9.6 kbit/s Piecewise LPC residual excited coder using multiple-stage vector quantization

This paper describes a speech coder which exploits the combination of piecewise LPC analysis, full residual excitation and vector quantization in order to yield very good quality at 9.6 kbit/s. The piecewise approximation of the speech spectrum permits a higher spectral accuracy than standard LPC and reduces the computational load by about 40%. The full residual excitation overcomes the disadvantages of the base-band model, previously used at this bitrate. Finally, the vector quantization approach permits a dramatic bit saving over scalar quantization for LPC parameter compression, and provides a better distortion performance in the residual representation.