JP2985557B2 - Surround signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound image localization apparatus for reproducing an audio signal from a speaker, and more particularly to a surround signal processing apparatus for surround reproduction surrounding a listener.

[0002]

2. Description of the Related Art Conventionally, in order to reproduce stereophonic sound capable of obtaining a sound field or a sound image localization from the listener's position to the rear, two speakers in front of a stereo arrangement and speakers in a rear arrangement for surround have been used. One or two, minimum 3
Speakers are required, and surround playback using one system of surround signals or 3-1 for high definition
When reproducing to the center channel as in the system, one or two speakers are further required as a center speaker, and an amplifier and a cable for the channel to be reproduced are required.

[0005] That is, as speaker settings necessary for surround reproduction, for example, as shown in FIG. 8, speaker sets of L and R channels located on the left and right in front of the listener M and SLs located on the left and right behind the listener M. And rear speaker set for surround of SR channel,
Or, in addition to this, a center speaker for the C channel at the front center was required.

However, in ordinary households, it is difficult to arrange the rear speaker and the center speaker in terms of space and cost, and as a real speaker set, as shown in FIG. If only the left and right channel speaker sets located in front of and right of M are provided, a sufficient surround effect cannot be obtained in that case. In particular, the surround playback method using one monaural surround signal is characterized by expressing the sound field behind the listener and expressing the movement of the sound image. In the prior art, a rear speaker must be installed. I couldn't show that effect.

[0005]

As described above, in the prior art, in the surround reproduction system using one rear surround signal, it is necessary to install rear speakers behind the listener, There has been a problem that the stereoscopic sound effect similar to that of the original surround reproduction cannot be obtained by reproducing only the speakers. In addition, for a single surround signal for the center, it was necessary to install a speaker in the front center of the listener.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in the conventional example, and a rear system is required so that a rear speaker set is required even if reproduction is performed only by the front left and right speakers. It is an object of the present invention to obtain a surround signal processing device capable of obtaining the same three-dimensional sound effect as the surround reproduction using the surround signal. Similarly, a surround sound that can obtain the same three-dimensional sound effect as that of a surround reproduction using a single surround signal for the center, which originally requires the front center speaker, can be obtained by reproduction using only the front left and right speakers. Another object is to obtain a signal processing device.

[0007]

In order to achieve the above object, according to the present invention, two original speakers L and R of a two-channel stereo are provided for two speakers in front of a listener at a predetermined position.
In addition to each channel signal of, the sound image localization signal obtained by converting the rear channel signal is given,
Alternatively, two pairs of speakers are provided in the front, and only the signals of the original L and R channels are given to one pair.
The other pair is provided with the sound image localization signal. By performing such sound image localization, even if the rear speaker behind the listener does not actually exist, it is possible to perform surround reproduction in which sound can be heard from behind. In order to convert the rear channel to obtain a desired sound image localization signal, transfer characteristics h _1L of each space from a pair of speakers actually arranged to the left and right ears of the listener,
h _1R , h _2L , h _2R, and transfer characteristics p _Lx , p of each space from a speaker placed only at the time of measurement to one of the two predetermined rear positions where the sound image is to be localized from the left and right ears of the listener _An operation is performed using _Rx . That is, a filter operation using a convolver (convolution operation processing circuit) or the like is performed.

In the case of a surround signal having a center channel signal in addition to the rear channel signal, the center channel signal is converted to obtain a sound image localization signal for sound image localization in the front center, and a front left and right speaker is provided. Can be given to. In this case as well, the reproduction is performed in addition to the original L and R channel signals and the converted signal of the rear channel signal, or the reproduction is performed from another pair of speakers to which only the converted signal of the rear channel signal is provided. It may be. Further, in the case of a surround signal having only a center channel signal without a rear channel signal, the same conversion can be performed.

Further, if the rear sound image localization position is symmetrical, only one filter in the signal conversion circuit for obtaining the sound image localization signal is required, and the inverted signal obtained by inverting the output signal is used. , The same effect as when two filters are used can be obtained. Also, in the case of the sound image localization position at the front center, the same sound image localization signal to be applied to the left and right speakers may be provided at the front center of the listener, so that only one filter in the signal conversion circuit can be used.

That is, according to the present invention, there is provided a surround signal processing apparatus which responds to three channel signals of a left channel signal, a right channel signal of a two-channel stereo, and a rear channel signal for obtaining a surround sound effect, A left channel spatial localization signal for localizing one component of a sound reproduced from a pair of speakers that are actually arranged in front and left of the listener at a predetermined position to two predetermined left and right symmetric positions behind the listener. And the transfer characteristics h _1L , h _1R , h _2L , h _2R of the respective spaces from the pair of speakers actually arranged to the left and right ears of the listener in order to obtain a spatial localization signal for the right channel. , Transfer characteristics p _Lx , p _Rx of the respective spaces from the speaker arranged only at the time of measurement at one of the rear predetermined positions to the left and right ears of the listener. Cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R − a signal conversion circuit for converting the rear channel signal by having transfer characteristics cf _Lx and cf _Rx satisfying h _2L · h _1R ;
Means for adding the left channel spatial localization signal and the inverted signal of the right channel spatial localization signal to the left channel signal; and the right channel spatial localization signal and the inverted signal of the left channel spatial localization signal. Means for adding to the right channel signal.

