Voice coding at 800 BPS and lower data rates with LPC vector quantization

Design of an 800 bps LPC vocoder based on vector quantization is presented. Subjective evaluation under different channel error and acoustic-ambient noise conditions are discussed. The results indicate that it preserves much of the intelligibility as well as robustness of LPC. Further reduction in bit rate is achieved by eliminating frame to frame redundancy in the vocoder parameters. Techniques include frame repeat coding and the newly developed matrix coding technique.