Spectral subtraction based on phonetic dependency and masking effects

A speech state-dependent spectral subtraction method to regulate the blind spectral subtraction for improved enhancement is proposed. In this method, a modified subtraction rule is applied over the speech selectively contingent to the speech state being voiced or unvoiced, in an effort to incorporate the acoustic characteristics of phonemes. The aim is to remedy the subtraction induced signal distortion attained by two state-dependent procedures: spectrum sharpening and minimum spectral bound. In order to remove the residual noise, the proposed method employs a procedure utilizing the masking effect. The proposed spectral subtraction, including state-dependent subtraction and residual noise reduction using the masking threshold, shows effectiveness in terms of the compensation of spectral distortion in the unvoiced region as well as residual noise reduction.