According to the present invention, a left channel signal and a right channel signal of a two-channel stereo, a rear channel signal for obtaining a surround sound effect, and a center sound image localization of the two-channel stereo are improved. A surround signal processing apparatus that responds to a four-channel signal of a center channel signal of a listener, wherein one component of a sound reproduced from a pair of speakers that are actually arranged on the left and right sides of the listener at a predetermined position is transmitted to the rear of the listener. In order to obtain a first spatial localization signal for the left channel and a first spatial localization signal for the right channel for localization at two predetermined positions symmetrical to each other, the listener's listener is transmitted from the pair of speakers actually arranged. Transfer characteristics h of each space to the left and right ears
_1L , h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of each space from a speaker arranged only at the time of measurement at one of the rear predetermined positions to the left and right ears of the listener. Using, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _A first signal conversion circuit that converts the rear channel signal by having transfer characteristics cf _Lx and cf _Rx that satisfy _2L · h _1R , And a second spatial localization signal for the left channel for localization at predetermined positions of
In order to obtain a spatial localization signal, transfer characteristics h _1L , h _1R , h _2L , h _2R of each space from the pair of speakers actually arranged to the left and right ears of the listener and the front center Cf _Lx = (h _{2 R} · p _Lx −h _2L ·) using transfer characteristics p _Lx and p _Rx of the respective spaces from the speaker arranged only at the time of measurement at the predetermined position to the left and right ears of the listener. p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _1R has transfer characteristics cf _Lx and cf _Rx A second signal conversion circuit for converting the center channel signal, a first spatial localization signal for the left channel, a second spatial localization signal for the left channel, and a first spatial localization signal for the right channel.
Means for adding an inverted signal of a spatial localization signal to the left channel signal; and a first spatial localization signal for the right channel, a second spatial localization signal for the right channel, and an inverted signal of the first spatial localization signal for the left channel. To the right channel signal.

Further, according to the present invention, there is provided a surround signal processing apparatus which responds to three channel signals of a left channel signal, a right channel signal of a two-channel stereo, and a rear channel signal for obtaining a surround sound effect. A left channel space localization for localizing one component of a sound reproduced from a pair of speakers that are actually arranged in front and left of the listener at a predetermined position to two predetermined left and right symmetric positions behind the listener. In order to obtain a difference signal between the signal and the spatial localization signal for the right channel, transfer characteristics h _1L , h _1R , and h _2L of each space from the pair of speakers actually arranged to the left and right ears of the listener. , _H2R ,
Cf _Lx = (h _2R) using transfer characteristics p _Lx and p _Rx of each space from a speaker arranged only at the time of measurement at one of the two rear predetermined positions to the left and right ears of the listener. _{· p Lx -h 2L · p Rx} ) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H where transmission characteristic which satisfies _{H = h 1L · h 2R -h} 2L · h 1R a signal conversion circuit for converting the rear channel signal by having cf _Lx and cf _Rx ;
Surround signal processing comprising: means for adding the difference signal to one of the left channel signal and the right channel signal; and means for adding an inverted signal of the difference signal to the other of the left channel signal and the right channel signal. An apparatus is provided.

According to the present invention, a left channel signal and a right channel signal of a two-channel stereo, a rear channel signal for obtaining a surround sound effect, and a sound image localization at the center of the two-channel stereo are improved. A surround signal processing apparatus that responds to a four-channel signal of a center channel signal of a listener, wherein one component of a sound reproduced from a pair of speakers that are actually arranged on the left and right sides of the listener at a predetermined position is transmitted to the rear of the listener. In order to obtain a difference signal between the first spatial localization signal for the left channel and the first spatial localization signal for the right channel for localization at the two predetermined positions symmetrical to the left and right, the pair of speakers actually arranged is transfer characteristics h _1L of each of the spaces up to the left and right ears of the listener, h _1R, h _2L, and h _2R, one of two predetermined positions of the rear Transfer characteristic p _Lx of each space from the placed only at the time of measurement the speaker to the left and right ears of the listener, by using the _{p Rx, cf Lx = (h} 2R · p Lx -h 2L · p Rx) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _1R satisfies the transfer characteristics cf _Lx and cf _Rx. A first signal conversion circuit for converting a channel signal, and a second spatial localization signal for localizing a component of the sound reproduced from the pair of speakers to a predetermined position at the front center of the listener. Transfer characteristics h _1L , h _1R , h _2L , h of each space from a pair of speakers actually arranged to the left and right ears of the listener
_{Using 2R} and transfer characteristics p _Lx and p _Rx of the respective spaces from the speaker arranged only at the time of measurement at the predetermined position at the front center to the left and right ears of the listener, cf _Lx = (h _2R · _{p Lx -h 2L · p Rx)} / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · h 1R transfer characteristics cf satisfying the _A second signal conversion circuit for converting the center channel signal by having _Lx and cf _Rx, and a means for adding the difference signal and the second spatial localization signal to one of the left channel signal and the right channel signal And a means for adding an inverted signal of the difference signal and the second spatial localization signal to the other of the left channel signal and the right channel signal.

Further, according to the present invention, when the left channel signal and the right channel signal of the two-channel stereo are reproduced from the first pair of speakers that are actually arranged in front of and right and left of the listener at the predetermined position. A surround signal processing device that responds to a one-channel signal that is a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers that are actually disposed in front of and to the left and right of the listener. To obtain a left channel spatial localization signal and a right channel spatial localization signal for localizing the sound reproduced from the second pair of speakers at two predetermined positions symmetrical behind the listener. transfer characteristic h _1L of each of the space from the second pair of speakers that the are actually disposed to the left and right ears of the listener, h _1R, h _2L by using the h _2R, transfer characteristic p _Lx of each space from the speaker disposed only at the time of measurement at one predetermined position of the rear until the left and right ears of the listener, and a p _Rx, cf _Lx = (h _2R · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _1R A signal conversion circuit for converting the rear channel signal by having characteristics cf _Lx and cf _Rx ;
Means for adding the left channel spatial localization signal to the inverted signal of the right channel spatial localization signal; and means for adding the right channel spatial localization signal to the inverted signal of the left channel spatial localization signal. A processing device is provided.

