JPH0851698A - Surround signal processing device and video / audio reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] A monaural rear surround signal is processed with a simple structure and reproduced by a pair of speakers such as a television receiver to produce a surround effect. The rear surround signal S is made into two uncorrelated signals by the additional signal processing circuit OP. Adder 2 and differencer 3
Then, a sum signal and a difference signal are generated from the two signals. The filters 4 and 5 process the sum signal and the difference signal. A sum signal and a difference signal are generated from the signals processed by the filters 4 and 5, and reproduced from the speakers SP1 and SP2. The transfer characteristics P and N of the filters 4 and 5 are P = (F + K) / (S +
A) and N = (F−K) / (S−A) are set. However, S is the transfer characteristic from a pair of speakers to the ear on the same side of the listener LM, A is the transfer characteristic to the ear on the opposite side, and F is 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 up to the ear on the opposite side. Furthermore, reproduction is performed with a difference (level difference, time difference, etc.) from the front signal.

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 device for reproducing an acoustic signal by a speaker, and more particularly to a surround signal processing device for surround reproduction surrounding a listener. For example, a pair of front speakers can be used to artificially reproduce the center and rear surround signals, and
This is a surround signal processing device capable of constructing a 4-channel surround system with one speaker. This surround signal processing device (sound image localization device) is realized with an extremely simple configuration.

[0002]

[Prior art]

(Technical background) Conventionally, in order to reproduce a stereophonic sound that can obtain a sound field or sound image localization from the listener's position to the rear, two speakers (front speakers) in front of a stereo and a surround speaker are used. A total of at least three speakers, one rear speaker (rear speaker) or two, is required, and like the surround playback or high definition 3-1 system that uses one surround signal,
When reproducing up to the center channel, one or two speakers are further required as a center speaker, and an amplifier and a cable for the reproduced channel are required.

That is, as the setting of the speaker necessary for the surround reproduction, for example, as shown in FIG. 12 (A), L and R located on the left and right in front of the listener LM.
A channel speaker set and rear left and right rear speaker sets for surround of the SL and SR channels, or in addition to this, a center speaker of the C channel in the front center part are required.

However, in a general household, it is difficult to arrange the rear speaker and the center speaker in terms of space and cost, and an actual speaker set is as shown in FIG. 12 (B). In this case, it is not possible to obtain a sufficient surround effect by only providing the speaker sets of L and R channels located on the left and right in front of the listener LM. In particular, the surround reproduction method using a monaural surround signal (one system of rear surround signal) is characterized by expressing the sound field behind the listener and expressing the movement of the sound image.
The effect could not be exhibited without installing the rear speaker.

However, recently, there has been considered a surround signal processing device capable of obtaining a stereophonic effect similar to the case where a rear speaker set is provided by reproducing only front left and right speakers.

(Prior Art) This is to convert the rear channel signal in addition to the original L and R channel signals of the two-channel stereo to the two speakers in front of the listener at a predetermined position. The sound image localization signal obtained by the above, or by providing two pairs of speakers in front,
Only the signals of the original L and R channels are given to the pair, and the sound image localization signals are given to the other pair. By performing such sound image localization, it is possible to perform surround reproduction as if a sound is heard from the rear even if the rear speaker behind the listener does not actually exist.

In order to obtain the desired sound image localization signal by converting the rear channel, the transfer characteristics of each space from the pair of speakers that are actually arranged to the left and right ears of the listener and the sound image are localized. The calculation is performed using the transfer characteristics of the respective spaces from the speaker, which is placed at one of the two predetermined positions behind which the user wants to be made, only during measurement to the left and right ears of the listener. That is, a filter operation using a convolver (convolution operation processing circuit) or the like is performed.

The structure and principle of a conventional surround signal processing device using this sound image localization signal will be described below. FIG. 13 is a configuration diagram illustrating a system outline of a surround signal processing device using a sound image localization technique.
In FIG. 13, 20 is 2 as an example of 4 channels.
In order to perform the surround reproduction surrounding the listener LM by receiving the stereo signals L and R of the channels, the center channel signal C for improving the localization of the stereo center, and the rear channel signal S for obtaining the surround stereophonic effect. , Rear channel signal S and center channel signal C
It is a surround signal processing device for converting and into a sound image localization signal for localizing each of them to an intended position in space. By reproducing the stereo signals L and R and the sound image localization signal from the speakers SP1 and SP2 arranged in front of the listener LM on the left and right, rear speakers SP3 arranged on the rear of the listener LM which are originally required, SP4, a center speaker SP5 arranged in the front center of the listener LM, and a rear speaker SP6 arranged in the rear center of the listener LM are unnecessary to obtain a surround stereophonic effect.

FIG. 14 is a diagram for explaining the principle of localizing a sound image at an intended position in the space surrounding the listener LM by the two speakers SP1 and SP2 arranged in stereo. 14, the transfer characteristics (frequency response of impulse response) from the left speaker SP1 to the left and right ears of the listener LM are now h1L and h1R, and the right speaker S is shown in FIG.
The transfer characteristic from P2 to the left and right ears of the listener LM is h2L,
h2R. Further, the transfer characteristics to the left and right ears of the listener LM when an actual speaker is placed at the target localization position x are pLx and pRx. Here, each transfer characteristic is obtained by arranging a speaker, a human head or a dummy head, and a microphone at both binaural positions in an anechoic space, and performing appropriate waveform processing and the like.

Next, a signal conversion circuit 2 whose transfer characteristic is represented by cfLx and cfRx at the source X of the acoustic signal to be localized.
Consider that the signals obtained through 1A and 21B are reproduced by the speakers SP1 and SP2, respectively. At this time, letting the signals obtained in the left and right ears of the listener LM be eL and eR,

EL = h1L · cfLx · X + h2L · cfRx · X (11a) eR = h1R · cfLx · X + h2R · cfRx · X (11b)

On the other hand, when the source X is reproduced from the target localization position, the signal obtained in the left and right ears of the listener LM is dL,
If dR, then dL = pLx · X (12a) and dR = pRx · X (12b).

