PURPOSE: To reproduce and to recognize acoustic image in normal position when stereo sound source is heard by a head phone by mixing the signal which delays and reduces a reverse signal with a left and a right signal.

CONSTITUTION: The left signal 2 and the right signal 3 outputted from an amplification output circuit 1 are respectively delayed about 600μs ± 100μs by delay circuits 41 and 42. The left signal 2 and the right signal 3 are mixed with signals 61 and 62 abtained by respectively reducing the output of these signals about 10% ± 20% with the aid of reduction circuits 51 and 52 by mixing circuits 81 and 82 and outputted to the head phone 9. Thus an acoustic reproduction by the sound source position is feasible.