c to 511f, multipliers 510x1 to 510x5, and adder 503e
constitute the crosstalk cancellation signal generation filter 1806a shown in FIG. 18, and delay
units 511b and 511g to 511j. The multipliers 510x6 to 510x10 and the adder 503f constitute
the crosstalk cancellation signal generation filter 1806b shown in FIG. Here, all the coefficients
of the multipliers 510x1 to 510x10 can be made equal, and such a case is a comb-type filter.
Therefore, when the comb filter is used, it is possible to reduce the required amount of memory
for holding the coefficient described in (B) of the first problem of the prior art.
[0081]
The operation of the sound image localization apparatus according to the second embodiment
configured as described above is similar to that of the feedback type sound image localization
apparatus according to the related art. FIG. 7 is a diagram for explaining the frequency
characteristics of the filter. The figure a) shows the amplitude characteristic, and the figure b)
shows the phase characteristic. Also, in each case, the solid line indicates the characteristic of the
comb filter used in the second embodiment, and the broken line indicates the characteristic
obtained from the ratio of the head transfer function. In general, the comb filter has a linear
phase type low pass characteristic. As shown in the figure, in both the amplitude characteristic
and the phase characteristic, the low band portion exhibits similar characteristics. As described in
the first embodiment, the effect of the crosstalk cancellation processing is particularly effective
for the low band portion of the acoustic signal, and the characteristics of the low band portion
are similar, so that the comb filter is used. It can be seen that good processing can be performed
on the low band portion when it has been. And, for the high frequency part having different
08-05-2019
23
characteristics, since the effect of the crosstalk cancellation processing is small, it can be said
that the influence of the difference of the characteristics is small.
[0082]
FIG. 6 is a block diagram showing the configuration of a second example of the sound image
localization apparatus of the second embodiment. As illustrated, in this example, low-pass filters
620 a and 620 b are added to the sound image localization apparatus of the first example. The
low pass filter 620a includes an adder 603c, multipliers 610f1 and 610f2, and a delay unit 611a.
The low pass filter 620 b is configured of an adder 603 d, multipliers 610 f 3 and 610 f 4, and a
delay unit 611 b.
[0083]
The operation of the sound image localization apparatus of the second example of the second
embodiment configured as described above is one in which high frequency components are
removed from the input to the crosstalk cancellation signal generation filters 1806a and 1806b
shown in FIG. Other than that is the same as the first example. As described above, in the
generation of the crosstalk cancellation signal, it is not necessary to consider the high frequency
component of the acoustic signal so much, and in this example, the high frequency component is
excluded from the processing target. It is possible to improve the accuracy of sound image
localization more than that. According to the second example, the circuit size is slightly larger
than that of the first example by the low-pass filter.
[0084]
In the second example, the low pass filter is provided in front of (on the input side) the crosstalk
cancellation signal generation filter, but may be provided on the rear (output side) The same
effect is obtained.
[0085]
FIG. 8 is a diagram showing the configuration of a third example of the sound image localization
apparatus of the second embodiment.
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24
As illustrated, in this example, a comb filter similar to the first example is used, but the comb
filter is configured by an FIR with a small number of taps. In the configuration shown in the
figure, the number of taps is two, and the values of the coefficients can all be, for example, -0.46.
In this case, the filter has a linear phase low pass characteristic. The sound image localization
apparatus configured in this way performs the same operation as the first example.
[0086]
In the acoustic system using the sound image localization apparatus, when the speaker interval is
set narrow (for example, about an open angle of about 10 to 20 degrees), the ratio SC / SM of the
head transfer function shown in FIG. It will take a value. Therefore, in consideration of the
stability of sound image localization and the reduction of high frequency components due to the
diffraction of the acoustic signal, in such a case, even a filter with a small number of taps can be
sufficiently approximated. Therefore, in such a case, by using the configuration as shown in FIG.
8, the required amount of memory for storing the coefficients can be further reduced compared
to the first example shown in FIG. The amount of data held in the delay circuit is also small, and
the circuit scale can be miniaturized.