Now, if the signals obtained in the left and right ears of the listener LM by reproduction of the speakers SP1 and SP2 match the signals when the source is reproduced from the target position, the listener LM has a speaker at the target position. The sound image will be recognized as if it were. That is, the conditions eL = dL, eR =
From dR and equations (11a) (11b) (12a) (12b), X
Is erased,

H1L · cfLx + h2L · cfRx = pLx (13a) h1R · cfLx + h2R · cfRx = pRx (13b)

From equations (13a) and (13b), cfLx,
When cfRx is calculated, cfLx = (h2R.pLx-h2L.pRx) / H ... (14a) cfRx = (-h1R.pLx + h1L.pRx) / H ... (14b) where H = h1L.h2R- h2L / h1R (14c)

Therefore, the signal conversion circuit 21 of the transfer characteristics cfLx and cfRx calculated by the equations (14a) to (14c).
If a signal to be localized is processed using A and 21B (hereinafter, referred to as a localization filter for position x or simply a filter), the sound image at the target position x can be localized.

In other words, the surround signal should be processed by a pair of localization filters with the rear speaker installation position having the sound image fixed position x, and reproduced from the front speakers SP1 and SP2. Then, a plurality of pairs of localization filters are combined to form a surround signal processing device as shown in FIGS. 15 and 16, for example.

FIG. 15 shows a rear channel signal SL which receives the two-channel stereo signals L and R output from the surround decoder SD, the one-channel center channel signal C and the two-channel surround (rear) channel signals SL and SR. , SR is a device for performing a sound image localization process so as to reproduce the SR at the left and right symmetrical positions to the listener.

In this device, the rear channel signals SL and S are
A pair of localization filters (filters 21A, 21
B, 21A, 21B) are provided, and sound images are localized at the positions of the virtual rear speakers SP3, SP4 shown in FIG. That is, the L, R and C signals and the sound image localized signal are added and reproduced from the pair of front speakers SP1 and SP2. In this device, the rear channel signal S
It is necessary to perform sound image localization processing on L and SR with a total of four filters.

Although not shown, there is also a device for performing sound image localization processing on the front front channel signals L and R, and in this case, a total of eight filters are required. Further, there is a device for performing sound image localization processing for the front L, R and center C as well, and in this case, a total of 10 filters are required.

FIG. 16 shows a conventional apparatus compatible with a surround reproduction system using a monaural rear surround signal. In this configuration, a pair of localization filters (filters 21A and 21B) for one channel are provided, and the rear surround signal S is localized at the position of the virtual rear speaker SP6 shown in FIG. 13 with a total of two filters. I was letting it.

[0022]

By the way, in the above-mentioned conventional surround signal processing device (FIG. 15), a sound image localization processing filter (comprising filters 21A, 21B ...) Is required for each rear stereo signal. That is, four filters are required, which increases the hardware scale. Therefore, there is a problem that it cannot be used for consumer products such as a television receiver.

Further, a surround signal processing device using a monaural rear surround signal (FIG. 16)
However, since the sound field behind the listener could not be sufficiently expressed and the movement of the sound image could not be clearly expressed because only the localization was performed at one position in the rear, the sufficient surround effect was not obtained.

However, the applicant of the present invention, like the pair of speakers for the rear of the surround reproduction system, has the listener L
It has been found that the sound image localization processing device can be simplified when two different sound sources are localized at positions (left and right) symmetrical with respect to M.

That is, according to the present invention, when the stereo image for the rear is localized in a position (left and right) symmetrical with respect to the listener LM (position where a pair of virtual rear speakers are installed), the sound image is filtered. By optimizing the coefficient of
It is intended to provide a new surround signal processing device in which a sound image localization processing device is composed of only two filters, an adder and a subtractor.

In particular, for a surround reproduction system using one monaural rear surround signal, a pair of rear surround signals are generated and used as rear stereo signals. The surround effect is improved by localizing it to the location. At the same time, the sound image localization processing device is configured with only one filter by optimizing the pair of rear surround signal generation methods and the filter coefficients, and the sound image localization is performed at two positions in the rear.

[0027]

In order to solve the above-mentioned problems, according to the present invention, for example, as shown in FIG. 1, input is made from a pair of transducers which are arranged substantially symmetrically in front of a listener. A surround signal processing device that reproduces a rear surround signal for one system and localizes a rear surround signal to a sound image at two rear positions that are substantially symmetrical with respect to a listener. The filter 5 for processing and means for reproducing the signal processed by the filter and its inverted signal from the pair of transducers, the transfer characteristic of the filter being (F−K) / (S−A) ( Where S is the transfer characteristic from the pair of transducers to the same ear of the listener, A is the transfer characteristic from the pair of transducers to the opposite ear of the listener, and F is the sound image. Surround signal processing device, wherein the transfer characteristic from the position to be positioned to the same ear of the listener is set, and K is the transfer characteristic from the position to which the sound image is localized to the ear on the opposite side of the listener)). Is provided.

