Sethos: the UPC speech understanding system

In EuroSpeech'95, the authors presented the first version of Sethos, the speech understanding system which has been developed at the UPC. In this paper some improvements are incorporated at different levels of Sethos: language model, models of the semantic units and acoustic models. These improvements increase the percentage of correctly decoded sentences from 60% to 80%. Some experiments are presented to evaluate the influence of each information source on the final performance. Furthermore, the computational cost is analyzed arriving to an important conclusion: the configuration which gives the best performance is also the less expensive. The reason is that as better is the modeling, narrower is the beam of the search.