JP2003134598A - Method of processing surround signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply rear localization to the in-phase components of two-channel rear surround signals by means of a pair of speakers installed at the front. SOLUTION: A matrix 1 separates/extracts the respective in-phase components of a pair of right and left two-channel rear sound signals at the rear to generate an in-phase component signal za and a pair of signals, xa and ya, formed by isolating the in-phase component signal za from the pair of right and left rear surround signals. The sum signal xb and the difference signal yb of a pair of in-phase component signal-isolated signals, and the in-phase component signal za are processed by means of filters, 2a, 2b, 2c, respectively based on a head transfer function. In addition, the difference signal xd and the sum signal yd of a filtered signal xc and a filtered signal yc are generated. The sum signal SLx of the difference signal xd and a filtered in-phase component signal zc and the difference signal SRy of the sum signal yd and the filtered in-phase component signal zc are assigned as a new pair of rear surround signals for sound image localization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surround signal processing method for performing sound image localization processing when a rear surround signal is reproduced by a speaker, and more particularly, by a 2ch (channel) stereo speaker installed in front of a listener. The present invention relates to a surround signal processing method capable of reproducing a multi-channel audio signal including a rear surround signal.

[0002]

2. Description of the Related Art Conventionally, for a format including a rear surround 1ch monaural surround signal, for example, Japanese Unexamined Patent Publication (Kokai) No. Hei 8 (1999) -83138 is used.
As described in Japanese Patent Publication No. 051698,
There is known a technique in which a sound image localization technique is used for a ch monaural surround signal to generate a signal for locating a sound image of a surround sound in the rear of a listener, and the signal is reproduced by a front 2ch speaker.

FIG. 4 is a block diagram showing an example of a conventional surround signal processing device corresponding to a monaural surround signal. The supplied monaural surround signal Smono is processed by the filter 2b in which the transfer characteristic N of the sound image localization processing filter is set, and a sound for performing sound image localization behind the listener is created and output from the speakers 4L, 4R. To do.

The transfer characteristic N of the filter 2b is N = (FK) / (S-A) (where S is the transfer characteristic from a pair of speakers to the ear on the same side of the listener, and A is a pair). From the speaker to the ear on the opposite side of the listener, F is the transfer characteristic from the position where the sound image is to be localized to the ear on the same side of the listener, and K is the opposite side from the position where the sound image is to be localized. Transmission characteristics up to the ear)
Is set.

Further, for the format including the rear surround signals of the rear two channels, for example, Japanese Patent Laid-Open No. 10-13.
As described in Japanese Patent No. 6499, a sound image localization technique is used for each of the 2ch rear surround signals to generate a signal that localizes a sound image to the right rear and left rear of the listener, and the front 2ch speaker is used. Techniques for reproducing are known.

FIG. 5 is a block diagram showing an example of a conventional surround signal processing device corresponding to a rear surround signal of 2ch. For the supplied 2ch rear surround signals X and Y, the first filter 2a in which the transfer characteristic P of the sound image localization processing filter is set and the second filter in which the transfer characteristic N of the sound image localization processing filter is set 2b
Processing is performed to create a sound for sound image localization behind the listener, and the sound is output from the speakers 4L and 4R.

The transfer characteristics P and N of the first filter 2a and the second filter 2b are P = (F + K) / (S + A) N = (FK) / (S-A) (however, S is the transfer characteristic from the pair of speakers to the ear on the same side of the listener, A is the transfer characteristic from the pair of speakers to the ear on the opposite side of the listener, and F is the same side of the listener from the position where the sound image is desired to be localized. To the ear, K is the transfer characteristic from the position where you want to localize the sound image to the ear opposite to the listener)
Is set.

In the surround signal processing apparatus shown in FIG. 5, when the rear surround signal is monaural, that is, when only one of the rear surround signals X or Y is supplied, the first filter described above is used. The configuration of the surround signal processing device shown in FIG. 4 can be realized by invalidating the processing in either the 2a or the second filter 2b.

