JP2985704B2 - 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 surround signal processing apparatus such as a Dolby surround, and more specifically, to a surround signal processing apparatus.
The present invention relates to an improved signal processing for supplying a natural surround sound by reducing the correlation between the left and right rear sounds.

[0002]

2. Description of the Related Art In recent years, in the audio-visual field, as is known from, for example, a Dolby surround active matrix type sound field control device disclosed in US Pat. Technological trends are changing to a method of dynamically controlling the sound field, a so-called surround method.

However, in the above-described conventional sound field control device,
The rear sound is merely a one-channel sound, and cannot sufficiently express the sound field behind the listener and cannot clearly express the movement of the sound image. Therefore, the sound is reproduced only by the left and right speakers in front of the listener. In some cases, there was a problem that the sense of spread was lacking.

Further, in a multi-channel audio system in a surround signal processing such as a 3-channel system such as a 3-channel front system and a rear 1-channel system in Dolby surround or Hi-Vision sound reproduction, the rear surround sound is monaural, and the rear surround sound is reproduced in a surround reproduction device. Since the surround channel is simply branched into the 2ch signal SL and SR, when this is reproduced by a speaker, the listener who is listening at the center of the reproduction system can easily locate the surround sound inside the head, and the original surround effect is not obtained. Had been inhibited.

In order to solve this problem, for example, as disclosed in Japanese Patent Laid-Open Publication No.
There are a method in which different delay times are given to L and SR, and a method in which one of the left and right signals is reversed in phase.

[0006]

However, 2ch
Those that give different delay times to the signals SL and SR have a disadvantage that the sound image is from one side. In the case where the left and right sides were reversed in phase, the left and right separation feeling was improved, but the reversed phase feeling was strong. In particular, Japanese Patent Application No. 6-1 already proposed by the present inventors.
As described in Japanese Patent No. 97356, the method using only two front speakers and localizing the rear surround sound to the rear of the listener by the sound image localization technique is performed by sign inversion (phase inversion) to weaken the correlation to reduce the spread effect. However, since the 2ch signals SL and SR are synthesized in the air for the surround sound, there is a tendency for a strong sense of reverse phase to appear. Further, the one subjected to the reverse phase processing has a problem that the sound quality is deteriorated due to the canceling action in a high frequency range.

The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problems. Therefore, a surround signal processing that can obtain a good surround sound field control by lowering the correlation between the left and right rear sounds and a natural and spacious feeling can be obtained. The aim is to obtain a device.

[0008]

