Time compression increases the rate of speech without altering its pitch. The present study investigated time compression as a means of improving the efficiency of audiotext applications for a variety of user populations. Subjects from three age groups (20-30, 40-50, and 60-70 years old) and two native language groups (native and nonnative English speakers) interacted with a prototype of an Interactive Voice Response system. Four prototypes were constructed, each containing speech compressed at a different rate: 30%, 20%, 10%, and uncompressed. Each subject telephoned one of the prototypes to learn how to use Call Forwarding and to order another telephone service feature. Compression rate did not significantly interact with age or native language. Across compression rates, 60-year-olds spent significantly more time on the phone than did 20- and 40-year-olds. Moreover, 60-year-olds were significantly less successful at forwarding phone calls, and reported more difficulty and confusion, than other subjects. Nonnative English speakers spent significantly more time on the phone than did native English speakers. Despite this difference, nonnative speakers were just as successful at forwarding phone calls, and rated the system and the announcer just as favorably as did native speakers of English. There was no main effect of compression rate on call duration; faster speech did not result in significantly shorter phone calls.
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