Language processing for speech understanding

This report considers language understanding techniques and control strategies that can be applied to provide higher-level support to aid in the understanding of spoken utterances. The discussion is illustrated with concepts and examples from the BBN speech understanding system, HWIM (Hear What I Mean). The HWIM system was conceived as an assistant to a travel budget manager, a system that would store information about planned and taken trips, travel budgets and their planning. The system was able to respond to commands and answer questions spoken into a microphone, and was able to synthesize spoken responses as output. HWIM was a prototype system used to drive speech understanding research. It used a phonetic-based approach, with no speaker training, a large vocabulary, and a relatively unconstraining English grammar. Discussed here is the control structure of the HWIM and the parsing algorithm used to parse sentences from the middle-out, using an ATN grammar.