In order to achieve the above object, a surround signal processing apparatus according to the present invention comprises:
In a surround signal processing device configured to reproduce surround sound from a pair of speakers arranged in a substantially symmetrical front position with respect to a listener based on an input of a rear monaural surround signal, the surround sound is reproduced from the pair of speakers. By providing signal processing means for performing signal processing so that a pair of left and right surround signals have decorrelation with each other, it is possible to reduce the correlation or weaken the correlation between the rear left and right surround sound during sound field control. Very good surround sound field control can be obtained, and in particular, a surround space with a natural and enhanced sense of spaciousness can be created, and a pair of left and right surround signals reproduced from the pair of speakers can be substantially left and right with respect to a listener. A sound image localization circuit that performs signal processing to localize the sound image at a symmetrical rear position is provided. When the sound field control, it is possible to localize the imaginary sound image at symmetrical positions of the rear left and right about the rear sound,
Further, the signal processing means is constituted by a comb filter for generating a sum signal and a difference signal of a delay signal of the rear monaural surround signal and a signal before the delay, and a pair of surround filters via the comb filter. By providing a signal to the sound image localization circuit, at the time of sound field control, a pair of surround sounds having a non-correlation with each other by a comb filter is located at a rear position substantially symmetrical to the listener by the sound image localization circuit. The sound image can be localized, with a very simple configuration, the expression of the sound field behind and the movement of the sound image become clearer, a sufficient surround effect can be obtained, and the signal processing means can be used as the sound image localization. A pair of surround signals from a circuit is made up of a comb filter that makes the pair of surround signals uncorrelated with each other. When the sound field is controlled, a pair of surround sounds whose sound images have been localized to the listener in a substantially symmetrical rear position by the sound image localization circuit can be decorrelated by a comb filter. With a very simple configuration, the expression of the sound field and the movement of the sound image in the rear become clearer, a sufficient surround effect is obtained, and further, the sound image localization circuit is moved from the comb filter An adder that adds the sum signal and the difference signal output as a pair of surround signals, a subtractor that subtracts the sum signal and the difference signal, and a convolution operation such as a convolver that inputs the output of the adder First to process
A second filter for inputting the output of the differentiator and performing a convolution operation such as a convolver, a differencer for subtracting the output of the first filter and the output of the second filter, An adder for adding the output of the filter and the output of the second filter is used, and the transfer characteristics P and N of the first and second filters are calculated as P = (F + K) / (S + A) N = (F −K) / (S−A) (where S is the transfer characteristic from the pair of speakers to the ear on the same side of the listener, A is the transfer characteristic from the pair of speakers to the opposite ear of the listener, and F is Transfer characteristics from the position where you want to localize the surround signal to the sound image to the ear on the same side of the listener,
K is the transfer characteristic from the position where the surround signal is to be localized to the sound image to the ear on the opposite side of the listener).
By setting the transfer characteristics, it is possible to set a range in which the surround reproduction is performed with a certain width at the sound image localization position.

[0009]

1 is a block diagram showing a first embodiment of a surround signal processing apparatus according to the present invention. In the first embodiment, when sound field control is performed,
For the back sound, localize the virtual sound images to the rear left and right, and decorrelate them with each other (uncorrelated or weakly correlated)
Thus, a very good surround sound is obtained, and in particular, a surround space with a natural and improved spaciousness is created.

In FIG. 1, reference numeral 1 denotes a monaural rear surround signal S (hereinafter simply referred to as a surround signal) supplied after the level is adjusted by a master level control unit (not shown) when reproducing a monaural rear surround sound in a multi-channel audio reproduction system. ), A sum and a difference from the original signal are made, and a comb filter (com filter) as a signal processing means for outputting as a 2-channel rear surround signal is shown. This comb filter 1 is inputted. For example, a delay circuit 1a that gives a delay amount in the range of 0 to 20 ms to the surround signal S and outputs the result as a delay signal T, and a sum signal (S + T) obtained by adding the delay signal T to the original surround signal S is represented by L
adder 1b which outputs a rear surround signal of channel ch
And a difference device 1c that outputs a difference signal (ST) obtained by subtracting the delay signal T from the original surround signal S as an Rch rear surround signal.

FIG. 2 is an amplitude characteristic diagram of an output signal for explaining the effect of the comb filter 1 which delays the surround signal S, makes a sum and a difference from the original signal, and outputs the result as a rear surround signal of 2 ch. By passing the original rear surround signal S through the comb filter 1, left and right separation is performed from the frequency spectrum, whereby 2ch rear surround signals SL and SR having less left and right correlation can be obtained.
This indicates that a good surround effect can be obtained.

In FIG. 1, a sound image localization for sound image localization processing at a specific position behind each of the 2ch rear surround signals SL and SR from the comb filter 1 is added by adding the results of the further filtering processing. Circuits 3L and 3R denote left and right speakers installed in front of the listener. The sound image localization circuit 2 includes a rear surround signal as disclosed in Japanese Patent Application No. 6-197356 already proposed by the present inventors. Left and right sound image localization filters having a pair of convolvers provided with filter coefficients Hr and Hl based on a head-related transfer function at a rearward position substantially symmetrical to the listener and provided for each channel of SL and SR. An Lch sound image localization circuit having 21a and 21b, and an R channel having similar right and left sound image localization filters 21c and 21d. Sound image localization circuit of h, left filter 2
Adder 21e for adding the outputs of 1a and 21d, and adder 21f for adding the outputs of right filters 21b and 21c
, And a signal subjected to the sound image localization processing at a specific rear position is reproduced from a pair of front speakers 3L and 3R. Actually, the left and right front sounds are further added to the pair of speakers 3L and 3R by the adders 21e and 21f to form a surround sound.