[0087]
FIG. 9 and FIG. 10 are diagrams showing the configuration of a fourth example of the sound
image localization apparatus of the second embodiment. As shown in FIG. 9, the sound image
localization apparatus of this example is different from the apparatus of the third example in the
high pass main path filters 917a and 917b, the band division circuits 915a and 915b, and the
band synthesis circuit 916a, And 916 b. These are similar to the high pass main pass filters 117a
and 117b, the band division circuits 115a and 115b, and the band synthesis circuits 116a and
116b described in the second example of the first embodiment. The same applies to the high
pass main path filters 1017a and 1017b, the band dividing circuits 1015a and 1015b, and the
band combining circuits 1016a and 1016b shown in FIG.
[0088]
In the operation of the sound image localization apparatus of this example configured as
described above, band division processing and band combination processing are performed in
08-05-2019
25
the same manner as the second example of the first embodiment, and the other is the first
example of the second embodiment. Would be similar to Therefore, as in the second example of
the first embodiment and the third example of the second embodiment, the required amount of
memory can be reduced, and the circuit scale can be reduced.
[0089]
In the configuration shown in FIG. 9, the crosstalk cancellation signal generation filter, which is
an FIR filter having two taps similar to the third example, is disposed between the direction
localization filter and the band synthesis circuit in the configuration shown in FIG. In the
configuration shown, although provided in the rear (output side) of the band synthesis circuit, it
is provided in front of the band division circuit (input side), or between the band division circuit
and the direction localization filter It is also possible to input only the low frequency component
outputted from the band dividing circuit as a processing object, and the same effect is obtained.
[0090]
As described above, according to the sound image localization apparatus of the second
embodiment, by using a comb filter in which all the coefficients of the multipliers 510x1 to
510x10 shown in FIG. 5 are equal, calculation processing using a filter is performed. The
parameters (coefficients) are the only ones, and it is possible to perform good sound image
localization with a small amount of memory required to hold the coefficients.
[0091]
In the second embodiment, although the schematic configuration is the feedback sound image
localization apparatus shown in FIG. 18, the feedforward apparatus shown in FIG. 17 b) or the
first embodiment shown in FIG. In the above apparatus, it is also possible to use a comb filter,
and the same effect can be obtained.
[0092]
Third Embodiment
The sound image localization apparatus according to the third embodiment of the present
invention uses a circuit including a delay buffer and a cumulative sum register (or memory)
instead of the comb filter in the second embodiment.
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26
FIG. 11 is a block diagram showing the configuration of the sound image localization apparatus
of the third embodiment.
The schematic configuration of the sound image localization apparatus according to the third
embodiment is a feedback type according to the prior art shown in FIG. 18 as in the second
embodiment. As shown in FIG. 11, in the sound image localization apparatus according to the
third embodiment, adders 1103a, 1103b, 1103c, and 1103d, main path filters 1107a and
1107b, crosstalk path filters 1108a and 1108b, and delays are provided. , And multipliers
1110f1 to 1110f4, and 1110x1, 1110x5, 1110x6, and 1110x10, and the input acoustic signals
are input from the input terminals 1104a and 1104b and the result of signal processing is
performed. The obtained signals are output from output terminals 1105 a and 1105 b. As in FIG.
2 and the like, dotted lines in the arrangement of delay elements in the figure indicate that the
number is arbitrary.
[0093]
In the figure, the portion consisting of adder 1103c, multipliers 1110f1 and 1110f2 and delay
unit 1111m, and the portion consisting of adder 1103d, multipliers 1110f3 and 1110f4 and
delay unit 1111n are the second part of the second embodiment. It constitutes a low pass filter
similar to the example. Then, in the sound image localization apparatus according to the third
embodiment, the delay shown in FIG. 11 is used as a substitute for the comb filter constituting
the crosstalk cancellation signal generation filter (1806a and 1806b in FIG. 18) in the second
embodiment. It comprises the units 1111a, 1111b, 1111c to 1111f, and 1111g to 1111j, the
multipliers 1110x1, 1110x5, 1110x6, and 1110x10, and the adders 1103e to 1103h.
[0094]
In order to generate a crosstalk cancellation signal used at a certain time, the comb filter
included in the device of the second embodiment shown in FIG. 5 is, at that time, an average of
data held by the delay units 511c to 511f of the same figure. An arithmetic process
corresponding to the process to be determined is performed. Therefore, based on the crosstalk
cancellation signal obtained at a certain time, the oldest data among the held data is reduced by
1 / n and the latest data is further added by 1 / n. The crosstalk cancellation signal at the time of.
