Techniques for information retrieval from voice messages

The components of a speech message information retrieval system include an acoustic front end which provides an incomplete transcription of a spoken message, and a message classifier that interprets the incomplete transcription and classifies the message according to message category. The techniques and experiments described are concerned with the integration of these components and represent the first demonstration of a complete system that accepts speech messages as input and produces as estimated message class as output. The complete system has been implemented on special-purpose digital signal processing hardware and demonstrated using live speech input. The results obtained on a conversational speech task have demonstrated the feasibility of the technology and also illustrate the need for further work. Even with a perfect acoustic front end, a message classification accuracy of only 78% was obtained with a 126 keyword vocabulary