JP2991452B2 - Sound signal reproduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] The present invention relates to a sound reproducing apparatus for reproducing a stereo sound signal, wherein a direct sound signal and a reflected sound signal are generated for each channel, and a direct sound signal of one channel is generated. By adding the reflected sound signal of the channel and the signal obtained by shifting the level and the phase of the reflected sound signal of the other channel for each channel and reproducing them from the speakers,
Reproduces realistic sound by making the reflected sound more spacious than the direct sound.

[Industrial applications]

The present invention relates to a sound reproducing device for reproducing a stereo sound signal.

[Conventional technology]

2. Description of the Related Art Conventionally, a stereo sound reproducing device for reproducing a stereo sound signal (hereinafter, referred to as a stereo reproducing device) has been put to practical use. As a signal source of such a stereo sound signal, a magnetic tape reproducing device, a CD (compact disk) reproducing device, or the like is used.

Such a stereo reproducing apparatus is intended to reproduce a stereo sound signal having a right channel sound signal and a left channel sound signal to realize a realistic sound reproduction. On the other hand, in recent years, a sound field reproducing device that reproduces not only two channels of a right channel and a left channel but also a reflected sound that can be heard from around a listener and realizes a more realistic sound reproduction has been put to practical use. I have.

Here, the direct sound, the early reflection sound, and the reverberation sound will be briefly described. FIG. 4 is a time chart for explaining direct sound, early reflection sound, and reverberation sound.

This time chart is an example, and differs depending on the place or sound field to be set (for example, when setting an outdoor venue, there is almost no reverberation).

At time t0, an impulse-like sound is generated from the sound source, and then at time t1, the direct sound reaches the listening point. From the direct sound, the position of the sound source can be determined in terms of hearing, and the sound can be localized.

After that, a sound reflected from a collision with a wall, a ceiling, or the like, that is, an initial reflected sound arrives from time t2 to time t3 after a lapse of time T1. Then, at time t3, the reverberation sound reflected from the wall or the ceiling a plurality of times and reaching from around the listening point reaches the listening point. This reverberation gradually attenuates and disappears at time t4. The presence of these early reflections and reverberation provides a sense of realism.

Hereinafter, the initial reflected sound and the reverberant sound will be collectively referred to as a reflected sound.

FIG. 5 is a block diagram showing a sound field reproducing device. The sound field reproducing device 10 includes an acoustic signal processing device 1 and speakers FL, FR, RL, R
Consists of R and The sound signal processing device 1 generates a direct sound and a reflected sound from a stereo sound signal from a signal source (not shown), and the speakers FL and F arranged in front of the listener 2.
Plays back direct and reflected sound from R,
Plays only reflections from RR.

In this way, the listener can hear the direct sound corresponding to the played sound from the front, so that the instrument sound and the like can be localized and heard in front, and the reflected sound can be heard from around the listener, so that the performance venue Is given, and the listener hears as if he or she is playing in a space (for example, a concert hall) different from the room where the sound field reproducing device 10 is installed.

[Problems to be solved by the invention]

In the sound field reproducing device 10 as shown in FIG. 5, two speakers are provided in front of and two behind the listener of the listener, and a total of four speakers are required. is there.

Therefore, it is conceivable to widen the interval between the pair of left and right speakers provided in front and reproduce sound with a feeling of expansion. However, in this case, the direct sound and the reflected sound are heard from the same range.

Considering that performances are performed on a stage provided in a specific area in front of the listener in a general performance venue, direct sound should be heard from a specific area in front of the listener. Since the reflected sound reaches the listener after being reflected by a wall or the like around the performance hall, it is desirable that the reflected sound can be heard from a much wider range than the direct sound.

SUMMARY OF THE INVENTION An object of the present invention is to provide an audio signal reproducing apparatus capable of making the ranges in which a direct sound and a reflected sound are heard by two speakers different from each other.

[Means for solving the problem]

In order to solve the above problems, the present invention provides an apparatus for reproducing a stereo sound signal, comprising: a sound signal generating means for outputting a direct sound signal and a reflected sound signal; and a phase and level of a reflected sound signal of each channel. A phase / level shift means for changing each of them; an adder for adding a direct sound signal of one channel, a reflected sound signal of the channel, and an output signal of the phase / level shift means of the other channel; And a speaker for reproducing an output signal.