[0009]

However, in the rear surround signal processing in the rear surround signal processing apparatus shown in FIG. 5, the X output from the pair of front speakers is used.
The values of pa and Ypa are Xpa = X (P + N) + Y (P−N) and Ypa = X (P−N) + Y (P + N), respectively.

Therefore, when the in-phase component of the supplied rear surround signals X and Y is α, the output signal Xpa
Since the sum of the output signal Ypa and the output signal Ypa is 4αP and the difference is 0, the in-phase components α of the output signals Xpa and Ypa are the same on the left and right, and the surround sound, which should have a sound image localized in the rear, is received. The sound is localized in front of the listener.

Therefore, as described above, according to the conventional technique, a method corresponding to the 5ch format including the surround sound up to the rear 2ch, which reproduces the rear surround signal for the rear using the pair of speakers for the front in a pseudo manner. Then, when the rear surround sound is stereo (SL / SR), there is a problem that the in-phase component of both channels (rear 2ch) is not localized rearward, but becomes frontal localization.

Further, in the conventional rear surround signal processing apparatus shown in FIGS. 4 and 5, the rear surround signal processing is possible when the channels of the rear surround signal are in the audio format up to monaural (1 ch) or stereo (2 ch). However, for example, it is impossible to process the audio format including the surround 3ch rearward signals in the next-generation discrete 6ch era. Therefore, as described above, when the rear surround sound is 3ch, there is a problem that the conventional technique cannot process the rear surround signal.

In order to solve the above problems, the present invention improves the quality of localization of the sound image of the surround sound to the rear of the listener, and further, even when a rear surround signal of the rear 3 channels is supplied, it can be processed. It is an object of the present invention to provide a rear surround signal processing device such that

[0014]

In order to achieve the above object, the present invention separates / extracts the in-phase component of rear 2ch (left / right pair) rear surround sound from each other to obtain an in-phase component signal and a left / right pair. Generates a pair of signals in which the in-phase component signal is separated from the rear surround signal of, and processes the sum signal, the difference signal, and the in-phase component signal of the pair of signals in which the in-phase component signal is separated by a filter based on the head related transfer function. Further, a sum signal and a difference signal of the sum signal and the difference signal that have been subjected to the filter processing are generated, and a difference signal between the generated sum signal and the filtered in-phase component signal, a generated difference signal and a filter The sound signal localization is performed by using the sum signal with the processed in-phase component signal as a new pair of rear surround signals.

That is, in the surround signal processing method, a sound signal in which a pair of left and right rear surround signals are encoded is reproduced from a pair of speakers arranged at a front position substantially symmetrical to the listener. In-phase component separation and extraction step of separating and extracting the in-phase component of the pair of rear surround signals and generating the in-phase component signal of the left and right pair of left and right rear surround signals and the pair of left and right output signals, respectively, and a head related transfer function A convolver with a filter coefficient set based on it (convolution operation processing circuit)
And the filter coefficient P is P = (F + K) / (S + A) (where S is the transfer characteristic from the pair of speakers to the ear on the same side of the listener, and A is the pair of speakers on the opposite side of the listener). (Transmission characteristic to the ear, F is the transmission characteristic from the position where the sound image is desired to be localized to the ear on the same side of the listener, K is the transmission characteristic from the position where the sound image is desired to be localized to the ear on the opposite side of the listener)
A first filter for filtering the first sum signal of the pair of left and right output signals generated in the in-phase component separation and extraction step by the first filter set to 1 to generate a first filter output signal. A processing step and a convolver (convolution operation processing circuit) in which a filter coefficient is set based on a head-related transfer function are realized, and a filter coefficient N is set to N = (F−K) / (S−A) A second filter processing step of filtering the first difference signal of the pair of left and right output signals generated in the in-phase component separation and extraction step by the second filter to generate a second filter output signal; A convolver (convolution operation processing circuit) in which a filter coefficient is set based on a partial transfer function is realized, and the filter coefficient n is n = (f−k) / (S−A) (where f is a sound The transfer characteristic from the position where the listener wants to be localized to the ear on the same side of the listener, and k is the transfer characteristic from the position where the sound image is desired to be localized to the ear on the opposite side of the listener). A third filtering step of filtering the in-phase component signal generated in the in-phase component separation and extraction step to generate a third filter output signal; and the third filtering step generated in the first and second filtering steps. The second of the first and second filter output signals
And a difference signal between the second sum signal and the third filter output signal, and a sum of the second difference signal and the third filter output signal. A sound image localization step that generates a signal and outputs it as a new pair of left and right rear surround signals, and the new left and right sound images output in the sound image localization step in order to localize the sound images to rear positions that are substantially symmetrical to the listener. And a step of adding a pair of rear surround signals to a pair of left and right front stereo signals, the surround signal processing method being provided.

