JPH023600B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a device for reproducing sound using two speakers, and provides a sound image localization device that can localize a sound image in any direction within a 360° circumference around a listener. The sound image localization devices currently in use divide an input signal that does not have localization information into two or more parts, and change the voltage level ratio of each output.
The device that changes this voltage level ratio is panoramic
It is called a potentiometer (abbreviated as panpot). Figure 1 shows two channels currently on the market.
This shows the case where a two-channel panpot is used when producing a source for speaker reproduction. The electrical signal input to input terminal _I1 can be changed to the output line at different voltages by moving the output voltage level ratio control stake in panpot 1.
The signals are output to O ₁ and O ₂ and recorded on a two-channel tape recorder 2. Usually this panpot 1 is
Built into the recording audio adjustment console. Figure 2 shows a source recorded through the sound image localization device shown in Figure 1, which is connected to a 2-channel amplifier and a 2-channel amplifier.
This shows a state in which the user is listening using speakers. Signals input to input terminals I ₂ and I ₃ are amplified by a two-channel amplifier 3 and reproduced by two speakers 4 and 4' placed symmetrically at 30 degrees with respect to the median plane C of the listener 5. In Fig. 2, the direction angle of the sound image 6 is measured with the horizontal direction as the starting point, and γ=
The relationship between I ₂ /I ₃ and the input voltage level ratio is shown in the table below. This table is the ON THE DIRECTIONAL
LOCALIZATION OF SOUND IN THE
STERFEOPHONIC SOUND FIELD"Y.
MAKITA EBUREVIEW PARTA−
This is the data from Technical No.73.JUNE 1962.

[Table] In other words, the sound image localization direction that can be controlled by changing γ is within the range of ±60° to 90°, in other words, only between the two speakers 4, 4, and the sound image localization direction can be controlled in the lateral and rearward directions. is not localized. Of course, the effect remains unchanged even if the output lines O ₁ and O ₂ are directly connected to I ₂ and I ₃ without going through the tape recorder 2. Figure 3 shows a case where an input signal is distributed to output lines O ₁ , O ₂ , O ₃ , and O ₄ with voltage level ratios using a 4-channel panpot 1 in a 4-channel 4-speaker reproduction device. ing. Figure 4 shows the results of a psychological experiment based on playback conditions, with γ = O ₃ / O ₁ as the horizontal axis, and the direction angle of the sound image 6 as the origin from the median plane C of subject 5, counterclockwise. Let the value measured in
- Indicated by < symbol. Figures 3 and 4 are
“About directional localization based on the type of sound source and the position of the sound source” Mamoru Kuriyagawa Auditory Research Committee Materials of the Acoustical Society of Japan
This is data for November 1971. From this data, it can be seen that the 4-channel, 4-speaker reproduction system has the following drawbacks. In other words, the 4-channel reproduction method, which controls the sound image direction localization by changing the input voltage level ratio of speakers placed in front and rear, can be used to
This means that the sound image cannot be localized in the domain). However, on the other hand, lateral sound image localization has become an indispensable condition for faithfully reproducing the recording field during playback and for ensuring the naturalness of the reproduced sound field. In Fig. 5, speakers 4'' and 4 are placed in the lateral direction of the subject, that is, at 90 degrees left and right with respect to the midline C, and conventional two-channel stereo reproduction speakers 4 and 4' are placed in the direction of the subject with respect to the midline C. They are arranged 30 degrees left and right for 4-channel 4-speaker playback, and an electrical signal without localization information is input to input terminal _I1 .
Channel pan pot 1 connects the output line
By varying the voltage level ratio of each of O ₁ , O ₂ , O ₃ , and O ₄ , the sound image 6 can be distributed not only between the speakers 4 and 4' but also between the speakers 4 and 4'' and between the speakers 4' and 4'.
