TIME DISCRIMINATION IN A MONOTONIC, ISOCHRONOUS SEQUENCE

In acoustic communication timing seems to be an exceedingly important aspect. The just noticeable difference (jnd) for small perturbations o f an isochronous sequence of sounds is particularly important in music , in which such sequences frequently occur. This article reviews the l iterature in the area and presents an experiment designed to resolve s ome conflicting results in the literature regarding the tempo dependen ce for quick tempi and relevance of music experience. The jnd for a pe rturbation of the timing of a tone appearing in an isochronous sequenc e was examined by the method of adjustment. Thirty listeners of varied musical background were asked to adjust the position of the fourth to ne in a sequence of six, such that they heard the sequence as perfectl y isochronous. The tones were presented at a constant interonset time that was varied between 100 and 1000 ms. The absolute jnd was found to be approximately constant at 6 ms for tone interonset intervals short er than about 240 ms and the relative jnd constant at 2.5% of the tone interonsets above 240 ms. Subjects' musical training did not affect t hese values. Comparison with previous work showed that a constant abso lute jnd below 250 ms and constant relative jnd above 250 ms tend to a ppear regardless of the perturbation type, at least if the sequence is relatively short. (C) 1995 Acoustical Society of America.