Use of acoustic sentence level and lexical stress in HSMM speech recognition

The authors describe the results of an experiment to study the effectiveness of using acoustic stress to improve automatic speech recognition. The CSTR speech recognition system uses hidden semi-Markov models (HSMM) with a separate lexical search component. A hybrid prosodic component has been included which determines the sentence level stress and marks the vowel of stressed syllables as stressed in the phoneme lattice. Lexical stress is marked on all content words in the lexicon. Adding stress information to the system in this way resulted in a 65% reduction in word error rate and a 45% reduction in sentence error rate, relative to a baseline system without prosody