JPH08336199A - Sound signal processor - Google Patents

Abstract

PURPOSE: To improve an acoustic effect by arranging an adjusting means making the sound signals reproduced from a pair of speakers have an amplitude difference in a circuit making the sound signals have uncorrelation with each other and making the signals into pseudo stereo. CONSTITUTION: This device is provided with a means making a pair of sound signals have an amplitude difference. As the means, an amplifier 4a is provided at the front stage of a circuit 11 on the side of the input in a first filter 23 and an amplifier 4b, is provided on the side of the input in a second filter 24. In order to differentiate the amplitude adjusting ratio of the both amplifiers 4a and 4b, the input of the first filter 23 is properly adjusted. Thus, an effect preventing unnatural localization feeling can be prevented without losing spread feeling at the time of a sound reproduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is particularly applicable to a case where a rear surround signal such as a front 3ch and rear 1ch 3-1 system in sound reproduction of Dolby surround or high definition is a monaural sound having only one system, The present invention relates to a surround signal processing device for providing a natural sound so as to prevent in-head localization when realizing sound by sound image localization.

[0002]

2. Description of the Related Art In recent years, a multi-channel stereo technique has become widespread in the audiovisual field, and a method of intentionally changing the direction of controlling the sound image to the side or the rear of the listener and controlling the sound field. There is. However, general households require four or five speakers and are not widely used. Therefore, by reproducing a sound source that requires a rear speaker from two front speakers by sound image localization, sound field control that obtains an effect equivalent to that of multi-channel stereo by two speakers of a general stereo is used as Dolby Surround. Playback systems such as the HDTV 3-1 system and the like are known.

[0003]

However, in a reproduction system such as Dolby Surround or HDTV 3-1 system, the rear signal is one monaural system, and if the sound is electrically localized to the left and right positions, the surround sound is produced. Intracranial localization occurs. In addition, even when normal 5 speaker reproduction is performed, when localization is performed at a position symmetrical with respect to the rear 2 speakers, in-head localization is often performed. Therefore, in order to prevent this in-head localization, for example, as in Japanese Patent Laid-Open No. 5-207597, addition of reflected sound or changing of delay time is performed so that rear monaural sound to be sound-localized becomes different signals for left and right. I took the means of. However, in that case, the sound image may be biased to one side, and a good effect cannot be obtained. Further, in order to solve this problem, the present inventors have already proposed in Japanese Patent Application No. 6-197356 a method in which the sound image localization signal is reproduced in opposite phase on the left and right sides to obtain a natural sound image and a sound image feeling. However, even in this case, the opposite sense remains,
In addition, the sound quality was unnatural, and a good effect was not obtained.

Therefore, the present invention has been made in view of these problems. When the rear surround signal is a monophonic signal of one system, a virtual sound image is placed at a symmetrical position behind the listener by a sound image localization process. It is an object of the present invention to obtain a surround signal processing device capable of creating a surround space in which a natural and expansive feeling is enhanced by enhancing a sound effect when pseudo stereo processing is performed in order to prevent in-head localization when reproducing.

[0005]

In order to achieve the above object, a surround signal processing device according to the present invention comprises:
In a surround signal processing device configured to reproduce a surround sound from a pair of speakers arranged in a substantially symmetrical front position based on an input of a rear monaural surround signal, the left and right reproduced from the pair of speakers. A pseudo stereo circuit that makes a pair of surround signals pseudo-stereo by making them uncorrelated to each other is provided with an amplitude adjusting means for giving an amplitude difference to a pair of rear surround signals, so that the rear surround signal is a monophonic system. When a signal is a signal, when a virtual sound image is reproduced in a symmetrical position behind the listener, a pair of rear surround signals are manipulated during pseudo-stereo processing to prevent in-head localization and antiphase sense It is possible to create a surround space that enhances the sound effect and enhances the natural and expansive feeling.

Further, the amplitude adjusting means has a pair of amplitude adjusting means for adjusting the amplitude of each of the pair of rear surround signals, and the level difference between the pair of rear surround signals is changed by making the amplitude adjustment rates different. To reproduce an effective sound field.