08-05-2019
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[0095]
In the sound image localization apparatus according to the third embodiment shown in FIG. 11,
the delay units 1111a and 1111b hold the signal at the immediately preceding time, and the
delay units 1111c to 1111f and 1111g to 1111j are used for this signal. Among the data stored
in the memory, the oldest one (in the figure, the delayers 1111 f and 1111 j with the largest
delay) is 1 / n by the multipliers 1110x5 and 1110x10, and the adders 1103g and 1103h
Perform subtraction processing using. Further, with respect to the result of this subtraction
processing, the latest data (regarded in the figure, the delay units 1111c and 1111g having the
smallest delay) among the data held in each delay unit are multiplied by 1110x1 and 1110x6. 1 /
n, and addition processing is performed using adders 1103 e and 1103 f. The addition result is a
crosstalk cancellation signal as in the case of the one obtained by the arithmetic processing of
the comb filter as described above. Also, the generated signal is held in the delay units 1111a
and 1111b for signal generation at the next time.
[0096]
In the sound image localization apparatus according to the third embodiment, the data stored in
the delay units 1111c to 1111f and 1111g to 1111j are accessed only when the oldest data is
taken out and when the latest data is stored. It will be The delayer included in the comb filter of
the second embodiment is frequently accessed, and therefore, the delayer of the third
embodiment is different from the delayer which needs to use a high-speed memory. It is possible
to use relatively slow memory. Further, in the third embodiment, the multiplication processing
and the addition processing are also reduced compared to the second embodiment. Therefore, in
the sound image localization apparatus of the third embodiment, the problem relating to the
access time of the memory described in the first problem (C) and the processing speed which is
the second problem in the sound image localization apparatus according to the related art Can
solve the problems with
[0097]
As described above, according to the sound image localization apparatus of the third
embodiment, the delay buffers (the delay units 1111 c to 1111 f and 1111 g to 1111 j in FIG.
11) and the cumulative sum register (the same) are used as filters used for crosstalk cancellation
processing. By using a comb filter alternative circuit including FIGS. 1111a and 1111b, the
frequency of access to the memory, addition processing, and multiplication processing are
reduced, so that the computer system for realizing the sound image localization apparatus Even
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when there is a limit to the high-speed memory capacity and the processing speed of the
processor etc., the localization of a good sound image is enabled.
[0098]
Also in the third embodiment, as in the second embodiment, the general configuration is the
feedback sound image localization apparatus shown in FIG. 18, but the feedforward apparatus
shown in FIG. In the device of the first embodiment shown in FIG. 1 b), it is also possible to use a
comb filter alternative circuit, and the same effect is obtained.
[0099]
Fourth Embodiment
The sound image localization apparatus according to the fourth embodiment of the present
invention can perform both feedforward and feedback sound image localization by switching.
FIG. 12 is a diagram showing the configuration of a first example of the sound image localization
apparatus of the fourth embodiment. As shown, the sound image localization apparatus of this
example has a configuration in which adders 1203 c and 1203 d and changeover switches 1218
a and 1218 b are added to the apparatus shown in FIG. 18.
[0100]
FIG. 12 shows the case where the changeover switches 1218a and 1218b are both set to the
feedback side (FB side in the figure). In this state, the crosstalk cancellation signals generated by
the crosstalk cancellation signal generation filters 1206a and 1206b are input to the adders
1203a and 1203b. That is, it becomes a feedback type device that outputs the crosstalk
cancellation signal to the input side, and is equivalent to the device shown in FIG. In this case, the
apparatus of the fifth embodiment operates in the same manner as the apparatus of the first
example according to the prior art.
[0101]
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On the other hand, when the changeover switches 1218a and 1218b shown in FIG. 12 are both
set on the feed forward side (FF side in the figure), the crosstalk generated by the crosstalk
cancellation signal generation filters 1206a and 1206b The cancellation signal is input to the
adders 1203 c and 1203 d. That is, it becomes a feedforward type device which outputs the
crosstalk cancellation signal to the output side, which is equivalent to the device shown in FIG. In
this case, the apparatus of the fifth embodiment operates in the same manner as the apparatus of
the second example according to the prior art.
