Method and system for speech recognition using continuous density hidden Markov models

Abstract

A method and system for achieving an improved recognition accuracy in speech recognition systems which utilize continuous density hidden Markov models to represent phonetic units of speech present in spoken speech utterances is provided. An acoustic score which reflects the likelihood that a speech utterance matches a modeled linguistic expression is dependent on the output probability associated with the states of the hidden Markov model. Context-independent and context-dependent continuous density hidden Markov models are generated for each phonetic unit. The output probability associated with a state is determined by weighing the output probabilities of the context-dependent and context-independent states in accordance with a weighting factor. The weighting factor indicates the robustness of the output probability associated with each state of each model, especially in predicting unseen speech utterances.