JPH05191897A - Stereophonic acoustic sound reproducing device - Google Patents

Abstract

PURPOSE:To give an elevation angle to the direction and distance feelins of a sound source felt by an auditor. CONSTITUTION:An overhead sound signal processing part 9 deducts the elevation angle of the sound source from right and left sound signals L and R and central sound signal (L+R) from first to third output terminals of a directivity adjuster 63 and a delay difference signal phi(L-R) from a noise removal circuit 67, forms an overhead sound signal OH based on the obtained elevation angle and supplies it to the fifth input terminal of a interlocked sound volume adjuster 64. The sound signal OH from the interlocked sound volume adjuster 64 is amplified via an amplifier 77 and outputted in sound by right and left overhead speakers 81 and 82 located at the right and left overhead positions of the auditor. Thus, by the sound to be outputted from the right and left overhead speakers 81 and 82, the elevation angle can be given to the direction and distance feelings of the sound source felt by the auditor 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereophonic sound reproducing apparatus capable of stereoscopically reproducing stereo sound in an audio-dio tape recorder, a video-tape recorder and the like.

[0002]

2. Description of the Related Art Conventionally, in an audio reproducing apparatus which outputs stereo sound such as an audio tape recorder, a video tape recorder, a television receiver, etc., different sounds are respectively generated from two left and right speakers to give a listener a realistic sensation. I have it.

FIG. 2 is a block diagram showing a stereo circuit of a sound reproducing apparatus for outputting such conventional 2-channel stereo sound.

In FIG. 2, the input terminals 11 and 12 are supplied with the left audio signal L and the right audio signal R from the audio demodulation circuit, respectively. Input terminals 11 and 12
The left and right audio signals L and R supplied to the left and right are amplified via the left and right amplifiers 13 and 14, respectively, and output as audio to the listener 17 by the left and right speakers 16 and 17, respectively.

In such a device that outputs two-channel stereo sound, the sound heard by the listener 17 has a strong left sound output from the left speaker 15 in the left ear and a right speaker in the right ear. The right audio output from 16 becomes stronger. In this way, by making a difference between the sounds heard by the left and right ears, the sound source of the sound sensed by the listener 17 has a sense of direction to the left and right to give a sense of presence.

However, in such a conventional sound reproducing device for outputting 2-channel stereo sound, the listener hears only the sound from the front, and the reverberation sound from the rear such as the performance in the music hall is obtained. I can't. In response to this, a sound reproducing device that outputs surround sound has been put into practical use.

[0007] The surround in the sound reproducing device refers to a concept of sound that gives a listener a feeling of being surrounded and a feeling of being spread while the sense of direction of the sound source of the original signal is preserved.

FIG. 3 is a block diagram for explaining a surround circuit of a sound reproducing apparatus for outputting such conventional 3-channel surround sound.

In FIG. 3, input terminals 21 and 22 are respectively supplied with a left audio signal L and a right audio signal R from an audio demodulation circuit. Input terminals 21, 22
The left and right audio signals L and R supplied to the first and second input terminals of the interlocking volume adjuster 23 are respectively supplied to the first and second input terminals of the difference signal detection circuit 24. Supplied. The difference signal detection circuit 24 subtracts the left audio signal and the right audio signal to detect the difference signal (LR) which is a reverberation component and supplies it to the delay circuit 25. The delay circuit 25 performs a phase shift of the phase φ by delaying the difference signal (LR), and outputs the delayed difference signal φ (LR) as a low-pass filter (hereinafter referred to as LPF).
26) and a noise removal circuit 27 to remove low-frequency components and noise, and supply the result to the third input terminal of the interlocking volume controller 23.

The interlocking volume adjuster 23 has input terminals 11, 1
The left and right audio signals L and R supplied to the second input terminal 2 and the delay difference signal φ (L−R) from the third input terminal are interlocked to adjust the volume, and the first to third outputs, respectively. Output from the terminal. The left and right audio signals L and R from the first and second output terminals of the interlocking volume controller 23 are supplied to the left and right amplifiers 28 and 2, respectively.
It is amplified via 9 and is output as sound by the left and right front speakers 30, 31 arranged on the left and right front sides of the listener 17. The delay difference signal φ (LR) from the third output terminal of the interlocking volume adjuster 23 is amplified through the amplifier circuit 32, and the left and right surround speakers 33, which are arranged on the left and right rear sides of the listener 17, The audio is output by 34. In this case, the delay difference signal φ (L-
The input terminal for inputting (R) is the left surround speaker 3
The polarity is opposite to that of 3, and the right surround speaker 34 outputs the sound corresponding to the inverted delay difference signal −φ (LR).

