Abstract: The present invention relates to a sound volume control device whereby the sound volume of an audio device is automatically controlled as a function of background noise. The apparatus includes a background noise detector means for generating driving signals; means for generating a control signal corresponding to the driving signals; and means for controlling the audio signal in accordance with the control signal, thereby providing the most suitable sound volume according to the background noise without manually controlling a volume switch. In a preferred arrangement, the driving signals are also used to drive the segments of a digit display, to give a visual indication of the sound pressure of the background noise.