Integration of utterance verification with statistical language modeling and spoken language understanding

Abstract

Methods for utterance verification (UV) and their integration into statistical language modeling and spoken language understanding formalisms for a large vocabulary spoken understanding system are presented. The paper consists of three parts. First, a set of acoustic likelihood ratio based utterance verification techniques are described and applied to the problem of rejecting portions of a hypothesized word string that may have been incorrectly decoded by a large vocabulary continuous speech recognizer. Second, a procedure for integrating the acoustic level confidence measures with the statistical language model is described. Finally, the effect of integrating acoustic level confidence into the spoken language understanding unit (SLU) in a call-type classification task is discussed. These techniques were evaluated on utterances collected from a highly unconstrained call routing task performed over the telephone network. They have been evaluated in terms of their ability to classify utterances into a set of fifteen semantic actions corresponding to call-types that are accepted by the application.