Further, the pseudo stereo circuit is provided with a delay means for providing a time difference between the pair of rear surround signals, and the delay means provides decorrelation to obtain a pair of rear surround signals for pseudo stereo. At the same time, the delay time can be variably set, so that the delay time can be freely set together with the amplitude to reproduce an effective wide sound field.

Further, the delay means has a pair of delay means for respectively delaying the pair of rear surround signals, and by making the delay times different, the delay time is respectively increased together with the amplitude of the pair of rear surround signals. It is possible to freely set and select the most effective value to clarify the virtual sound image and produce various sound fields.

Further, based on the input of a pair of rear surround signals for pseudo stereo output from the above pseudo stereo circuit, reproduction is performed from a pair of speakers arranged at a front position substantially symmetrical to the listener. By further providing a sound image localization circuit that localizes a pair of left and right surround signals to a rear position that is substantially symmetrical to the listener, a virtual sound image can be localized to a rear symmetrical position for the rear sound. It is possible to create a surround space with an increased sense of spaciousness.

Further, by further providing a reflected sound adding circuit for adding a reflected sound to a pair of rear surround signals which are pseudo-stereo-converted by adjusting the amplitudes of a plurality of rear surround signals having different delay times and adding them, It is possible to give a sense of distance to the virtual sound image, to obtain a realistic sensation such as in a hall or a movie theater, and to reproduce the sound field in various acoustic spaces very well.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows that the present inventors have already filed Japanese Patent Application No. 7-2866.
FIG. 5 is a block diagram of a circuit for demonstrating the configuration of a surround signal processing device which is a premise of the present invention proposed in No. 5, and which is a circuit for converting a rear monaural sound into pseudo stereo and performing localization processing. That is, the surround signal processing device shown in FIG.
Surround sound is reproduced from a pair of speakers 3L, 3R arranged at a front position that is substantially symmetrical to the listener based on the input of the rear mono surround signal S. A pseudo stereo circuit 1 having a comb-shaped filter for generating a sum signal and a difference signal between a delayed signal of the rear surround signal S and a signal before the delay for signal processing to have decorrelation, and the pseudo stereo circuit. A sound image localization circuit 2 is provided for locating a pair of surround sounds output from the circuit 1 and having a non-correlation with each other at a rear position substantially symmetrical to the listener.

Here, the pseudo stereo circuit 1 adds a delay amount to the surround signal S and outputs it as a delay signal S ', and a sum signal obtained by adding the original surround signal S and the delay signal S'. Adder 12 that outputs S + S '
And an adder 13 that outputs a difference signal SS ′ obtained by subtracting the delay signal S ′ from the original surround signal S.

Further, the sound image localization circuit 2 includes an adder 21 for obtaining an addition output of a sum signal and a difference signal output as a pair of surround signals from the pseudo stereo circuit 1.
An adder 22 for obtaining a subtraction output of the sum signal and the difference signal,
A first filter 23 that inputs the output of the adder 21 and performs a convolution operation such as a convolver, and the differencer 2
The second filter 24 which inputs the output of 2 and performs convolution operation processing such as a convolver, the first filter output and the second filter 24.
Differentiator 25 for subtracting the filter output of the second filter and an adder 26 for adding the first filter output and the second filter output
It has and.

Then, the first and second filters 2
The transfer characteristics P and N of Nos. 3 and 24 are P = (F + K) / (S + A) (1.1) N = (F−K) / (S−A) (1.2) (where S is a pair of Transfer characteristics from the speaker to the ear on the same side of the listener, A is the transfer characteristics from the pair of speakers to the ear on the opposite side of the listener, and F is the ear on the same side of the listener from the position where the surround signal is desired to be localized. Transfer function up to,
K is set to the transfer function from the position where the surround signal is desired to be localized to the ear on the opposite side of the listener), and by setting the transfer function, the range for surround reproduction can be set with a width at the localization position of the sound image. It is done like this.

