JP2006303799A - Audio signal regeneration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce any input signal by widening a sound image. <P>SOLUTION: A signal correlation calculation section 1 calculates a correlation coefficient between signals from two-channel input signals Lin, Rin. According to the calculated correlation coefficient, a correlation reduction processing section 2 performs the correlation reduction processing of the two-channel input signals. By inputting the two-channel signals on which the correlation reduction processing is performed in the correlation reduction processing section 2, a wide stereo processing section 3 then performs processing for widening the sound image of the regeneration signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acoustic signal reproducing apparatus that reproduces an expanded sound image.

As a conventional acoustic signal reproducing apparatus, there is a technique that gives different time delays and phase shifts between left and right signals as a technique for expanding and reproducing sound images of left and right stereo signals.
There is also a technique using a sum signal and a difference signal of left and right input signals. Patent Document 1 discloses a stereo enhancement system that generates a widened stereo image by processing and reproducing difference signal components generated from left and right input signals. When the level of the difference signal between the left and right stereo signals is increased, the ambient sound and reverberation sound present in the difference signal are enhanced, so that the sound image of the sound reproduced from the left and right speakers can be expanded.

  In live performances, this ambient sound is perceived at an appropriate level, but in recorded performances it is masked by direct sound and not perceived at the same level, thus compensating for the loss. However, since enhancement at all frequencies adversely affects human perception of sound, the difference signal in the selected frequency band is enhanced.

  The difference signal component is processed through a correction represented by a frequency response shown as an enhanced perception or normalized curve, and the processed difference signal is generated from the left and right input signals and the left and right input signals. Combined with the sum signal and output.

JP 11-504478 A (Detailed description of preferred embodiment, FIG. 1)

  Since the conventional acoustic signal reproducing apparatus is configured as described above, there is a problem that it is difficult to obtain a sense of spread when the correlation between the left and right input signals is high. In addition, there is a problem of feeling uncomfortable due to unnaturalness due to a sense of reverse phase.

  The present invention has been made to solve the above-described problems, and an acoustic signal reproducing apparatus capable of expanding and reproducing a sound image for any input signal regardless of the high correlation of the input signals. The purpose is to obtain.

  The acoustic signal reproduction device according to the present invention includes a signal correlation calculation unit that calculates a correlation coefficient between signals from a two-channel input signal, and a two-channel signal according to the correlation coefficient calculated by the signal correlation calculation unit. A correlation reduction processing unit that performs correlation reduction processing of an input signal, and a wide stereo processing unit that inputs a signal of two channels subjected to correlation reduction processing by the correlation reduction processing unit and performs processing to widen the sound image of the reproduced signal It is provided.

  According to the present invention, an effect that a sound image can be reproduced with any input signal can be obtained.

Embodiment 1 FIG.
1 is a block diagram showing the configuration of an acoustic signal reproducing apparatus according to Embodiment 1 of the present invention. This acoustic signal reproduction device includes a signal correlation calculation unit 1, a correlation reduction processing unit 2, and a wide stereo processing unit 3.

Next, the operation will be described.
The signal correlation calculation unit 1 receives an L channel (Lch) input signal Lin and an R channel (Rch) input signal Rin, calculates a correlation coefficient R between the Lch input signal Lin and the Rch input signal Rin, and outputs the correlation coefficient R. The correlation reduction processing unit 2 inputs the Lch input signal Lin, the Rch input signal Rin, and the correlation coefficient R calculated by the signal correlation calculation unit 1, and inputs the Lch input signal Lin and Rch by an amount suitable for the correlation coefficient R. A correlation reduction process of the input signal Rin is performed. The wide stereo processing unit 3 receives the output of the correlation reduction processing unit 2 and performs a process of expanding the sound image of the reproduced signal.

The signal correlation calculation unit 1 calculates the correlation coefficient R, for example, by obtaining the cross-correlation of two signals of the Lch input signal Lin and the Rch input signal Rin. Here, the cross-correlation may be simple with no time delay. For example, the correlation coefficient R is obtained by the following equation (1) using E (•) as the expected value calculation.
R = E (Lin (x) · Rin (x)) (1)
This expected value calculation can be substituted by time averaging. The correlation coefficient R has a large absolute value when the correlation between the Lch input signal Lin and the Rch input signal Rin is high, and has a small absolute value when the correlation is small. When there is no correlation, R = 0.

