JPH05153698A - Sound field enlargement controller - Google Patents

Abstract

PURPOSE:To enlarge an acoustic field to the outside of the left and the right loudspeakers so that an acoustic image to be positioned fixedly in the vicinity of the front of a listener does not become blurred. CONSTITUTION:A degree of correlation between each acoustic signal of both left and right channels is detected by a correlation detecting part 19 or 19a, and in response to a result of its detection, a level of a crosstalk signal of each right and left channel generated by correcting a level and a phase of the acoustic signal of each left and right channel is adjusted. In such a way, a vocal voice, etc., whose degree of correlation is high can be reproduced by a high tone quality by which an acoustic image does not become blurred in the forward direction of listeners 3a, 4a, and also, and acoustic image positioned fixedly in the vicinity of the left and the right ends of a sound field formed by loudspeakers SL, SR can be positioned fixedly on the outside of the loudspeakers SL, SR.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field expansion control apparatus suitable for use in a sound reproducing apparatus such as a television receiver in which the left and right speakers are closely spaced.

[0002]

2. Description of the Related Art In a sound reproducing device such as a television receiver in which the distance between the left and right speakers is narrow, when the listener moves away to a desired listening position, the left and right speakers expand in the forward direction of the listener. The angle becomes smaller than 30 ° at which an ideal sound field can be formed, and it is not possible to perform realistic sound reproduction.

Therefore, conventionally, a part of the phase and level of the sound signal of the right channel is corrected and superimposed on the sound signal of the left channel, and a part of the phase and level of the sound signal of the left channel is similarly corrected. Then, a sound reproducing device is used which is superposed on the sound signal of the right channel. As a result, an effect equivalent to the case where the speakers of the left and right channels are arranged outside the position where they are actually arranged, that is, so that the divergence angle is large, is obtained.
In this way, the sound field is expanded and the sense of realism is improved.

[0004]

In the above-mentioned prior art,
Regardless of the state of the acoustic signal, the sound field originally formed between the left and right channel speakers is extended to the outside of these speakers. Therefore, although the sound image of a musical instrument or the like to be localized at the left and right ends of the sound field can be expanded further outward, the sound field such as vocal sound to be localized in the front direction of the listener is also expanded. Will end up. Therefore, the sound image is blurred and the sound quality is deteriorated.

An object of the present invention is to provide a sound field expansion control device capable of suppressing deterioration of sound quality and expanding a sound field.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an acoustic signal source for outputting stereo acoustic signals of both left and right channels and at least one of the phase and level of the acoustic signals of the left and right channels from the acoustic signal source are provided. Crosstalk signal creating means for creating a crosstalk signal for each of the right and left channels by correction, a detecting means for detecting the degree of correlation between the acoustic signals of the left and right channels from the acoustic signal source, and a detection result of the detecting means In response to the above, the adjusting means for adjusting the level of the crosstalk signal, and the adding means for adding the acoustic signals of the left and right channels from the adjusting means to the acoustic signals of the left and right channels from the acoustic signal source, respectively, and outputting It is a sound field expansion control device characterized by including.

Further, the present invention corrects at least one of the phase and the level of the acoustic signal source for outputting stereo audio signals of the left and right channels and the acoustic signal of each of the left and right channels from the acoustic signal source to correct each of the right and left sides. Crosstalk signal creating means for creating a channel crosstalk signal, detecting means for detecting the degree of correlation between the left and right channel acoustic signals from the acoustic signal source, and a detection result of the detecting means, The present invention is characterized by including adjusting means for delaying the crosstalk signal, and adding means for adding the acoustic signals of the left and right channels from the adjusting means to the acoustic signals of the left and right channels from the acoustic signal source and outputting the resultant signals. It is a sound field expansion control device.

Further, the detecting means of the present invention is characterized in that the degree of correlation is detected based on the level difference between the acoustic signals of the left and right channels.

Further, the detecting means of the present invention is characterized in that the degree of correlation is detected based on the ratio between the level difference and the level sum between the acoustic signals of the left and right channels.

