A speech encoder includes an adaptive codebook that generates an adaptive codevector representing a pitch component, a random codebook that generates a random codevector representing a random component, and a synthesis filter that generates a synthetic speech signal by being excited by the adaptive codevector...http://www.google.com/patents/US7809557?utm_source=gb-gplus-sharePatent US7809557 - Vector quantization apparatus and method for updating decoded vector storage