When obtaining the correlation coefficient more simply, the correlation coefficient R ′ may be obtained by the following equation (2).
R ′ = (Lin−Rin) (2)
In this case, the correlation between the Lch input signal Lin and the Rch input signal Rin decreases as the correlation coefficient R ′ increases, and the correlation increases as the correlation coefficient R ′ decreases.

  The correlation reduction processing unit 2 performs a correlation reduction process between the Lch input signal Lin and the Rch input signal Rin when the absolute value of the correlation coefficient R is large based on the correlation coefficient R calculated by the signal correlation calculation unit 1. On the contrary, when the absolute value of the correlation coefficient R is small, the correlation reduction processing is suppressed. When the correlation coefficient R ′ substituted with the difference signal is used instead of the correlation coefficient R, if the absolute value of the correlation coefficient R ′ is small, the correlation between the Lch input signal Lin and the Rch input signal Rin is reduced. If the process is increased and the absolute value of the correlation coefficient R ′ is large, the correlation reduction process is suppressed. The correlation reduction processing unit 2 performs a correlation reduction process as shown in FIGS.

  FIG. 2 is a block diagram showing an internal configuration of the wide stereo processing unit 3. The wide stereo processing unit 3 includes filters 31 and 32 and adders 33 and 34, and performs a process of expanding the sound image of the reproduction signal by a method called crosstalk cancellation. The filters 31 and 32 are filters having inverse characteristics to the transfer function of the crosstalk signal, and the adder 33 adds the Lch input signal Lin and a signal having the inverse characteristics of the Rch input signal Rin from the filter 32 and outputs the result. Similarly, the adder 34 adds and outputs a signal having an inverse characteristic of the Rch input signal Rin and the Lch input signal Lin from the filter 31.

  Normally, when two signals are reproduced from the left and right speakers, the left signal reaches not only the left ear but also the right ear. Similarly, the right signal reaches not only the right ear but also the left ear. By eliminating the signal from the right speaker to the left ear and the signal from the left speaker to the right ear, which is called spatial crosstalk, the sound image of the reproduction signal can be expanded.

  The wide stereo processing unit 3 is also realized by a process of enhancing the difference signal component of the left and right signals as shown in the conventional example, for example.

  Since these wide stereo processes use the difference between the left and right signals, when the correlation between the left and right signals is high, a sufficient effect is not exhibited and the sound image cannot be widened. Therefore, the effect of wide stereo processing is enhanced by performing correlation reduction processing according to the level of correlation between the input signals by the correlation reduction processing unit 2 on the input of the wide stereo processing unit 3, which is more than conventional. The sound image can be expanded.

  In addition, in order to compensate for the sound quality deterioration due to the wide stereo processing, a signal obtained by multiplying the left and right input signals by a gain can be added to the left and right signals after the wide stereo processing, respectively. Further, in order to further expand the sound image, a pseudo rear signal can be created from the left and right input signals, and a rear localization process can be added thereto and then added to the left and right signals after the wide stereo process.

  As described above, according to the first embodiment, the correlation reduction process of the 2ch input signal is performed according to the correlation coefficient of the 2ch input signal, and the wide stereo process is performed. However, the effect that the sound image can be widened and reproduced can be obtained.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing the configuration of an acoustic signal reproduction apparatus according to Embodiment 2 of the present invention. This acoustic signal reproducing apparatus includes a signal correlation calculation unit 1, a correlation reduction processing unit 2, a wide stereo processing unit 3, a multiplier (first multiplier) 4, a multiplier (second multiplier) 5, an adder ( A first adder (6), an adder (second adder) 7, and an adder (third adder) 8 are provided.

Next, the operation will be described.
The signal correlation calculation unit 1, the correlation reduction processing unit 2, and the wide stereo processing unit 3 all perform the same processing as in FIG. 1 of the first embodiment. Multiplier 4 multiplies Lch input signal Lin by a predetermined coefficient and outputs the result to adder 6. The multiplier 5 multiplies the Rch input signal Rin by a predetermined coefficient and outputs it to the adder 6. The adder 6 inputs and adds the two signals from the multiplier 4 and the multiplier 5 and outputs a left and right sum signal. The adder 7 adds the Lch signal from the wide stereo processing unit 3 and the sum signal of the adder 6 and outputs the result. The adder 8 adds the Rch signal from the wide stereo processing unit 3 and the sum signal of the adder 6 and outputs the result.