[0010]

According to the present invention, the stereophonic sound signals of the left and right channels from the acoustic signal sources such as the magnetic tape reproducing device and the radio receiver are input to the crosstalk signal creating means,
At least one of the phase and the level is corrected and converted into a crosstalk signal of each of the right and left channels.

Detecting means is provided in association with the crosstalk signal generating means, and the detecting means determines the degree of correlation between the acoustic signals of the left and right channels from the acoustic signal source, for example, the acoustic signals of the both channels. Detection is performed based on the level difference between signals or the ratio of the level difference and the level sum. The detection result of the detection means is given to the adjustment means, and the adjustment means responds to the detection result and adjusts or delays the level of the crosstalk signal.

The crosstalk signals of the left and right channels thus adjusted by the adjusting means are added together by the adding means for the channels corresponding to the left and right acoustic signals from the acoustic signal source. The acoustic signal from the adding means is sonicated by a speaker or the like via a power amplifier or the like.

Therefore, when the degree of correlation is high, that is, when the sound image such as vocal sound is relatively localized in the front direction of the listener, the level of the crosstalk signal is reduced or the delay time is reduced. ,
It is possible to suppress the blurring of the sound image and reduce the deterioration of the sound quality. When the degree of correlation is low, the level of the crosstalk signal is increased or the delay time is increased,
As a result, the sound field can have a sense of expanse, and sound reproduction with a realistic sensation can be performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sound reproducing device 1 according to an embodiment of the present invention.
3 is a block diagram showing the electrical configuration of FIG. In addition, in FIG. 1, the listener is only 3a, and in the center between the left and right speakers,
Listen to the sound. In front of the listener 3a, speakers SL and SR for left and right channels are arranged at relatively narrow intervals. From a sound signal source 11 such as a magnetic tape reproducing device or a radio receiver, a left channel sound signal is derived on a line 12 and a right channel sound signal is derived on a line 13. The acoustic signals of both channels are analog /
After being converted into digital acoustic signals by the digital converters ADL and ADR, they are input to the signal processing device 14.

The signal processing device 14 is realized by a so-called digital signal processor or the like, and a memory 15 is provided correspondingly. Further, a control unit 18 for controlling the arithmetic processing operation of the signal processing device 14 in response to an input operation from the input unit 17 is provided. Signal processing device 1
In response to the control signal from the control unit 4, 4 performs delay calculation, attenuation calculation, etc. using the memory 15, creates a crosstalk signal as described later, and outputs the sound from the acoustic signal source 11. Add to signal.

From the signal processing device 14, digital acoustic signals of left and right channels are derived. The digital audio signal of each channel is converted into an analog audio signal by the digital / analog converters DAL and DAR, amplified by the power amplifiers APL and APR, and given to the speakers SL and SR of the corresponding channels. Sounded.

FIG. 2 is a functional block diagram for explaining the signal processing operation in the signal processing device 14. The signal processing block in the signal processing device 14 is roughly composed of sound image control units U1 to U3 and filter units F4L, F4R;
5L, F5R and delay sections T4L, T4R; T5L, T5
It is configured to include R, adders ML and MR, and a correlation detector 19.

In general, the propagation characteristics of sound differ depending on the frequency. Therefore, in order to align the phases of all the frequency bands of the sound heard near the entrance of the ear canal of the listener 3a, the sound signal is set for each predetermined frequency band. And is corrected by the sound image control units U1 to U3.

Therefore, the sound signal of the left channel input to the sound image control unit U1 is input to the bandpass filter unit (hereinafter abbreviated as BPF) F1L, and the frequency band in which the sound image control unit U1 should perform the sound image control. The signal component at f1, eg 200-400 Hz, is filtered. BPF
The output of F1L is input to the crosstalk generator C1 described later. Similarly, the sound signal of the right channel is BPFF1.
After the signal component of the frequency band f1 is filtered by R, it is input to the crosstalk generator C1.

Similarly, in the sound image control unit U2,
The acoustic signal of the left channel is BPFF2L and frequency band f
2, for example, a signal component of 400 to 800 Hz is filtered and then input to the crosstalk generation unit C2, and the acoustic signal of the right channel is input to the crosstalk generation unit C2 via the BPFF2R.