Here, the filter coefficients Hr of the left sound image localization filters 21a and 21d and the right sound image localization filter 2
The filter coefficients Hl of 1b and 21c are as described in Japanese Patent Application No.
Similar to No. 197 356, is set to Hr = (SF-AK) / (S 2 -A 2) Hr = (SK-AF) / (S 2 -A 2). Here, S is a pair of speakers 3L,
A transmission characteristic from the 3R to the ear on the same side of the listener, A is a transmission characteristic from the pair of speakers 3L, 3R to the ear on the opposite side of the listener, and F is the same as the listener from the position where the surround signal is to be localized. K is the transfer characteristic from the position where the surround signal is desired to be localized to the sound image to the ear on the other side of the listener, and these transfer characteristics are measured at a predetermined position in the anechoic space. Are arranged, measured with microphones placed at the positions of both ears of a human head (or a dummy head), and subjected to appropriate waveform processing on the measured data. Also,
The sign "+" indicates the sum operation of the transfer characteristics, the sign "-" indicates the difference operation of the transfer characteristics, the sign "/" indicates the deconvolution operation, and the same side means, for example, the right ear for the right speaker and the opposite. The side indicates, for example, the left ear for the right speaker.

Therefore, according to the above configuration, by passing the original surround signal S through the comb filter 1, left and right separation is performed from the frequency spectrum.
2ch rear surround signal S with less left-right correlation
L and SR are obtained, and the results of the further filtering processing by the sound image localization processing circuit 2 are added to cause sound image localization to be respectively performed backward, and the signals subjected to the sound image localization processing are reproduced from a pair of front speakers 3L and 3R. As a result, it is possible to localize the virtual sound images to the rear left and right with respect to the rear sound, and to decorrelate or weaken the correlation with each other, to obtain an extremely good surround sound, and especially to obtain a natural and expanded surround space. Can be created.

Second Embodiment Next, FIG. 3 is a block diagram showing a second embodiment of the surround signal processing device of the present invention. The configuration of the second embodiment shown in FIG. 3 is a modification of the first embodiment. That is, the first embodiment uses the rear surround signal SL via the comb filter 1
The SR is further filtered by the sound image localization processing circuit 2 to add the result, and the sound image is localized rearward, and the signal subjected to the sound image localization processing is transmitted to a pair of front speakers 3L,
In contrast to the reproduction from the 3R, a pair of left and right sound image localization filters 21a having the same configuration as in the first embodiment.
Lch having a sound image localization circuit having a pair of right and left sound image localization filters 21c and 21d.
h, the signal subjected to the sound image localization processing by the sound image localization circuit is
2c with less left-right correlation due to comb filter 12
h rear surround signal and a pair of front speakers 3
L and 3R.

Here, as the comb filter 12, there are provided delay circuits 12a to 12d for obtaining delay signals output from respective filters of the Lch and Rch sound image localization circuits, and delay signals via the delay circuits 12a and 12b. Adders 12e and 12f for obtaining a sum signal of the signal before the delay, differencers 12g and 12h for obtaining a difference signal between the delay signal via the delay circuits 12c and 12d and the signal before the delay, and an adder 12e An adder 12i for obtaining an addition output of the subtractor 12g and the output of the differentiator 1g.
And an adder 12j for obtaining an added output with 2h.

