Abstract:
The effect of a change in tempo on the ability to detect frequency changes in sequences of tones was examined after extensive training with four patterns. In a previous study, uniform tone-duration increases of up to 300% were found to have little effect on frequency discrimination thresholds under high-uncertainty testing [G. R. Kidd and C. S. Watson, J. Acoust. Soc. Am. Suppl. 1 84, S141 (1988)]. The present study examined the effect of tempo changes under low-uncertainty testing after prolonged training at a single tempo. Twelve listeners were trained for several days (over 3000 trials) with a set of four isochronous ten-tone patterns (750-ms total duration). Following training, frequency discrimination was evaluated at five tempos (total pattern durations of 375, 536, 750, 1050, and 1500 ms) using a 2AFC remembered-standard paradigm in which one pattern on each trial differed from a training pattern by a single altered frequency. Although the slowest tempo produced a slight threshold elevation for some listeners, only the fastest tempo consistently produced a substantial threshold elevation, with little or no effect of the smaller tempo changes. These results suggest that the representation of both unfamiliar and familiar tone patterns are relatively insensitive to uniform tempo changes. [Work supported by NIDCD and ONR.]