AUTOMATIC SOUND VOLUME CONTROL DEVICE

An automatic volume control device for a car stereo or the like which adjusts the volume according to an environmental noise level includes a microphone and a low pass filter circuit whose characteristic is designed so as to correspond to the human auditory characteristic at a low frequency end, but so as to cut out higher frequency components such as voices, etc. A time constant circuit serves to smooth volume transients in case the environmental noise sharply increases.