[0102]
In general, in the feedback type device, the reproducibility from the low range is good. However,
as described in the problems of the prior art (third problem), in a sound system using a feedbacktype sound image localization apparatus, low-frequency energy is the cause when a smalldiameter speaker is used. Can lead to distortion of the sound. The feedforward type device is
suitable for such a system because it has high-pass type frequency characteristics in which the
low band is cut. Therefore, the sound image localization apparatus according to the fourth
embodiment can be used as both a feedback type and a feedforward type sound image
localization apparatus by switching the switch, so that a speaker with a large aperture is used as
a feedback type. By using such a speaker, it is possible to obtain good reproduction sound
quality. On the other hand, when a speaker with a small diameter is used, distortion of the sound
can be prevented by using a feedforward type.
[0103]
As described above, according to the sound image localization apparatus of the fourth
embodiment, by providing the changeover switches 1218 a and 1218 b, feedback is set by
setting the changeover switch corresponding to the sound system using the apparatus. It
becomes possible to use as a sound image localization apparatus of a more appropriate type
among a type or a feedforward type.
[0104]
FIG. 13 is a view showing a second example of the sound image localization apparatus according
to the fourth embodiment, and FIG. 14 is a view showing a configuration of the third example of
the sound image localization apparatus according to the fourth embodiment.
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As shown in FIG. 13, in the apparatus of the second example, a changeover switch is added to the
apparatus that performs crosstalk cancellation processing on the input side according to the first
embodiment. Also, in the device of the third example shown in FIG. 14, a switch is added to the
feedback type device of FIG. 18 as in the first example, and in the first example, the back of the
crosstalk cancellation signal generation filter While a switch is provided on the output side, a
switch is added on the front side (input side). The sound image localization apparatus of the
second example or the third example shown in FIG. 13 or FIG. 14 is also used as a sound image
localization apparatus of a more appropriate type of feedback type or feed forward type
corresponding to the acoustic system. It is possible to
[0105]
Embodiment 5 The sound image localization apparatus according to the fifth embodiment of the
present invention is such that the degree of initial delay can be switched in generation of the
crosstalk cancellation signal. FIG. 15 is a diagram showing the configuration of a sound image
localization apparatus according to the fifth embodiment. As shown, the sound image localization
apparatus of the fifth embodiment is obtained by adding delay devices 1511a to 1511d and
changeover switches 1518a and 1518b to the feedback type apparatus shown in FIG.
[0106]
In the state shown in FIG. 15, changeover switches 1518a and 1518b are set to output the
outputs of crosstalk cancellation signal generation filters 1506a and 1506b to adders 1503b and
1503a without passing through a delay unit. . In this state, the sound image localization
apparatus according to the fifth embodiment is equivalent to the apparatus shown in FIG. The
operation of the apparatus of the fifth embodiment in this state is similar to that of the second
example of the prior art.
[0107]
Then, in the sound image localization apparatus according to the fifth embodiment, using the
delayed crosstalk cancellation signal held in the delay unit 1511 b and the delay unit 1511 d by
setting of the changeover switches 1518 a and 1518 b, and using the delay crosstalk
cancellation signal It is possible to use the delayed crosstalk cancellation signal held by the delay
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unit 1511a and the delay unit 1511c. The operation of the apparatus of the fifth embodiment in
this state is that the delayed crosstalk cancellation signal is used for the crosstalk cancellation
processing, and except for this point, it is similar to the second example of the prior art. .
[0108]
The arithmetic processing performed by the crosstalk cancellation signal generation filter is to
multiply the coefficient represented by the ratio of the head related transfer functions SC and SM
shown in FIG. Here, as shown in FIG. 19 b), since the crosstalk path is longer than the main path,
a difference in arrival time between the left and right occurs for the acoustic signal transmitted
from the speaker. Here, when the opening angle between both speakers is small, the arrival time
difference is small, and when the opening angle is large, the arrival time difference is large, so it
is necessary to consider this in the difference in sound image localization. The arrival time
difference corresponds to the initial delay amount in the crosstalk cancellation signal generation
filter. Therefore, in a sound system using a sound image localization apparatus, if a fixed initial
delay amount is used, there is a possibility that the crosstalk cancellation processing can not be
satisfactorily performed, for example, when the installation position of the speaker is changed.