In the surround signal processing device having the above-mentioned configuration, when controlling the sound field, it is possible to weaken the decorrelation or the correlation with the rear left and right surround sounds, so that an extremely good surround sound field can be obtained. , In particular, it is possible to create a surround space with a natural and expanded feeling, and it is possible to localize a virtual sound image in a position symmetrical to the rear with respect to the rear sound, and with a very simple configuration, the representation of the sound field in the rear and the sound image. The movement of is clear, and a sufficient surround effect can be obtained.

That is, in the configuration shown in FIG. 1, since the input surround sound S is a monophonic signal of one system, the input surround signal S is passed through the pseudo-stereo processing circuit 1 which is a comb filter in order to decorrelate the input signal S. Is the delay circuit 11
Of the signal S'delayed by the adder 12 is obtained by the adder 12, and the other output is obtained by the adder 13 of the subtraction output of the signal S'delayed. By inputting the sound source signal of the virtual sound image to each of the sound image localization circuits of No. 197356, as shown in FIG. 2, the virtual sound images of S + S 'and S-S' are placed at the positions symmetrical to the rear of the listener for the rear sound. Each can be localized.

By the way, when the configuration shown in FIG. 1 is expressed above, the inputs P _in and N to the first and second filters 23 and 24 are shown.
_in can be expressed by the following equation. P _in = (S + S ′) + (S−S ′) = 2S (2.1) N _in = (S + S ′) − (S−S ′) = 2S ′ (2.2) That is, the first filter 23. The input P _in is input to the surround signal S as it is, and the input N _in to the second filter 24 is input to a signal S ′ obtained by delaying the input surround signal S. This is shown in the figure,
It can be modified as shown in FIG.

Further, in the configuration shown in FIG. 1, the adder 1 for adding the signal S'delayed through the delay circuit 11 is added.
The positive / negative relationship of the delayed signal S ′ with respect to 2 and 13 may be changed, and when the sign of the delayed signal S ′ is changed, the inputs P _in and N _in to the first and second filters 23 and 24 are P _in = (S−S ′) + (S + S ′) = 2S (3.1) N _in = (S−S ′) − (S + S ′) = − 2S ′ (3.2), and similarly. , The adder 21 in the sound image localization circuit 2
And when the sign of the input to 22 is changed, P _in = (S + S ′) − (S−S ′) = 2S (4.1) N _in = (S + S ′) + (S−S ′) = It can be transformed to 2S (4.2). This is the first filter 23
The delayed signal S ′ is input to the second filter 24, and the surround signal S is input to the second filter 24 as it is.

In the present invention, the above (4.1), (4.
In the signal processing shown by the equation (2), the signals input to the first and second filters 23 and 24 are given an amplitude difference in order to further increase the sense of sound field spread. This configuration is shown in FIG. That is, FIG. 4 is a block diagram showing a surround signal processing device according to the present invention. As the amplitude adjusting means for giving an amplitude difference to a pair of surround signals, the delay circuit 11 is provided on the input side to the first filter 23. The amplitude adjusting amplifier 4a is provided in the preceding stage, and the amplitude adjusting amplifier 4b is provided on the input side of the second filter 24 so that the amplitude adjusting rate is made different to provide the amplitude difference, which is provided in the pseudo stereo circuit 1. To be

In FIG. 4, if the first filter 23
When the input on the side is set to 0, it becomes the same as the signal processing method of Japanese Patent Application No. 6-1973356 already proposed by the present inventors. That is, the localization relationship on the left and right of the virtual sound image shown in FIG. 2 is S ′, −S ′, which corresponds to the localization of the virtual sound in the opposite phase on the left and right unless delay is taken into consideration. this is,
It can prevent localization in the head and give a sense of spaciousness, but a sense of antiphase remains. Therefore, by appropriately adjusting the input on the side of the first filter 23, without impairing the feeling of spaciousness,
It produces the effect of preventing unnatural localization.

