On the just‐noticeable difference for tempo in speech

The rate or tempo of speech modulates listeners’ phonetic expectations, e.g., about VOT or about segment durations. In addition, variations in tempo contribute directly to speech communication, e.g., by expressing the communicative importance of speech fragments. It is not clear, however, how large tempo differences in speech have to be in order to be noticeable and to contribute to speech perception. This paper attempts to determine the jnd for tempo in speech, by means of detection of gradual changes in tempo. Participants listened to 10‐s spoken texts, in which overall tempo was linearly accelerated (to 80%) or decelerated (to 120%) over a 5‐s interval. They were instructed to press a button as soon as they detected a tempo change in the text; jnd’s were computed from their response times. Preliminary results suggest that the average jnd’s for tempo in speech are about 14% (acceleration) and 15% (deceleration). These values are far larger than those reported for tempo in music (about 3% to 6%), which s...