This figure shows a control device that can freely control the localization between four positions. In this device, it is possible to localize the sound image between the speakers 4 and 4'' and between the speakers 4' and 4 by varying the voltage level ratio between O ₁ and O ₃ and between O ₂ and O ₄ . Figure 6 shows the average angle of the five subjects measured from the midline C of the sound image 6 when the voltage level ratio γ (O ₃ /O ₁ or O ₄ /O ₂ ) between the two channels was changed. It shows the results obtained through psychological experiments to determine the relationship between the sound image 6 and the value θ.
can be localized between the 30° direction of the speakers 4 and 4' and the 90° direction of the speakers 4'' and 4. Figure 7 shows the positioning of the speakers 4 and 4' behind the subject. The left and right speakers 4'' and 4 are arranged at 90 degrees left and right with respect to the horizontal direction, and the level ratio of each of the output lines O ₁ , O ₂ , O ₃ , O ₄ is adjusted by the 4 channel pan pot. This figure shows a control device that localizes the sound image to the rear of the subject by changing the position of the sound image. Figure 8 shows the electrical signal level ratio γ between O ₁ and O ₂
The relationship between (O ₂ /O ₁ ) and the sound image direction θ was determined through a psychological experiment, and is shown as the average value of 5 subjects.By changing γ, the relationship between the speaker 4,
It is possible to localize the sound image between 4'. Figure 9 shows the level ratio γ and sound image 6 when the electrical signal level ratio γ (O ₃ /O ₁ or O ₄ /O ₂ ) between O ₁ and _{O 3} and between O 2 _and O 4 is changed. The relationship with the localization direction θ was determined through a psychological experiment, and is shown as the average value of five subjects. By changing γ in this way, it is possible to localize the sound image between the speakers 4'', 4 and 4, 4'. 22 is a switch circuit that switches the electrical signal applied to the input terminal _I1 to one of the output lines _O1 to _O12 , 23a to 23l are front and rear determination circuits, and 24a
~24l is a binaural difference generation circuit, 4 and 4' are speakers,
5 is a subject, and 6 is an imaginary sound source generated by the above-mentioned front/back judgment circuit and binaural difference creation circuit. By switching the switch circuit shown in FIG. 10, the virtual sound source 6 can be localized every 30 degrees around the listener 5. Figure 11 shows the results of a psychological experiment using the device shown in Figure 10, where the horizontal axis is the set sound source direction;
The vertical axis is the sound image direction recognized by the test subjects, and the results of the eight test subjects are shown by the size of the circle. In this way, the virtual sound source 6 can be localized at a predetermined point within 360 degrees around the listener 5, but since the transfer function is simulated in each direction, the localization direction of the virtual sound source 6 can be continuously controlled. That is difficult. Note that Figures 10 and 11 are data from "About directional localization in stereo reproduction" by Masatoshi Shinbo et al., materials from the Institute of Electronics and Communication Engineers, January 1978. For example, the front and rear judgment circuit 23C and the binaural difference generation circuit 24C in FIG.
Assuming that the circuit localizes an imaginary sound source at the point,
The characteristic of the front/back determining circuit 23C is H〓 ₁ /H ₁₁ , and the characteristic of the binaural difference generating circuit 24C is H ₁₁ H〓 ₂ −H ₁₂ H〓 ₁ /H ₁₁ H〓 ₁ −H ₁₂ H〓 ₂ . Note that H ₁₂ H〓 ₁ and H〓 ₂ are transfer functions shown in FIG. 12, respectively. According to the circuit shown in FIG. 12, the listener 5 perceives the sound as being radiated from the speakers 6 while listening to the sound radiated from the speakers 4 and 4'. The present invention eliminates the drawbacks of each of the conventional examples and provides a sound image localization device that can localize a sound image to any point around the listener 5. An embodiment of the present invention will be described below. This will be explained with reference to FIG. The present embodiment is a sound image localization device that can localize a sound image at any point in the range from 0° to 90° left and right with the midline C of the listener 5 as the starting point. In Fig. 13, 1 and 1' are 4-channel panpots, 7 is an 8-channel input 4-channel output audio mixer, and O ₁ and O' ₁ are mixed and output to output terminal M ₁ , and similarly O ₂ and O′ ₂ ,