  In general, when a process for expanding a sound image is performed on a signal, if a signal that should be localized in the center is processed in the same manner, “blurring” may occur, and the quality of hearing may be deteriorated. For example, in music playback, the vocal to be localized in the center is blurred. In order to prevent this, a signal to be localized at the center is extracted from the 2ch input signal and added to the reproduction signal. Since the signal to be localized at the center is included in the left and right channels in the same phase and in the same way, it can be extracted by taking the sum of the left and right signals with the adder 6. This is added to the right and left reproduction signals by the adder 7 and the adder 8, respectively, and the component localized at the center is emphasized.

  As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained, and the signal components to be localized are added to the left and right output reproduction signals to obtain the reproduction signal. Even if the sound image is widened, the component localized at the center is not blurred, and an effect of preventing deterioration in quality on hearing can be obtained.

Embodiment 3 FIG.
4 is a block diagram showing the configuration of an acoustic signal reproducing apparatus according to Embodiment 3 of the present invention. This acoustic signal reproduction apparatus includes a signal correlation calculation unit 1, a correlation reduction processing unit 2, a wide stereo processing unit 3, a multiplier (first multiplier) 9, a multiplier (second multiplier) 10, and an adder 6. , An adder 7 and an adder 8 are provided.

Next, the operation will be described.
The signal correlation calculation unit 1, the correlation reduction processing unit 2, and the wide stereo processing unit 3 all perform the same processing as in FIG. Further, the adder 6, the adder 7, and the adder 8 perform the same processing as that in FIG. 3 of the second embodiment. The multiplier 9 receives the correlation coefficient R calculated by the signal correlation calculation unit 1, multiplies the Lch input signal Lin by a predetermined coefficient corresponding to the correlation coefficient R, and outputs the result to the adder 6. The multiplier 10 receives the correlation coefficient R calculated by the signal correlation calculation unit 1, multiplies the Rch input signal Rin by a predetermined coefficient corresponding to the correlation coefficient R, and outputs the result to the adder 6.

  When the correlation coefficient R obtained by the signal correlation calculation unit 1 is large, the component to be localized is large in the center. Therefore, the coefficient multiplied by the multiplier 9 and the multiplier 10 is increased, and conversely, the correlation coefficient R is If it is small, the component to be localized is small in the center, so the coefficient size is adaptively controlled so as to reduce the coefficient.

  As described above, according to the third embodiment, the same effect as in the first embodiment can be obtained, and the amount of addition of the signal component to be localized at the center according to the level of correlation between the input signals is increased. By adjusting the height, it is possible to obtain an effect that the sound image can be expanded and reproduced for any input signal without blurring the central localization component.

Embodiment 4 FIG.
FIG. 5 is a block diagram showing a configuration of an acoustic signal reproducing apparatus according to Embodiment 4 of the present invention. This acoustic signal reproduction device includes a signal correlation calculation unit 1, a band division filter (first band division filter) 11, a band division filter (second band division filter) 12, a correlation reduction processing unit 13, a band synthesis filter (first band division filter). 1 band synthesis filter) 14, band synthesis filter (second band synthesis filter) 15, and wide stereo processing unit 3.

Next, the operation will be described.
Both the signal correlation calculation unit 1 and the wide stereo processing unit 3 perform the same processing as in FIG. The band division filter 11 band-divides the Lch input signal Lin into a low frequency / high frequency signal and outputs it. The band division filter 12 divides the Rch input signal Rin into a low band / high band side signal and outputs it. The correlation reduction processing unit 13 is a phase between the high frequency side signals of the Lch input signal Lin and the Rch input signal Rin divided by the band division filter 11 and the band division filter 12, and the input signal calculated by the signal correlation calculation unit 1. The correlation number R is input, and the correlation reduction processing of the high-frequency signal of 2ch is performed with an amount suitable for the correlation coefficient R.

  The band synthesis filter 14 synthesizes and outputs the low frequency side signal of the Lch input signal Lin and the high frequency side signal of the Lch input signal Lin that has been subjected to the correlation reduction processing. The band synthesis filter 15 synthesizes and outputs the low frequency side signal of the Rch input signal Rin and the high frequency side signal of the Rch input signal Rin subjected to the correlation reduction processing.

