A Statistical View on the Expressive Timing of Piano Rolled Chords

Rolled or arpeggiated chords are notated chords performed by playing the notes sequentially, usually from lowest to highest in pitch. Arpeggiation is a characteristic of musical expression, or expressive timing, in piano performance. However, very few studies have investigated rolled chord performance. In this paper, we investigate two expressive timing properties of piano rolled chords: equivalent onset and onset span. Equivalent onset refers to the hidden onset that can functionally replace the onsets of the notes in a chord; onset span refers to the time interval from the first note onset to the last note onset. We ask two research questions. First, what is the equivalent onset of a rolled chord? Second, are the onset spans of different chords interpreted in the same way? The first question is answered by local tempo estimation while the second question is answered by Analysis of Variance. Also, we contribute a piano duet dataset for rolled chords analysis and other studies on expressive music performance. The dataset contains three pieces of music, each performed multiple times by different pairs of musicians.