The magnitude

and power spectrum are non-negative variables, and any negative estimates

of these variables should be mapped into non-negative values. This nonlinear rectification process distorts the distribution of the restored signal.

The processing distortion becomes more noticeable as the signal-to-noise

ratio decreases. In this chapter, we study spectral subtraction, and the

different methods of reducing and removing the processing distortions. -The　magnitude

and power spectrum are non-negative variables, and any negative estimates

of　these　variables　should　be　mapped　into　non-negative　values.　This　nonlinear　rectification　process　distorts　the　distribution　of　the　restored　signal.

The　processing　distortion　becomes　more　noticeable　as　the　signal-to-noise

ratio　decreases.　In　this　chapter,　we　study　spectral　subtraction,　and　the

different methods of reducing and removing the processing distortions.