Speech coding based on adaptive mel‐cepstral analysis and its evaluation

This paper proposes the ADPCM speech coding system using mel-cepstrum as the parameter for the short-term prediction. In the proposed coding system, the backward type adaptive prediction is applied based on the adaptive mel-cepstrum analysis. Operations such as noise shaping and postifitering are executed through the melcepstrum. Consequently, it is expected that the noise shaping and the postfiltering have the effect which is matched to the human auditory characteristics. This paper presents the configuration of the coding system with some improvements such as the addition of the pitch predictor, and the quality of the coded speech is evaluated. It is shown as a result that the proposed coding system realizes the same speech quality at 16 kbit/s as that of the 32-kbit/s ADPCM, even though there is no algorithm delay.