[0109]
In the crosstalk cancellation signal generation filter, the frequency characteristics of the part
excluding the initial delay do not show a large difference if the opening angle is about 30 to 60
degrees, and the change of the opening angle is made by switching the initial delay. It is possible
to cope. In the sound image localization apparatus according to the fifth embodiment, the amount
of initial delay can be changed stepwise by setting the changeover switch.
[0110]
As described above, according to the sound image localization apparatus of the fifth embodiment,
the delay devices 1511 a to 1511 d and the changeover switches 1518 a and 1518 b are added
to the feedback type device, so that the sound image In an acoustic system using a localization
apparatus, even when the opening angle of the speaker is changed, it is possible to easily
perform good sound image localization correspondingly.
[0111]
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Sixth Embodiment
The sound image localization apparatus according to the sixth embodiment of the present
invention switches and uses the crosstalk cancellation signal generation filter.
[0112]
FIG. 16 is a block diagram showing the configuration of a sound image localization apparatus
according to the sixth embodiment. As shown, the sound image localization apparatus according
to the sixth embodiment includes main pass filters 1607a and 1607b, crosstalk pass filters
1608a and 1608b, adders 1603a to 1603f, and crosstalk cancellation signal generation filter
1606a, And 1606b, delay devices 1611a to 1611d, multipliers 1610x1 to 1610x4, inverting
circuits 1631a and 1631b, and changeover switches 1618a to 1618f, and an input acoustic
signal is input from input terminals 1604a to 1604d. And output the device output of the sound
image localization device from 1605 a and 1605 b.
[0113]
The delayers 1611a and 1611b, the multipliers 1610x1 and 1610x2, and the adder 1603c
constitute a first two-tap FIR filter, and the delayers 1611c and 1611d, the multipliers 1610x3
and 1610x4, The adder 1603 d constitutes a second 2-tap FIR filter, and both of them are used
as a crosstalk cancellation signal generation filter. The changeover switches 1618a to 1618f are
switched according to the speaker interval in the sound system using the sound image
localization apparatus.
[0114]
Main path filters 1607a and 1607b, crosstalk path filters 1608a and 1608b, adders 1603a to
1603b, and crosstalk cancellation signal generation filters 1606a and 1606b are similar to the
feedback type sound image localization apparatus shown in FIG. It is. The operation of the sound
image localization apparatus of the sixth embodiment configured as described above will be
described below in the case where the speaker interval is wide and the case where it is narrow.
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[0115]
First, when the speaker spacing is wide, the switches 1618a, 1618b, 1618e, and 1618f are set to
the W side, and the switches 1618c and 1618d are in the open state (the state illustrated). As a
result, acoustic signals input from input terminals 1604c and 1604d pass through the sound
image localization apparatus of the sixth embodiment through adders 1603e and 1603f, and are
output from output terminals 1605a and 1606b. .
[0116]
On the other hand, the signals input from the input terminals 1604 a and 1604 b are input to the
crosstalk cancellation signal generation filters 1606 a and 1606 b via the switches 1618 a and
1618 b after direction localization processing. The signals output from the first and second twotap FIR filters are not used because the switches 1618 c and 1618 d are open. Therefore, in this
case, the system operates as equivalent to the feedback sound image localization apparatus
shown in FIG.
[0117]
On the other hand, when the speaker spacing is narrow, the switches 1618a, 1618b, 1618e, and
1618f are set to the N side, and the switches 1618c and 1618d are connected. Therefore, after
being processed in the first and second 2-tap FIR filters, the direction localization processed
signal is input to the adders 1603a and 1603b via the switch 1618c and the switch 1618d.
Therefore, the first and second two-tap FIR filters are used for the crosstalk cancellation process.
