JP2788476B2 - Sound equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention faithfully reproduces a sound of a frequency that can be used in a sound quality change detection experiment to detect a change in the frequency distribution of brain waves in a listener. The present invention relates to a sound quality change detection method based on electroencephalogram measurement using a generated acoustic device.

(Prior Art) In examining human susceptibility to a high-frequency sound exceeding 20 kHz, which is the so-called upper limit of the human audible range, a sound quality change detection experiment using an acoustic device as shown in FIG. 5 is conventionally performed. Have been. This conventional acoustic device has a sound source 1 composed of, for example, a tape recorder or the like that generates music and the like in a low frequency band that is an audio frequency band and a high frequency band that exceeds the audio frequency band. The signal is switched by the switch 21 and passed through the low-pass filter 23 or the all-pass filter 25, the output of these filters is amplified by the preamplifier 27 and the power amplifier 29, and the listener 35 and the tweeter 37 pass through the network 31 and the attenuator 33. To listen to.

In the device configured as described above, the filters 21 and 25 are switched by the switch 21 so that the listener can listen to music only in the low frequency band, or listen to music in the high frequency band in addition to the low frequency band. In order to determine whether the listener can detect the change in the sound quality, a psychological experiment was performed in the form of a question and answer.

(Problems to be Solved by the Invention) First, in the above-described conventional audio device, the electric signal in the audio frequency band passes through different circuits depending on when the electric signal passes through the low-pass filter 23 and when the electric signal passes through the all-pass filter 25. Therefore, there is a problem that a delicate difference in characteristics in the audio frequency band between the two circuits affects the sound quality, and that accurate measurement cannot be performed. More specifically, for example, in view of the situation where even in recent years even a difference in sound quality due to a difference in material of an audio cable much simpler than an electronic circuit becomes a problem, the above-described difference in the electronic circuit is a major problem. .

Also, in the playback device system from the amplifier to the speaker, the signal component passing through the system differs greatly between when the signal passes through the all-pass filter and when the signal passes through the low-pass filter. There is a problem that a sound quality change occurs in a frequency band.

Furthermore, in the psychological method using the conventional sound device,
There is a problem that the language and consciousness of the listener intervene, the instability is high, and the reliability is lacking.

The present invention has been made in view of the above, and its purpose is to eliminate the above-described conventional problems.
Even if the frequency band is switched, an accurate signal is always generated without being affected by the circuit, and by using an audio device that can be used for accurate measurement of brain waves, the listener's subjectiveness such as language and consciousness can be An object of the present invention is to provide a sound quality change detection method based on electroencephalogram measurement that eliminates judgment and improves the stability and reliability of the result.

[Configuration of the invention]

(Means for Solving the Problems) A signal generating means for generating a signal in a predetermined audio frequency band and a frequency band exceeding the audio frequency band, a signal from the signal generating means, and a low frequency signal in a low frequency band Low-pass means for passing the signal, high-pass means for passing a high-frequency signal in a high-frequency band from which the low-frequency band has been removed among the signals generated by the signal generating means, high-pass means, and the signal generating means Opening / closing means for selectively transmitting a signal from the signal generating means to the high-pass means, and low-frequency output means for amplifying and outputting a low-frequency signal passed through the low-pass means. And high-frequency output means for amplifying and outputting a high-frequency signal passed through the high-frequency output means, and generating a voice by combining the low-frequency signal from the low-frequency output means and the high-frequency signal passed through the high-frequency output means Sound generating means The gist is to have

(Operation) In the sound quality change detection method by brain wave measurement of the present invention, a low-frequency band signal that has passed through the low-pass means is always output through the same path, and a high-frequency band signal that has passed through the high-pass means is output. By using a sound device capable of selectively outputting a signal in addition to the signal in the low frequency band, the brain wave of the listener can be measured, so that the detection of a change in sound quality can be objectively confirmed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a circuit configuration of an audio device according to one embodiment of the present invention. The acoustic device shown in FIG. 1 has a sound source 1 composed of, for example, a tape recorder or the like that generates a signal such as music in a low frequency band which is an audio frequency band and a high frequency band exceeding the audio frequency band. After amplifying the signal through the preamplifier 3, the signal is directly passed through the low-pass filter 5 and selectively passed through the high-pass filter 9 via the switch 7.
The low-frequency band signal that has passed through the low-pass filter 5 is amplified by the power amplifier 11 and then output from the speaker 17 via the network 15 and further output from the tweeter 19 via the attenuator 21 from the network 15. ing. A signal in a high-frequency band selectively passed through the high-pass filter 9 via the switch 7 is amplified by the power amplifier 13 and then output from the tweeter 23. The low-pass filter 5 and the high-pass filter 9
Have characteristics as shown by curves A and B in FIG. 2, respectively.

