Using Natural-Language Knowledge Sources in Speech Recognition

High accuracy speech recognition requires a language model, to specify what word sequences are possible or at least likely. Standard n-gram language models for speech recognition ignore linguistic structures, but more linguistically sophisticated language models are possible. Unification grammars are widely used in natural languageand these can be compiled into non-left-recursive context-free grammars that can then be used in realtime speech recognizers by dynamically expanding them into state-transition networks. A hybrid language model incorporating both a unification grammar and n-gram statistics has been shown to increase speech recognition accuracy. Probabilistic context-free grammars and probabilistic unification grammars are also possible.