Abstract
Mobile and wireless telecommunication systems are expanding rapidly, and many new systems are in development. To address the impact on speech communication, this paper describes a new conversation-based test of transmission quality designed to be sensitive to degradations common in mobile systems. An experiment using this conversation test added roundtrip delays of 0, 600 and 1200 ms to the transmission path. Three types of dependent variables were collected: subjective ratings of quality and listening effort, measures of conversational dynamics, and scores of task performance. Although neither the subjective ratings or task performance varied across delay conditions, there was a significant effect on one measure of conversational dynamics, the number of interruptions. Arguments are presented that changes in conversational events may be superior to traditional subjective measures for evaluating mobile systems.
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