Design and Description of a 600 bps Speech Coder Based on Melpe

This paper describes a 600 bps speech coder based on the enhanced mixed excitation linear prediction model[1] (MELPe). The algorithm of this speech coder includes features of MELPe, which can obtain high quality synthesized speech and is robust in difficult background noise environments. To reduce the bit rate, we have developed a modified multi-frame joint vector quantization that takes advantage of inherent inter-frame redundancy. The predicted multi-stage vector quantizer (PMSVQ) is designed to quantize the line spectrum frequency (LSF) parameters. Simulation results have proven that an efficient and high quality coding has been achieved at bit rate 600 bps, and the proposed coder is better than the existing 2400 bps LPC10e standard[2].