Studying Expressive Piano Technique
The 600Hz sampling rate of the key position sensor is sufficient to capture anywhere from 10 to over 100 samples during the brief interval of each key-press. The sensor can thus record not only the velocity but the shape of a key press, providing new insight into the details of what pianists call "touch".
The sound of a piano note is determined almost exclusively by the speed with which the hammer strikes the string, but the motion of the key itself can be controlled in several dimensions. Preliminary studies with professional pianists indicate a link between the expressive content of a musical passage and the shape of its key-presses. In the example below, from Beethoven's 4th piano sonata (op. 7), the note marked sfz is played percussively (the finger already in motion when it strikes the key), with heavy initial pressure which relaxes over the course of the note. These motions align closely with the musical character of the phrase. Standard MIDI keyboards would not show any of these expressive details.
Comparison of MIDI and continuous key position for a passage from Beethoven Piano Sonata #4. The initial spike in key velocity for the starred note indicates that the note was played percussively (the finger was in motion when it struck the key).
We are actively researching the relationship between expressive intent and physical gesture in piano performance, both to better understand creative musical expression at the piano keyboard and to refine the design of the MRP to allow it to respond more intuitively to beginner and expert performers.