Towards Fine-Grain User-Simulation for Spoken Dialogue Systems

Continuous advances in the field of spoken dialogue systems make the processe of design, implementation and evaluation of these systems more and more com-s plex. To solve problems emerging from this complexity, a technique which has attracted increasing interest during the last decades is based on the automatic generation of dialogues between the system and a user simulator, which is another system that represents human interactions with the dialogue system. This chapter describes the main methodologies and techniques developed to create user simulators, and presents a discussion of their main characteristics and the benefits that they provide for the development, improvement and assessment of this kind of systems. Additionally, we propose a user simulation technique to test the performance of spoken dialogue systems. The technique is based on a novel approach to simulating different levels of user cooperativeness, which allows carrying out a more detailed system assessment. In the experiments we have evaluated a spoken dialogue system designed for the fast food domain. Theevaluation has focused on the performance of the speech recogniser, semantic analyser and dialogue manager of this system. The results show that the technique provides relevant information to obtain a solid evaluation of the system, enabling us to find problems in these modules which cannot be observed taking into account just one cooperativeness level.