Speech interaction system - how to increase its usability?

This paper discussed different issues related to the usability of speech interaction system. It includes the usability concept, different design approaches, design process and evaluation questions for speech interaction system. Usability is a very fuzzy concept, especially when it related to the speech interaction system: it is hard to measure and it is very much context dependent. The traditional user-centered design approach may not be suitable for the speech interaction system design since the users might not have enough knowledge to see what the technology can do. Usage-centered design may be the better method but there is not comprehensive theory and methodology for the design process and evaluation.