Dialogue Management for Telephone Information Systems

Dialogue Management for Telephone Information Systems Scott McGlashan and Norman Fraser and Nigel Gilbert Social and Computer Sciences Research Group University of Surrey Guildford, U.K. Eric Bilange Cap Gemini Innovation 118 rue de Tocqueville 5017 Paris, France Paul Heisterkamp Daimler-Benz AG Wilhehn-Runge-Strasse 11 D-7900 Ulna, Germany Nick Youd Logica Cambridge Ltd 104 Hills Road Cambridge, U.K. Abstract A distributed approach to spoken dialogue management for real-time telephone informa- tion systems is outlined. 1 Introduction The approach to dialogue managenaent described here has been developed as part of the Sundial project (Speech UNderstanding in DIALogue) whose goal is to build real-time integrated computer systems capable of maintaining co-operative dialogues with users over stan- dard telephone lines. 1 Systems have been developed for four languages - French, German, Italian and English - within the task domains of flight reservations and en- quiries and train enquiries. Each system consists of five components: a speech recognition component inputs acoustic speech signals fi'om the telephone and outputs a word lattice; a parser extracts a plausible string from the lattice and assigns it syntactic and semantic representations; a dialogue man- ager gives these representations an interpretation, de- cides how the dialogue lnay continue and, if it is the system's turn to speak, plans a system utterance; a text. generator constructs a. detailed linguistic representation from the plan; and a text-to-speech system synthesizes the representation for transmissiol~ by telephone. '2 2 Two Problems of Dialogue Management The SUNDIAL dialogue manager addresses two prob- lems facing spoken dialogue systems. The first is that, for maxinmm usefulness, dialogue management needs to be generic: i.e. the dialogue manager module must be able to interpret and generate utterances in more 1SUNDIAL is partly funded by the Commission of the Europeam Communities under the ESPRIT II programme ~s project P2218. 2See Peckham (1991) for an overview of the Sundial system. thai] one language and across more than one task do- main. The. second problem is that dialogue management must provide co-operative interaction with the user. To achieve this, the system needs to produce utterances which are perceived by the user as natural, coherent and helpful within the context of the dialogue. The purpose and modality of the dialogue forms part of this context: in our case, task-driven spoken dialogues. The system needs to deal with inconsistent task information, such as that obtained when the speech recognizer and parser yield a. plausible but incorrect interpretation; for exam- pie, the user said 1 want to fly to Lannion, but the system understands London rather than Lannion. 3 A Distributed Solution The Sundial solution to these problems lies, in part, ill the distributed architecture of the dialogue man- ager. Tile dialogue manager is responsible for providing a co-operative interaction with the user (Gerlach and ttoracek, 1989). From the user's point of view, system utterances must be appropriate and helpful to the user iTi the cur'rel~t dialogue context. To achieve this, both interpretation of user utterances and planning of system utterances must. be informed by the …

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