Restoration of wide band signal from telephone speech using linear prediction residual error filtering

This paper describes a system that can enhance the quality of speech signals that are severely band limited during regular telephone speech transmission. We have already proposed a spectrum widening method that utilizes aliasing in sampling rate conversion and digital filtering for spectrum shaping. This paper proposes a new method using linear prediction (LP) residual error processing and LP parameter (coefficients) mapping that offers improved performance in terms of the spectrum distortion characteristics. Real time hardware implementation procedures are discussed. The proposed method can effectively enhance speech quality.