According to the second embodiment, Lch and Rc
h, the surround signal subjected to the sound image localization processing by the sound image localization circuit is converted into a 2ch rear surround signal having less left-right correlation by the comb filter 12 and reproduced from the pair of front speakers 3L, 3R.
As in the embodiment, the back sound is localized to the rear left and right in the left and right, and the decorrelation or the correlation between them can be weakened, so that a very good surround sound is obtained, and the feeling of spread is particularly natural and improved. Surround space can be created.

Third Embodiment Next, FIG. 4 is a block diagram showing a third embodiment of the surround signal processing device of the present invention. In the third embodiment shown in FIG. 4, the number of delay circuits of the comb filter in the second embodiment shown in FIG. 3 is reduced, thereby simplifying the filter configuration of the sound image localization circuit. The configuration is equivalent to that of the embodiment.

That is, in the third embodiment shown in FIG. 4, as the comb filter 13, delay circuits 13a and 13a for obtaining delay signals of outputs from respective filters of the sound image localization circuit are provided.
3b, and adders 13c and 1 that obtain a sum signal of the delay signal via the delay circuits 13a and 13b and the signal before the delay.
3d and difference units 13e and 13e for obtaining a difference signal between the delay signal via the delay circuits 13a and 13b and the signal before the delay.
3f, an adder 13g for obtaining an added output of the output of the adder 13c and the differentiator 13f, and an adder 13h for obtaining an added output of the output of the adder 13d and the differentiator 13e. An equivalent function is obtained even if the delay circuit of the comb filter in the second embodiment shown is halved.

Accordingly, the left and right sound image localization filters 21c and 21d used for reproducing a pair of speakers in the second embodiment shown in FIG. 3 can also be omitted from the sound image localization circuit, and the left and right sound image localization filters can be omitted. It is only necessary to provide 21a and 21b, which can be simplified.

Fourth Embodiment Next, FIG. 5 is a block diagram showing a fourth embodiment of the surround signal processing apparatus of the present invention. In the fourth embodiment shown in FIG. 5, the sound image localization circuit 2 of the first embodiment shown in FIG. 1 is simplified with a shuffler filter configuration. That is, as the sound image localization circuit 24, the sum signal (S + T) and the difference signal (S + T) output as 2-channel rear surround signals SL and SR from the comb filter 1 that outputs the surround signal S as two signals having different delay times. −T)
a, a subtractor 24b for subtracting the sum signal (S + T) and the difference signal (ST), and a convolution operation such as a convolver by inputting an output of the adder 24a having a transfer characteristic P described later. A first filter 24c, a second filter 24d having a transfer characteristic N to be described later and receiving an output of the differentiator 24b and performing a convolution operation such as a convolver;
A differentiator 24e for subtracting the output of the first filter 24c and the output of the second filter 24d;
c and an adder 24f for adding the output of the second filter 24d to the pair of speakers 3L and 3R in front of the listener after the sound image localization processing is performed at a specific position approximately symmetrically behind the listener. Has been made to play from. Here, the first and second filters 24c and 2c
The transfer characteristics P and N of 4d are expressed by the following equations, as disclosed in Japanese Patent Application No. 6-197356 already proposed by the present inventors. P = (F + K) / (S + A) N = (F−K) / (S−A)

In the surround signal processing apparatus configured as described above, by passing the original surround signal S through the comb filter 1, left and right separation is performed from the frequency spectrum, and the 2ch surround signal S with less left / right correlation is obtained.
L and SR can be obtained, a good surround effect can be obtained, and the 2-channel surround signals SL and SR are processed by the sound image localization circuit 24 having a shuffler filter and reproduced from a pair of speakers 3L and 3R in front of the listener. , From the left speaker 3L to the listener's right ear, from the right speaker 3R to the listener's left ear, that is, the crosstalk is canceled, and the left speaker 3
The signal from L can be heard only by the left ear of the listener, and the signal from the right speaker 3R can be heard only by the right ear of the listener. Further, processing is performed in accordance with the transfer characteristics F and K, and the signal is roughly behind the listener. The sound image is localized at a symmetrical specific position.

