Continuous Speech Understanding System LITHAN.

Abstract

We have developed LITHAN (LIsten-THink-ANswer) speech understanding system which automatically recognizes continuously uttered speech utilizing higher linguistic information such as syntactic, semantic, pragmatic information. This system predicts possible words utilizing linguistic information at the unrecognized portion of the input utterances, and identifies the predicted word by using the optimum matching algorithm between a recognized phoneme string and the phoneme string of the word dictionary. The system could parse sentences by tree searching, but the results of phoneme recognition and word identification are not always correct, therefore, we propose a new tree search method. LITHAN uses many types of a priori information ; the statistic of each phoneme ; the similarity matrix between phonemes ; the word dictionary ; the spoken grammar with the additional information as regards the spoken grammar ; the semantic and pragmatic information. We have applied this efficient, flexible system to restricted utterances which include about 100 words used to perform operational command and query the status of a computer network. When tested on a sample of 200 sentences spoken by 10 male speakers at a normal speed, 64% of the sentences and 93% of the output words were recognized correctly.