VPQ: a spoken language interface to large scale directory information

This paper describes VPQ (Voice Post Query), a dialog system that provides spoken access to the information in the AT&T corporate personnel database (>120,000 entries). An explicit design goal is to have the user’s initial interaction with the system be rather unconstrained and to rely on tighter, prompt constrained, dialog only when absolutely necessary. The purpose of VPQ is both a) to explore and exploit the capabilities of “state of the art” speech recognition systems for this highperplexity task, and b) to develop the natural language understanding and dialog control components necessary for effective and efficient user interactions. The VPQ task spans a wide range of possible dialog scenarios. They range from simple “one-shot” to complex multi-turn interactions. The former correspond to interactions where the initial utterance is unambiguous and the system’s response appropriately terminates the interaction either by providing the desired information or completing a call to the requested person. The more complex interactions occur primarily whenever ambiguities or errors require resolution. Current speech recognition accuracy of 80% is adequate to pursue such an ambitious task. This paper highlights the inherent challenges in such a task, the major components of the system, the rationale for their design, and how they perform. The VPQ project targets a variety of access devices, including telephony, desktop and handheld devices offering multi-modal user interfaces. In this paper we focus on describing the telephony interface.