A representational approach to knowledge-based acoustic-phonetic processing in speech recognition

We propose an approach to acoustic-phonetic processing in speech recognition systems based on an intermediate representation, the ´Speech Sketch´, whose purpose is to bridge the representational gap between acoustic evidence and phonetic knowledge. The Speech Sketch makes parameter behaviour, rather than parameter values, explicit. We report on a small scale testbed for this approach. In this work we have attempted to discriminate between the semivowels in vowel-semivowel-vowel utterances using, as our acoustic evidence, LPC-derived formant frequency estimates. Our Speech Sketch is based on linear descriptions and our acoustic-phonetic knowledge is represented in frame-like structures. For three male speakers the performance of this software is comparable with that of a human expert presented with the same parametric data.