APHODEX, design and implementation of an acoustic-phonetic decoding expert system

The acoustic-phonetic decoding of complete sentences is a major bottleneck in continuous speech recognition. Our group, who has been working in this area for the past twelve years, first developed systems based on synchronous centi-second pattern-matching. In order to improve the accuracy of present phonetic decoders, we are now developing an expert production-rule system that should emulate the competence of an experienced spectrogram reader. After a brief description of the methodology used to elucidate the expert´s knowledge and strategies, the paper explains how this expertise has been implemented ; results from the present experimental version of our system (APHODEX) are discussed. In order to increase efficiency while maintaining the same degree of accuracy, we are concurrently designing a system in which the expert´s knowledge is represented by frames. An overall description of the system, which describes the phonetic decoding process in terms of a frame language is given in the second part of this paper.