An Improved MELP Speech Coder

Mixed Excitation Linear Prediction(MELP) coder has been adopted as the new US Federal Standard at 2.4kbps. An improved MELP speech coder is proposed in this paper. The concept of similarity between linear filters and a new method of vector quantization based on classifying the LPC coefficients are proposed. By these two methods the bit rates of MELP coder can be reduced to as low as 1.7kbps without evident damage to the synthetic speech quality.