Further, as shown in FIG. 3, one pair of rear surround signals input is reproduced from a pair of transducers arranged substantially symmetrically to the listener and arranged in front of the listener, to the listener. On the other hand, a surround signal processing device for locating a rear surround signal in a sound image in two substantially symmetrical rearward positions, and means for generating uncorrelated first and second signals from the input rear surround signal, The first
And a means for generating a sum signal and a difference signal from the second signal, a first filter for processing the sum signal, a second filter for processing the difference signal, and the first and second filters Means for generating a sum signal and a difference signal from the signals processed by the above and outputting them from the pair of transducers, and the transfer characteristics P and N of the first and second filters.
P = (F + K) / (S + A) N = (FK) / (S-A) (where S is the transfer characteristic from the pair of transducers to the ear on the same side of the listener, and A is the pair of transducers). To the opposite ear of the listener, F is the transfer characteristic from the position where you want to localize the sound image to the same ear of the listener, and K is the ear from the position where you want to localize the sound image to the opposite ear of the listener. The present invention provides a surround signal processing device, which is characterized in that

Further, as shown in FIGS. 8 to 11, display means for reproducing an image, a pair of speakers arranged on both sides of the display means for reproducing sound, and an input front stereo signal. A video / audio reproducing device comprising a surround signal processing device for sound image localization at two front positions, a unit for generating a sum signal and a difference signal from an input stereo signal, and a first filter for processing the sum signal. A second filter for processing the difference signal, the first filter
And a means for generating a sum signal and a difference signal from the signal processed by the second filter and outputting the sum signal and the difference signal from the pair of speakers, and the surround signal processing device is configured.
The transfer characteristics P and N of the first and second filters are: P = (F + K) / (S + A) N = (F−K) / (S−A) (where S is a pair of loudspeakers Transfer characteristics to the ear on the same side, A is a transfer characteristic from the 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 desired to be localized to the ear on the same side of the listener, and K is (Transfer characteristics from the position where you want to localize the sound image to the ear on the opposite side of the listener)
The present invention provides a video / audio reproducing apparatus characterized in that the front stereo signal is localized on both sides of the display means or on the display means.

[0030]

According to the apparatus configured as described above, the input signal is processed by the filter, and the processed signal and its inverted signal are output, so that the input signal is substantially symmetrical to the listener. Surround image of different surround signals is localized at each position. According to the device configured as described above, the sum signal and the difference signal of the input signals are processed by the first and second filters, and the sum signal and the difference signal of the processed signals are processed. And are output, and different surround signals are localized at two positions that are substantially symmetrical with respect to the listener.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surround signal processing device and a video / audio reproducing device according to the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 5 is a block diagram of a surround signal processing device. As shown in the figure, the surround signal processing device includes a surround processing circuit (surround decoder) SD, an additional signal processing circuit OP, and a sound image localization processing means 1.
It is roughly composed of. The sound image localization processing means 1 which is the main part of the present invention is composed of an adder 2, a difference device 3, a first filter 4, a second filter 5, an adder 6 and a difference device 7. The surround processing circuit SD includes front input stereo signals L and R, center input signal C, and rear input stereo signals (surround signals) SL and S from the input signal.
It is a known decoder that demodulates and generates R. The additional signal processing circuit OP is a circuit that performs amplitude delay adjustment, reflection sound addition, etc. on the signals L, R, C, SL, and SR from the surround processing circuit SD, and is installed as necessary. It is a thing.

The first filter 4 and the second filter 5 are convolution operation means (for example, digital signal processor) such as a convolver, which have P and N transfer characteristics described later, respectively.

The rear stereo signals SL and SR from the surround processing circuit SD and the additional signal processing circuit OP are input to the sound image localization processing means 1 and are added by the adder 2 and the difference device 3 to the sum signal of the two signals and the difference. Signals and are generated. The generated sum signal is processed by the first filter 4, and the generated difference signal is processed by the second filter 5. The signals processed by the first and second filters 4, 5 are added by an adder 6,
The difference unit 7 generates a sum signal and a difference signal of both signals and makes them the processed output signals.

Further, in the adders 8 and 9, the processed output signal is added to the front stereo signals L and R and the center signal C. The added stereo signal is a pair of transducers (hereinafter, a pair of speakers SP1 and S1).
P2 as an example) and heard by the listener LM. It should be noted that the pair of speakers SP1 and SP2 are speakers arranged in the front at positions substantially symmetrical with respect to the listener LM.

Further, in the above structure, the transfer characteristics P and N of the first and second filters are: P = (F + K) / (S + A) N = (FK) / (S-A) As shown in FIG. 6 (A) (illustration of sound image localization), S is a pair of speakers SP1 and SP2 from the listener LM.
Characteristic to the ear on the same side, A is a pair of speakers SP
1, the transfer characteristic from SP2 to the ear on the opposite side of the listener LM, F is the position where the surround signal is desired to be sound image localized (the virtual rear shown by SP3 and SP4, which are positions that are substantially symmetrical with respect to the listener LM) From the installation / reproduction position of the speaker for listening) to the ear on the same side of the listener LM, and K is the transmission characteristic from the position where the surround image is desired to be sound image localized to the ear on the opposite side of the listener LM. In addition, these transfer characteristics are measured by a microphone placed at both ears of the human head (or dummy head) with a speaker for measurement placed at a predetermined position in an anechoic space, and waveform processing appropriate for the measured data is performed. Is applied.

The symbol "+" indicates a sum operation of transfer characteristics, the symbol "-" indicates a difference operation of transfer characteristics, and the symbol "/" indicates a deconvolution operation. The same side means the right ear for the right speaker, and the opposite side means the left ear for the right speaker, for example.

In the surround signal processing device thus constructed, the rear stereo signals SL and SR (surround signals) from the surround processing circuit SD are processed and reproduced from the pair of speakers SP1 and SP2. The stereo signal goes from the left speaker SP1 to the right ear of the listener LM and goes from the right speaker SP2 to the left ear of the listener LM, that is, crosstalk is canceled. To the listener LM, the signal from the left speaker SP1 is heard only in the listener's left ear, and the signal from the right speaker SP2 is heard only in the listener's right ear. Further, processing according to the transfer characteristics of F and K is performed, and a desired sound image localization position (SP3
, SP4 position). Next, this point will be described in detail in comparison with the conventional example.