In order to achieve the above object, the present invention provides a sum signal and a difference signal of a pair of left and right rear surround signals and a rear center surround signal for rear surround sound of rear 3 channels (a pair of left and right and center). Are processed by a filter based on the head-related transfer function, and
The sum signal and the difference signal of the sum signal and the difference signal that have been subjected to the filter processing are generated, and the difference signal between the generated sum signal and the center rear surround signal that has been subjected to the filter processing, and the generated difference signal and the filter processing. The sound signal localization is performed by using the sum signal with the rear surround signal in the center as a new pair of rear surround signals.

That is, it is a surround signal processing method in which an audio signal in which a pair of left and right and three rear surround signals at the center are encoded is reproduced from a pair of speakers arranged at a front position substantially symmetrical to the listener. To realize a convolver (convolution operation processing circuit) in which the filter coefficient is set based on the head-related transfer function, and the filter coefficient P is P = (F + K) / (S + A) (where S is a listener from a pair of speakers). To the ear on the same side of A, A is a transfer characteristic from a pair of speakers to the ear on the opposite side of the listener, F is a transfer characteristic from the position where the sound image is to be localized to the ear on the same side of the listener, K Is the transfer characteristic from the position where you want to localize the sound image to the ear opposite to the listener)
Filtering the first sum signal of the pair of left and right rear surround signals by the first filter set to
A first filter processing step of generating a first filter output signal and a convolver (convolution operation processing circuit) in which filter coefficients are set based on a head related transfer function are realized, and a filter coefficient N is N = (F- K) / (S-A) set to the second filter to filter the first difference signal of the pair of left and right rear surround signals,
A second filter processing step of generating a second filter output signal and a convolver (convolution operation processing circuit) in which the filter coefficient is set based on the head related transfer function are realized, and the filter coefficient n is n = (f- k) / (S−A) (where f is the transfer characteristic from the position where you want to localize the sound image to the ear on the same side of the listener, k is the position from the position where you want to localize the sound image to the ear on the opposite side of the listener) And a third filtering step of filtering the central rear surround signal by a third filter set to a transfer characteristic) to generate a third filter output signal, and the first and second filtering steps. Generating a second sum signal and a difference signal of the first and second filter output signals generated in the step, a difference signal between the second sum signal and the third filter output signal, and , The second difference signal and the third difference signal
The sound image localization step of generating a sum signal with the filter output signal of, and outputting as a new pair of left and right rear surround signals, and the sound image localization step in order to localize the sound images to rear positions that are substantially symmetrical to the listener. And a step of adding the newly output pair of left and right rear surround signals to the pair of left and right front stereo signals.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surround signal processing method of the present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram showing an embodiment of a surround signal processing device that realizes a surround signal processing method of the present invention, and is a configuration diagram corresponding to a format including a rear 2ch surround signal.