In the present embodiment, the delay amount by the delay circuit 11 as a delay means for obtaining a pair of rear surround signals pseudo-stereo-ized by giving a time difference to the pair of rear surround signals to give the decorrelation. Is 5m
s and the amplitude adjustment ratios of the amplitude adjusting amplifiers 4a and 4b are made different, the difference in the input levels to the first filter 23 and the second filter 24 of the sound image localization circuit 2 becomes equal to the second filter 24. On the other hand, the input on the side of the first filter 23 is set to a value lower by 2 dB. Therefore, since the input on the second filter 24 side has a level difference in addition to the preceding sound effect, it is possible to effectively reproduce a sound field having a spread. In the configuration of FIG. 4, the delay circuit 11 is
Although the case where it is provided on the first filter 23 side is shown, it may be provided only on the second filter 24 side.

Further, by developing the configuration example shown in FIG. 4 described above, delay circuits 11a and 11b are first provided as delay circuits.
FIG. 5 shows what is provided for each input stage of the second filters 23 and 24. With such a configuration, the relationship between the delay times of the first and second filters 23 and 24 can be freely variably set, and the amplitude can be freely changed, so that the most effective amplitude and delay effect can be obtained. Can be taken. For example, depending on the environment of the listening room,
It is only necessary to change the input level to each filter 23 and 24,
In a dead room, the input of the first filter 23 side is appropriately added to soften the anti-correlation. In a live room, the input of the first filter 23 side is narrowed down to clarify the virtual sound image. It is possible to produce a place.

When a DSP (digital signal processor) actually performs signal processing, since only one surround sound system exists, one delay line is sufficient and efficiency is high. Further, by appropriately extracting signals having different delay times from this delay line, reflected sound can be added, a sense of distance can be obtained in the virtual sound image, and a realistic sensation as heard in a hall or movie theater can be obtained. . This configuration is shown in FIG.

That is, FIG. 6 uses a reflected sound adding circuit 5 for adding a reflected sound to a pair of rear surround signals which are pseudo-stereo-ized by adjusting the amplitudes of a plurality of rear surround signals having different delay times and adding them. It is a block diagram which shows the surround signal processing apparatus which enabled it to expand the sound field. The reflected sound adding circuit 5 extracts a plurality of rear surround signals S having different delay times from the delay line 11c as a delay unit, appropriately adjusts the amplitude by the amplitude adjusting amplifier 51, and adds them by the adder 52. , It is possible to add a reflected sound to a pair of rear surround signals that are made into pseudo-stereo, and it is possible to reproduce a sound field in various acoustic spaces from listening in a large space such as a dome to a mini theater which is a small space. It can be reproduced very well. The first and second filters 23 and 24 shown in each figure are FIR filters, and the frequency phase characteristics of the head-related transfer characteristics can be completely simulated.

[0025]

As described above, according to the present invention, the surround sound is reproduced from the pair of loudspeakers arranged at the front position substantially symmetrical to the listener based on the input of the rear surround signal. In the surround signal processing device described above, the pair of left and right surround signals reproduced from the pair of speakers are pseudo-stereo-converted into a pseudo-stereo by making them uncorrelated to each other, and a pair of rear surround signals have an amplitude difference. When the rear surround signal is a monophonic signal of one system, a pseudo stereo process is performed to prevent in-head localization when reproducing a virtual sound image at a symmetrical position behind the listener when the rear surround signal is a monophonic signal. At that time, the sense of antiphase can be softened by manipulating the amplitude of a pair of rear surround signals, which enhances the acoustic effect and spreads naturally. But there is an effect that can create a surround space was improved.

The amplitude adjusting means has a pair of amplitude adjusting means for adjusting the amplitude of each of the pair of rear surround signals, and by making the amplitude adjusting rates different, the level difference between the pair of rear surround signals is increased. There is an effect that it is possible to reproduce an effective wide sound field by providing.

Further, the pseudo stereo circuit is provided with a delay means for giving a time difference to the pair of rear surround signals, and the pair of rear surround signals pseudo-stereo are obtained by providing the decorrelation with the delay means. At the same time, by making the delay time variably set, there is an effect that the delay time can be freely set together with the amplitude, and an effective sound field with a spread can be reproduced.

Further, the delay means has a pair of delay means for delaying the pair of rear surround signals respectively, and by making the delay times different, the delay time and the amplitude of the pair of rear surround signals are respectively delayed. There is an effect that it is possible to freely set and select a value with the greatest effect to clarify the virtual sound image and produce various sound fields.

