Analysis of tempo classes in performances of Mozart sonatas

This preliminary study investigates the relationship between tempo indications in a score and the tempo performed by musicians. As several 18 century theorists point out, the chosen tempo should depend not only on the tempo indication, but also on other factors such as the time signature and the fastest note values to be played. It is examined whether the four main tempo indications (Adagio, Andante, Allegro, and Presto) imply specific tempo classes which can be found in professional performances or whether other factors influence the choice of performed tempo. In Experiment I, 34 movements of Mozart sonatas performed by one professional pianist are analysed. The mode of the inter-beat interval distribution of a performance is considered to be a representation of the performed tempo. The tempo values depend on what is taken as the beat level; performed tempo did not group according to tempo indications. Event density (score events per second) is found to separate the data into just two clusters, namely slow and fast movements. In experiment II, the tempo values of 12 movements of the first experiment were derived from commercial recordings (Barenboim, Pires, Schiff, Uchida) with the help of an interactive beat tracking system. The pianists’ tempos are surprisingly homogenous; they deviate from each other more in slower movements than in the faster ones.