For restoration of time-domain signals, an

estimate of the instantaneous magnitude spectrum is combined with the

phase of the noisy signal, and then transformed via an inverse discrete

Fourier transform to the time domain. In terms of computational

complexity, spectral subtraction is relatively inexpensive. However, owing

to random variations of noise, spectral subtraction can result in negative

estimates of the short-time magnitude or power spectrum-For　restoration　of　time-domain　signals,　an

estimate　of　the　instantaneous　magnitude　spectrum　is　combined　with　the

phase　of　the　noisy　signal,　and　then　transformed　via　an　inverse　discrete

Fourier　transform　to　the　time　domain.　In　terms　of　computational

complexity, spectral subtraction is relatively inexpensive. However, owing

to　random　variations　of　noise,　spectral　subtraction　can　result　in　negative

estimates　of　the　short-time　magnitude　or　power　spectrum