PURPOSE: To attain reproduction rich in the listening sense by detecting a frequency having the maximum energy level in an extracted specific frequency band and emphasizing the component corresponding to the frequency detected in the frequency components included in an audio signal.

CONSTITUTION: A comparator 20 compares outputs signals f50, f60, ...,f150 from band-pass filters F1∼Fn so as to detect a frequency having the maximum energy level based on the comparison and a control signal sc corresponding to said frequency is outputted. The control signal Sc is used to vary variable resistors RV1, RV2 in an equalizer 30 at the same time. That is, the equalizer circuit 30 amplifies the component corresponding to the frequency commanded based on the comparison/detection result of the comparator 20 and adds the result to an audio signal to apply correction. Thus, even if audio signals with different spectrum distribution are inputted, the reproduction rich in low sound sense is realized at all times.