The surround signal processing apparatus shown in FIG. 1 detects the in-phase components of the rear surround signals X and Y in the matrix 1 and separates and extracts them, and extracts the extracted in-phase component signals as in-phase component signals za and rear. A signal obtained by separating the in-phase component signal za from the surround signal SL (the signal designed to be heard from the rear left of the listener) and the rear surround signal SR (the signal designed to be heard from the rear right of the listener) is output signals xa and A matrix (in-phase component separation / extraction means) 1 for outputting as an output signal yb, a convolver (convolution operation processing circuit) in which a filter coefficient is set based on a head related transfer function (transfer characteristic), is realized according to the setting of the filter coefficient. First to third filters 2 for converting an input signal and outputting the converted signal as an output signal
a, 2b, 2c, first to sixth adders 3 that add a plurality of supplied input signals and output one output signal
a, 3b, 3c, 3d, 3e, 3f, and a pair of speakers (transducers) 4L, 4R arranged in a front position substantially symmetrical to the listener.

Next, the connection form of the configuration shown in FIG. 1, the operation of each means, and the signal flow will be described. Matrix 1
To the rear surround signals SL and SR.
The matrix 1 detects the in-phase components of the supplied rear surround signals SL and SR, separates and extracts them, and extracts the extracted in-phase component signals z and rear surround signals SR and S.
The in-phase component signal za is separated from L, and the output signal xa and the output signal ya are output.

The in-phase component signal za output from the matrix 1 is supplied to the third filter 2c and processed.
In the third filter 2c, the filter coefficient n is n = (f−k) / (S−A) (where f is the transfer characteristic from the position where the sound image is desired to be localized to the ear on the same side of the listener, k is The transfer characteristic from the position where the sound image is desired to be localized to the ear on the opposite side of the listener) is set. The third filter 2c processes the in-phase component signal za and outputs the output signal zc.

On the other hand, for the output signals xa and ya, the first adder 3a obtains the sum signal xb of the output signals xa and ya, and the second adder 3b.
By the difference signal yb between the output signal xa and the output signal ya
Is obtained. In the second adder 3b, the output signal x
Since the inverted signal of a is added, as a result, the output signal xa
It is possible to obtain the difference signal yb of the output signal ya.

The sum signal xa and the difference signal yb output from the first and second adders 3a and 3b are the first filter 2a and the sound image localization for which the transfer characteristics P of the sound image localization processing filter are set, respectively. It is supplied to the second filter 2b in which the transfer characteristic N of the processing filter is set and processed.

The transfer characteristics P and N of the first filter 2a and the second filter 2b are P = (F + K) / (S + A) N = (FK) / (S-A) (however, S is the transfer characteristic from the pair of speakers to the ear on the same side of the listener, A is the transfer characteristic from the pair of speakers to the ear on the opposite side of the listener, and F is the same side of the listener from the position where the sound image is desired to be localized. To the ear, K is the transfer characteristic from the position where you want to localize the sound image to the ear opposite to the listener)
Is set.

From the output signal xc output by being processed by the first filter 2a and output by the second filter 2b, and further by the third adder 3c,
A difference signal xd between the output signal xc and the output signal yc is obtained,
The sum signal yd of the output signal xc and the output signal yc is obtained by the fourth adder 3d. The third adder 3c
Then, since the inverted signal of the output signal yc is added, as a result, it becomes possible to obtain the difference signal yd between the output signal xc and the output signal yc. Further, the difference signal xd and the sum signal yd obtained as described above are the same as the output signal Xpa and the output signal Ypa obtained by the conventional surround signal processing device shown in FIG.

The fifth adder 3e is supplied with the output signal zc and the output signal xd output from the third filter 2c, and outputs the sum signal SLx of the output signal zc and the output signal xd. The sixth adder 3f is supplied with the inverted signal of the output signal zc and the output signal yd and outputs the difference signal SRy between the output signal za and the output signal ya. The sum signal SLx and the difference signal SRy thus obtained are output to the outside as sounds from the speakers 4L and 4R, respectively.

In this way, by separating / extracting the in-phase components of the rear surround signals SL and SR with the matrix 1, the correlation between the signals in the output signals xa and ya is eliminated, and the output signals xa and ya. Have an independent component, and the output signal zc obtained by processing the in-phase component signal za with the newly installed third filter 2c is used to output the sum signal SLx and the speaker 4R output from the speaker 4L. Difference signal SRy output from
In order to realize the rearward localization of the sound image by outputting the sum signal SLx and the difference signal SRy to the outside, the quality of the sound image localization behind the listener is improved, and the rear surround signals SL and SR are all rearward localized. It becomes possible.

