PURPOSE: To enjoy music or the like in a proper sound volume without being troubled by surrounding sound by catching the loudness of the surrounding sound with a microphone and controlling the sound volume of a reproduction signal in a proper volume.
CONSTITUTION: A surrounding sound is detected by a microphone 5 and the result is outputted as an electric signal. The output signal amplified, detected and filtered by a level detection circuit 6 and the result is outputted as a signal representing the quantity of an external sound. A sound volume control circuit 3 adjusts automatically the reproduced sound signal incoming from a headphone stereo main body 7 to have a proper sound volume designated in advance. Then the control circuit 4 receives a command signal from a remote control section 2 to control each configuration block of the headphone stereo main body 7 and the sound volume control circuit 3. Thus, a sound signal in response to the control is sent from the sound volume control circuit 3 and a reproduction with a proper sound volume is outputted from the headphone 1.