Furthermore, in the sound image control unit U3, the acoustic signal of the left channel is BPFF3L in the frequency band f3,
For example, after the signal component of 800 to 1600 Hz is filtered, it is input to the crosstalk generation unit C3, and the acoustic signal of the right channel is input to the crosstalk generation unit C via the BPFF3R.
Input to 3.

Further, a part of the left channel acoustic signal from the analog / digital converter ADL is passed through a high pass filter section (hereinafter abbreviated as HPF) F4L or a low pass filter section (hereinafter abbreviated as LPF) F5L. Via the delay units T4L and T5L, respectively.
After being delayed by L, t5L, they are input to the addition unit ML. Similarly, a part of the sound signal of the right channel from the analog / digital converter ADR is the HPFF4R or LP.
The delay units T4R and T5 are further passed through the FF5R.
After being delayed by time t4R, t5R at R, the adder MR
Entered in. The cutoff frequency f4 of HPFF4L and F4R is selected to be 1600 Hz, and LPFF5
The cutoff frequency f5 of L and F5R is selected to be 200 Hz.

The correlation detector 19 detects the degree of correlation between the acoustic signals of the left and right channels as will be described later, and responds to the detection result via the line 20 to the crosstalk generators C1 to C3. Output a detection signal.

FIG. 3 is a functional block diagram for explaining the crosstalk generator C1 in detail. The BPFF1
A part of the acoustic signal of the left channel via L is the coefficient part Q1.
The right crosstalk signal is input to the addition unit M1 via L, the attenuation unit AL, and the phase unit PL, and is added to the right channel acoustic signal from the BPFF1R via the coefficient unit Q1R. The output from the adder M1 is output to the delay unit TR at time tR.
It is delayed by a certain amount, further multiplied by a coefficient bR in the attenuator BR and attenuated, and then output to the adder MR.

Similarly, a part of the sound signal of the right channel via the BPFF1R is added as a left crosstalk signal via the coefficient part Q2R, the attenuation part AR and the phase part PR to the addition part M.
2 and is added to the left channel acoustic signal from BPFF1L via the coefficient part Q2L. The output from the adder M2 is delayed by the delay unit TL for the time tL, further multiplied by the coefficient bL in the attenuator BL to be attenuated, and then output to the adder ML.

Each coefficient part Q1L, Q2R; Q2L, Q
1R is each coefficient q1L in response to the detection signal from the correlation detection unit 19 input via the line 20,
q2R; q2L and q1R are multiplied by the input acoustic signal to be attenuated. The phase parts PL and PR correct the phase of the input acoustic signal by θL and θR, respectively, and the attenuation parts AL and AR multiply the input acoustic signal by the coefficients aL and aR to attenuate it.

The phase correction amounts θL and θR and the coefficient q1
The constants for digital signal processing such as L, q2R; q2L, q1R; aL, aR are the time tL, tR of the delay units TL, TR and the coefficients bL, bR of the attenuation units BL, BR.
At the same time, it is set by the control unit 18 in response to an input operation from the input unit 17. The remaining crosstalk generators C2 and C3 are also constructed similarly to the crosstalk generator C1, except that the phase correction amounts θL and θR are the same.
The coefficients aL, aR, etc. are set to mutually different values in this embodiment.

FIG. 4 is a functional block diagram of an embodiment of the correlation detector 19. After the polarity of the right channel acoustic signal R via the BPFF1R is inverted by the inverting unit 21,
The adding section 22 adds the sound signal L of the left channel via the BPFF 1L. In this way, the addition unit 22 outputs the signal LR obtained by subtracting the right channel acoustic signal R from the left channel acoustic signal L. The signal from the adder 22 is calculated as an absolute value by the absolute value calculator 23, and then output to the line 20 as the detection signal.

Although the correlation detecting section 19 creates the detection signal based on the level difference LR between the acoustic signals L and R of the left and right channels, as another embodiment of the present invention, the correlation shown in FIG. Like the detection unit 19a, the detection signal may be created based on the ratio (LR) / (L + R) of the level difference LR between the left and right acoustic signals L and R and the level sum L + R. ..