According to such a conventional sound reproducing device for outputting three-channel surround sound, the left and right surround speakers 33, 34 arranged behind the listener 17.
From the reverberation component delay difference signal φ (LR), -φ (L-
Since R) is obtained, the listener feels a reverberant sound reflected from a distance from behind, such as a performance in a music hall, and can give a sense of direction and distance of a sound source.

[0012] However, in such a conventional sound reproducing apparatus which outputs three-channel surround sound, the sound reproduction of a movie, the voice of an announcer of a sports broadcast, or the like is essentially 1.
The sound that should be heard from one sound source comes from the left and right directions, giving an unnatural feeling. In response to this, an acoustic device that outputs 4-channel surround sound has been put into practical use.

FIG. 4 is a block diagram for explaining a surround circuit of a conventional sound reproducing device for outputting 4-channel surround sound.

In FIG. 4, the input terminals 41 and 42 are respectively supplied with the left audio signal L and the right audio signal R from the audio demodulation circuit. Input terminals 41, 42
The left and right audio signals L and R supplied to the first and second audio signals are respectively supplied to the first and second input terminals of the directionality emphasizing circuit 43.
The direction emphasis circuit 43 guides the left audio signal L and the right audio signal R to the first and second output terminals, and performs subtraction and addition of the left audio signal and the right audio signal. The sum signal (L + R) and the difference signal (L-R) are created by and are led to the third and fourth output terminals, respectively.

Left and right audio signals L and R and sum signals (L + R) from the first to third output terminals of the direction control emphasizing circuit 43.
Are supplied to the first and third input terminals of the interlocking volume adjuster 44.

The difference signal (LR) from the fourth output terminal of the direction control emphasizing circuit 43 is supplied to the delay circuit 45. The delay circuit 45 performs a phase shift of the phase φ by delaying the difference signal (LR), and the delay difference signal φ (L-R).
R) is supplied to the fourth input terminal of the interlocking volume controller 44 via the LPF 46 and the noise removing circuit 47.

The interlocking volume adjuster 44 includes left and right audio signals L and R from the first to fourth input terminals and a sum signal (L +).
R) and the delay difference signal φ (L−R) are interlocked with each other to adjust the volume and output from the first to fourth output terminals. The left and right audio signals L and R from the first and second output terminals are
It is amplified via the left and right amplifiers 48 and 49, and is output as sound by the left and right front speakers 51 and 52 arranged on the left and right front sides of the listener 17, respectively. The sum signal (L + R) from the third output terminal is amplified by the amplifier circuit 50 and output as voice by the central speaker 53 arranged between the left and right front speakers 51, 52. Fourth
The delay difference signal φ (L−R) from the output terminal is amplified by the amplifier circuit 54 and is output as sound by the left and right surround speakers 55 and 56 arranged on the left and right back surfaces of the listener 17. In this case, the input terminal for inputting the delay difference signal φ (LR) of the right surround speaker 56 has a polarity opposite to that of the left surround speaker 55.

According to such a conventional sound reproducing device for outputting 4-channel surround sound, the sum signal (L + R) from the central speaker 53 causes one of the voices of a movie dialogue, a sports broadcast announcer, etc. It is possible to stabilize the sense of direction of the sound that should be heard from the sound source.

However, in the surround circuit shown in FIG. 4, the direction and distance of the sound source are determined by the front speaker 5
1, 52, central speaker 53, surround speaker 5
Only the direct sound from 5, 56 was limited to the plane where these speakers were arranged, and the stereoscopic effect of the sound image was poor.

[0020]

In the above-mentioned conventional sound reproducing apparatus, the direction and distance of the sound source that the listener feels are
Only the direct sound from a plurality of speakers was limited to the plane where these speakers were arranged, and the stereoscopic effect of the sound image was poor.

An object of the present invention is to provide a stereophonic sound reproducing apparatus which eliminates the above-mentioned problems and can give an elevation angle to the direction and distance of a sound source that a listener feels.