O ₃ and O′ ₃ , O ₄ and O′ ₄ are mixed and each output terminal M ₂ ,
Output to M ₃ and M ₄ . 9, 9 is a binaural difference generation circuit, and a post-judgment circuit 8
The binaural difference creation circuit 9 is a circuit for localizing the virtual sound source in the direction of 90 degrees to the left of the listener 5, and the front/rear judgment circuit 8' is a circuit for localizing the virtual sound source in the direction of 90 degrees to the right of the listener 5. , and the transfer function in the left and right 90° directions is H _1S ,
When H _2S , the circuits 8 and 8' have H _1S /H ₁₁ and the circuits 9 and 9' have H ₁₁ H _2S −H ₁₂ H _2S /H ₁₁ H _1S −H ₁₂ H _2S . 10 is a 6-channel input 2-channel output audio mixer, and among the inputs N ₁ to N ₆ of this mixer 10, N ₁ and
N ₃ and N ₆ are mixed and output to one output terminal, and N ₂ , N ₄ and N ₅ are mixed and output to the other output terminal. When the two outputs of the mixer 10 are amplified by the amplifier 3 and applied to the speakers 4 and 4', the listener 5 becomes in the same listening state as if there were speakers also in the left and right directions. In other words, although it is a two-speaker reproduction, the listening condition is similar to the four-speaker reproduction shown in FIG. 5, and as in the embodiment shown in FIG. , the sound image can be localized at any point in front of the listener 5 from 90 degrees to the left to 90 degrees to the right. FIG. 14 shows the results of a psychological experiment in the example shown in FIG. In Figure 14,
The horizontal axis shows the direction in which the sound image is localized by adjusting the panpots 1 and 1', and the vertical axis shows the sound image direction recognized by the subjects (5 people). According to this example,
It is possible to localize the sound image in the ±30° to ±90° directions, which was impossible with conventional two-channel, two-speaker reproduction. FIG. 15 shows a second embodiment of the invention. In Fig. 15, 11 and 11' are 6-channel pan pots, 12 is a 12-channel input and 6-channel output audio mixer, and 8, 8', 8'',
Reference numeral 8 denotes a front and rear judgment circuit, and 9, 9', 9'', 9 denote a binaural difference generation circuit.
This is a circuit for localizing an imaginary sound source in a 90° direction.
The front and back judgment circuits 8'', 8 and the binaural difference creation circuits 9'', 9 are circuits for localizing an imaginary sound source in the direction of ±150° behind the listener 5, and according to this embodiment, the direction of the false sound source is localized in the direction of ±90°. The listening condition is the same as after placing the speakers also in the ±150° direction. For this reason,
Similar to the embodiment shown in FIG.
By adjusting 1 and 11', the sound image can be localized at any point within a 360° range around the listener 5, even though the sound is reproduced by two speakers. Note that the front and rear determination circuits 8'' and 8 in FIG.
And the binaural difference generating circuits 9'', 9 have transfer functions in the ±150° direction as H _1R and H _2R respectively, H _1R /H ₁₁ and H ₁₁ H _2R − _{H 12} H _1R /H ₁₁ H _1R − H ₁₂ H _2R.As shown in Fig. 15, the speakers 4,
4' and the virtual sound source localized behind the listener 5 are front-back symmetrical with respect to the auditory sound 5, the line including the binaural difference generating circuits 9'' and 9 in FIG. 15 may be removed. Figure 16 shows the psychological experiment results for the example shown in Figure 15.
It can be seen that the sound image is continuously localized in all 360° directions around the area. In the embodiment shown in FIG. 15, the imaginary sound source is localized in the ±150° direction, but it is not limited to the ±150° direction.
It is only necessary to localize it behind the listener 5. As described above, according to the present invention, by providing a front-rear judgment circuit and a binaural difference creation circuit that output signals for localizing an imaginary sound source in the 90° left and right directions of the listener, a sound image that is impossible with a 4-channel reproduction method is created. Of course, it is possible to localize the sound 90 degrees left and right from the listener.
