Microtiming deviations in groove

Metrical music is commonly perceived assegmented into phrases at durations above the levelof the tactus, up to temporal intervals ofapproximately 3 secs. These segments are normallycontiguous and non-overlapping. Examples ofsimilar temporal segmentation are found in humanutterances and in human mother-infant interactions.Standard reference beat patterns such as the Cubanclave and African bell patterns are in this order ofduration, and have rotation symmetry only at thelevel of the whole pattern. The start point of thepatterns is either musically inherent or culturallyunderstood. Various researchers have found theexistence of musically meaningful deviations of lessthan 60ms from quantised rhythm, a level of timingcontrol not possible through closed-loopkinaesthetic feedback control,which has a cycletime in the order of 100ms. I propose that referencebeat patterns provide a guide to performers in agroup as to the start point of a recurring open-looptiming control interval.