Robust and Flexible Mixed-Initiative Dialogue for Telephone Services

Proceedings of EACL '99 Robust and Flexible Mixed-Initiative Dialogue for Telephone Services Relafio Gil, Jos~ ~ and Tapias, Daniel and Gancedo, Maria C. Charfuelan, Marcela ~ and Hern£ndez, Luis A. Speech Technology Group, Telefdnica Investigacihn y Desarrollo, S.A. C. Emilio Vargas, 6 28043 - Madrid (Spain) Teh34.1.549500. Fax:34.1.3367350. e-mail:jretanio@gaps.ssr.upm.es Abstract In this work, we present an experimental analysis of a Dialogue System for the au- tomatization of simple telephone services. Starting from the evaluation of a preliminar version of the system we 1 conclude the ne- cessity to desing a robust and flexible system suitable to have to have different dialogue control strategies depending on the charac- teristics of the user and the performance of the speech recognition module. Experimen- tal results following the PARADISE frame- work show an important improvement both in terms of task success and dialogue cost for the proposed system. 1 INTRODUCTION In this contribution we present some improve- ments on the design of a Dialogue Management System for the automatization of simple telephone tasks in a PABX environment (automatic name dialing, voice messaging, ... ). From the point of view of its functionality, our system is a very simple one because there is no need of advanced Plan Recognition strategies or General Problem Solving methods. However we think that even for these kind of dialogue sytems there is still a long way to demonstrate their usability in real situa- tions by the "general public". In our work we will concentrate on systems designed for the telephone line and for a wide range of potential users. Therefore our evalua- tions will be done taking into account different lev- els of speech recognition performance and user be- haviours. In particular we will propose and eval- uate strategies directed to increase the robustness against recognition errors and flexibility to deal with a wide range of users. We will use the PAR- ADISE evaluation framework (Walker et al., 1998) to analyze both task success and agent dialogue behaviour related to subjective user satisfaction. 1~ Dep. SSR. ETSIT-UPM Spain 2 ROBUST AND FLEXIBLE SYSTEM Following the classification of Dialogue Systems proposed by Allen (Allen, 1997), our baseline clia- logue system could be described as a system with topic-based performance capabilities, adaptive single task, a minimal pair clarification/correction dialogue manager and fixed mixed-initiative. One of the most important objectives of our di- alogue manager has been the implementation of a collaborative dialogue model. So the system has to be able to understand all the user actions, in whatever order they appear, and even if the focus of the dialogue has been changed by the user. In order to achieve this, we organize the information in an information tree, controlled by a task knowl- edge interpreter and we let the data to partici- pate in driving the dialogue. However, to control a mixed-initiative strategy we use three separate sources of information: the user data, the world knowledge embedded in the task structure and the general dialogue acts. Therefore, from this preliminar evaluation …

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