Fifth Embodiment Next, FIG. 6 is a block diagram showing a fifth embodiment of the surround signal processing apparatus of the present invention. The configuration of the fifth embodiment shown in FIG. 6 is equivalent to the configuration of the fourth embodiment shown in FIG.
That is, as in the above-described fourth embodiment, when only the front two speakers are used and the rear surround signals SL and SR are located at symmetrical positions behind the listener, the configuration of the shuffler filter is used as the sound image localization circuit. However, in the shuffler filter, the sum and difference of the two input signals are processed, and the sound image is transferred to the target position through the first and second filters 24c and 24d having transfer characteristics of P and N, respectively. Has been localized. In this case, the two input signals are (S + T) and (S
−T), and their sum and difference are 2S and 2T, respectively. If 2 meaning gain is omitted, S and T signals are handled. However, since S and T originally have a delay, it is only necessary to create a signal with and without a delay in the input signal and perform filter processing.

In particular, in the Dolby surround system, a surround signal is delayed by about 20 ms in order to separate a forward sound and a surround signal.
As shown in FIG. 6, the signal S obtained by delaying the surround signal by 20 ms is input to the first filter 24c, and the signal T delayed by (20 + 5) ms via the delay circuit 1a is input to the second filter 24d. It will be good.

In each of the embodiments described above, the surround reproduction is performed by the speakers of the front two channels. However, the present invention is also applicable to the normal front left L, the right R, and the center three C and rear C. A reproducing device using a total of 5 channels of left and right 2 channels, which are obtained by splitting a monaural signal, may be used. If a 2 channel surround signal is reproduced by a rear surround speaker having an ordinary 5 speakers, the correlation between the 2 channels is reduced. Localization is improved, and a better surround effect is obtained.

[0026]

As described above, according to the present invention,
In a surround signal processing device configured to reproduce surround sound from a pair of speakers arranged in a substantially symmetrical front position with respect to a listener based on an input of a rear monaural surround signal, the surround sound is reproduced from the pair of speakers. By providing signal processing means for performing signal processing so that a pair of left and right surround signals have decorrelation with each other, it is possible to reduce the correlation or weaken the correlation between the rear left and right surround sound during sound field control. Very good surround sound field control can be obtained, and in particular, there is an effect that a surround space with a natural and expanded feeling can be created, and the pair of left and right surround signals reproduced from the pair of speakers can be used by the listener. A sound image localization circuit that performs signal processing to localize the sound image at a substantially symmetrical rear position with respect to Thus, during sound field control, there is an effect that the virtual sound image can be localized at a position symmetrical to the rear left and right with respect to the rear sound, and the signal processing unit is provided with a delay signal of the rear monaural surround signal. And a comb filter that generates a sum signal and a difference signal of the signal before the delay and a signal before the delay, by providing a pair of surround signals through the comb filter to the sound image localization circuit, when controlling the sound field, The sound image localization circuit allows the sound image localization circuit to localize the sound image at a substantially symmetrical rear position with respect to the listener by a pair of surround sounds that are uncorrelated with each other by the comb filter. The expression of the sound field and the movement of the sound image become clearer, a sufficient surround effect is obtained, and the signal processing means is connected to a pair of surrounds from the sound image localization circuit. A pair of surround signals through the comb filter are reproduced from the pair of speakers by a comb filter that makes the signals have decorrelation with each other. A pair of surround sounds, in which the sound image is localized at a substantially symmetric rear position with respect to the listener, can be made uncorrelated with each other by a comb-shaped filter.With an extremely simple configuration, the sound field representation and Movement of the sound image becomes clearer, a sufficient surround effect is obtained, and the sound image localization circuit further adds the sum signal and the difference signal output as a pair of surround signals from the comb filter. And a subtractor that subtracts the sum signal and the difference signal, a first filter that receives an output of the adder and performs a convolution operation such as a convolver,
A second filter that receives the output of the differentiator and performs a convolution operation such as a convolver, a subtractor that subtracts an output of the first filter and an output of the second filter, and an output of the first filter. And an adder for adding the output of the second filter. The transfer characteristics P and N of the first and second filters are calculated as follows: P = (F + K) / (S + A) N = (F−K) / (S-A) (where S is the transfer characteristic from the pair of speakers to the ear on the same side of the listener, A is the transfer characteristic from the pair of speakers to the opposite ear of the listener, and F is the sound image of the surround signal. Transfer characteristics from the position you want to localize to the ear on the same side of the listener,
K is the transfer characteristic from the position where the surround signal is to be localized to the sound image to the ear on the opposite side of the listener).
By setting the transfer characteristics, there is an effect that it is possible to set a range in which the surround reproduction is performed by giving a width to the sound image localization position.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a surround signal processing device of the present invention.