Further, f = F with filter coefficients P, N and n,
When k = K, the localization positions of the output signal xc obtained by the first filter 2a having the P filter coefficient and the output signal yc obtained by the second filter 2b having the N filter coefficient, and n The localization position of the output signal zc obtained by the third filter 2c having the filter coefficient can be set at two positions Xp and Yp behind the listener as shown.

When f and k are set to values different from F and K, for example, it becomes possible to localize the rear surround signals SL and SR having independent components to the rear left and right of the listener. The in-phase components of the rear surround signals SR and SL can be localized in a narrower area behind the listener.

Next, a case where the rear surround signal of the rear 3ch is localized for the sound image will be described. FIG. 2 is a configuration diagram showing an embodiment of a surround signal processing signal device that realizes the surround signal processing method of the present invention.
It is a block diagram corresponding to the format including the rear surround signal of ch.

In the format including the rear 3ch surround signals, the rear 3ch surround signals are designed for the right rear, the center of the rear, and the left rear, respectively, and each has a high degree of separation. Therefore, in the configuration corresponding to the format including the rear 2ch surround signal shown in FIG. 1, the matrix 1 is omitted, and instead of the in-phase component signal,
The rear surround signal SC (a signal designed to be heard from the rear center of the listener) is used to perform the same processing as that described in the description of FIG. 1 and output from the speakers 4L and 4R to localize the sound image rearward. Create an audio signal.

As described above, when the 3ch rear surround signals SL, SC, and SR are supplied, the fact that each of them has a high degree of separation (low correlation) is used to utilize the rear center rear surround signal SC for rear center. Is processed by the newly installed third filter 2c, a sum signal SLx output from the speaker 4L and a difference signal SRy output from the speaker 4R are obtained using the output signal zc. SLx
In order to output the sound signal and the difference signal SRy to the outside to realize the rearward localization of the sound image, the sound image localization to the rear of the listener is realized and the rear surround signals SL, SC and SR are realized even when the rear surround signal of 3ch is supplied. It is possible to localize all backwards.

Next, a surround signal processing device which enables sound image localization regardless of which one of the rear surround signals of 1ch to 3ch is supplied will be described. Figure 3
It is a block diagram which shows one Embodiment which concerns on the surround signal processing apparatus which implement | achieves the surround signal processing method of this invention, Comprising: It is a block diagram corresponding to the format in which a rear surround signal contains the multi-channel audio signal of 1ch to 3ch.

When the rear surround is monaural, the rear surround signal is supplied from the SC input section, and the switch 5 to which the signal is supplied from the SC input section is set to the b side. As a result, the surround signal processing device shown in FIG. 4 is realized.

When the rear surround is 2 ch, the two rear surround signals SL and SR are supplied from the input parts, and the three switches 5 are all set to the a side (the signal supplied from the matrix 1 is output). To do. As a result, the surround signal processing device shown in FIG. 1 is realized.

When the rear surround is 3 channels, all the three switches 5 are set to the b side so that the signals are directly supplied to the three switches 5 without passing through the matrix 1. As a result, the surround signal processing device shown in FIG. 2 is realized.

Then, the signal SL generated by the surround signal processing by the surround signal processing method of the present invention.
x and SRy, the front center signal C attenuated by the attenuator (attenuation means) 6 (for example, 3 dB of attenuation),
The 7th adder 3g and the 8th adder 3h add to the front left signal L and the front right signal R, respectively, so that a pair of speakers arranged in front of the listener can produce rear surround sound from 1ch to 3ch. It is possible to relocate and reproduce the sound image of.

