Abstract:
This experiment varied the time pattern of 25 tones sequences to determine its effect on subjects' abilities to discriminate small time changes within one of two isochronous test regions. A two-alternative forced-choice procedure was used in which a small time change ((plus or minus)(Delta)t=21, 39, or 57 ms) occurred equally often in one of the two test regions. Test regions were distinguished from surrounding context regions, where timing was variable, by higher frequency tones. Both the absolute amount of temporal variability (small, large) and the nature of temporal variability (rate-accelerating, rate-decelerating, and rate-alternating) within context regions were varied. Results showed that listeners' ability to detect time changes within test regions was poorer with large amounts of contextual variability than with smaller amounts. However, minimal effects of the patterning of tempo (rate) within context regions were found.