The above-mentioned principle diagram (FIG. 14) and equation (14a)
Based on (14c), consider a sound image localization process that localizes two different sound sources at symmetrical positions. The speakers SP1 and SP2 for reproduction are installed at positions substantially symmetrical with respect to the listener LM, which is the premise of the present invention, and two different surround signals are shown at two positions (SP3 and SP4 at the rear). A sound image is localized at a reproduction position by a typical speaker), and the above-described principle diagram (FIG. 14) is simplified in consideration of the fact that the two rear locations where the sound image is localized are substantially symmetrical with respect to the listener LM. The configuration shown in FIG. Reference numeral 1 denotes the sound image localization processing means shown in FIG. 5, which is a sound image localization processing means which is the main part of the present invention and which causes two different sound source localizations at symmetrical positions.

As shown in FIGS. 6A and 6B, the listener LM has a central position with respect to the two front speakers SP1 and SP2, that is, the head-related transfer function is symmetrical left and right.
In this case, the transfer functions h1L and h2R from the speakers SP1 and SP2 to the ear to the same side are equal to S,
On the other hand, the transfer functions (crosstalk components) h1R and h2L to the ear on the opposite side are also equal transfer functions, and are designated as A. That is, h1L = h2R = S h1R = h2L = A

In order to perform further sound image localization, input X,
The sound image is localized by setting the signals to be transmitted to Y as pLx = F pRx = K in consideration of the symmetry and substituting them into the above equations (14a) to (14c). That is, if the input is X, the output X ', Y'from the speaker is

[0042]

[Equation 1]

Therefore, if the signal processing shown by the equations (1a) and (1b) is performed, the sound image is localized.

By the way, in the configuration of the sound image localization processing means 1 shown in FIG. 5, the transfer characteristics P and N of the first and second filters 4 and 5 are P = (F + K) / (S + A) N = (F -K) / (S-A). Outputs X'and Y'from the pair of speakers SP1 and SP2 (processed output from the sound image localization processing means 1)
Is calculated. The sum and difference of the inputs X and Y to the sound image localization processing means 1 are processed by the first and second filters 4 and 5, and the sum and difference of the processed outputs become the processing output of the sound image localization processing means 1.

[0045]

[Equation 2]

When the numerator is calculated here,

[0047]

(Equation 3)

Therefore, X'is

[0049]

[Equation 4]

It is Similarly, when Y'is obtained,

[0051]

(Equation 5)

Therefore, when an input of Y = 0 (X = SL) is added,

[0053]

(Equation 6)

Thus, the same result as the above-mentioned expressions (1a) and (1b) can be obtained. That is, if only the X side is input, as apparent from the equations (2a) and (2b), the sound image of the rear surround signal SL is localized at the localization position SP3 (illustrated in FIG. 6A described above) by the convolution processing. Will be done. Furthermore, X
= 0 (Y = SR) input,

[0055]

(Equation 7)

Thus, the equations (3a) and (3b) described above (2a) (2
Compared with the equation (b), the result is that the coefficients (transfer characteristics) that are the opposite of the input Y are convolved. That is, the sound image of the signal input to the Y side is localized at a position symmetrical with respect to the signal input to the X side. That is,
By the convolution processing, the localization position SP4 (see FIG.
The sound image of the rear surround signal SR is localized at (A).

Therefore, when rear surround signals SL and SR are given as inputs of X = SL and Y = SR, the reason for superposition is satisfied, so that the rear stereo signal (surround signal) SL is input. The sound image is localized on the left side SP3, and the sound image of the rear stereo signal (surround signal) SR is localized on the right side SP4. That is, as shown in FIG. 7 (A), the surround signals SL, SR are reproduced from the position shown in FIG. 7 (B) only by providing a pair of speakers SP1, SP2 on both sides of the television receiver TV. Therefore, stereoscopic surround sound can be reproduced by a stereo signal from the front and a rear stereo signal (surround signal) localized rearward without installing rear speakers SP3 and SP4.

In this case, in the conventional case (FIG. 15 described above), four filters are necessary to localize the stereo image for the rear (surround signal) to different places, but the above embodiment (FIG. 5). As described in detail above, the filter can be configured with two filters including the first filter 4 and the second filter 5, and the hardware scale can be reduced by half.

The front stereo signals L, R,
The added signal of the center signal C and the rear stereo signal (surround signal) subjected to the sound image localization processing may be reproduced from a pair of speakers provided separately in front. For example, as shown in FIG. 7C, the rear speakers SP11 and SP12 may be provided on the front side, for example, both outsides of the television receiver TV. In this case, the adders 8 and 9 in FIG. 5 described above combine the added signal of the front stereo signals L and R and the center signal C and the rear stereo signal (surround signal) subjected to the sound image localization processing. Without adding, the added signals of the front stereo signals L and R and the center signal C are the front speakers SP1,
The rear stereo signal (surround signal) reproduced from SP2 and subjected to sound image localization processing is the rear speaker SP1.
Play from 1, SP12. With such a configuration, the characteristics and the installation direction of the front speakers SP1 and SP2 and the rear speakers SP11 and SP12 can be set individually,
A higher surround effect can be obtained.

FIG. 8 shows a rear stereo signal S.
Not only L and SR, but front stereo signals L and R
The sound image localization processing is also applied to Similarly to the sound image localization processing for the rear stereo signals SL, SR, the front stereo signals L, R are received by the listener LM.
Even when the sound image is localized at a position symmetrical with respect to (left-right) (position where a pair of virtual front speakers are installed), by adding the two filters by optimizing the filter coefficients as described above. Image localization processing can be performed only by the subtractor and the subtracter (sound image localization processing means 1). The front and rear sound image localization processing means 1 have coefficients set at their respective sound image localization positions. Conventionally, eight filters were required to localize the sound image of the front stereo signal and the rear stereo signal (surround signal) to different places, but as described in detail in the above embodiment, the first filter is used. The filter can be composed of four filters including the second filter 5 and the second filter 5, and the hardware scale can be small.

