19. A method of speech recognition comprising the steps of: providing a speaker dependent system for each of a plurality of training speakers; providing an acoustic space for each of the training speakers, each acoustic space being characterized by a set of acoustic features; grouping the speaker dependent systems with the acoustic spaces to build acoustic spaces with common features from all the speaker dependent systems; clustering the grouped acoustic spaces to form cluster systems based on a common acoustic characteristic; selecting from a group of cluster systems, a subset of cluster systems closest to adaptation data from a speaker; transforming the subset of cluster systems to bring the subset of cluster systems closer to the speaker based on the adaptation data to form adapted cluster systems; and combining the adapted cluster systems to create a speaker adapted system for decoding speech from the speaker.
26. The method of speech recognition as recited in claim 19, wherein the step of clustering includes the step of clustering by a top-down method.