Further, according to the present invention, when the left channel signal and the right channel signal of the two-channel stereo are reproduced from the first pair of speakers that are actually arranged in front of and right and left of the listener at the predetermined position. In addition, a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers that are actually arranged in front of and to the left and right of the listener and a sound image localization at the center of the two-channel stereo are improved. Signal processing device responsive to a two-channel signal of a center channel signal for
A first spatial localization signal for the left channel and a first spatial localization for the right channel for localizing one component of the sound reproduced from the second pair of speakers to two predetermined left-right symmetrical positions behind the listener. In order to obtain a signal, a transfer characteristic h _1L of each space from the second pair of speakers actually arranged to the left and right ears of the listener,
Using h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of the respective spaces from the speaker arranged only at the time of measurement at one of the rear predetermined positions to the left and right ears of the listener. _{, cf Lx = (h 2R ·} p Lx -h 2L · p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · a first signal conversion circuit for converting the rear channel signal by having transfer characteristics cf _Lx and cf _Rx satisfying h _1R, and a component of a sound reproduced from the second pair of speakers, In order to obtain a second spatial localization signal for the left channel and a second spatial localization signal for the right channel for localization at the center predetermined positions, the listener's listener is transmitted from the second pair of speakers actually arranged. Transfer characteristics h _1L , h _1R , h of each space to the left and right ears _2L ,
h _2R and the transfer characteristic p _Lx of each space from the front center speaker disposed only at the time of measurement at a predetermined position to the left and right ears of the listener, by using the _{p Rx, cf Lx = (h} 2R _{· p Lx -h 2L · p Rx} ) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H where transmission characteristic which satisfies _{H = h 1L · h 2R -h} 2L · h 1R a second signal conversion circuit that converts the center channel signal by having cf _Lx and cf _Rx ; and converts the first spatial localization signal for the left channel and the second spatial localization signal for the left channel into the first spatial localization signal for the right channel.
Means for adding the inverted signal of the spatial localization signal to the inverted signal of the spatial localization signal, and means for adding the first spatial localization signal for the right channel and the second spatial localization signal for the right channel to the inverted signal of the first spatial localization signal for the left channel. A surround signal processing device is provided.

Further, according to the present invention, when the left channel signal and the right channel signal of the two-channel stereo are reproduced from the first pair of speakers which are actually arranged in front of and right and left of the listener at the predetermined position. A surround signal processing device that responds to a one-channel signal that is a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers that are actually disposed in front of and to the left and right of the listener. And a difference signal between a left channel spatial localization signal and a right channel spatial localization signal for localizing the sound reproduced from the second pair of speakers to two predetermined positions symmetrical behind the listener. to obtain the transfer characteristic h _1L of each of the space from the second pair of speakers that the are actually disposed to the left and right ears of the listener, h _1R h _2L, h _2R and the transfer characteristic p _Lx of each space from the speaker disposed only at the time of measurement in one of two predetermined positions of the back until the left and right ears of the listener, by using the p _Rx, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h A signal conversion circuit that converts the rear channel signal by having transfer characteristics cf _Lx and cf _Rx that satisfy _1R ;
Means for obtaining an inverted signal of the difference signal.

Further, according to the present invention, when the left channel signal and the right channel signal of the two-channel stereo are reproduced from the first pair of speakers which are actually arranged in front of and right and left of the listener at the predetermined position. In addition, a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers that are actually arranged in front of and to the left and right of the listener and a sound image localization at the center of the two-channel stereo are improved. Signal processing device responsive to a two-channel signal of a center channel signal for
A difference between a first spatial localization signal for the left channel and a first spatial localization signal for the right channel for localizing the sound reproduced from the second pair of speakers to two predetermined positions symmetrical to the left and right of the listener. In order to obtain a signal, a transfer characteristic h _1L of each space from the second pair of speakers actually arranged to the left and right ears of the listener,
h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of each space from a speaker arranged only at the time of measurement to one of the two rear predetermined positions to the left and right ears of the listener. Using, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _A first signal conversion circuit for converting the rear channel signal by having transfer characteristics cf _Lx , cf _Rx satisfying _2L · h _1R , and a listener receiving one component of sound reproduced from the second pair of speakers In order to obtain a second spatial localization signal for localization at a predetermined position at the front center of the listener, each space from the second pair of speakers actually arranged to the left and right ears of the listener is obtained. Transfer characteristics h _1L ,
Using h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of the respective spaces from the speaker arranged only at the time of measurement at the predetermined position in the front center to the left and right ears of the listener, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _A second signal conversion circuit for converting the center channel signal by having transfer characteristics cf _Lx and cf _Rx satisfying _1R , a means for adding the difference signal to the second spatial localization signal, and an inverted signal of the difference signal To the second spatial localization signal.

[0018]

In the surround signal processing apparatus according to any one of the first to fourth aspects, a signal conversion circuit converts a rear channel signal into a spatial localization signal for localizing the stereo signal to the intended position in space, and converts the stereo signal and the spatial localization signal. By adding and reproducing from the left and right speakers in front of the listener, a three-dimensional sound effect of a surround reproduction method using one surround signal can be obtained only with the front speaker set without using the rear speaker set. .
Further, the surround signal processing apparatus according to the fifth to eighth aspects is different from the first aspect in that a speaker set dedicated to the spatial localization signal is provided separately from a normal speaker set. That is, by obtaining a spatially localized signal to be reproduced from another set of speakers different from one set of speakers reproducing a two-channel stereo signal, it is possible to independently adjust the listening angle of the speaker with respect to the listener. ing.

In the surround signal processing apparatus according to the second, fourth, sixth and eighth aspects, in addition to the conversion of the rear channel signal, the center channel signal is converted into a spatially localized signal for reproduction at the center position of the stereo speaker. Since these spatial localization signals are added by the addition means and reproduced from the left and right speakers in front, the sound image at the front center becomes clear without blurring. You can get the feeling that sound is coming out.

In the surround signal processing apparatus according to the first to fourth aspects, the spatial localization signal is added to each of the two-channel stereo signals, and the added output is reproduced from a set of speakers arranged in front of the listener. Since only one speaker set is required, the cost can be reduced.

