Expressive timing from cross-performance and audio-based alignment patterns: An extended case study

Audio recordings of classical music pieces reflect the artistic interpretation of the piece as seen by the recorded performing musician. With many recordings being typically available for the same music piece, multiple expressive rendition variations of this piece are obtained, many of which are induced by the underlying musical content. In earlier work, we focused on timing as a means of expressivity, and proposed a light-weight, unsupervised and audio-based method to study timing deviations among different performances through alignment patterns. By using the standard deviation of alignment patterns as a measure for the display of individuality in a recording, structural and interpretational aspects of a music piece turned out to be highlighted in a qualitative case study on five Chopin mazurkas. In this paper, we propose an entropy-based deviation measure as an alternative to the existing standard deviation measure. The obtained results for multiple short-time window resolutions, both from a quantitative and qualitative perspective, strengthen our earlier finding that the found patterns are musically informative and confirm that entropy is a good alternative measure for highlighting expressive timing deviations in recordings.