Insights Gained from Development and Long-Term Operation of a Real-Environment Speech-Oriented Guidance System

This paper presents insights gained from operating a public speech-oriented guidance system. A real-environment speech database (300 hours) collected with the system over four years is described and analyzed regarding usage frequency, content and diversity. Having the first two years of the data completely transcribed, simulation of system development and evaluation of system performance over time is possible. The database is employed for acoustic and language modeling as well as construction of a question and answer database. Since the system input is not text but speech, the database enables also research on open-domain speech-based information access. Apart from that research on unsupervised acoustic modeling, language modeling and system portability can be carried out. A performance evaluation of the system in an early stage as well as late stage when using two years of real-environment data for constructing all system components shows the relative importance of developing each system component. The system's response accuracy is 83% for adults and 68% for children.