The effect of tempo and tone duration on rhythm discrimination.

Rhythm constancy was investigated in two experiments. In Experiment 1, the first rhythm was presented at one tempo, the second rhythm was presented at a different tempo, and subjects judged whether the relative timing structures were identical (i.e., was the first rhythm merely sped up or slowed down to generate the second rhythm?). For the nonmetric rhythms used here, subjects perceived the rhythm in terms of the figural grouping of the tones, and rhythm constancy broke down between slower and faster tempos. In Experiment 2, the first rhythm was presented in tones of one duration; the second rhythm was presented in tones of a different duration; and subjects judged whether the timing structures of the tone onsets were identical (the two rhythms were presented at the same tempo). These results indicated a high degree of constancy; subjects found it easy to discriminate the timing structures. These results confirm that the onset timing is critical to rhythm perception and suggest that rhythm perception at slower rates (2 elements/sec) differs from rhythm perception at faster rates (3-4 elements/sec).