  The low-frequency component of the signal, for example, 1 kHz or less contains a large amount of main components such as audio, so that the sense of unnaturalness and discomfort will be felt if wide stereo processing with inverse correlation is applied more than necessary. There are the above problems. Therefore, in the fourth embodiment, the left and right input signals are divided into bands, and the wide stereo processing is performed after performing the correlation reduction processing only on the high frequency side signal, so that the sense of spread of the sound image by the wide stereo processing is effective. The portion obtained in (1) can be limited to a high-frequency side signal that does not cause any hearing problems.

  As described above, according to the fourth embodiment, the same effect as in the first embodiment can be obtained, and the wide stereo process is performed after the correlation reduction process is applied to the high-frequency signal of the 2ch input signal. As a result, an effect that the sound image of the reproduction signal can be widened without discomfort is obtained.

Embodiment 5. FIG.
FIG. 6 is a block diagram showing the internal configuration of the correlation reduction processing unit of the acoustic signal reproducing apparatus according to Embodiment 5 of the present invention. The correlation reduction processing unit 2 includes a multiplier (third multiplier) 201, a multiplier (fifth multiplier) 202, a multiplier (sixth multiplier) 203, and a multiplier (fourth multiplier). 204, an adder (fourth adder) 205 and an adder (fifth adder) 206. The overall configuration of the acoustic signal reproducing device may be any of FIG. 1 of the first embodiment, FIG. 3 of the second embodiment, FIG. 4 of the third embodiment, and FIG. 5 of the fourth embodiment. .

Next, the operation will be described.
The multiplier 201 multiplies the Lch input signal Lin by a predetermined coefficient (first coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. The multiplier 202 multiplies the Lch input signal Lin by a predetermined coefficient (second coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. The multiplier 203 multiplies the Rch input signal Rin by a predetermined coefficient (second coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. The multiplier 204 multiplies the Rch input signal Rin by a predetermined coefficient (first coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result.

  The adder 205 subtracts the Rch signal output from the multiplier 203 from the Lch signal output from the multiplier 201 and outputs the result. The adder 206 subtracts the Lch signal output from the multiplier 202 from the Rch signal output from the multiplier 204 and outputs the result. Thereby, the correlation is reduced by subtracting the component of the other signal from the left and right signals.

  For example, when the correlation coefficient R calculated by the signal correlation calculation unit 1 is large, the predetermined coefficient multiplied by the multiplier 201 and the multiplier 204 is decreased to increase the correlation reduction process, and the multiplier 202 And a predetermined coefficient multiplied by the multiplier 203 is increased. On the other hand, when the correlation coefficient R calculated by the signal correlation calculation unit 1 is small, in order to suppress the correlation reduction process, the predetermined coefficient multiplied by the multiplier 201 and the multiplier 204 is increased, and the multiplier 202 and The predetermined coefficient multiplied by the multiplier 203 is reduced.

  Each coefficient multiplied by the multiplier 201, the multiplier 202, the multiplier 203, and the multiplier 204 is a fixed value, for example, 1.0 for the multiplier 201 and the multiplier 204, and 1.0 for the multiplier 202 and the multiplier 18. May be specified as 0.2.

  As described above, according to the fifth embodiment, the same effects as those of the first to fourth embodiments can be obtained.

Embodiment 6 FIG.
FIG. 7 is a block diagram showing the internal configuration of the correlation reduction processing unit of the acoustic signal reproducing apparatus according to Embodiment 6 of the present invention. The correlation reduction processing unit 2 includes a decorrelation processing unit 211, a multiplier (seventh multiplier) 212, a multiplier (ninth multiplier) 213, a multiplier (tenth multiplier) 214, a multiplier (Eighth multiplier) 215, adder (sixth adder) 216, and adder (seventh adder) 217. The overall configuration of the acoustic signal reproducing device may be any of FIG. 1 of the first embodiment, FIG. 3 of the second embodiment, FIG. 4 of the third embodiment, and FIG. 5 of the fourth embodiment. .

Next, the operation will be described.
The multiplier 212 multiplies the Lch input signal Lin by a predetermined coefficient (third coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. The multiplier 215 multiplies the Rch input signal Rin by a predetermined coefficient (third coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. The decorrelation processing unit 211 decorrelates and outputs the Lch input signal Lin and the Rch input signal Rin.