In the surround signal processing apparatus according to the first to eighth aspects, the conversion circuit reproduces the rear channel signal at a symmetrical position on the left and right rear of the listener and in the opposite phase so that the two spatial localization signals have the opposite phase. With this configuration, the sound image localization position can be fixed at the rear position of the listener without any discomfort.

Furthermore, in the surround signal reproducing apparatus according to the third, fourth, seventh and eighth aspects, one or two conversion circuits are configured to convert to a spatially localized signal of a symmetrical sound image localization position. The speakers and the sound image localization positions in the stereo arrangement can be made bilaterally symmetric, and the filtering process in the conversion circuit can be reduced by half.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating the concept of the present invention. In the figure, reference numeral 1 denotes an example of four channels, which receives two-channel stereo signals L and R, a center channel signal C for improving the stereo localization, and a rear channel signal S for obtaining a surround stereophonic effect. hand,
A surround signal processing device that converts the rear channel signal S and the center channel signal C into spatially localized signals for localizing each at an intended position in space in order to perform surround reproduction surrounding the listener M;
By reproducing R and the spatial localization signal from speakers SP ₁ and SP ₂ arranged in front and left of the listener M, rear speakers SP ₃ and SP ₄ arranged in the rear and left and right of the listener M which is originally required. and in which obtaining a surround stereophonic effect center speaker SP ₅ to place the front center portion of the listener M and unnecessary. Note that the center channel signal C
In the case where there is no, only the rear channel signal S is processed, but such an aspect is also included in the present invention. On the other hand, it is also possible to process only the center channel signal C without the rear channel signal S.

FIG. 2 is a diagram for explaining the principle of the present invention in which a sound image is localized at an intended position in a space surrounding the listener M by the _two speakers SP ₁ and SP _{2 in the} stereo arrangement. The principle of the present invention will be described in detail with reference to FIG. In the figure, now the h _1L (frequency response of the impulse response) transfer characteristics from the speaker SP ₁ to the left until the left and right ears of the listener M, h _1R, also the right speaker SP ₂
, And transfer characteristics from the listener M to the left and right ears are denoted by h _2L and h _2R . Also, let p _Lx and p _Rx be transfer characteristics of the listener M to the left and right ears when an actual speaker is placed at the target localization position x. Here, each transfer characteristic is obtained by arranging a speaker and a human head or a dummy head and a microphone at the position of both ears in an anechoic space, and performing appropriate waveform processing or the like.

Next, the signal conversion circuit 1 in which the transfer characteristic is represented by cf _Lx and cf _Rx to the source X of the sound signal to be localized.
A and 1B respectively output signals obtained through speakers SP.
I think to play at _1, SP _2. At this time, a signal obtained at the left and right ears of the listener M e _L, when the _{e R, e L = h 1L} · cf Lx · X + h 2L · cf Rx · X ··· (1a) e R = h 1R · Cf _Lx · X + h _2R · cf _Rx · X (1b)

On the other hand, when the source X is reproduced from the target localization position, signals obtained at the left and right ears of the listener M are d _L , d
When _R, the _{d L = p Lx · X ···} (2a) d R = p Rx · X ··· (2b).

Now, if the signals obtained at the left and right ears of the listener M by the reproduction of the speakers SP ₁ and SP ₂ match the signals obtained when the source is reproduced from the target position, the listener M is moved to the target position as if the speakers M were at the target position. Will be recognized as if the sound image existed. That is, the conditions e _L = d _L , e _R = d _R
When the formula (1a), (1b), (2b), from (2b), when erasing the _{X, h 1L · cf Lx +} h 2L · cf Rx = p Lx ··· (3a) h 1R · cf Lx + h _2R · cf _Rx = p _Rx (3b)

From equations (3a) and (3b), cf _Lx ,
When cf _Rx is obtained, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H (4a) cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H ··· · (4b) where the _{H = h 1L · h 2R -h} 2L · h 1R ··· (4c).

Therefore, the signal conversion circuit 1A of the transfer characteristics cf _Lx and cf _Rx calculated by the equations (4a) to (4c),
If a signal to be localized is processed using 1B (hereinafter referred to as a cancel filter for the position x), the sound image at the target position x can be localized.

Although various methods for realizing a specific cancellation filter are conceivable, in the present invention, two methods for realizing using a finite impulse response (FIR) digital filter will be described. Conventionally,
Although there is an example in which similar processing is realized by an analog circuit, it is difficult to perform accurate phase processing, and it is impossible to obtain a sufficient effect in terms of cost. In the present invention, digital processing is introduced to obtain a clear effect.

FIG. 3 shows that the signal conversion circuits 1A and 1B of the transfer characteristics cf _Lx and cf _Rx which are also obtained by the equations (4a) to (4c) are realized by one FIR filter processing. Cf _Lx and cf _Rx corresponding to the number of positions x
Is prepared in advance and prepared as a ROM, and its filter coefficients are controlled using a controller and a ROM storing the coefficients.

FIG. 4 shows a case where the equations (4a) to (4c) are realized by a plurality of FIR filters, and a case where it is necessary to prepare a plurality of relationships between the speakers SP ₁ and SP ₂ and the listener M. The signal conversion circuit 1C relating to the filter coefficients (p _Lx , p _Rx ) and the filter coefficients (h _1L , h _1R , h _2L , h
_2R ) and the signal conversion circuit 1D according to
An object of the present invention is to reduce the capacity of the ROM to be prepared by variably controlling the filter coefficients (p _Lx , p _Rx ) with respect to the filter coefficients (h _1L , h _1R , h _2L , h _2R ). 2 and 3 indicate adders.