[0038]

As described above, according to the present invention, the in-phase component of the rear 2ch (left and right pair) rear surround sound is separated / extracted from each, and the in-phase component signal and the in-phase component from the pair of left and right rear surround signals are extracted. A pair of signals separated signals are generated, a sum signal and a difference signal of a pair of signals separated in-phase component signals, each of the in-phase component signals is processed by a filter based on a head-related transfer function, and further the filter processing is performed. The sum signal and the difference signal of the performed sum signal and the difference signal are generated, and the difference signal between the generated sum signal and the filtered in-phase component signal, the generated difference signal and the filtered in-phase component signal Since the sound image localization is performed using the sum signal of and as a new pair of rear surround signals, an in-phase component signal and a pair of output signals each having an independent component from the pair of left and right rear surround signals. By generating signals and performing optimal signal processing for each signal, the representation of the sound field in the rear and the movement of the sound image become clearer, a sufficient surround effect can be obtained, and conventionally, rear localization can be performed. The in-phase component of the 2ch rear surround signal, which was not present, can be localized in the rear by the pair of speakers installed in the front.

Further, according to the present invention, with respect to the rear surround sound of the rear three channels (a pair of left and right and a center), a sum signal and a difference signal of a pair of left and right rear surround signals, and a center rear surround signal, respectively. Processed by a filter based on a transfer function, and further generate a sum signal and a difference signal of the sum signal and the difference signal that have been subjected to the filter process, and generate the sum signal and the center rear surround signal that has been subjected to the filter process. The difference signal, the generated difference signal, and the sum signal of the filtered central rear surround signal are used as a new pair of rear surround signals for sound localization, so that the 3ch rear surround signal is installed in front. It is possible to perform rearward localization with a pair of speakers.

Further, by implementing a surround signal processing device compatible with rear surround signals from the rear 1ch to the rear 3ch, it is possible to perform a process compatible with the discrete 6ch format including the future 3ch rear surround signal, and the rear surround signal. Will be compatible with all formats from monaural to 3ch.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a surround signal processing device that realizes a surround signal processing method of the present invention, and is a configuration diagram corresponding to a format including a rear 2ch surround signal.

FIG. 2 is a configuration diagram showing an embodiment of a surround signal processing signal device that realizes a surround signal processing method of the present invention, and is a configuration diagram corresponding to a format including a rear 3ch rear surround signal.

FIG. 3 is a configuration diagram showing an embodiment of a surround signal processing device that realizes a surround signal processing method of the present invention, the rear surround signal corresponding to a format including a multi-channel audio signal of 1ch to 3ch. Is.

FIG. 4 is a configuration diagram showing an example of a conventional surround signal processing device compatible with a monaural surround signal.

FIG. 5 is a configuration diagram showing an example of a conventional surround signal processing device compatible with a rear surround signal of 2ch.

[Explanation of symbols]

1 matrix (in-phase component separating / extracting means) 2a first filter (transfer characteristic P) 2b second filter (transfer characteristic N) 2c third filter (transfer characteristic n) 3a first adder 3b second Adder 3c third adder 3d fourth adder 3e fifth adder 3f sixth adder 3g seventh adder 3h eighth adder 4L, 4R speaker 5 switch 6 attenuator (attenuator ) S Transfer characteristic from a pair of speakers to the ear on the same side of the listener A Transfer characteristic from a pair of speakers to the ear on the opposite side of the listener F From the position where the sound image is to be localized to the ear on the same side of the listener Transfer characteristic K Transfer characteristic from the position where you want to localize the sound image to the opposite ear of the listener f Transfer characteristic from the position where you want to localize the sound image to the ear on the same side of the listener k You receive from the position where you want to localize the sound image Propagation to the opposite ear of the listener Characteristic

Claims (2)

