CELP speech coding: comparisons in terms of quantization techniques for the synthesis filter parameters

"Vector quantization of the synthesis filter parameters in Code-Excited Linear Prediction (CELP) speech coders is a common procedure nowadays. This paper describes a CELP coder implementation and makes a comparison in terms of quality and bit rate when vector and scalar quantization of the synthesis filter parameters are employed.Usage of vector quantization in comparison to scalar quantization allows for a bit rate reduction of 340 bps, giving rise to a 4,06 kbps CELP coder, keeping a similar subjective evaluation."