[0118]
On the other hand, the acoustic signals input from input terminals 1604c and 1604d are input
from switches 1618e and 1618f to adders 1603a and 1603b, and after the phases are inverted
in inverting circuits 1631a and 1631b, The signals are input to the filters 1606a and 1606b via
the switches 1618a and 1618b. Filters 1606a and 1606b perform signal generation processing
based on the phase inversion signal, and output the generated signals to adders 1603a and
1603b.
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[0119]
In this case, paths from switches 1618e and 1618f to adders 1603a and 1603b function as a
main path, and filters 1606a and 1606b function to generate a crosstalk signal. This is an
effective process when processing an acoustic signal in which a sound image to be localized
forward and a sound image to be localized at an arbitrary position (horizontal direction,
backward, etc.) are processed, and the speaker spacing is narrow. Even by expanding the sound
image to be localized forward, the stereo effect can be made larger.
[0120]
That is, in the apparatus according to the sixth embodiment, sound signals of sound images to be
localized at arbitrary positions are input terminals 1604a and 1604b, and sound signals of sound
images to be localized forward to input terminals 1604c and 1604d. When the speaker interval
is large, the sound image to be localized forward is output as it is, and for the sound image to be
localized at an arbitrary position, the crosstalk cancellation processing similar to the second
example of the prior art is performed. It is something to do. Further, when the speaker spacing is
narrow, the sound image to be localized forward is given an effect of spreading it outward as
described above. On the other hand, with regard to the sound image to be localized at an
arbitrary position, the arithmetic processing performed by the crosstalk cancellation signal
generation filter used for the localization of the sound image is, as shown in Equation 6-3, a head
transfer function SC shown in FIG. Since this ratio is small due to the narrow speaker spacing, it
is possible to use a filter with a small number of taps, since the coefficient is expressed by the
ratio of the ratio of S to SM. Therefore, processing is performed using a 2-tap filter.
[0121]
As described above, according to the sound image localization apparatus of the sixth
embodiment, delay units 1611a to 1611d, multipliers 1610x1 to 1610x4, and adders 1603c to
1603d are provided as compared with the feedback type sound image localization apparatus
according to the related art. By providing a 2-tap FIR filter, changeover switches 1618a to 1618f,
and inverting circuits 1631a and 1631b, when the speaker interval is wide, feedback type sound
image localization is performed according to the prior art and the speaker interval is narrow. In
such a case, along with such sound image localization, it is possible to perform processing such
as expanding the sound image to be localized to the front more outward.
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[0122]
Although the sixth embodiment is configured according to the feedback sound image localization
apparatus shown in FIG. 18, the feedforward apparatus shown in FIG. 17 b) or the first
embodiment shown in FIG. It is also possible to conform to the device of the above, and the same
effect can be obtained.
[0123]
According to the sound image localization apparatus of the first aspect, the sound signal is input,
the signal processing is performed on the input sound signal, the virtual sound image is localized,
and the sound image localization signal is output. In a sound image localization apparatus,
crosstalk cancellation means for generating a crosstalk cancellation signal and performing
crosstalk cancellation processing using the generated crosstalk cancellation signal, and a signal
subjected to crosstalk cancellation processing in the crosstalk cancellation means On the other
hand, by providing a directional localization means for localizing the direction of the virtual
sound source position, crosstalk cancellation processing is first performed on the input audio
signal, and then sound image localization processing is performed. A signal to be held for
crosstalk cancellation processing and direction localization processing is used as a common
signal for holding It is possible to reduce the required amount of 憶 device.
[0124]
According to the sound image localization apparatus of claim 2, in the apparatus of claim 1, the
crosstalk cancellation means includes first and second crosstalk cancellation signal generation
filters, and first and second adders. And the first adder adds the first acoustic signal and the
signal generated by the second crosstalk cancellation signal generation filter, and the second
adder adds the second acoustic signal and the first acoustic signal to the first adder. And adding
the signal generated by the crosstalk cancellation signal generation filter to the first and second
main path filters and the first and second crosstalk path filters. , First and second adders, in the
first adder, the signal processed in the first main pass filter and in the second crosstalk pass filter
The addition processing is performed on the processed signal, and the addition processing is
performed on the signal processed in the second main path filter and the signal processed in the
first crosstalk path filter in the second adder. First, crosstalk cancellation processing is performed
on a sound signal to be input using a signal generated by the crosstalk cancellation signal
generation filter, and then sound image localization processing is performed by the main pass
filter and the crosstalk pass filter. It is possible to reduce the necessary amount of storage used
for holding by making common the signals to be held for the talk cancellation process and the
direction localization process.