Therefore, as shown in FIG. 9A, a pair of speakers SP1 and SP1 are provided on both sides of the television receiver TV.
By only providing SP2, as shown in FIG. 9 (B), the front stereo signals L and R are localized far away from both sides of the television receiver (display means). As in the case of a television receiver having a narrow width, the stereo feeling of the front sound is not deteriorated due to the restriction of the installation intervals of the speakers. With such a configuration, stereoscopic surround sound can be reproduced by the stereo signals L and R from the front, which have a stereo feeling, and the rear stereo signals (surround signals) SL and SR, which are localized rearward. In particular, the number of required filters can be halved as compared with the conventional one, so that the cost can be reduced and the filter can be incorporated in a consumer television receiver.

Further, FIG. 10 shows a rear stereo signal S.
In addition to L, SR, front stereo signals L, R,
The center image C is also subjected to sound image localization processing. The screen (display unit) is used for a horizontal screen television receiver, large projector, cinema screen, etc.
It is difficult to install a center signal speaker in the center (front) of the. Therefore, it is possible to provide the sound image localization processing means 10 by using the filter reduced as described above, and perform the sound image localization processing on the center signal C so as to perform front localization.

That is, in the conventional case, when the center signal C is reproduced, the display device is placed at the position where the center speaker is originally arranged, so that the center speaker is located at the left and right ends of the display, above and below the display, or above and below. I have no choice but to place it. At this time, in the arrangement of the left and right ends, the sound image is similar to normal stereo reproduction,
The clarity of the sound image is lower than when the speaker is actually placed at the required sound image position. In the upper and lower arrangements, the required sound image position and the speaker position are displaced.

Therefore, sound image localization processing is performed on the center signal C so as to perform front localization, and as shown in FIG. 11 (A), a pair of images is arranged on both sides of the television receiver in accordance with the screen position of the display DP. Speakers SP1 and SP2 are provided. With this configuration, the surround effect as shown in FIG. 11B is obtained, and the screen (display) DP is displayed.
The same effect as that when the center signal C is reproduced from the front speaker installed in front is produced, the position of the obtained sound image matches the image, and the quality of the sound image becomes clearer. In particular, compared with the case where the center signal C is reproduced from the speakers SP1 and SP2 as a monaural signal having the same left and right, the serif position on the screen becomes more accurate and the vertical shift does not occur.

Further, in a video / audio reproducing apparatus having a horizontally long display means such as a horizontally long screen television receiver, a large projector, a movie theater screen, etc., FIG.
As shown in, not only the sound image of the center signal C is localized, but also the sound signals of the front stereo signals L and R are localized inside, that is, on the display means DP (on the display).

(Embodiment 2) Next, a configuration example applied to a surround reproduction system using a monaural 1-system rear surround signal will be described. FIG. 3 is a configuration example of a surround reproduction system using a surround signal of one system. The rear signal S is a monaural 1-system surround signal, and is essentially a surround signal reproduced by the rear speaker SP6 shown in FIG. The rear signal S demodulated by the surround processing circuit (surround decoder) SD is subjected to amplitude delay adjustment and reflected sound addition by the additional signal processing circuit OP, and then divided into two parts, which are then rearranged by the sound image localization processing means 1 described above. Sound image localization processing is performed at two locations. At this time, in the additional signal processing circuit OP, different amplitude adjustments, different delay adjustments, and different reflected sound additions are performed to produce rear-side signals SR and SL that are uncorrelated to the left and right and rear-side signals SR and It is advisable to localize the sound image at two locations in the back. This is because if the sound signal localization for the monaural rear signal S is left as it is at two locations on the left and right behind, the sound is localized or in-head localization.

In this manner, the monaural surround signal of one system is reproduced as the rear signals SR and SL which are different on the left and right sides by performing sound image localization processing on the left and right two positions as shown in FIG. 4 (A). Then, as compared to the conventional case (FIG. 16) in which the sound image localization processing is performed at one position (right behind) in the rear, the sound field in the rear and the movement of the sound image become clearer, and a sufficient surround effect can be obtained. Even in this case, only two filters are required, which can be realized with a simple configuration.

(Embodiment 3) Next, a configuration example in which surround reproduction is realized with an extremely simple configuration will be described. FIG. 1 is another configuration example applied to a surround reproduction system using a monaural rear system surround signal, and is an example realized with an extremely simple configuration. Further, FIG. 2 is a configuration diagram for explaining a simplified and simplified process, in which the phase shift means 11 is added to the configuration of FIG. 3 described above. In this configuration example, a surround processing circuit (surround decoder) SD
The rearward signal S demodulated by the
(Indicated by reference numeral 11 in FIG. 2) and phase shifts to produce rear signals S, −S having opposite phases on the left and right. Then, these rear-phase rear signals S, -S are used as rear stereo signals, and sound image localization processing is performed at two rear left and right locations for surround reproduction. In this case, the sound image localization processing means (shown by reference numeral 1'in FIG. 1) is further simplified.

In this configuration, since S and -S are used as the rear stereo signal, the signal to the filter 4 shown in FIG. 2 becomes 0, and it is not necessary to input / output the signal to / from this system. That is, in the adder 2 shown in FIG. 2, S + (− S) = 0. Further, in the subtractor 3 shown in FIG. 2, S-(-S) = 2S, and the rear surround signal S may be input to the filter 5 after being doubled. Since there is an amplitude adjusting means (for example, the additional signal processing circuit OP at the preceding stage) and the adjustment can be performed here, it is not always necessary to double, that is, S.