[Constitution of Invention]

[0023]

A stereophonic sound reproducing apparatus according to the present invention creates delayed left and right difference signals for producing a surround effect based on an input left audio signal and right audio signal. Surround signal creating means, a sum signal creating means for creating left and right sum signals based on the input left audio signal and right audio signal, and the left audio signal, right audio signal, and delayed left and right audio signals. The elevation angle of the sound source is estimated from the difference signal and the left and right sum signals, and based on this estimation, the left audio signal, the right audio signal, the delayed left and right difference signals, and the left and right sum signals are calculated. Thus, the overhead audio signal creating means for creating an overhead audio signal, the left and right front speakers which are provided on the left and right front sides of the listener and output the left audio signal and the right audio signal respectively, and these left and right speakers Between the front speakers of Central front speakers that are arranged to output the left and right sum signals by voice, left and right surround speakers that are arranged on the left and right rear sides of the listener and that output the left and right delay difference signals by voice, and an overhead of the listener. And an overhead speaker that outputs the overhead audio signal as a voice.

[0024]

According to this structure, the overhead audio signal generating means estimates the elevation angle of the sound source from the left audio signal, the right audio signal, the delayed left and right difference signals, and the left and right sum signals, and this estimation is performed. An overhead sound signal is created based on the above, and the overhead speaker outputs the sound from above the listener's head. Therefore, an elevation angle can be given to the direction and distance of the sound source that the listener feels.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a surround circuit showing an embodiment of a stereophonic sound reproducing apparatus according to the present invention.

In FIG. 1, the left and right audio signals L and R from the input terminals 61 and 62 are directional control emphasis circuits 63, respectively.
Are supplied to the first and second input terminals of. The direction emphasis circuit 63 outputs the left and right audio signals L and R to the first and second audio signals, respectively.
Of the sum signal (L) by conducting addition and subtraction of the left audio signal L and the right audio signal R while guiding to the output terminal of
+ R) and a difference signal (LR) are created and led to the third and fourth output terminals.

Left and right audio signals L and R and sum signals (L + R) from the first to third output terminals of the direction control emphasizing circuit 63.
Are respectively supplied to the first to third input terminals of the interlocking volume adjuster 64.

The difference signal (LR) from the fourth output terminal of the direction control emphasizing circuit 63 is converted into a delay difference signal φ (LR) by the delay circuit 65, and the LPF 66 and the noise eliminating circuit 6 are provided.
It is supplied to the fourth input terminal of the interlocking volume controller 64 via 7. The circuit configuration up to this point is similar to that of the conventional example of FIG.

The difference between the present embodiment is that the overhead audio signal processing unit 9 has left and right audio signals L and R from the first to third output terminals of the directionality adjuster 63, and a central audio signal (L + R).
And the elevation angle of the sound source is estimated from the delay difference signal φ (L−R) from the noise removal circuit 67, and an overhead audio signal OH is created based on this and supplied to the fifth input terminal of the interlocking volume controller 64. The overhead audio signal OH is output by the left and right overhead speakers 81 and 82 arranged above the left and right heads of the listener 17.

The signal processor 9 will be described in more detail. Left and right audio signals L and R from the first to third output terminals of the directivity adjuster 63, a central audio signal (L + R) and a noise removing circuit 67. The high-frequency component of the delay difference signal φ (LR) from is removed by the analog LPF 91 and is supplied to the analog / digital conversion circuit (hereinafter referred to as A / D circuit) 92. The A / D circuit 92 outputs the signal L, from which the high frequency component is removed,
R, L + R, φ (LR) are converted into a digital signal a and supplied to the digital sound processor 93. The digital sound processor 93 temporarily stores the digital signal a as the digital signal a0 in the memory 94, and
The signals L, R, L + R, φ (L
The data b of -R) such as volume and wavelength are supplied to the microcomputer 95. The microcomputer 95 converts the data b from the digital sound processor 93 into the data b.
The data b1 is stored in the RAM 96 as 1 and the stored data b1 is read out after a predetermined time to obtain a new digital signal a.
Based on the comparison result, the ROM
The operation data d is read out by supplying the read data c to 97, and this operation data d is read by the digital sound processor 9
Supply 3 The digital sound processor 93 reads the digital signal a0 stored in the memory 94, performs arithmetic processing on the digital signal a0 based on the arithmetic data d, and outputs the digital signal e of the arithmetic result to the digital signal f via the digital filter 98. Is supplied to a digital / analog conversion circuit (hereinafter referred to as D / A circuit) 99. The D / A circuit 99 creates an overhead audio signal OH by performing digital-analog conversion on the digital signal f and supplies it to the fifth input terminal of the interlocking volume adjuster 64.

