A Speech-Based Human-Computer Interaction System for Automating Directory Assistance Services

摘要

The automation of Directory Assistance Services (DAS) through speech is one of the most difficult and demanding applications of human-computer interaction because it deals with very large vocabulary recognition issues. In this paper, We present a spoken dialogue system for automating DAS. Taking into account the major difficulties of this endeavor a stepwise approach was adopted. In particular, two prototypes D1.1 (basic approach) and D1.2 (improved version) were developed successively. The results of D1.1 evaluation were used to refine D1.1 and gradually led to D1.2 that was also improved using a feedback approach. Furthermore, the system was extended and optimized so that it can be utilized in real-world conditions. We describe the general architecture and the three stages of the system's development in detail. Evaluation results concerning both the speech recognizer's accuracy and the overall system's performance are provided for all prototypes. Finally, we focus on techniques that handle large vocabulary recognition issues. The use of Directed Acyclic Word Graphs (DAWGs) and context-dependent phonological rules resulted in search space reduction and therefore in faster response, and also in improved accuracy.