1. In a computer system, a method of vector quantization, comprising the following steps: a. from a training set of vectors, creating a vector quantization codebook representative of a set of training vectors, said codebook comprising a representative set of n quantized vectors from said training vectors; b. for each i quantized vector (VQ.sub.i) of said n quantized vectors, determining an i threshold (Threshold.sub.i) to be associated with said i quantized vector, wherein said i threshold comprises half a distance between said i quantized vector and a k quantized vector (VQ.sub.k) of said n quantized vectors, wherein i&lt;k.ltoreq.n, and said k quantized vector is the closest quantized vector to said i quantized vectors of a set of quantized vectors having an index k wherein i&lt;k.ltoreq.n; c. for each i quantized vector of said n quantized vectors, associating in said vector quantization codebook said i threshold with said i quantized vector; and d. using said vector quantization codebook to encode a set of input vectors (V.sub.1 -V.sub.TOT).