That is, the signal to the filter 4 becomes 0,
Since it is not necessary to perform input / output processing of signals to / from this system, the adder 2, the differencer 3, the first filter 4, the adder 6, (the differencer 7 and the phase shift means 11) are not necessary. Therefore, as shown in FIG. 1, the configuration of the sound image localization processing means 1 ′ includes only the filter 5, the amplitude adjuster 12, and the inverter 13, and the number of filters is one, and the hardware scale is further reduced. can do.

Therefore, as shown in FIG. 4B, if a television receiver is constructed by integrally providing a pair of speakers SP1 and SP2 on both sides, surround sound can be easily reproduced with only two speakers. it can. Moreover, as described above, the surround signal processing device, as shown in FIG.
Since it has an extremely simple structure, it can be applied to a television receiver which is an inexpensive consumer product.

In this way, when the monaural 1-system surround signal is used as the rear signals of opposite phases on the left and right sides and the sound image localization processing is performed on the two left and right sides, the rear 1
Compared with the conventional method in which sound image localization processing was performed at the location (right behind),
The sound field in the rear and the movement of the sound image become clearer, and a sufficient surround effect can be obtained. In this case, only one filter is needed, and the configuration is extremely simple.

In each of the above embodiments, the transfer characteristics F and K from the position where the sound image is desired to be localized to the listener are changed, that is, the transfer characteristics P and N of the first and second filters 4 and 5. The sound image may be localized at any desired position by changing the. Specifically, transfer characteristics P and N (filter coefficients) according to a plurality of sound image localization positions
Is stored in a memory such as a RAM or a ROM, and a transfer characteristic corresponding to a desired sound image localization position is read from the memory by the CPU or the like (for example, reference numeral 14 shown in FIG.
As described above), the first and second filters 4 and 5 may be set. According to this structure, the left and right sound images can be rotated around the listener LM and the surround sound can be reproduced at the best position.

In this embodiment, the pair of speakers SP1 and SP2 are used as the pair of transducers.
A headrest type speaker or headphones may be used.
In this case, the crosstalk transfer characteristic A basically does not exist, and in the above example, approximately A = 0 and can be omitted. In this case, a frequency characteristic relating to headphones may be further added, and a more realistic sound field can be reproduced.

Further, in any of the embodiments, as shown in FIG.
As shown in FIGS. 7, 9, and 11, in a video / audio reproducing device such as a television receiver, a pair of (stereo) speakers are generally provided on both sides of a display unit (display) for reproducing a video. (SP1, SP2) are provided. Since the viewer (listener LM) views the display in a substantially front view, a pair of speakers (SP1
, SP2) are installed at positions substantially symmetrical to the listener (LM). In the case where two different surround signals are sound image localized at the two rear positions, there is no problem even if the two rear sound positions are limited to substantially symmetrical positions with respect to the listener LM, rather the surround effect is produced. From the viewpoint of, it is a desirable position. Therefore, a video / audio reproducing device such as a television receiver and the above-described sound image localization processing means 1 which is an essential part of the present invention (this is because a pair of speakers are installed at positions substantially symmetrical with respect to a listener. It is extremely useful to add a surround function in combination with a simplified one) on the assumption that the sound image is localized at two locations that are substantially symmetrical to the listener.

(Embodiment 4) In these embodiments, the surround effect is further improved by making a difference between the front and rear surround signals for surround reproduction. The basic configuration shown in FIG. 3 will be described as an example.

(A) Example of a structure in which a relative level (strength) difference is provided so that the sense of distance is made different. In the basic structure shown in FIG. 3 described above, a plurality of level adjusting means are provided for front reproduction. There is a level difference between the signal and the rear surround signal. For example, the surround effect is enhanced by increasing the level of the rear surround signal with respect to the front signal. The level adjustment may be performed by the additional signal processing circuit OP or by providing separate level adjusters before and after the filters 4 and 5 and before the adders 8 and 9. For example, reference numerals 22 to 26
A variable multiplier that functions as an attenuator may be provided at the location indicated by.

A plurality of level differences (for example, standard and before and after) are set in advance so that they can be selected according to the listener's preference, the content of the music (sound) to be reproduced, and the state of the reproducing apparatus. It is good to leave. Also, if there is a level difference between the front signal to be reproduced and the rear surround signal, the distance (feeling) from both signals will be different,
The distance between the position of the listener and the position of the listener can be adjusted, and the position range in which the surround effect depends on the position where the speaker is installed is widened, which is also desirable. The level (intensity) difference may be continuously variable.

(B) Example of Structure with Relative Time Difference In the basic structure shown in FIG. 3 described above, a plurality of delay means are provided so that the time difference between the front signal for reproduction and the rear surround signal is reproduced. To have. For example, if the rear surround signal is delayed by about 12 to 120 ms with respect to the front signal, the rear surround signal becomes clear and the rearward localization becomes clear. Even in this case, the delay time of the rear surround signal may be variable so that it can be selected according to the listener's preference, the content of the music (sound) to be reproduced, and the state of the reproducing device. The time difference may be implemented by the additional signal processing circuit OP or by providing separate delay devices before and after the filters 4 and 5 and before the adders 8 and 9.

(C) Example of structure in which reflected sound is added to rear surround signal In the basic structure shown in FIG. 3, the added signal processing circuit OP adds reflected sound to the rear surround signal. As for the reflected sound, the rear surround signal is delayed by several tens of ms as the initial reflected sound and several hundred ms as the higher-order reflected sound.
It is added so that the level gradually decreases. Adding reflected sound to the rear surround signal improves the out-of-head feeling of the sound in the rear and eliminates the sickness of the sound. In this case, it is advisable to variably adjust the level of the reflected sound to be added.

