Lexical access and verification in a broad phonetic approach to continuous digit recognition

This paper describes an implementation of a robust method of lexical access and a detailed phonetic verification component for recognizing continuous digits using a broad phonetic approach. The lexical access component uses a scoring method which takes into account soft labeling errors due to input signal variability. Verification is based on the use of a small set of detailed acoustic features which characterize phone hypotheses. Evaluation of the lexical access method on a database of 74 new random length digit strings, each spoken by 5 new speakers, shows the method to be tolerant to front-end errors and variations in pronunciation. Evaluation of the verification component indicates that use of a few detailed phonetic features is adequate for verification of phones in the digit vocabulary.