Expressiveness in metronomic rolls for player piano: A new field of research?

Between the last years of the nineteenth century and the first two decades of the twentieth century, the production and use of rolls for player piano became widespread. These were strips of perforated paper wrapped around a cylinder, capable of activating in the instrument a pneumatic mechanism for the automatic operation of the piano keys. The metronomic-type rolls were produced manually, by transposing the piece's score into the paper's perforation. In this contribution, we propose a solution based on the automatic identification of peaks in the distribution of the Inter-Onset-Intervals (IOIs) of the notes for the detection, within metronomic rolls, of timing-related expressive areas, i.e. of musical passages in which deviations in the length of the holes with respect to what is prescribed in the score are operated intentionally to add expressiveness. The identified algorithm, applied to a dataset of approximately 700 rolls converted into MIDI format, showed good sensitivity, and made it possible to identify in a relatively short time numerous examples of intentional expressiveness in the analyzed repertoire, commonly and erroneously considered a mere mechanical transposition of the score. In the conclusions, some reflections on the relevance of this research in the musicological field are proposed.