Recent progress in spontaneous speech recognition and understanding

How to recognize and understand spontaneous speech is one of the most important issues in state-of-the-art speech recognition technology. In this context, a five-year large scale national project entitled "Spontaneous speech: corpus and processing technology" started in Japan in 1999. This paper gives an overview of the project and reports on the major results of experiments that have been conducted so far at Tokyo Institute of Technology, including spontaneous presentation speech recognition, automatic speech summarization, and message-driven speech recognition. The paper also discusses the most important research problems to be solved in order to achieve ultimate spontaneous speech recognition systems.