One of the most common ways of conveying expression in music is via "expressive timing" - the subtle changes in timing (tone durations) not called for in the score. Even simple rhythms are not 'perfectly' timed. This paper will present a comparative analysis of seven performances by well-known pianists (Barenboim, Brendel, Goode, Hungerford, Kempff, Pollini, and Schiff) of the beginning of the first movement of Beethoven's piano sonata op. 2 No. 1 as well as its analytical method. The author used the freeware Sonic Visualiser with the VAMP Plugin "Note Onset Detector" (v2.0) as well as the freeware Audacity. The novel analytical approach (to be demonstrated at the conference) resulted in in accuracy of +/- 0.01 seconds in the detection of note onsets. Goals of the analysis were to answer the following questions: How uniform or uneven is the pulse beat in the interpretations of different pianists, and is there a relationship to the tempo? Are notes falling on main beats held longer than other notes? Are short note values interpreted evenly or unevenly? If notes are held longer, are other notes played shorter to keep the pulse? How long are arpeggios? How are embellishments performed? Do or how do the performers slow the tempo at cadence points? The answers to such questions are of great importance not only for the understanding of performance practice, but also for the development of automatic performance systems, as they provide information on the underlying sound and sound interpretation of a "human" / "musical" interpretation.