  The multiplier 213 multiplies the decorrelated Lch signal from the decorrelation processing unit 211 by a predetermined coefficient (fourth coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1. Output. The multiplier 214 multiplies the decorrelated Rch signal from the decorrelation processing unit 211 by a predetermined coefficient (fourth coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1. Output. The adder 216 adds the Lch signal from the multiplier 212 and the Lch signal from the multiplier 213 and outputs the result. The adder 217 adds the Rch signal from the multiplier 215 and the Rch signal from the multiplier 214 and outputs the result.

  For example, when the correlation coefficient R calculated by the signal correlation calculation unit 1 is large, a predetermined coefficient multiplied by the multiplier 212 and the multiplier 215 is decreased to increase the correlation reduction process, and the multiplier 213 And a predetermined coefficient multiplied by the multiplier 214 is increased. On the other hand, when the correlation coefficient R calculated by the signal correlation calculation unit 1 is small, in order to suppress the correlation reduction process, the predetermined coefficient multiplied by the multiplier 201 and the multiplier 204 is increased, and the multiplier 202 and The predetermined coefficient multiplied by the multiplier 203 is reduced.

In this way, the correlation is reduced by adding a signal obtained by decorrelating each of the Lch input signal Lin and the Rch input signal Rin. An example of decorrelation by the decorrelation processing unit 211 can be realized by applying a principal component analysis technique. Now, assuming that the input signal vector is expressed by the following equation (3), the 2-row 2-column matrix Wt, which changes with time t, is multiplied from the right of X to make Lin (t) and Rin (t) non-linear. Correlate.
Xt = [Lin (t), Rin (t)] ^ T (3) Here, X ^ T represents transposition of a matrix. At this time, the matrix Wt is adaptively changed with time t by the following equation (4).
Wt + 1 = Wt−a (I−XX ^ T) Wt (4)
Here, a is a parameter for determining the adaptive speed, and is set to an appropriate value such as a = 0.001. As a result, the correlation coefficient R can be stochastically converged to zero.

  Further, instead of the decorrelation processing unit 211, the correlation reduction processing can be performed even if all-pass filters having different characteristics such as frequency characteristics are used for the input signals of 2ch. Here, the all-pass filter is a filter that passes signals of all frequencies and changes only the phase.

  The decorrelation processing unit 211 shown in FIG. 7 performs an all-pass filter (first all-pass filter) 221 (not shown) that passes the Lch input signal Lin, an all-pass filter (second pass) that passes the Rch input signal Rin. When replaced with an (all-pass filter) 222 (not shown), the multiplier (eleventh multiplier) 212 applies a predetermined value to the Lch input signal Lin according to the correlation coefficient R calculated by the signal correlation calculation unit 1. Multiply the coefficient (fifth coefficient) and output. The multiplier (twelfth multiplier) 215 multiplies the Rch input signal Rin by a predetermined coefficient (fifth coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1 and outputs the result. To do. The all-pass filter 221 changes the phase of the Lch input signal Lin and outputs it. The all-pass filter 222 changes the phase of the Rch input signal Rin and outputs it.

  A multiplier (a thirteenth multiplier) 213 multiplies the Lch signal from the all-pass filter 221 by a predetermined coefficient (sixth coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1. Output. The multiplier (fourteenth multiplier) 214 multiplies the Rch signal from the all-pass filter 222 by a predetermined coefficient (sixth coefficient) according to the correlation coefficient R calculated by the signal correlation calculation unit 1. Output. An adder (eighth adder) 216 adds the Lch signal from the multiplier 212 and the Lch signal from the multiplier 213 and outputs the result. An adder (9th adder) 217 adds the Rch signal from the multiplier 215 and the Rch signal from the multiplier 214 and outputs the result.

  As described above, according to the sixth embodiment, the same effects as those of the first to fourth embodiments can be obtained.