Next, an embodiment of the entire signal conversion circuit according to the present invention will be described. Embodiment 1 FIG. FIG. 5 illustrates the overall configuration of the signal conversion circuit according to the first embodiment. In FIG. 5, reference numeral 10 denotes a left and right total signal L in the form of a mixture of audio information obtained by adding a center channel signal C at the front center and a rear surround channel signal S to the left and right channel signals L and R of the listener M.
decoder for separating the original four-channel signals which in response to _t and R _t, 11 is an amplitude adjustment and reflected sound adding circuit of the signal.

[0034] 12 FIR digital filter as a signal conversion circuit for converting the process into the center space orientation signal in front localization in order to reproduce the channel signal C in the center of the stereo placement speakers L _c and R _c (convolver), 13 The spatial localization signal L _s which receives the surround channel signal S and reproduces it in opposite phases at symmetrical positions on the left and right rear of the listener M.
And the FIR digital filter (convolver) as a signal conversion circuit for converting processed R _s, the adjustment values of the filter coefficients and the amplitude adjustment and reflected sound adding circuit 11 is variable with the controller 14A and ROM 14b. 15 and 16 are inverters, 17 to 20
Is an adder, 21 and 22 are switches, and 23 to 26 are output terminals.

In the configuration shown in FIG. 5, the two-channel stereo signals L and R output from the decoder 10 are
And a 1-channel center channel signal C and a 1-channel surround (rear) channel signal S,
The FIR digital filters 12 and 13 process so that the center channel signal C is reproduced at the center position of the stereo speaker and the surround channel signal S is reproduced at a symmetrical position on the left and right rear of the listener M in opposite phases (see FIG. 7). stereo signals L, R and spatial orientation signals L _c, is summed by R _c, L _s, to not adder 17 to R _s 20.

By connecting the switches 21 and 22 in the upward direction in the figure, two speakers (not shown) arranged in front of the listener M connected to the respective output terminals 23 to 26 and similarly the listener M The stereo signals L are respectively output from two speakers dedicated to the spatial localization signal arranged in front.
And R, spatial orientation signal _{L c + L s -R s,} R c + R s -
The L _s adapted to reproduce, also the switch 21
And 22 are connected to the lower side in FIG.
When the stereo signal and the spatial orientation signals from the connected listener M the two front speakers 26 sum signal L + L _c + L _s
-R _s, is adapted to reproduce the _{R + R c + R s -L} s.

Embodiment 2 FIG. FIG. 6 is an overall configuration diagram of a signal conversion circuit according to the second embodiment corresponding to the first embodiment, and simplifies a filtering process in a sound image localization process. 6, the same parts as those in FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted. 27 and 28 are FIR digital filters 1 of the first embodiment.
FIR digital filters corresponding to 2 and 13, respectively.
29 denotes an inverter, and 30 to 32 denote adders.

In the above-mentioned configuration, as shown in FIG. 7, when the L and R speakers are arranged symmetrically at the left and right and the sound image localization position is also symmetrical at the left and right as shown in FIG. The filter coefficients of R may be equal, the coefficients of the center speaker are equal for L and R (L _c = R _c ), and can be realized by one filter.

On the other hand, the coefficients of the FIR digital filter 28 for realizing the rear loudspeaker by L _s -R _s can be realized by one filter by taking the difference of each time series between the L coefficient and the R coefficient. In FIG. 7, α and θ are the opening angle of the front speaker with respect to the listener M and the opening angle of the sound image position corresponding to the rear speaker. Therefore, by setting the loudspeaker and the sound image localization position to symmetrical positions, it is possible to realize the filtering process in half.

In the second embodiment, similarly to the first embodiment, the switches 21 and 22 are connected in the upper direction in the drawing, so that the listener M is connected to the output terminals 23 to 26 in front of the listener M. stereo signal from each of the two speakers arranged two spatial orientation signals only that the speaker and the like not shown disposed listener M front of which is L and R, the spatial orientation signal _{L c + L s -R s,} R c + R _s -L _s
And switches 21 and 2
2 is connected to the lower side in the figure, so that the output terminals 25 and 2 are connected.
Sum signal of the stereo signal and the spatial orientation signals from the connected listener M the two front speaker _{6 L + L c + L s} -R
_s, have been made to reproduce the _{R + R c + R s -L} s.

According to the method described in each of the above embodiments, it is possible to obtain a three-dimensional sound effect that can only be obtained by using the rear speaker set by using only the front speaker. When performing surround playback, it is necessary to adjust the output level of each speaker in advance by using a test tone. However, in the L and R speaker playback according to the above-described embodiment, the L and R speakers must be arranged at optimal positions. This eliminates the need to adjust the output levels of the center and surround signals.

In the example of FIG. 7, the signals of the rear channel are localized in the opposite phases to the left and right behind the listener M. In general, in surround reproduction using one rear surround signal, the rear channel reproduces signals in the left and right in-phase from the speaker. However, when using sound image localization, the in-phase component at the rear left and right symmetric position is located in the head or in the front. It tends to be localized, in which case the surround effect cannot be sufficiently exerted.

Therefore, this problem is solved by using a phase shift or a single delay. In the above embodiment, the rear channel signal is localized in the left and right opposite phases as a simple method. By this method, the orientation is easily fixed at the rear position, and a sufficient effect can be obtained. Originally, in a four-channel matrix surround or the like, the monaural component (LR) is reproduced backward and left in opposite phases, and almost no discomfort is caused by making the backward monaural signal in opposite phases.

In each of the above embodiments, as shown in FIGS. 5 and 6, the coefficient of the FIR digital filter in the signal conversion circuit is made variable by using the controller and the ROM, so that the position of the spatial localization is made variable. Selecting a coefficient that maximizes the effect from the positional relationship between the speaker that reproduces the spatial localization signal and the listener M, and selecting a coefficient that best matches the transfer characteristic of the head of the listener M. Etc. are possible.