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[0125]
According to the sound image localization apparatus of claim 3, in the sound image localization
apparatus which receives an audio signal, performs signal processing on the input audio signal,
localizes a virtual sound image, and outputs a sound image localization signal, A crosstalk
cancellation means for generating a crosstalk cancellation signal by using a comb filter and
performing crosstalk cancellation processing using the generated crosstalk cancellation signal,
and a direction localization means for localizing the direction of a virtual sound source position
And the crosstalk cancellation processing is performed using the signal generated by the
crosstalk cancellation signal generation filter using the comb filter, so that the coefficients are
held in the comb filter in which all the coefficients are common. It is possible to reduce the
required amount of storage required for
[0126]
According to the sound image localization apparatus of claim 4, a sound image localization
apparatus which receives an audio signal, performs signal processing on the input audio signal,
localizes a virtual sound image, and outputs a sound image localization signal, The crosstalk
cancellation signal generated at a certain time is held, a plurality of signals generated by delaying
the held signal are held, and a specific one of the held plurality of signals is multiplied by a
predetermined coefficient. And a crosstalk cancellation unit that generates a crosstalk
cancellation signal at a time subsequent to the certain time and performs crosstalk cancellation
processing using the generated crosstalk cancellation signal; By including directional localization
means for localizing the direction of the sound source position, crosstalk cancellation using a
comb filter alternative circuit is realized. Since the crosstalk cancellation using a signal signal
generating filter produces, in addition to be further reduced the required amount of memory, it
becomes possible to reduce the amount of arithmetic processing.
[0127]
According to the sound image localization apparatus of the fifth aspect, the apparatus according
to the third aspect or the fourth aspect further comprises a low pass filter for processing an input
signal or an output signal to the crosstalk cancellation means. Then, the crosstalk cancellation
processing is performed on the signal from which the high frequency component has been
removed, using the signal generated by the crosstalk cancellation signal generation filter using
the comb filter or the comb filter alternative circuit. By limiting the processing target of the
above to an appropriate signal, it is possible to improve the processing accuracy.
[0128]
According to the sound image localization apparatus of claim 6, in the sound image localization
apparatus which receives an audio signal, performs signal processing on the input audio signal,
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localizes a virtual sound image, and outputs a sound image localization signal, A crosstalk
cancellation signal generation filter for generating a crosstalk cancellation signal and a crosstalk
cancellation signal generated by the crosstalk cancellation filter are output to the input side of
the crosstalk cancellation signal generation filter for crosstalk cancellation processing A crosstalk
canceling means having a changeover switch for switching whether to output the signal to the
output side and use it for crosstalk cancellation processing, and a direction localization means for
localizing the direction of a virtual sound source position Switch between feedback processing
and feedforward processing Since performed, without increasing the circuit scale increases, in
response to setting of the sound system, it is possible to perform an appropriate sound image
localization.
[0129]
According to the sound image localization apparatus of claim 7, in the sound image localization
apparatus which receives an audio signal, performs signal processing on the input audio signal,
localizes a virtual sound image, and outputs a sound image localization signal, A crosstalk
cancellation means comprising: a crosstalk cancellation signal generation filter for generating the
crosstalk cancellation signal; and delay means for processing an input signal or an output signal
to the crosstalk cancellation signal generation filter, the delay time being variable And the
directional localization means for localizing the direction of the virtual sound source position, the
amount of initial delay in the crosstalk cancellation processing is switched to perform processing,
and therefore the circuit scale is not greatly increased. , It becomes possible to perform
appropriate sound image localization corresponding to the setting of the sound system.
[0130]
According to the sound image localization apparatus of claim 8, the input sound signal to be
localized in the first direction and the input sound signal to be localized in the second direction
can be input, and the input sound signal A sound image localization apparatus for performing
signal processing on the image, localizing a virtual sound image, and outputting a sound image
localization signal, comprising: first and second filters; A first mode used as a cancellation signal
generation filter, and a second mode using the first filter as a filter for localization in the second
direction and using the second filter as a crosstalk cancellation signal generation filter A
crosstalk cancel means having a changeover switch for switching between modes and a direction
localization means for localizing the direction of a virtual sound source position are provided.