(Operation)

It is known that a sound field generated by a sound reproduced from a speaker can be widened by shifting a level and a phase of a stereo sound signal and adding them to the other channel.

Therefore, the level and phase of the reflected sound signal are shifted by the phase / level shift means, and the adder is used to determine the phase and level of the direct sound signal of one channel, the reflected sound signal of this channel, and the reflected sound signal of the other channel. The reflected sound signal can be reproduced with a wider sense than the direct sound signal by adding the shifted sound and reproducing the sound from the speaker.

(Example of the invention)

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First
FIG. 1 is a block diagram showing an embodiment of the present invention.

The stereo signal generator 20 generates an audio signal SR which is a right channel stereo audio signal and an audio signal SL which is a left channel stereo audio signal in a stereo system, and is, for example, a magnetic tape reproducing device.
The acoustic signal S output from the stereo signal generator 20
R and SL are called linear sound signals.

The reflected sound generators 21 and 22 generate reflected sound signals ZR1 and ZL1 for each channel based on the direct sound signals SR and SL. In these reflected sound generation units 21 and 22, the direct sound signals SR and SL are
By performing processing using a level converter or the like, a reflected sound as shown in FIG. 4 is generated.

The reflected sound conversion unit 23 shifts the phase and level of the reflected sound signals ZR1 and ZL1, and adds them to the reflected sound signals ZL1 and ZR1, respectively, to produce wide reflected sound signals ZL2 and ZR2 that have a sense of spread in the reflected sound signals. It is something to convert.

Adders 25 and 26 are direct sound signals SR and SL and wide reflected sound signal ZR
2 and ZL2, respectively, and add them to the speakers 30 and 31.

FIG. 3 is a block diagram showing details of the reflected sound conversion unit 23.

Bandpass filters (BPF) 41,61 and BPF42,62 and BPF43,
Reference numeral 63 denotes a signal for passing signals of different frequency bands (bands) B1, B2, and B3 in the reflected sound signals ZR1 and ZL1. As a result, the reflected sound signals ZR1 and ZL1 are respectively set to band B1.
BB3 to form band signals RB1 to RB3 and LB1 to LB3.

The level converters 44 and 64 change the levels of the band signals RB1 and LB1 by a level amount corresponding to the band B1,
The phase converters 47 and 67 output converted signals obtained by changing the phases of the output signals of the level converters 44 and 64 by a shift amount corresponding to the band B1. Adders 50 and 70 add the band signals RB1 and LB1 and the converted signals output from the phase converters 67 and 47, respectively. That is, the adders 50 and 70 add, in a predetermined band, the converted signal obtained by changing the level and phase of the reflected sound signal of one channel and the reflected sound signal of the other channel.

In band B2, level converters 45 and 65 and phase converter 4
8, 68 output converted signals obtained by converting the levels and phases of the band signals RB2, LB2, and the adders 51, 71 output the band signals RB2, LB2.
And the converted signals output from the phase converters 68 and 48.

In band B3, level converters 46 and 66 and phase converter 4
9 and 69 output converted signals obtained by converting the levels and phases of the band signals RB3 and LB3, and the adders 52 and 72 output the band signals RB3 and LB3.
And the conversion signals output from the phase converters 69 and 49.

In this way, for each of the bands B1 to B3, the converted signal obtained by changing the level and phase of the reflected sound signal of one channel and the reflected sound signal of the other channel is added.
The adder 53 adds the output signals of the adders 50 to 52 to form a wide reflected sound signal ZR2, and the adder 73 adds the outputs of the adders 70 to 72 to form the wide reflected sound signal ZL2. Form.

FIG. 2 is a characteristic diagram showing a level difference and a phase difference between human ears with respect to a point sound source, and is a specific diagram when a point sound source is arranged at a predetermined position shifted from the front of the listener.