In the acoustic device configured as described above, when the switch 7 is turned off, only the signal in the low frequency band of the signal from the sound source 1 is transmitted from the preamplifier 3 via the low-pass filter 5 and further from the low-pass filter 5 Amplifier 1
1, the speaker 17 and the speaker 17 are output via the network 15, the attenuator 21 and the like. When the switch 7 is turned on, the signal from the sound source 1 In addition to being output from the speaker 17 and the tweeter 19 through the filter 5 as described above, the signal in the high-frequency band of the signal from the sound source 1 is amplified by the preamplifier 3 and then passed through the switch 7 to the high-pass filter 9. And the high-frequency band signal passed through the high-pass filter 9 is output from the tweeter 23 via the power amplifier 13, whereby both the low-frequency band signal and the high-frequency band signal are simultaneously output. ing.

In this case, the signal in the low frequency band is transmitted from the sound source 1 to the preamplifier 3, the low-pass filter 5, the power amplifier 11, the network 15, the attenuator 21, the speaker 17, and the tweeter 19.
And the high-frequency band signal also passes through the same independent path from the sound source 1 to the preamplifier 3, the switch 7, the high-pass filter 9, the power amplifier 13, and the tweeter 23. There is no effect on the sound quality of such low-frequency band signals, and there is no difference in the signal components passing through the playback device system. It can be used for accurate measurement of changes in brain waves due to.

FIG. 3 shows the listener using the sound device shown in FIG. 1 to hear only the low-frequency band signal, or without informing the listener of the high-frequency band signal in addition to the low-frequency band signal. FIG. 7 is a configuration diagram illustrating an outline of a measurement method when listening and measuring a change in a brain wave of a listener. In the figure, the speaker 17 and the tweeters 19 and 23 of the sound apparatus of FIG. 1 are installed in front of the listener, and the sound generated from these speakers and the tweeter is heard by the listener. The EEG transmitter 41 detects and transmits an electroencephalogram, and the EEG receiver 43 receives and records the EEG.

FIG. 4 shows a case in which three test subjects 1, 2, and 3 are allowed to listen only to a low-frequency band signal that has passed only the low-pass filter 5 using the measurement method shown in FIG. It is a figure which shows the time average value of the frequency distribution of the brain wave of a listener measured when the high-pass filter 9 was added to the filter 5 and both the low frequency band and the high frequency band were listened. As can be clearly seen from the figure, the frequency distribution of the EEG is clearer when listening to the high-frequency band signal in addition to the low-frequency band signal as compared to the case where only the low-frequency band signal is listened. In this case, it can be seen that the α-wave band of 8 to 13 Hz has increased.

〔The invention's effect〕

As described above, according to the present invention, a low-frequency band signal that has passed through the low-pass means is always output through the same path, and a high-frequency signal that has passed through the high-pass means is output. Since the signal in the low frequency band can be selectively output in addition to the signal in the low frequency band, the signal in the low frequency band is always output via the same independent path without passing through another path when outputting the signal in the high frequency band. Therefore, the sound quality of the low-frequency band signal is not affected, and the paths through which the low-frequency band signal and the high-frequency band signal pass are independent, and the signal components passing through the reproducing device system are different. Therefore, it can be used for accurate measurement of a change in the frequency distribution of brain waves due to a signal in a high frequency band without generating a change in sound quality in a low frequency band.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an audio device according to an embodiment of the present invention, FIG. 2 is a diagram showing characteristics of a low-pass filter and a high-pass filter used in the audio device of FIG. 1, and FIG. Is a diagram showing a configuration when the acoustic device of FIG. 1 is used for brain wave measurement, FIG. 4 is a diagram showing an electroencephalogram spectrum measured by the measuring method of FIG. 3, and FIG. 5 is a diagram of a conventional acoustic device. FIG. 3 is a block diagram illustrating a configuration. 1 ... sound source, 3 ... preamplifier, 5 ... low-pass filter, 7 ... switch, 9 ... high-pass filter, 11, 13
… Power amplifier, 17… Speaker, 19, 23… Tweeter.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Toshiki Nagumo 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside Tokyo Electric Power Company (56) References Jikai Sho 61-2204 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) A61B 5 / 04,5 / 12 G08B 3/10

Claims (1)

(57) [Claims] 1. A signal generating means for generating a signal in a predetermined audio frequency band and a frequency range exceeding the audio frequency band, a signal from the signal generating means being input, and passing a low frequency signal in a low frequency band. Low-pass means, high-pass means for passing a high-frequency signal in a high-frequency band from which the low-frequency band has been removed among the signals generated from the signal generating means, the high-pass means and the signal generating means, Opening / closing means for selectively transmitting a signal from the signal generating means to the high-pass means; and low-frequency output means for amplifying and outputting a low-frequency signal passing through the low-pass means. High-frequency output means for amplifying and outputting a high-frequency signal that has passed through the high-pass means, and converting the low-frequency signal from the low-frequency output means and the high-frequency signal that has passed through the high-frequency output means into sound. Generate Acoustic device, characterized in that it comprises a voice generator.