An architecture for spoken dialogue management

Abstract

We propose an architecture for integrating discourse processing and speech recognition (SR) in spoken dialogue systems. It was first developed for computer-mediated bilingual dialogue in voiceto-voice machine translation applications and we apply it here to a distributed battlefield simulation system used for military training. According to this architecture discourse functions previously distributed through the interface code are collected into a centralized discourse capability. The Dialogue Manager (DM) acts as a third-party mediator overseeing the translation of input and output utterances between English and the command language of the backend system. The DM calls the Discourse Processor (DP) to update the context representation each time an utterance is issued or when a salient non-linguistic event occurs in the simulation. The DM is responsible for managing the interaction among components of the interface system and the user. For task-based human-computer dialogue systems it consults three sources of nonlinguistic context constraint in addition to the linguistic Discourse State: (1) a User Model, (2) a static Domain Model containing rules for engaging the backend system, with a grammar for the language of well-formed, executable commands, and (3) a dynamic Backend Model (BEM) that maintains updated status for salient aspects of the non-linguistic context. In this paper we describe its four-step recovery algorithm invoked by DM whenever an item is unclear in the current context, or when an interpretation error is, and show how parameter settings on the algorithm can modify the overall behavior of the system from Tutor to Trainer. This is offered to illustrate how limited (inexpensive) dialogue processing functionality, judiciously selected, and designed in conjunction with expectations for human dialogue behavior can compensate for inevitable limitations in SR, NL processor, the backend software application, or even in the user’s understanding of the task or the software system. 1. SPOKEN DIALOGUE SYSTEMS 1.1 Integrating Discourse and SR Waibel et al., (1989) and De Mori et al., (1988) extend stochastic language modeling techniques to the discourse level to improve spoken dialogue systems. The complexity of discourse state descriptions leads to a sparse data problem during training, and idiosyncratic human behavior at run time can defeat even the best probabilistic dialogue model. Symbolic approaches to spoken discourse data identify discourse constraints on language model selection at run time. Our work collects discourse-level processing into a centralized discourse capability as part of a modular user interface dialogue architecture. Its use in a spoken dialogue interface to a distributed battlefield simulation system used for military training is diagrammed in Figure 1.