When the L and R signals are reproduced from the two front speakers and the spatial localization signal is reproduced from the two front speakers different from the above speakers, when the spatial localization signal is reproduced from the speakers dedicated to the spatial localization signal, A better effect can be obtained by optimizing the arrangement and characteristics. For example, even if the speakers are not separate cabinets, the spatial localization signal can be reproduced by a so-called in-speaker in the same cabinet and the opening angle and the like can be adjusted independently to optimize.

As shown in FIGS. 5 and 6, when reproducing the center channel, in the normal reproduction not according to the above embodiment,
Originally, the display device is placed at the position where the center speaker is to be arranged. Therefore, the center speaker has to be arranged either above or below the display, or above or below the display from both left and right ends of the display. At this time, in the former case, the sound image is the same as in normal stereo reproduction, and it is said that the clarity of the sound image is slightly lower than in the case where a speaker is actually arranged at a necessary sound image position. In the latter case, a shift occurs between the required sound image position and the speaker position. On the other hand, in the present invention, the center channel completely simulates the speaker at that position, so that the position of the obtained sound image is accurate and the quality of the sound image is clearer.

Further, according to each of the above embodiments, it is possible to reduce the cost of the speaker set (speaker, amplifier, terminal, cable, etc.) and obtain a good surround effect.

[0048]

As described above, according to the present invention, one or both of the rear channel signal and the center channel signal are converted into spatial localization signals for localizing each of the rear channel signals and the center channel signals at intended positions in the space, and the stereo signal and the space signal are converted. Since the localization signal is reproduced from the speaker in front of the listener, a speaker set in the rear of the listener is not required, and only a front speaker set is used, and a surround reproduction type stereo system using one rear surround signal is used. The sound effect can be obtained. In particular, in the present invention, since the spatial localization signals given to the left and right speakers made from the rear channel signals have opposite phases, the sound image is easily fixed at the rear position, and a sufficient surround effect can be obtained. Further, by processing the center channel signal in the same manner and localizing the center channel signal in front of the listener, it is possible to improve the sense of realism of a sound image in image reproduction or the like.

According to the fifth to eighth aspects, the spatial localization signal is reproduced from another set of speakers different from one set of speakers for reproducing two-channel stereo signals. The opening angle of another set of speakers dedicated to the spatial localization signal can be independently adjusted and optimized, so that an effect of obtaining a good surround effect can be obtained.

According to the first to fourth aspects of the present invention, the spatial localization signal is added to the two-channel stereo signal by the adding means, and the added output is output from a set of speakers arranged in front of the listener. Since the reproduction is performed, an effect that the cost of the speaker set can be reduced can be obtained.

According to the second, fourth, sixth, and eighth aspects of the present invention, the center channel signal is converted into a spatial localization signal for localization at the front center of the listener in addition to the rear channel signal. As a result, a clear sound image can be obtained at the central position in front of the listener, and an effect that a better surround effect can be obtained can be obtained.

According to the third, fourth, seventh and eighth aspects of the present invention, the conversion circuit is configured to convert to a spatially-localized signal at a symmetrical sound image localization position, thereby providing a speaker and a sound image in a stereo arrangement. There is an effect that the localization position can be made symmetrical and the filtering process can be halved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating the concept of a surround signal reproduction device according to the present invention.

FIG. 2 is a configuration diagram illustrating the principle of a surround playback device according to the present invention.

FIG. 3 is a diagram illustrating a specific content of a cancel filter that realizes the signal conversion circuit of FIG. 2;

FIG. 4 is a diagram illustrating a specific content of another example different from FIG. 3 of the cancel filter for realizing the signal conversion circuit of FIG. 2;

FIG. 5 is a configuration diagram of a signal conversion circuit according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram of a signal conversion circuit according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a sound image localization position, which is used for description of FIGS. 5 and 6;

FIG. 8 is an explanatory diagram of a speaker setting at the time of surround reproduction of a conventional example and a speaker setting in an actual general home.

[Explanation of symbols]

Reference Signs List 1 Surround signal processing device 1A, 1B, 1C, 1D Signal conversion circuit 2, 3, 17-20, 30-32 Adder 10 Decoder 11 Amplitude adjustment and reflection sound adding circuit 12, 13, 27, 28 Signal conversion circuit (FIR Digital filter) 14A Controller 14B ROM 15, 16, 29 Inverter 21, 22 Switch 23-26 Output terminal C Center channel signal L Left channel signal Lc, Rc, Ls, Rs Spatial localization signal Lt, Rt Left and right total signal M R Right channel signal S Rear channel signal SP1 to SP5 Speaker X Source signal x Target sound image localization position

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-207597 (JP, A) JP-A-5-244697 (JP, A) JP-A-5-328500 (JP, A) 128400 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04S 1/00-7/00

Claims (8)

