As a priority-setting exercise, we compared interactions between users and a simple spoken dialog system to interactions between users and a human operator. We observed usability events, places in which system behavior differed from human behavior, and for each we noted the impact, root causes, and prospects for improvement. We suggest some priority issues for research, involving not only such core areas as speech recognition and synthesis and language understanding and generation, but also less-studied topics such as adaptive or flexible timeouts, turn-taking and speaking rate.

In this study we examined prosodic characteristics of a word used in several distinct senses in a task-oriented corpus of spontaneous speech. We compared the pitch characteristics of the word "right" used in three different senses: as an acknowledgment, as a direction, and as an affirmative answer to a question. Significant differences in intonation for different classes of usage were found, although the differences are not reliable enough to allow systems to use prosody alone to distinguish between usages. These results suggest that pitch change as reported by a pitch tracker could serve as a confirming cue when analyzing ambiguous speech recognizer output, or could serve as input to a probabilistic parser to aid in disambiguating senses of homonyms.

In most database systems, a query embedded in a program written in a conventional programming language is optimized when the program is compiled. The query optimizer must make assumptions about the values of the program variables that appear as constants in the query, the resources that can be committed to query evaluation, and the data in the database. The optimality of the resulting query evaluation plan depends on the validity of these assumptions. If a query evaluation plan is used repeatedly over an extended period of time, it is important to determine when reoptimization is necessary. Our work aims at developing criteria when reoptimization is required, how these criteria can be implemented efficiently, and how reoptimization can be avoided by using a new technique called dynamic query evaluation plans. We experimentally demonstrate the need for dynamic plans and outline modifications to the EXODUS optimizer generator required for creating dynamic query evaluation plans.