PURPOSE: To prevent an image movement at the time of a speaker reproduction, in a non-correlating device which generates the voice signal of 2 channel with the sense of expance from a monaural voice signal.

CONSTITUTION: A musical interval converter 102 writes an input signal in a storage device by a prescribed writing frequency, reads the data from the storage device by a reading frequency different from the writing frequency, and converts the time axis of the input signal corresponding to the rate of the writing frequency to the reading frequency. A gain adjusting means 103 adjusts the gain of the output signal of the musical interval converter 102 according to a continuously changing delay time between the input signal and the output signal generated due to a difference between the writing frequency and the reading frequency.