Rushing or Dragging? An Analysis of the "Universality" of Correlated Fluctuations in Hi-Hat Timing and Dynamics

Abstract: A previous analysis of fluctuations in a virtuoso (Jeff Porcaro) drum performance [R\"as\"anen et al., PLoS ONE 10(6): e0127902 (2015)] demonstrated that the rhythmic signal comprised both long range correlations and short range anti-correlations, with a characteristic timescale distinguishing the two regimes. We have extended R\"as\"anen et al.'s approach to a much larger number of drum samples (N=132, provided by a total of 58 participants) and to a different performance (viz., Rush's Tom Sawyer). A key focus of our study was to test whether the fluctuation dynamics discovered by R\"as\"anen et al. are "universal" in the following sense: is the crossover from short-range to long-range correlated fluctuations a general phenomenon or is it restricted to particular drum patterns and/or specific drummers? We find no compelling evidence to suggest that the short-range to long-range correlation crossover that is characteristic of Porcaro's performance is a common feature of temporal fluctuations in drum patterns. Moreover, level of experience and/or playing technique surprisingly do not play a role in influencing a short-range to long-range correlation cross-over. Our study also highlights that a great deal of caution needs to be taken when using the detrended fluctuation analysis technique, particularly with regard to anti-correlated signals.