VOICE CONVERTER

A voice converter provides for pitch and formant shifting of an input voice signal. An audio filter extracts the volume level of the input voice signal, and outputs the extracted volume level as first volume data. A second audio filter extracts the volume level of an output voice signal, and outputs the extracted volume level as second volume data. A difference judging circuit compares the first and second volume data with each other, and determines a volume gain and a distorting factor which is supplied to a distortion circuit. When the volume of the output voice after conversion is smaller than that of the input voice, the volume gain is increased. In a case where the input voice is to be shifted toward higher frequencies, when the volume of the output voice after conversion is smaller than that of the input voice, it is determined that the volume of a high-pitched sound region is insufficient, and the distorting factor is increased in order to enlarge the amount of higher harmonics which are to be added to the input voice.