Sound from a point sound source, that is, a sound wave, is transmitted concentrically around the point sound source, and the listener recognizes that the sound source is present in a direction perpendicular to the tangent line of the concentric circle. When a point sound source is located at a position shifted from the front of the listener, the level difference of the sound wave at the ear on the far side relative to the ear on the side near the point sound source depends on the frequency f as shown in FIG. Change. Similarly, the phase difference of the sound wave at the other ear with respect to the ear near the point sound source also changes according to the frequency f.

For this reason, the sound waves output from the speakers 30 and 31, respectively, are synthesized at the listening position at the listening position, as shown in FIG.
The adjustment is performed so as to have the characteristic shown in FIG. 2B, that is, the level shift amount by the level converters 44 to 46 and 64 to 66 provided for each band and the phase shift by the phase converters 47 to 49 and 67 to 69. By adjusting the volume, the synthesized wave of the sound waves generated from the speakers 30 and 31 can be made closer to the sound wave from an apparent point sound source outside the volume speaker, and the reflected sound signal ZR
1, ZL1 can be reproduced by a speaker on an imaginary line provided outside the speakers 30, 31. Therefore, first, a point sound source (speaker) is arranged at a desired position on a desired virtual line, and at the listening position, the sound source shown in FIG.
The binaural level difference and the phase difference with respect to the frequency as shown in (b) are measured, and then the level converters 44 to 44 are set so that the synthesized wave of the reflected sound wave output from the speakers 30 and 31 has the characteristic. 46,64-66 Level shift amount and phase converter 47
A desired virtual sound source can be obtained by adjusting the amount of phase shift by 49, 67〜69.

The reflected sound converter 23 shown in FIG. 3 divides the reflected sound signals ZR1 and ZL1 into three bands B1 to B3 and processes them in order to obtain a level amount and a phase shift amount to be converted according to the frequency. However, if the reflected sound signals ZR1 and ZL1 are further divided into multiple bands, the measured characteristics can be made closer to those shown in FIG. 2, and more ideal sound field characteristics can be obtained.

As described above, in the present embodiment, among the sounds reproduced by the speakers 30 and 31, the direct sound signals SR and SL corresponding to the direct sounds are output as they are by the speakers 30 and 31,
It is played as if there is a sound source between and 31. on the other hand,
The reflected sound is reflected sound signal ZR1, ZL1 and wide reflected sound signal ZR2, Z
L2 reproduces the sound as if the sound source is located outside the speakers 30 and 31. Therefore, the reflected sound arrives from a wide range with respect to the direct sound, and can be made closer to the reach of the direct sound and the reflected sound in the performance hall, so that a sense of reality can be improved.

In this embodiment, the direct sound is substantially a speaker.
Although the sound was localized between 30, 31
The direct sound may be subjected to processing such as the reflection sound conversion unit 23 so that the sound is localized outside of 0 and 31. However, in this case, the level conversion unit and the phase conversion unit are set so that the range where the direct sound is localized is narrower than the range where the reflected sound is localized.

〔The invention's effect〕

As described above in detail, according to the present invention, the direct sound is output as it is by the speakers, reproduced as if there is a sound source between the pair of speakers, and the reflected sound reaches from a wider range than the direct sound. As a result, the direct sound and the reflected sound in the performance hall can be brought close to the reproduction state, and the sense of realism can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing a level difference and a phase difference between human ears with respect to a point sound source, and FIG. FIG. 4 is a time chart for explaining direct sound, early reflection sound, and reverberation sound, and FIG. 5 is a block diagram showing a sound field reproducing device. In the figure, 20: stereo signal generator, 21, 22: reflected sound reproducing unit, 23: reflected sound converting unit, 25, 26, 50 to 53, 70 to 73: adder, 3
0,31: Speaker, 41 to 43, 61 to 63: BPF, 44 to 46, 64 to 66: Level converter, 47 to 49, 67 to 69: Phase converter

Claims (1)

(57) [Claims] 1. An apparatus for reproducing a stereo sound signal, comprising: a sound signal generating means for outputting a direct sound signal and a reflected sound signal; and a phase / level shifter for changing the phase and level of the reflected sound signal of each channel. Means, an adder for adding the direct sound signal of one channel, the reflected sound signal of the channel, and the output signal of the phase / level shift means of the other channel, and a speaker for reproducing the output signal of each adder. A sound signal reproducing device comprising: