Method of and device for speech signal coding and decoding by parameter extraction and vector quantization techniques

Abstract From the Canadian patent

A method of speech signal processing is disclosed which does not require excessive computation and which operates at low bit rates. The method comprises filtering blocks of digital samples of speech signals by a linear-prediction inverse filter followed by a shaping filter, the coefficients of which are chosen from a codebook of quantized filter coefficient vectors to obtain a residual signal subdivided into vectors. Each vector is classified by an index q depending on a zero-crossing frequency and a r.m.s. value. Each vector is then normalized first on the basis of a quantized r.m.s. value, and then on the basis of a vector of quantized short-term mean values;the mean-square error occuring …