(57) [Claims] 1. A surround signal processing apparatus that responds to a three-channel signal of a two-channel stereo left channel signal, a right channel signal, and a rear channel signal for obtaining a surround sound effect, comprising: a listener at a predetermined position; Left channel space localization signal and right channel space for localizing one component of a sound reproduced from a pair of speakers that are actually arranged on the left and right of the front of the listener at two predetermined left and right symmetrical positions behind the listener. In order to obtain a localization signal, the transfer characteristics h _1L , h _1R , h _2L , h _2R of each space from the pair of speakers actually arranged to the left and right ears of the listener and the predetermined rear portion transfer characteristic p _Lx of each space from the speaker disposed only at the time of measurement at one position to the left and right ears of the listener, by using the p _Rx, cf _Lx = ( _{2R · p Lx -h 2L · p} Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H where transmission that satisfies _{H = h 1L · h 2R -h} 2L · h 1R A signal conversion circuit for converting the rear channel signal by having characteristics cf _Lx and cf _Rx; and a means for adding the left channel spatial localization signal and the inverted signal of the right channel spatial localization signal to the left channel signal. A means for adding the right channel spatial localization signal and an inverted signal of the left channel spatial localization signal to the right channel signal. 2. A two-channel stereo left channel signal, a right channel signal, a rear channel signal for obtaining a surround sound effect, and a center channel signal for improving sound image localization at the center of the two-channel stereo. A surround signal processing device responsive to a channel signal, comprising: two predetermined symmetric left and right rear components of a sound reproduced from a pair of speakers that are actually disposed in front of and right of a listener at a predetermined position. In order to obtain a first spatial localization signal for the left channel and a first spatial localization signal for the right channel for localization at the respective positions, each of the pair of speakers arranged from the actually disposed pair to the left and right ears of the listener transfer characteristics h _1L of space, and _{h 1R, h 2L, h 2R} , or speakers placed only at the time of measurement at one predetermined position of the rear Transfer characteristic p _Lx of each space to the left and right ears of the listener, by using the _{p Rx, cf Lx = (h} 2R · p Lx -h 2L · p Rx) / H cf Rx = (- h 1R _{· p Lx + h 1L · p} Rx) / H _{where, H = h 1L · h 2R} -h transfer characteristic satisfies _2L · h _1R cf _Lx, the first signal for converting said rear channel signals by having cf _Rx A conversion circuit, and a second spatial localization signal for the left channel and a second spatial localization signal for the right channel for localizing one component of the sound reproduced from the pair of speakers at a predetermined position at the front center of the listener. In order to measure the transfer characteristics h _1L , h _1R , h _2L , h _2R of the respective spaces from the pair of speakers actually arranged to the left and right ears of the listener, and to measure at the predetermined position in the front center From the speaker placed only at the time of Using the transfer characteristic p _Lx of each space, and a _{p Rx, cf Lx = (h} 2R · p Lx -h 2L · p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx ) / H where H = h _1L · h _2R −h _2L · h _1R , which has transfer characteristics cf _Lx and cf _Rx to convert the center channel signal, and a second signal conversion circuit for the left channel. Means for adding a first spatial localization signal, the second spatial localization signal for the left channel, and an inverted signal of the first spatial localization signal for the right channel to the left channel signal; Means for adding a second spatial localization signal for the right channel and an inverted signal of the first spatial localization signal for the left channel to the right channel signal. 3. A surround signal processing apparatus which responds to three channel signals of a left channel signal, a right channel signal of a two channel stereo, and a rear channel signal for obtaining a surround sound effect, wherein a listener at a predetermined position Left channel space localization signal and right channel space for localizing one component of a sound reproduced from a pair of speakers that are actually arranged on the left and right of the front of the listener at two predetermined left and right symmetrical positions behind the listener. In order to obtain a difference signal between the localization signals, transfer characteristics h _1L , h _1R , h _2L , h _2R of each space from the pair of speakers actually arranged to the left and right ears of the listener, transfer characteristic p _Lx of each space from the speaker disposed only at the time of measurement in one of two predetermined positions of the back until the left and right ears of the listener, and a p _Rx using _{, Cf Lx = (h 2R ·} p Lx -h 2L · p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · a signal conversion circuit that converts the rear channel signal by having transfer characteristics cf _Lx and cf _Rx that satisfy h _1R ; and a unit that adds the difference signal to one of the left channel signal and the right channel signal. Means for adding an inverted signal of the difference signal to the other of the left channel signal and the right channel signal. 4. A four-channel stereo signal including a left channel signal, a right channel signal, a rear channel signal for obtaining a surround sound effect, and a center channel signal for improving sound image localization at the center of the two-channel stereo. A surround signal processing device responsive to a channel signal, comprising: two predetermined symmetric left and right rear components of a sound reproduced from a pair of speakers that are actually disposed in front of and right of a listener at a predetermined position. In order to obtain a difference signal between the first spatial localization signal for the left channel and the first spatial localization signal for the right channel for localization to the respective positions, the left and right ears of the listener are obtained from the pair of speakers actually arranged. Transfer characteristics h _1L , h _1R , h _2L , h _2R
Cf _Lx = (h) using transfer characteristics p _Lx and p _Rx of the respective spaces from the speaker arranged only at the time of measurement at one of the two rear predetermined positions to the left and right ears of the listener. _2R · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _1R A first signal conversion circuit for converting the rear channel signal by having the characteristics cf _Lx and cf _Rx; and for localizing one component of the sound reproduced from the pair of speakers to a predetermined position at the front center of the listener. Second
In order to obtain a spatial localization signal, transfer characteristics h _1L , h _1R , h _2L , h _2R of each space from the pair of speakers actually arranged to the left and right ears of the listener, and the front center Cf _Lx = (h _{2 R} · p _Lx −h _2L ·) using transfer characteristics p _Lx and p _Rx of the respective spaces from the loudspeaker arranged only at the time of measurement at the predetermined position to the left and right ears of the listener. p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _2L · h _1R has transfer characteristics cf _Lx and cf _Rx A second signal conversion circuit for converting the center signal, thereby adding the difference signal and the second spatial localization signal to one of the left channel signal and the right channel signal; The inverted signal and the second spatial localization signal are And means for applying to the other channel signal and the right channel signal, a surround signal processing apparatus having. 5. When a left channel signal and a right channel signal of a two-channel stereo are reproduced from a first pair of speakers that are actually arranged in front of and right and left of a listener at a predetermined position, the listener's 1 which is a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers actually arranged on the front left and right.