That is, the polarity of the sound signal R of the right channel via the BPFF1R is inverted by the inverting unit 21, and then the sound signal L of the left channel via the BPFF1L is added by the adding unit 22.
And is output to the division unit 24. Division unit 24
In addition, after the acoustic signals L and R of the left and right channels from the BPFF1L and F1R are mutually added by the adder 25,
It has been entered. The division unit 24 calculates the ratio between the level difference L−R of the acoustic signals L and R of the left and right channels and the level sum L + R, and outputs it to the absolute value calculation unit 26. Absolute value calculator 2
6 calculates the absolute value of the output from the division unit 24,
It outputs to 0 as the detection signal.

The detection signal becomes smaller as the correlation between the left and right acoustic signals L and R becomes higher, that is, the level difference becomes smaller. Corresponding to this, coefficient units Q2L and Q1
The coefficients q2L and q2R of R become large, and the coefficient unit Q1L,
The coefficients q1L and q2R of Q2R become small. Therefore, the level of the crosstalk signal that has undergone the phase and level correction signal processing via the coefficient units Q1L and Q2R decreases, and the level of the acoustic signal that has undergone no signal processing via the coefficient units Q2L and Q1R increases. As a result, the higher the degree of correlation between the left and right channels such as vocal sound, the higher the ratio of no-signal processing, and the sound image can be clearly localized in front of the listener 3a with high sound quality.

On the other hand, when the correlation between the acoustic signals L and R between the left and right channels is low, the ratio of the crosstalk signal subjected to the signal processing increases and the sound field is changed as shown in FIG. Can be expanded. That is, the localization positions of the respective sound images of the musical instruments, vocal sounds, and the like indicated by reference numerals H1 to H5 in FIG. 6 are changed as indicated by reference numerals H1a to H5a by performing the signal processing as described above. Can be made

In FIG. 6, left and right speakers SL and SR from a sound image represented by reference mark H1a to a sound image represented by reference mark H2a and from a sound image represented by reference mark H4a to a sound image represented by reference mark H5a. The sound image localized to the outside is generated by the crosstalk signal and the signal of no signal processing, and is changed from the sound image indicated by the reference sign H2a to the reference sign H.
The sound image in the relatively front direction up to the sound image shown by 4a is generated by the signal of the signalless processing. In this way, the sound field is expanded to the outside of the left and right speakers SL and SR, and it is possible to perform sound reproduction with a high sense of presence.

Further, the time tR of the delay unit TR is set to the delay unit TL.
Of the coefficient bR of the coefficient part BR
Is set to be smaller than the coefficient bL of the coefficient portion BL so that the sound from the right channel speaker SR is transmitted to the left channel speaker SL.
Of the two speakers SL, SR, the difference in direction angle between the speakers SL, SR with respect to the front direction of the listener, of the two speakers SL, SR. It is possible to correct an asymmetrical sound field caused by a symmetric sound field. Therefore, it can be suitably implemented in an automobile or the like. By reducing the delay time and level of the sound on the left channel side, it is possible to form an optimum sound field for the listener on the speaker SL side.

In order to prevent a sudden change in the sound field due to a sudden change in the degree of correlation, the coefficients q1L and q2R and the coefficients q2L and q1R may cross each other and change. Alternatively, it may be changed by providing a hysteresis characteristic or the like.

FIG. 7 shows a sound image controller C according to another embodiment of the present invention.
Fig. 1a is a functional block diagram of 1a, this embodiment is similar to the previously described embodiment and corresponding parts have the same reference numerals. It should be noted that in this embodiment, each coefficient part Q1L, Q2R;
The delay units T1L and T1 are provided before the Q2L and Q1R, respectively.
2R; T2L and T1R are provided. The times t1L and t2R of the delay units T1L and T2R are the same as the line 2
The lower the level of the detection signal input via 0, that is, the higher the degree of correlation, the delay unit T
It is set longer than the time t2L, t1R of 2L, T1R. This is for the listener 3a to utilize the so-called Haas effect, in which the earliest sound is perceived as the main sound, and the sound arriving later is canceled, and the so-called Haas effect is used. , T1R is, for example, several m to several tens msec.

