Downbeat delays are a key component of swing in jazz

To which extent and how do jazz musicians synchronize their timing to create swing? Swing is a salient feature of jazz music, yet its main psychoacoustical and musical components have remained elusive—save the obvious long-short subdivision of quarter notes. In particular, the possible role of microtiming deviations for swing has been a subject of long-standing controversy. Adopting an operational definition of swing we present a study which ultimately demonstrates a positive effect of certain microtiming deviations on swing. We manipulate the timing of original piano recordings to carry out an experiment with professional and semi-professional jazz musicians measuring the swing of different timing conditions. Thereby we prove that slightly delayed downbeats and synchronized offbeats of a soloist with respect to a rhythm section enhance swing. Analyzing a set of 456 jazz improvisations we find that many jazz musicians do use minute downbeat delays. These results show that systematic microtiming deviations in the form of downbeat delays are a key component of swing in jazz.