A surround signal processing device responsive to a channel signal, wherein a spatial reproduction signal for a left channel for localizing a sound reproduced from the second pair of speakers to two predetermined positions symmetrically behind the listener. And the transfer characteristics h _1L , h _1R , h _2L of the respective spaces from the second pair of speakers actually arranged to the left and right ears of the listener in order to obtain the spatial localization signal for the right channel. h _2R ,
Using the transfer characteristics p _Lx and p _Rx of each space from the speaker arranged only at the time of measurement at one of the rear predetermined positions to the left and right ears of the listener, cf _Lx = (h _2R · p _{Lx -h 2L · p Rx) / H} cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · h 1R transfer characteristic satisfying cf _Lx, a signal conversion circuit that converts the rear channel signal by having cf _Rx ; a unit that adds the left channel spatial localization signal to an inverted signal of the right channel spatial localization signal; Means for adding to the inverted signal of the left channel spatial localization signal. 6. When a left channel signal and a right channel signal of a two-channel stereo are reproduced from a first pair of speakers that are actually arranged in front of and right and left of a listener at a predetermined position, the listener's A rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers actually arranged on the front left and right, and a center channel signal for improving sound image localization at the center of the two-channel stereo. A surround signal processing device responsive to a two-channel signal, comprising: a left channel for localizing one component of a sound reproduced from the second pair of speakers to two predetermined left-right symmetric positions behind a listener; A second pair of speakers actually arranged to obtain a first spatial localization signal for the first channel and a first spatial localization signal for the right channel. Transfer characteristics h _1L of each of the spaces up to the left and right ears of al the listener,
Using h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of the respective spaces from the speaker arranged only at the time of measurement at one of the rear predetermined positions to the left and right ears of the listener. _{, cf Lx = (h 2R ·} p Lx -h 2L · p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · a first signal conversion circuit for converting the rear channel signal by having transfer characteristics cf _Lx , cf _Rx satisfying h _1R, and a component of sound reproduced from the second pair of speakers being forward of a listener. In order to obtain a second spatial localization signal for the left channel and a second spatial localization signal for the right channel for localization at the center predetermined positions, the listener's listener is transmitted from the second pair of speakers actually arranged. Transfer characteristics h _1L , h _1R , h of each space to the left and right ears _2L , h
_{Using 2R} and transfer characteristics p _Lx and p _Rx of the respective spaces from the speaker arranged only at the time of measurement at the predetermined position at the front center to the left and right ears of the listener, cf _Lx = (h _2R · _{p Lx -h 2L · p Rx)} / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H _{where, H = h 1L · h 2R} -h 2L · h 1R transfer characteristics cf satisfying the _A second signal conversion circuit that converts the center channel signal by having _Lx and cf _Rx ; and converts the first spatial localization signal for the left channel and the second spatial localization signal for the left channel into the first spatial localization for the right channel. A surround signal comprising: a unit for adding the first spatial localization signal for the right channel and the second spatial localization signal for the right channel to an inverted signal of the first spatial localization signal for the left channel. Processing equipment. 7. When a left channel signal and a right channel signal of a two-channel stereo are reproduced from a first pair of speakers that are actually arranged on the left and right in front of the listener at a predetermined position, the listener's 1 which is a rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers actually arranged on the front left and right.
A surround signal processing device responsive to a channel signal, wherein a spatial reproduction signal for a left channel for localizing a sound reproduced from the second pair of speakers to two predetermined positions symmetrically behind the listener. And a transfer characteristic h _1L , h _1R of each space from the actually arranged second pair of speakers to the left and right ears of the listener in order to obtain a difference signal between the left channel and the right channel spatial localization signal. h _2L ,
Using h _2R and transfer characteristics p _Lx and p _Rx of each space from a speaker arranged only at the time of measurement at one of the two rear predetermined positions to the left and right ears of the listener, cf _Lx = _{(h 2R · p Lx -h 2L} · p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H where, satisfies _{H = h 1L · h 2R -h} 2L · h 1R A surround signal processing apparatus comprising: a signal conversion circuit that converts the rear channel signal by having transfer characteristics cf _Lx and cf _Rx that perform the conversion; and a unit that obtains an inverted signal of the difference signal. 8. When a left channel signal and a right channel signal of a two-channel stereo are reproduced from a first pair of speakers which are actually arranged in front of and at the left and right of the listener at a predetermined position, the listener's A rear channel signal for obtaining a surround sound effect by a signal reproduced from a second pair of speakers actually arranged on the front left and right, and a center channel signal for improving sound image localization at the center of the two-channel stereo. A surround signal processing device responding to a two-channel signal, comprising: a left channel first device for localizing a sound reproduced from the second pair of speakers to two predetermined left-right symmetrical positions behind a listener; A second pair of speakers actually arranged to obtain a difference signal between the spatial localization signal and the first spatial localization signal for the right channel; Transfer characteristics h _1L of each of the spaces up to the left and right ears of al the listener,
h _1R , h _2L , h _2R and transfer characteristics p _Lx , p _Rx of each space from a speaker arranged only at the time of measurement to one of the two rear predetermined positions to the left and right ears of the listener. Using, cf _Lx = (h _{2 R} · p _Lx −h _2L · p _Rx ) / H cf _Rx = (− h _1R · p _Lx + h _1L · p _Rx ) / H where H = h _1L · h _2R −h _A first signal conversion circuit for converting the rear channel signal by having transfer characteristics cf _Lx , cf _Rx satisfying _2L · h _1R , and a listener receiving one component of sound reproduced from the second pair of speakers In order to obtain a second spatial localization signal for localization at a predetermined position at the front center of the listener, each space from the second pair of speakers actually arranged to the left and right ears of the listener is obtained. Transfer characteristics h _1L , h _1R , h
_2L, by using the h _2R, transfer characteristic p _Lx of each space from the front center speaker disposed only at the time of measurement at a predetermined position to the left and right ears of the listener, and a p _Rx, cf _Lx = ( _{h 2R · p Lx -h 2L ·} p Rx) / H cf Rx = (- h 1R · p Lx + h 1L · p Rx) / H where, satisfies _{H = h 1L · h 2R -h} 2L · h 1R A second signal conversion circuit for converting the center channel signal by having transfer characteristics cf _Lx and cf _Rx ; a means for adding the difference signal to the second spatial localization signal; Means for adding to the spatial localization signal.