[Claims] 1. A surround signal processing method for reproducing an audio signal in which a pair of left and right rear surround signals are encoded from a pair of speakers arranged in a front position substantially symmetrical to a listener, An in-phase component separation / extraction step of separating and extracting in-phase components of a pair of rear surround signals, and generating independent in-phase component signals of the pair of left and right rear surround signals and the pair of left and right output signals; A convolver (convolution operation processing circuit) in which the filter coefficient is set based on the filter coefficient P is P = (F + K) / (S + A) (where S is from the pair of speakers to the ear on the same side of the listener). Transfer characteristics, A is the transfer characteristics from the pair of speakers to the ear on the opposite side of the listener, and F is the distance from the position where the sound image is desired to be localized to the ear on the same side of the listener. , K is the transfer characteristic from the position where you want to localize the sound image to the ear opposite to the listener)
A first filter for filtering the first sum signal of the pair of left and right output signals generated in the in-phase component separation and extraction step by the first filter set to 1 to generate a first filter output signal. A processing step and a convolver (convolution operation processing circuit) in which the filter coefficient is set based on the head related transfer function are realized, and the filter coefficient N is set to N = (F−K) / (S−A). A second filter processing step of filtering a first difference signal of the pair of left and right output signals generated in the in-phase component separation and extraction step with a second filter to generate a second filter output signal; A convolver (convolution operation processing circuit) in which a filter coefficient is set based on a partial transfer function is realized, and the filter coefficient n is n = (f−k) / (S−A) (where f is a sound The transfer characteristic from the position where the image is to be localized to the ear on the same side of the listener, k is the transfer characteristic from the position where the sound image is to be localized to the ear on the opposite side of the listener) is set by the third filter, A third filter processing step of filtering the in-phase component signal generated in the in-phase component separation and extraction step to generate a third filter output signal, and a third filter processing step of generating the first and second filter processing steps Generating a second sum signal and a difference signal of the first and second filter output signals, a difference signal between the second sum signal and the third filter output signal, and the second signal A sound image localization step of generating a sum signal of the difference signal and the output signal of the third filter and outputting it as a new pair of left and right rear surround signals, and a sound image at a rear position substantially symmetrical to the listener. In order to position, and an adding step of adding the new pair of left and right rear surround signal outputted by the sound image localization step to the left and right pair of front stereo signal, the surround signal processing method having. 2. A surround signal processing method for reproducing an audio signal in which a pair of left and right and three rear surround signals in the center are encoded from a pair of speakers arranged at a front position substantially symmetrical to a listener. To realize a convolver (convolution operation processing circuit) in which the filter coefficient is set based on the head-related transfer function, and the filter coefficient P is P = (F + K) / (S + A) (where S is a listener from a pair of speakers). To the ear on the same side of A, A is a transfer characteristic from a pair of speakers to the ear on the opposite side of the listener, F is a transfer characteristic from the position where the sound image is to be localized to the ear on the same side of the listener, K Is the transfer characteristic from the position where you want to localize the sound image to the ear opposite to the listener)
Filtering the first sum signal of the pair of left and right rear surround signals by the first filter set to
A first filter processing step of generating a first filter output signal and a convolver (convolution operation processing circuit) in which filter coefficients are set based on a head related transfer function are realized, and a filter coefficient N is N = (F- K) / (S-A) set to the second filter to filter the first difference signal of the pair of left and right rear surround signals,
A second filter processing step of generating a second filter output signal and a convolver (convolution operation processing circuit) in which filter coefficients are set based on a head-related transfer function are realized, and a filter coefficient n is n = (f- k) / (S−A) (where f is the transfer characteristic from the position where you want to localize the sound image to the ear on the same side of the listener, k is the position from the position where you want to localize the sound image to the ear on the opposite side of the listener) A third filtering process for filtering the central rear surround signal with a third filter set to a transfer characteristic) to generate a third filter output signal; and the first and second filtering processes. Generating a second sum signal and a difference signal of the first and second filter output signals generated in step, a difference signal between the second sum signal and the third filter output signal, and And a sound image localization step of generating a sum signal of the second difference signal and the third filter output signal and outputting it as a new pair of left and right rear surround signals, and a rear position substantially symmetrical to the listener. And a step of adding the new pair of left and right rear surround signals output in the step of sound image localization to a pair of left and right front stereo signals, respectively.