FIG. 2 is a filter characteristic diagram of the comb filter 1 of FIG.

FIG. 3 is a block diagram illustrating a configuration of a second embodiment of the surround signal processing device according to the present invention;

FIG. 4 is a block diagram illustrating a configuration of a third embodiment of a surround signal processing device according to the present invention.

FIG. 5 is a block diagram showing a configuration of a fourth embodiment of the surround signal processing device of the present invention.

FIG. 6 is a block diagram showing a configuration of a fifth embodiment of the surround signal processing device of the present invention.

[Explanation of symbols]

 1, 12, 13 Comb filters (signal processing means) 1a Delay circuit 1b Adder 1c Differentiator 12a to 12d Delay circuit 12e, 12f, 12i, 12j Adder 12g, 12h Differentiator 13a, 13b Delay circuit 13c, 13d, 13g, 13h Adders 13e, 13f Difference devices 2, 24 Sound image localization circuits 21a, 21d Left sound image localization filters 21b, 21c Right sound image localization filters 21e, 21f Adders 24a, 24f Adders 24b, 24e Difference devices 24c First filters 24d second filter 3L, 3R speaker

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-22399 (JP, A) JP-A-6-289858 (JP, A) JP-A-6-98400 (JP, A) JP-A-7-98 212897 (JP, A) JP-A-53-97401 (JP, A) JP-A-57-115100 (JP, A) JP-A-62-128232 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) H04S 1/00-7/00

Claims (1)

(57) [Claims] 1. A surround signal processing device configured to reproduce surround sound from a pair of speakers arranged at a substantially symmetrical front position with respect to a listener based on an input of a rear monaural surround signal. A signal processing means for performing signal processing so that the pair of left and right surround signals reproduced from the pair of speakers are uncorrelated with each other; and a pair of left and right surround signals reproduced from the pair of speakers are transmitted to a listener. A sound image localization circuit for performing signal processing to localize the sound image at a substantially symmetrical rear position, wherein the signal processing means includes a sum signal and a difference signal between the delayed signal of the rear monaural surround signal and the signal before the delay. A comb filter for generating a signal, and a pair of surround signals passing through the comb filter is supplied to the sound image localization circuit. Wherein the sound image localization circuit comprises:
An adder that adds the sum signal and the difference signal output as a pair of surround signals from the comb filter, a subtractor that subtracts the sum signal and the difference signal, and an output of the adder A first filter for performing a convolution operation such as a convolver, a second filter for receiving an output of the differentiator and performing a convolution operation such as a convolver,
A subtractor for subtracting the output of the second filter and the output of the second filter, and an adder for adding the output of the first filter and the output of the second filter. P = (F + K) / (S + A) N = (F−K) / (S−A) (where S is from a pair of speakers to the ear on the same side of the listener) A is a transfer characteristic from a pair of speakers to the ear on the opposite side of the listener, F is a transfer characteristic from a position where the surround signal is to be localized in the sound image to the ear on the same side of the listener,
K is a surround signal processing device that is set to a transfer characteristic from a position at which the surround signal is desired to be localized in the sound image to an ear on the opposite side of the listener.