A Robust Dialogue System with Spontaneous Speech Understanding and Cooperative Response

A spoken dialogue system that can understand spontaneous speech needs to handle extensive range of speech in comparision with the read speech that has been studied so far. The spoken language has looser restriction of the grammar than the written language and has ambiguous phenomena such as interjections, ellipses, inversions, repairs, unknown words and so on. It must be noted that the recognition rate of the speech recognizer is limited by the trade-off between the looseness of linguistic constraints and recognition precision, and that the recognizer may output a sentence as recognition results which human would never say. Therefore, the interpreter that receives recognized sentences must cope not only with spontaneous sentences but also with illegal sentences having recognition errors. Some spoken language systems focus on robust matching to handle ungrammatical utterances and illegal sentences.