Development of Speech Understanding System Using Artificial Intelligence Techniques

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The objectives of this research include to build a continuous speech recognition system for Korean speech as well as performing fundamental research for knowledge-based techniques and its applications to speech understanding system. Understanding of continuous speech is generally a tough problem, since acoustic information is unreliable. This requires us to employ not only acoustic information but also linguistic one to disambiguate the acoustic processing. In this international research with a Korean researcher, we discussed the common issues frequently and obtained the possibility of the application of our speech recognition expert system named SPREX to Korean speech recognition. The following are the summary of the research results obtained this year.1) We investigated the characteristics of Korean speech and found several differences : It has about two-times more vowels including semi-vowels and many nasals. So, we extended the mechanism and the knowledge of the SPREX to enable it applicable to Korean speech recognition. Furthermore, we found the front end module in SPREX responsible for describing the trajectory of feature parameters should re-program in order to cope with Korean speech description.2) For preparation to the speech understanding system building, we also investigated the characteristics of Korea language to know the difference between Japanese and it. Based on the investigation, we found no serious difference in designing the language processing subsystem for the speech understanding system, that is, the system we currently develop for Japanese language is applicable to Korean in principle.3) Speech data base plays an important role in speech research, especially in our research on different languages. Although it is just in the elementary stage, we began the investigation of the structure of speech data base for Korean spoken language as well as Japanese.