Further, the reflected sounds added to the left and right surround signals are made different, for example, delay time, level,
If the frequency characteristic and the attenuation characteristic are different for the left and right, the out-of-head feeling of the sound in the rear is further improved, and the sound moves away from the head.

Further, in the above embodiment, the above-mentioned FIG.
As shown in (B), when setting the transfer characteristic of the filter, the transfer characteristic 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 the transfer characteristic K is where the sound image is to be localized. The transfer characteristic from the position to the ear on the opposite side of the listener is set, and the position is precisely determined based on the position where the sound image is to be localized (positions of virtual speakers SP3, SP4).

However, the transfer characteristics of the filter may be obtained by averaging the transfer characteristics of the position where the sound image is to be localized and the position close to this position. For example, FIG.
As shown in (C), when the position where the sound image is to be localized (virtual speaker positions SP3, SP4) is 60 degrees (L1, R1) left and right with respect to the center line SC, the position is close to this position. The transfer characteristics from the right and left 80 degrees (L3, R3) and the left and right 45 degrees (L2, R2) are determined and averaged. That is, the transfer characteristics of a total of M positions of the position where the sound image is desired to be localized and the position close to this position are obtained,

[0084]

[Equation 8]

[0085]

[Equation 9]

As a result, the transfer characteristics P and N of the filter are set. Here, S is the transfer characteristic from the pair of transducers to the same ear of the listener, A is the transfer characteristic from the pair of transducers to the ear on the opposite side of the listener, and Fi is the position where the sound image is to be localized and this position. I in adjacent positions
Transfer characteristic from the third position to the same ear of the listener, K
i is a transfer characteristic from the i-th position in the position where the sound image is desired to be localized and the position close to this position to the ear on the opposite side of the listener.

When the transfer characteristics P and N of the filter are set in this way, the sound image localization position has a width, the range in which the surround effect occurs is widened, and not only one listener but a large number of listeners simultaneously. The surround reproduction can be provided to the listener, which is optimal when reproducing the large projector or the screen of the movie theater shown in FIG. In addition,
In this case, the transfer characteristic based on the position where the sound image is desired to be localized and the transfer characteristic obtained by averaging the transfer characteristics of the adjacent positions may be switched and selected.

[0088]

As described above in detail, according to the surround signal processing device of the present invention, the signal processing is performed with an extremely simple structure, and the acoustic signals from the pair of transducers are different from the installation position. The surround image can be localized in the sound image. Therefore, even when the surround signal reproduced from the pair of rear speakers is simulated by the pair of front speakers to construct a four-channel surround system with two speakers, the hardware scale is small. It can be made inexpensive and can be used for consumer equipment such as a television receiver.

In particular, when applied to a surround reproduction system using a single monaural rear surround signal, an extremely simple structure makes it possible to express the sound field in the rear and move the sound image more clearly, You can get a nice surround effect.

Further, if the front and rear surround signals for surround reproduction are reproduced with a difference, the surround effect can be further improved.

Furthermore, if the transfer characteristics of the filter are obtained by averaging the transfer characteristics of the position where the sound image is desired to be localized and the position close to this position, a range is generated at the sound image localization position and the range for surround reproduction is generated. Can be widened.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a surround signal processing device according to the present invention.

FIG. 2 is a diagram illustrating simplification of the configuration of a surround signal processing device.

FIG. 3 is a configuration diagram showing an embodiment of a surround signal processing device according to the present invention.

FIG. 4 Surround signal processing device (video / audio reproduction device)
It is a figure explaining the effect of.

FIG. 5 is a configuration diagram showing an embodiment of a surround signal processing device according to the present invention.

FIG. 6 is a diagram illustrating a sound image localization process of a surround signal processing device.

FIG. 7: Surround signal processing device (video / audio reproduction device)
It is a figure explaining the effect of.

FIG. 8 is a configuration diagram showing an embodiment of a surround signal processing device according to the present invention.

FIG. 9: Surround signal processing device (video / audio reproduction device)
It is a figure explaining the effect of.

FIG. 10 is a configuration diagram showing an embodiment of a surround signal processing device according to the present invention.

FIG. 11 is a diagram illustrating the effect of the surround signal processing device (video / audio reproduction device).

FIG. 12 is a diagram illustrating a general surround system.

FIG. 13 is a diagram illustrating a conventional sound image localization process.

FIG. 14 is a diagram illustrating the principle of sound image localization processing.

FIG. 15 is a configuration diagram of a conventional surround signal processing device.

FIG. 16 is a configuration diagram of a conventional surround signal processing device.

[Description of Reference Signs] 1,1 ′ Sound image localization processing means 2 Adder 3 Difference device 4 First filter (transfer characteristic P) 5 Second filter (transfer characteristic N) 6 Adder 7 Difference device 8, 9 Adder 10 Sound image localization processing means 11 Phase shift means 12 Amplitude adjuster 13 Inverter LM Listener (viewer) SP1, SP2 Pair of speakers (transducers) SP3, SP4, SP5, SP6 Virtual position where sound image is to be localized S pair From the speaker to the ear on the same side of the listener A Transfer characteristic from the pair of speakers to the ear on the opposite side of the listener F Transfer characteristic from the position where the sound image is to be localized to the ear on the same side of the listener K Transfer characteristics from the position where the sound image is desired to be localized to the ear opposite to the listener X, Y (first and second) inputs to the sound image localization processing means X ′, Y ′ Output of the sound image localization processing means SD Sara Command processing circuit (surround decoder) OP additional signal processing circuit L, stereo signal C center for signals S 1 line surround signal SL for the rear for R front stereo signal for SR rear (surround signals)

Claims (11)

