Conversational speech systems for on-board car navigation and assistance

This paper describes our latest efforts in building a speech recognizer for operating a navigation system through speech instead of typed input. Compared to conventional speech recognition for navigation systems, where the input is usually restricted to a fixed set of keywords and keyword phrases, complete spontaneous sentences are allowed as speech input. We will present the interaction of speech input, parsing and the necessary reactions to the requested queries. Our system has been trained on German spontaneous speech data and has been adapted to navigation queries using MLLR. As the system is not restricted to command word input, a parser is necessary to further process the recognized utterance. We show that within a lab environment our system is able to handle arbitrary spontaneous sentences as input to a navigation system successfully. The performance of the recognizer measured in word error rate gives a result of 18%. The parser has also been evaluated and yields an error rate of 20%.