The speech enhancement of the G.723.1 vocoder using multi-order formant postfilter

Abstract

The speech quality of CELP type vocoders is improved by compensating the formant distortion with a formant postfilter. The formant postfilter is generally composed of the conventional ARMA filter with the 1-order tilt compensation filter. We propose a new method to improve speech quality using multi-order tilt compensation filter instead of the 1-order tilt compensation filter. This algorithm is applied to G.723.1 for Internet phone or videoconferencing. Consequently, spectrum distortion is improved about 3.22% and speech quality is improved about 0.04 of MOS score maximally.