By adjusting the delay time according to the degree of correlation in this manner, the sound quality of the sound image localized between the speakers SL and SR is achieved even for an acoustic signal having a low degree of correlation between the left and right channels such as reverberant sound. Can be suppressed and the sound field can be expanded to the outside of the left and right speakers SL and SR.
Therefore, in order to increase the presence, the acoustic signal source 1
It can be suitably used for a configuration in which an initial reflection sound, a reverberation sound, and the like are added to the acoustic signal from 1. In this case, the correlation detector 19 or 19a needs to detect the degree of correlation based on the acoustic signal before the addition of the initial reflected sound or the reverberant sound.

[0038]

As described above, according to the present invention, the level or delay time of the crosstalk signal is adjusted in accordance with the correlation between the left and right channel acoustic signals, so that the correlation is high and For a vocal sound or the like localized in the front direction of a person, it is possible to suppress the blurring of the sound image and reduce the deterioration of the sound quality. Further, the sound images near the left and right ends of the sound field having a low degree of correlation can be localized further outward, and sound reproduction with a realistic sensation can be performed. In this way, the sound field can be expanded without deteriorating the sound quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a sound reproducing device 1 according to an embodiment of the present invention.

2 is a functional block diagram of a signal processing device 14 used in the sound reproduction device 1. FIG.

FIG. 3 is a block diagram for explaining in detail a function of a crosstalk generation unit C1 in the signal processing device 14.

FIG. 4 is a functional block diagram of a correlation detection unit 19 used in the signal processing device 14 according to an embodiment of the present invention.

FIG. 5 is a functional block diagram of a correlation detection unit 19a according to another embodiment of the present invention.

FIG. 6 is a plan view showing the expansion of the sound field according to the present invention.

FIG. 7 is a crosstalk generator C1 according to another embodiment of the present invention.
It is a functional block diagram of a.

[Explanation of symbols]

1 Sound Reproducing Device 3a Listener 11 Sound Signal Source 14 Signal Processing Device AL, AR; BL, BR; Q1L, Q2R; Q2L, Q
1R Coefficient section C1 to C3, C1a Crosstalk generation section ML, MR; M1, M2 Addition section PL, PR Phase section T4L, T4R; T5L, T5R; TL, TR; T1
L, T2R; T2L, T1R delay unit U1 to U3 sound image control unit

Claims (4)

[Claims] 1. A cross between right and left channels by correcting at least one of a phase and a level of a sound signal of the left and right channels from the sound signal source for outputting stereo sound signals of the left and right channels. Crosstalk signal creating means for creating a talk signal, detecting means for detecting the degree of correlation between the left and right channel acoustic signals from the acoustic signal source, and the crosstalk signal in response to the detection result of the detecting means. Of the sound signals of the left and right channels from the adjusting means, and adding means for adding the sound signals of the left and right channels from the sound signal source to the sound signals of the left and right channels, respectively, and outputting the sound signals. Field expansion control device. 2. A cross between right and left channels by correcting at least one of a phase and a level of a sound signal of the left and right channels from the sound signal source for outputting stereo sound signals of the left and right channels. Crosstalk signal creating means for creating a talk signal, detecting means for detecting the degree of correlation between the left and right channel acoustic signals from the acoustic signal source, and the crosstalk signal in response to the detection result of the detecting means. A sound field expansion characterized by including an adjusting means for delaying each of the left and right channels from the adjusting means, and an adding means for adding and outputting the acoustic signals of the left and right channels from the acoustic signal source respectively. Control device. 3. The sound field expansion according to claim 1, wherein the detection means detects the degree of correlation based on the level difference between the left and right channel acoustic signals. Control device. 4. The detection means detects the degree of correlation based on the ratio of the level difference between the acoustic signals of the left and right channels and the level sum. The sound field expansion control device described in.