Viva Co., Ltd.

Tetsuya Takizawa

An automatic volume adjusting apparatus comprises a volume adjusting device connected between a sound signal source and a loudspeaker; a first rectifier circuit for generating a first signal having a D.C. level corresponding to the level of a sound signal supplied from the colume adjusting device to the loudspeaker; a microphone and a second rectifier circuit for generating a second signal having a D.C. level corresponding to the level of a composite sound constituted by the sound generated by the loudspeaker and the ambient noise; a subtraction circuit for generating a third signal having a level corresponding to the level difference between the first and second signals, i.e. the level of the ambient noise; a gate circuit for sampling the third signal at predetermined intervals; and an integrator circuit for holding the output of the gate circuit for a predetermined period of time. The output of the integrator circuit controls the volume adjusting device.

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Yamato, Japan

Tetsuya Takizawa