[Claims] 1. A rear surround signal, which is input to one rear system, is reproduced from a pair of transducers arranged in front of the listener so as to be substantially symmetrical with respect to the listener. A surround signal processing device for locating a rear surround signal in a sound image at two locations, comprising: a filter for processing an input rear surround signal; and a signal processed by the filter and its inverted signal from the pair of transducers. (F-K) / (S-A) (where S is the transfer characteristic from a pair of transducers to the ear on the same side of the listener, A is a pair). Transfer characteristics from the transducer to the opposite ear of the listener, F is transfer characteristics from the position where the sound image is desired to be localized to the same ear of the listener, and K is the sound image is localized. Position the surround signal processing apparatus is characterized in that setting the transfer characteristic) and to the opposite side of the ears of the listener from. 2. A pair of transducers arranged substantially symmetrically to the listener and arranged in front of the listener reproduces an input rear surround signal for one system, and is substantially symmetrical symmetrically to the listener. A surround signal processing device for locating a rear surround signal in a sound image at two places, comprising means for generating uncorrelated first and second signals from an input rear surround signal, and the first and second Means for generating a sum signal and a difference signal from the signal, a first filter for processing the sum signal, and a second filter for processing the difference signal
And a means for generating a sum signal and a difference signal from the signals processed by the first and second filters and reproducing them from the pair of transducers, the transmission of the first and second filters The characteristics P and N are P = (F + K) / (S + A) N = (FK) / (S-A) (where S is the transfer characteristic from the pair of transducers to the ear on the same side of the listener, A Is the transfer characteristic from the pair of transducers to the ear on the opposite side of the listener, 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, and K is the transfer characteristic from the position where the sound image is desired to be localized. Surround signal processing device characterized in that it is set to transfer characteristics up to the opposite ear). 3. Display means for reproducing video, and a pair of speakers arranged on both sides of the display means for reproducing audio.
A video / audio reproducing device comprising a surround signal processing device which reproduces an inputted one-system rear surround signal from the pair of speakers and localizes a rear surround signal in a sound image at two rear positions. The surround signal processing device is configured from a filter that processes a rear surround signal, and a unit that reproduces the signal processed by the filter and its inverted signal from the pair of speakers, and the transfer characteristic of the filter is set. , (F−K) / (S−A) (where S is the transfer characteristic from the pair of speakers to the same ear of the listener, and A is the transfer characteristic from the pair of speakers to the opposite ear of the listener). , F is the transfer characteristic from the position where the sound image is to be localized to the same ear of the listener, K is the transfer characteristic from the position where the sound image is to be localized to the opposite ear of the listener)
A video / audio reproducing device characterized in that 4. Display means for reproducing video, and a pair of speakers arranged on both sides of the display means for reproducing audio.
A video / audio reproducing device comprising a surround signal processing device which reproduces an inputted one-system rear surround signal from the pair of speakers and localizes a rear surround signal in a sound image at two rear positions. Means for generating uncorrelated first and second signals from the rear surround signal, means for generating a sum signal and a difference signal from the first and second signals, and a first processing the sum signal Second filter for processing the difference signal
And the means for generating a sum signal and a difference signal from the signals processed by the first and second filters and reproducing the signals from the pair of speakers, and the surround signal processing device, The transfer characteristics P and N of the first and second filters are: P = (F + K) / (S + A) N = (F−K) / (S−A) (where S is the same for the listener from a pair of speakers) Transfer characteristic to the ear on one side, A is the transfer characteristic from the pair of speakers 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 sound image. (Transfer characteristics from the position where you want to localize the sound source to the ear opposite the listener)
A video / audio reproducing device characterized in that 5. A video / audio reproducing apparatus according to claim 3, wherein a front left / right stereo signal and a center surround signal are reproduced together with the rear surround signal. 6. Display means for reproducing video, and a pair of speakers arranged on both sides of the display means for reproducing audio.
A video / audio reproducing device comprising a surround signal processing device for locating an input front stereo signal to two front sound images, and means for generating a sum signal and a difference signal from the input stereo signal, and the sum signal. A first filter that processes a signal, a second filter that processes the difference signal, and a pair of speakers by generating a sum signal and a difference signal from the signals processed by the first and second filters From the means to output from
While configuring the surround signal processing device, the transfer characteristics P and N of the first and second filters are: P = (F + K) / (S + A) N = (FK) / (SA) (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 from the position where the sound image is desired to be localized to the listener. (Transmission characteristic to the ear on one side, K is the transmission characteristic from the position where the sound image is localized to the ear on the opposite side of the listener)
And a stereo image for the front is located far away from both sides of the display means or on the display means. 7. A video / audio reproducing apparatus according to claim 6, wherein the center surround signal is reproduced and the center surround signal is sound image localized on the display means. 8. The surround signal processing apparatus according to claim 1, wherein the front signal is reproduced and a front signal and a rear surround signal to be reproduced have a relative level difference. The surround signal processing device according to claim 2, the video / audio reproduction device according to claim 3, or the video / audio reproduction device according to claim 4. 9. The surround signal processing apparatus according to claim 1, wherein the front signal is reproduced and a front signal and a rear surround signal to be reproduced have a relative time difference. The surround signal processing device according to claim 4, the video / audio reproduction device according to claim 3, or the video / audio reproduction device according to claim 4. 10. The surround signal processing apparatus according to claim 1, wherein the front signal is reproduced and a reflected sound is added to the rear surround signal, and the surround signal processing apparatus according to claim 2, The video / audio reproduction device according to claim 3, or the video / audio reproduction device according to claim 4. 11. The surround signal processing according to claim 1, wherein transfer characteristics of the filter are obtained by averaging transfer characteristics of a position where a sound image is to be localized and a position close to this position. Device, surround signal processing device according to claim 2, video / audio reproduction device according to claim 3,
The video / audio reproduction device according to claim 4, or the video / audio reproduction device according to claim 6.