1. Pattern recognition apparatus for classifying an arbitrary input signal into one of N known classes, comprising: an analyzer for processing the arbitrary input signal to generate a set of representation values corresponding to the input signal; a plurality of phoneme recognizers coupled to the analyzer, each phoneme recognizer recognizing a distinct category of phonemes, wherein each distinct category of phonemes comprises one or more classes of phonemes; a plurality of likelihood processors that respectively process outputs of the plurality of phoneme recognizers to produce likelihood values that are indicative of the class membership of the input signal; and a combination rule processor for processing outputs of the plurality of likelihood processors to make a final decision regarding the class of the input signal.