The processing is performed by switching and using the crosstalk cancellation signal generation
filter used for the processing of localizing the sound image to be localized in the first direction
and the processing of localizing the sound image to be localized in the second direction. It is
possible to perform appropriate sound image localization in accordance with the setting of the
acoustic system without significantly increasing the circuit scale.
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[0131]
Brief description of the drawings
[0132]
1 is a block diagram showing a configuration of a sound image localization apparatus according
to Embodiment 1 of the present invention.
[0133]
2 is a diagram showing an example of the configuration of the filter provided in the sound image
localization apparatus of the embodiment.
[0134]
3 is a diagram showing an example of the configuration of the filter provided in the sound image
localization apparatus of the embodiment.
[0135]
4 is a block diagram showing a configuration of a sound image localization apparatus which is an
application example of the same embodiment.
[0136]
5 is a block diagram showing a configuration of a sound image localization apparatus according
to Embodiment 2 of the present invention.
[0137]
6 is a block diagram showing a configuration of a sound image localization apparatus which is an
application example of the same embodiment.
[0138]
<Figure 7> It is the figure which shows the frequency characteristic of the filter in order to
explain the function of the filter which is used in the same execution form.
[0139]
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<Figure 8> It is the block diagram which shows the constitution of the sound image localization
device which is the application example of same execution form.
[0140]
<Figure 9> It is the block diagram which shows the constitution of the sound image localization
device which is application example of the same execution form.
[0141]
10 is a block diagram showing a configuration of a sound image localization apparatus which is
an application example of the same embodiment.
[0142]
11 is a block diagram showing a configuration of a sound image localization apparatus according
to a third embodiment of the present invention.
[0143]
12 is a block diagram showing a configuration of a sound image localization apparatus according
to Embodiment 4 of the present invention.
[0144]
13 is a block diagram showing a configuration of a sound image localization apparatus which is
an application example of the same embodiment.
[0145]
14 is a block diagram showing the configuration of a sound image localization apparatus which
is an application example of the same embodiment.
[0146]
FIG. 15 is a block diagram showing the configuration of a sound image localization apparatus
according to a fifth embodiment of the present invention.
[0147]
FIG. 16 is a block diagram showing a configuration of a sound image localization apparatus
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according to a sixth embodiment of the present invention.
[0148]
FIG. 17 is a block diagram showing the configuration of a first example of a sound image
localization apparatus according to the prior art.
[0149]
18 is a block diagram showing a configuration of a second example of a sound image localization
apparatus according to the prior art.
[0150]
19 is a diagram for explaining the sound image localization.
[0151]
Explanation of sign
[0152]
101, 1701 crosstalk cancellation means 102, 1702 direction localization means 103, 503, 603,
803, 903, 1003, 1103, 1203, 1303, 1503, 1603, 1703, 1703, 1803 adders 104, 504, 604, 804,
904, 1004, 1104, 1204, 1304, 1404, 1604, 1704, 1804 input terminals 105, 505, 605, 805,
905, 1005, 1105, 1205, 1305, 1405, 1505, 1605, 1705, 1805 output terminals 106, 1206,
1306, 1406, 1506, 1606, 1706, 1806 Crosstalk cancellation signal generation filter 107, 507,
607, 807, 907, 1007, 1107, 1207, 130 , 1407, 1507, 1607, 1707, 1807 main pass filter 108,
508, 608, 808, 908, 1008, 1108, 1208, 1308, 1408, 1508, 1608, 1708, 1808 crosstalk pass
filter 110, 510, 610, 821, 822, 823, 824, 921, 922, 923, 924, 1021, 1022, 1023, 1024, 1110,
1510 multipliers 111, 511, 511, 811, 911, 1111, 1511, 1611 delays 115, 915, 1015 band
dividing circuit 116, 916, 1016 band synthesizing circuit 117, 917, 1017 high pass main pass
filter 1218, 1318, 1418, 1518, 1618 changeover switch 520 low pass filter 621 inverting circuit
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