PURPOSE: To generate a noise which has a formant shape and can be shifted in its center frequency optionally and easily by performing the necessary spectrum processing of a white noise and multiplying the processing result by a period waveform corresponding to a specified formant center frequency.

CONSTITUTION: The noise from a white noise generating circuit 1 is passed through a digital filter 2 for the spectrum processing where low-pass characteristics are given, thereby obtaining a right-down white noise. A multiplier 5 multiplies this noise by the sine wave of the period waveform corresponding to the specified formant center frequency outputted by a period waveform generating circuit 4 to generate a noise in the formant shape by the convolution of the frequency by the product of a time area. Consequently, the noise in the formant shape which can be shifted in center frequency optionally and easily can be generated by this constitution.