The sound image can be localized in directions that are impossible with two-channel, two-speaker reproduction, and the input signal is divided into a plurality of outputs in advance, and the voltage level ratio between each output is adjusted using a voltage level adjustment means. Accordingly, the sound image localization direction can be controlled continuously, reliably, and easily.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a recording system using a 2-channel panpot, Figure 2 is a schematic diagram of a conventional 2-speaker reproduction system, and Figure 3 is a schematic diagram of a 4-speaker reproduction system using a conventional 4-channel panpot. Figure 4 is a diagram showing the relationship between the voltage level ratio between two channels of the same reproduction system and the sound image localization direction, Figure 5 is a schematic diagram of a conventional 4-speaker reproduction system, and Figure 6 is a diagram showing the relationship between the voltage level ratio between two channels of the same reproduction system and the sound image localization direction. A diagram showing the relationship between the voltage level ratio between channels and the sound image localization direction. Figure 7 is a schematic diagram of another conventional 4-speaker reproduction system. Figures 8 and 9 are the voltage level ratio between two channels of the same reproduction system. FIG. 10 is a schematic diagram of a conventional sound image localization device that localizes a virtual sound source at a prescribed position around the listener.
Figure 1 is a diagram showing the results of a psychological experiment on sound image localization using the device, Figure 12 is a block diagram of a circuit for localizing an imaginary sound source at a prescribed position around the listener, and Figure 13 is an embodiment of the present invention. 14 is a diagram showing the results of a psychological experiment on sound image localization of the same device, FIG. 15 is a block diagram of another embodiment of the present invention, and FIG. 16 is a diagram showing the sound image localization of the same device. It is a figure showing the result of a psychological experiment. 1,1'...Panpot, 4,4'...Speaker, 5...Listener, 7...Mixer, 8,8',
8″, 8... Front and rear judgment circuit, 9, 9′, 9″, 9
...Binaural difference generation circuit, 10...Mixer, 11,
11'...Bread pot, 12...Mixer, 13
……mixer.

Claims (1)

[Scope of Claims] 1. Output dividing means for dividing an input signal into a plurality of outputs, voltage level adjusting means for adjusting the voltage level ratio between the respective outputs, and two of the outputs of the voltage level adjusting means. Adding means inputs the output to the first and second input terminals, and other outputs of the voltage level adjusting means are input, and at least the left and right sides of the listener
a front-rear judgment circuit and a binaural difference creation circuit that output signals for localizing an imaginary sound source in a 90° direction; and an output of the circuit is inputted to other input terminals of the addition means, and the circuit is arranged on the left and right in front of the listener. A sound image localization device characterized in that a sound image is applied to a speaker. 2 Voltage level adjustment means that adjusts the level ratio between each output with the output dividing means when the input signal is divided into four outputs, and two outputs of the outputs of this voltage level adjustment means are input to the first and second inputs. An anteroposterior determination circuit and a binaural difference creation circuit which input an addition means input to a terminal and the other two outputs of the voltage level adjustment means, and output a signal for localizing an imaginary sound source in a direction of 90 degrees left and right of the listener; 2. The sound image localization device according to claim 1, wherein the output of said circuit is inputted to another input terminal of said adding means, and is applied to speakers placed on the left and right in front of a listener. 3 Output dividing means for dividing an input signal into six outputs, voltage level adjusting means for adjusting the voltage level ratio between each output, and two outputs of the outputs of this voltage level adjusting means being divided into first and second outputs. A first front-rear judgment circuit and a binaural difference creation circuit which input an addition means input to an input terminal and two other outputs of the output of the voltage level adjustment means, and localize an imaginary sound source in a direction of 90 degrees to the left and right of the listener. and a second anteroposterior determination circuit and a binaural difference creation circuit for localizing an imaginary sound source behind the listener using the remaining two outputs of the voltage level adjustment means, the first anteroposterior determination circuit and a binaural difference creation circuit. The output of the circuit and the output of the second front/back determining circuit and the binaural difference generating circuit are input to other input terminals of the adding means, and are applied to speakers placed on the left and right in front of the listener. A sound image localization device according to claim 1.