JPS6230080Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vocoder that is less likely to cause howling.

A vocoder is a device that controls an audio signal other than a human voice using the human voice to obtain an audio signal similar to human utterances, and an example thereof is shown in the circuit block diagram of FIG.

In FIG. 1, the audio signal output from the sound source G is divided into a plurality of narrow frequency bands by the second bandpass filter group _F2 , and then the voltage-controlled variable gain amplifier group
A ₂ audio input signal. Then, the human voice is converted into an electrical signal by the microphone M, and inputted to the first band-pass filter group _F1 via the amplifier _A1 to generate electrical signals for each narrow frequency band (hereinafter referred to as voice signals). The amplitude value detection circuit group C detects the amount of the voice signal component for each band, and the detected signal voltage is used as each amplifier control voltage of the voltage-controlled variable gain amplifier group _A2 . The first bandpass filter group
Each of the narrow band pass filters F ₁₁ to _{F 1} n forming F 1 corresponds to each _of the narrow band pass filters F ₂₁ to F ₂ n forming the second band pass filter group F ₂ . It has an occupied frequency band. Then, the output signals of the voltage-controlled variable gain amplifier group _A2 are added together and the resultant sound is emitted from the speaker S via the amplifier _A3 .

In this way, the vocoder attempts to control the volume of the audio signal of the sound source G by voice signal for each frequency band to obtain a human vocal sound imitation signal similar to human vocalization.

However, when using a vocoder as described above at a high volume, the musical sound emitted from the speaker S is inputted again to the microphone M, and howling may occur due to positive acoustic feedback, which can cause problems in performance. It may happen.

Therefore, the present invention has been devised for the purpose of providing a vocoder that is less likely to cause howling.

The present invention will now be described in detail with reference to the drawings.
FIG. 2 is a diagram showing the frequency characteristics of the first and second bandpass filters of the vocoder of the present invention.

In the present invention, constants are set so that the center frequencies of the corresponding bandpass filters of the first bandpass filter group _F1 and the second bandpass filter group _F2 do not overlap, and the solid line ₁₁ ~ ₁ n is the first bandpass filter group
The frequency characteristics of each bandpass filter of F ₁ are expressed by the dashed line ₂₁
~ _2n represents the frequency characteristic of each bandpass filter of the second bandpass filter group _F2 .

Therefore, when the musical sound emitted from the speaker S is input again to the microphone M and forms a loop, the overlap of the frequency characteristics of the corresponding bandpass filters becomes the shaded area, and the Q of the resonance point including the sound field becomes As a result, howling is less likely to occur.

As described above, the present invention provides a very easy-to-use vocoder that can prevent howling with a simple configuration and is less likely to generate howling even when used at a high volume.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of a vocoder, and FIG. 2 is a diagram showing the frequency characteristics of the first and second band-pass filters of the vocoder of the present invention. M...Microphone, _A1 , _A3 ...Amplifier, _F1 ...First band pass filter group, C...Amplitude value detection circuit group, G...Sound source, _F2 ...Second band Pass filter group, F ₁₁ to _{F 1} n, F ₂₁ to F ₂ n... Narrow band pass filter, A ₂ ... Voltage controlled variable gain amplifier group, S...
speaker.

Claims (1)

[Scope of utility model registration request] An analysis means for frequency spectrum analysis via a group of band-pass filters that frequency-divides an input voice signal, and a group of audio signal filters that frequency-divides an audio signal from another sound source in the same way as the group of band-pass filters described above. In the vocoder, the vocoder is equipped with a level control means for respectively controlling and transmitting levels according to the frequency spectrum analysis results through the frequency spectrum analysis result, and a correspondence between the frequency spectrum analysis band-pass filter group and the audio signal filter group. A vocoder characterized in that the center frequencies of each filter are set so that they do not match.