The interlocking volume controller 64 includes left and right audio signals L and R from the first to fifth input terminals and a sum signal (L +).
R), the delay difference signal φ (L−R), and the overhead audio signal OH are interlocked to adjust the volume, and the first to fifth
Output from the output terminal of. The left and right audio signals L and R from the first and second output terminals are amplified by the left and right amplifiers 68 and 69, and are amplified by the left and right front speakers 71 and 72 arranged on the left and right front sides of the listener 17. Sound is output. The sum signal (L + R) from the third output terminal is amplified through the amplifier circuit 70, and the left and right front speakers 71, 7
Audio is output by the central speaker 73 disposed between the two. Delay difference signal φ (LR) from the fourth output terminal
Are amplified through the amplifier circuit 74 and are arranged on the left and right rear surfaces of the listener 17 to the left and right surround speakers 75, 76.
Is output by voice. In this case, the input terminal for inputting the delay difference signal φ (LR) of the right surround speaker 76 has a polarity opposite to that of the left surround speaker 75. The audio signal OH from the fifth output terminal is amplified by the amplifier circuit 77, and the audio signal OH is output as audio by the left and right overhead speakers 81 and 82 arranged above the left and right heads of the listener 17. ing.

The above digital sound processor 9
The operation of the embodiment of FIG. 1 will be described with reference to some examples of the calculation method of No. 3.

For example, in the case of relaying classical music in a music hall, when the data b1 stored in the RAM 96 by the microcomputer 95 is compared with the data b of the new digital signal a, the position of the sound source is constant, so that the audio signal L or The time difference of the R volume is less than or equal to a predetermined value. Based on the comparison result, the microcomputer 95 causes the ROM 97 to read the data d. Then, the digital sound processor 93 uses the data d
The reverberation component φ (LR) is output as a digital signal e based on As a result, the left and right overhead speakers 81, 8
The reverberation component φ (LR) is output as sound from 2 and the listener 17 can feel the sound due to the reflection on the ceiling of the music hall.

Next, the case where the sound source moves like the sound of a movie will be described.

For example, when an airplane, which is a sound source, approaches from the front, it is determined from the data b that L = R, and the data b1 stored in the RAM 96 and the data b of the new digital signal a are compared with each other. It is determined that the volume of the audio signals L and R of the
Based on the comparison result, the microcomputer 95
Causes the ROM 97 to read the data d. Then, the digital sound processor 93 causes the harmony voice (L +
R) is calculated by increasing the volume of the signals L and R at a higher rate than the volume of the signals L and R, and output as a digital signal e. As a result, the left and right overhead speakers 81, 8
From 2, the harmony voice (L + R) is increased and output at a high rate of rise, and the listener 17 can be given the sensation that the airplane, which is the sound source, is overhead.

When the airplane, which is the sound source, moves away from the front, it is determined from the data b that L = R and the sound volumes of the audio signals L and R decrease with time, so that the digital sound processor 93 , And outputs a digital signal e as a calculation for decreasing the volume of the signals L and R with respect to the sum voice (L + R). Thus, the left and right overhead speakers 81, 82 output the Japanese voice (L + R) while decreasing at a high rate of decrease, giving the listener 17 a feeling that the airplane, which is the sound source, moves away from the overhead. ..

When an airplane, which is a sound source, approaches from the left side, L> R is determined from the data b and
When the data b1 stored in the RAM 96 and the data b of the new digital signal a are compared, the reverberation component φ (LR) increases, that is, the volume of the left audio signal L is temporally higher than that of the right audio signal R. As a result, the digital sound processor 93 receives the data b for the audio signal L.
A calculation is performed to increase the volume of the audio signal L at a higher rate than the rate of increase in the volume of the audio signal L in the comparison between 1 and the data b, and the digital signal e is output. Thus, the left and right overhead speakers 81, 82 output the voice signal L with a high rate of increase, and give the listener 17 the sensation that the airplane, which is the sound source, comes overhead from the left side. ..

