2. A speech recognition circuit according to claim 1 , wherein said lexical memory means stores said lexical tree data structure as an n phone model of words, where n is an integer, and said components comprise n phones.
3. A speech recognition circuit according to claim 2 , wherein said lexical memory means stores each lexical tree data structure as mono phone models of words, and said lexical tree processors are arranged to use said mono phone models to generate context dependant phone models of words dynamically for use in processing the speech parameters.