It is a block diagram which shows the structure of the acoustic signal reproducing | regenerating apparatus by Embodiment 1 of this invention. It is a block diagram which shows the internal structure of the wide stereo process part of the audio signal reproduction apparatus by Embodiment 1 of this invention. It is a block diagram which shows the structure of the acoustic signal reproducing | regenerating apparatus by Embodiment 2 of this invention. It is a block diagram which shows the structure of the acoustic signal reproducing | regenerating apparatus by Embodiment 3 of this invention. It is a block diagram which shows the structure of the acoustic signal reproducing | regenerating apparatus by Embodiment 4 of this invention. It is a block diagram which shows the internal structure of the correlation reduction process part of the acoustic signal reproduction apparatus by Embodiment 5 of this invention. It is a block diagram which shows the internal structure of the correlation reduction process part of the audio signal reproduction apparatus by Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Signal correlation calculation part, 2 Correlation reduction process part, 3 Wide stereo process part, 4 Multiplier, 5 Multiplier, 6 Adder, 7 Adder, 8 Adder, 9 Multiplier, 10 Multiplier, 11 Band division filter , 12 Band division filter, 13 Correlation reduction processing unit, 14 Band synthesis filter, 15 Band synthesis filter, 31 Filter, 32 Filter, 33 Adder, 34 Adder, 201 Multiplier, 202 Multiplier, 203 Multiplier, 204 Multiplication , 205 adder, 206 adder, 211 decorrelation processing unit, 212 multiplier, 213 multiplier, 214 multiplier, 215 multiplier, 216 adder, 217 adder.

Claims (7)

A signal correlation calculation unit for calculating a correlation coefficient between signals from two-channel input signals;
A correlation reduction processing unit that performs a correlation reduction process on the input signals of two channels according to the correlation coefficient calculated by the signal correlation calculation unit;
A sound signal reproduction apparatus comprising: a wide stereo processing unit that inputs a 2-channel signal subjected to correlation reduction processing by the correlation reduction processing unit and performs a process of expanding a sound image of the reproduction signal. First and second multipliers for multiplying two-channel input signals by respective predetermined coefficients;
A first adder for adding signals from the first and second multipliers;
2. The sound according to claim 1, further comprising: a second adder and a third adder for adding the signals added by the first adder to the output signals of the wide stereo processing unit and outputting the added signals. Signal reproduction device.   The acoustic signal according to claim 2, wherein the first and second multipliers adaptively change a predetermined coefficient to be multiplied according to the correlation coefficient calculated by the signal correlation calculation unit. Playback device. A signal correlation calculation unit for calculating a correlation coefficient between signals from two-channel input signals;
First and second band division filters for dividing the two-channel input signals into low-frequency / high-frequency signals, respectively;
A correlation reduction processing unit that performs a correlation reduction process of the high-frequency signal from the first and second band division filters according to the correlation coefficient calculated by the signal correlation calculation unit;
First and second band synthesis filters for synthesizing the low-frequency side signals from the first and second band division filters and the output of the correlation reduction processing unit, respectively;
A sound signal reproducing apparatus comprising: a wide stereo processing unit that inputs a signal of two channels from the first and second band synthesis filters and performs a process of expanding a sound image of the reproduced signal. The correlation reduction processing unit
A third and a fourth multiplier for multiplying the two-channel input signal by a first coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
Fifth and sixth multipliers that respectively multiply the two-channel input signal by the second coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
A fourth adder for subtracting the output of the sixth multiplier from the output of the third multiplier;
5. An acoustic signal reproducing apparatus according to claim 1, further comprising a sixth adder for subtracting the output of the fifth multiplier from the output of the fourth multiplier. . The correlation reduction processing unit
Seventh and eighth multipliers that respectively multiply the two-channel input signal by a third coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
A decorrelation processing unit for decorrelating and outputting the input signals of the two channels, and
Ninth and tenth multipliers that respectively multiply the signal that has been decorrelated by the decorrelation processing unit by a fourth coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
A sixth adder for adding the output of the seventh multiplier and the output of the ninth multiplier;
5. The acoustic signal reproducing apparatus according to claim 1, further comprising a seventh adder for adding the output of the eighth multiplier and the output of the tenth multiplier. The correlation reduction processing unit
Eleventh and twelfth multipliers that respectively multiply the two-channel input signal by a fifth coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
First and second all-pass filters having different characteristics for passing input signals of two channels respectively;
Thirteenth and fourteenth multipliers that respectively multiply the signals from the first and second all-pass filters by a sixth coefficient in accordance with the correlation coefficient calculated by the signal correlation calculation unit;
An eighth adder for adding the output of the eleventh multiplier and the output of the thirteenth multiplier;
5. The acoustic signal reproducing apparatus according to claim 1, further comprising a ninth adder for adding the output of the twelfth multiplier and the output of the fourteenth multiplier.

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