In addition, based on the input of a pair of pseudo-stereo-converted rear surround signals output from the pseudo-stereo circuit, reproduction is performed from a pair of speakers arranged at a front position substantially symmetrical to the listener. By further providing a sound image localization circuit that localizes a pair of left and right surround signals to a rear position that is substantially symmetrical to the listener, a virtual sound image can be localized to a rear symmetrical position for the rear sound. This has the effect of creating a surround space with an increased sense of spaciousness.

Furthermore, by further providing a reflected sound adding circuit for adding a reflected sound to a pair of rear surround signals which are pseudo-stereo-converted by adjusting the amplitudes of a plurality of rear surround signals having different delay times and adding them, There is an effect that a virtual sound image can be given a sense of distance, a realistic sensation of a hall or a movie theater can be obtained, and sound field reproduction in various acoustic spaces can be reproduced extremely well.

[Brief description of drawings]

FIG. 1 is a block diagram showing a surround signal processing device which is a prerequisite technique of the present invention and which performs rearrangement processing of a rear monaural sound into pseudo-stereo.

FIG. 2 is a diagram showing a localization position when a rear surround virtual sound image is localized from a pair of speakers arranged substantially symmetrically in front of a listener.

3 is a block diagram showing a signal processing configuration when the configuration of FIG. 1 is modified.

FIG. 4 is a block diagram showing a surround signal processing device according to the present invention, in which a pseudo stereo input is provided with an amplitude difference.

FIG. 5 is a diagram showing a surround signal processing device according to the present invention, and is a diagram showing a circuit configuration characterized in that a pair of pseudo stereo inputs are provided with respective time differences to obtain arbitrary characteristics.

FIG. 6 is a diagram showing a surround signal processing device according to the present invention, and is a diagram showing a circuit configuration in which a sound image localization process is performed so that a sound field can be expanded by using a reflected sound adding circuit.

[Explanation of symbols]

1 Pseudo Stereo Circuit 2 Sound Image Localization Circuit 3L, 3R A Pair of Speakers 11, 11a, 11b Arranged at Front Positions that are Approximately Left-Right Symmetrical to the Listener 11c Delay Line (Delay Means) 4a, 4b Amplitude Adjustment amplifier (amplitude adjusting means) 5 Reflection sound addition circuit.

Claims (6)

[Claims] 1. A surround signal processing device for reproducing surround sound from a pair of speakers arranged in a front position substantially symmetrical to a listener based on an input of a rear monaural surround signal. A pseudo stereo circuit that makes a pair of left and right surround signals reproduced from a speaker pseudo-stereo by making them non-correlated to each other is provided with amplitude adjusting means for giving an amplitude difference to a pair of rear surround signals. Surround signal processing device. 2. The surround signal processing device according to claim 1, wherein the amplitude adjusting means has a pair of amplitude adjusting means for adjusting the amplitude of each of the pair of rear surround signals, and the amplitude adjusting rates are made different. Surround signal processing device characterized by. 3. The surround signal processing device according to claim 1, wherein the pseudo stereo circuit is provided with a delay unit for providing a time difference between the pair of rear surround signals.
A surround signal processing device, wherein the delay time of the delay means can be variably set. 4. The surround signal processing device according to claim 3, wherein the delay means has a pair of delay means for respectively delaying the pair of rear surround signals, and makes the delay times different. Surround signal processing device. 5. The surround signal processing device according to claim 1, wherein the listener receives a pair of rear surround signals that are pseudo-stereoized and output from the pseudo-stereo circuit. And a sound image localization circuit that localizes a pair of left and right surround signals reproduced from a pair of speakers arranged in a substantially symmetrical front position to a rear position that is substantially symmetrical to the listener. Surround signal processing device. 6. The surround signal processing device according to claim 1, wherein a pair of rear surrounds are pseudo-stereoized by amplitude-adjusting and adding a plurality of rear surround signals having different delay times. A surround signal processing device further comprising a reflected sound adding circuit for adding a reflected sound to a signal.