When an airplane, which is a sound source, approaches from the right side, L <R is determined from the data b and
In comparison between the data b1 and the data b of the new digital signal a, the reverberation component φ (LR) decreases, that is, the sound volume of the right audio signal R increases greatly in time as compared with the left audio signal L. By the way, Digital Saud Processor 93
Performs a calculation on the audio signal R so as to increase it at a higher rate than the rate of increase of the audio signal R in the comparison between the data b1 and the data b, and outputs the digital signal e.
As a result, the left and right overhead speakers 81 and 82 increase the voice signal R at a high rate of increase and output the voice, thereby making the listener 17 feel as if the airplane, which is the sound source, comes overhead from the right side. You can

When the airplane, which is the sound source, moves away from the overhead to the left, it is determined from the data b that L> R, and in comparison between the data b1 and the data b of the new digital signal a, the reverberation component φ (L- R) is decreased, that is, the volume of the left audio signal L is greatly decreased in time compared with the right audio signal R, and the digital sound processor 9
3 performs a calculation on the audio signal L so as to reduce the audio signal L at a rate of decrease higher than the rate of decrease of the audio signal L in the comparison between the data b1 and the data b, and outputs the digital signal e. As a result, the left and right overhead speakers 81, 82 output the voice signal L while reducing the voice signal at a high descent rate.
The listener 17 can be made to feel as if the airplane, which is the sound source, is moving away from overhead to the left.

When the airplane, which is the sound source, moves away from the overhead to the right, it is determined that L <R from the data b, and the reverberation component φ (L-L- is compared with the data b1 and the data b of the new digital signal a. R) increases, that is, the right sound R decreases greatly in time as compared with the left sound volume L, and the digital sound processor 93 changes the sound signal R to the sound signal R in the comparison between the data b1 and the data b. The calculation is performed such that the rate of decrease is higher than the rate of decrease of the digital signal, and the digital signal e is output. Left and right overhead speakers 8
1, 82, the voice signal R is reduced and output as a voice at a high descent rate, and the listener 17 can feel as if the airplane, which is the sound source, is moving away from overhead to the right.

Regarding the calculation method of the digital sound processor 93, in addition to determining the volume as described above,
A method of creating a digital signal e by determining the type of a sound source (for example, musical instrument performance, human voice, vehicle sound) from the wavelengths of the signals L, R, L + R, and φ (LR) indicated by the data b. By using various types such as the above, the optimal audio signals are output as audio from the left and right overhead speakers 81 and 82.

According to such an embodiment, the overhead audio signal processing unit 9 can give the elevation angle to the direction and distance feeling of the sound source that the listener feels by the sounds output from the left and right overhead speakers 81 and 82. Therefore, the listener can hear a stereoscopic sound image.

[0044]

According to the present invention, the elevation angle can be given to the direction and the sense of distance of the sound source felt by the listener, so that the listener can hear a stereoscopic sound image.

[0045]

[Brief description of drawings]

[0046]

FIG. 1 is a block diagram of a surround circuit showing an embodiment of a stereophonic sound reproducing device according to the present invention.

[0047]

FIG. 2 is a block diagram showing a stereo circuit of a conventional 2-channel stereo audio reproduction apparatus.

[0048]

FIG. 3 is a block diagram illustrating a surround circuit of a conventional sound reproduction device for three-channel surround sound.

[0049]

FIG. 4 is a block diagram illustrating a surround circuit of a conventional 4-channel surround sound sound reproducing device.

[0050]

[Explanation of symbols]

 9 Overhead audio signal processing unit 63 Directional adjuster 65 Delay circuit 64 Interlocking volume adjuster 71 Left front speaker 72 Right front speaker 73 Center speaker 76 Right surround speaker 75 Left surround speaker 81 Left overhead speaker 82 Right Overhead speaker

Claims (1)

[Claims] 1. A surround signal creating means for creating a delayed left-right difference signal for producing a surround effect based on an input left audio signal and a right audio signal, and an input left audio signal, Sum signal creating means for creating left and right sum signals based on the right sound signal, and estimating the elevation angle of the sound source from the left sound signal, the right sound signal, the delayed left and right difference signals, and the left and right sum signals. An overhead audio signal creating means for creating an overhead audio signal by performing an operation on the left audio signal, the right audio signal, the delayed left and right difference signals, and the left and right sum signals based on this estimation. And the left and right front speakers, which are arranged on the left and right front sides of the listener and output the left audio signal and the right audio signal, respectively, and the left and right sum signals are arranged between the left and right front speakers. The center to output A surface speaker, left and right surround speakers that are provided on the left and right rear sides of the listener and output the left and right delay difference signals by voice, and are provided above the listener's head and output the overhead audio signal by voice. A stereophonic sound reproducing device comprising an overhead speaker.