A measurement of piano playing
Whether the hands land together, and which arrives first.
The same passage — Clair de lune, bars 15–16 — from the recordings that sit lowest and highest on this measurement. Every clip is a note list replayed on one sampled grand at one gain, so the only difference you are hearing is the playing.
Mean left-hand onset minus mean right-hand onset, per chord written to be struck together. Negative means the left hand leads.
Every piece in the library, with the range across its recordings. The units mean the same thing in every row, except for basic tempo, which is in each piece’s own beat.
| Piece | Recordings | Lowest | Median | Highest |
|---|---|---|---|---|
| Ravel Ondine | 61 | -40 | -12 | 18 |
| Schubert Op. 142/3 | 9 | -20 | -10 | -5 |
| Clair de lune | 27 | -32 | -7 | 36 |
| Chopin Étude 10/1 | 31 | -48 | -3 | 14 |
| Chopin Ballade 4 | 12 | -14 | -2 | 9 |
| Nocturne Op. 9/2 | 32 | -36 | -1 | 55 |
| Chopin Étude 10/12 | 19 | -22 | 0 | 8 |
| Nocturne Op. 48/1 | 27 | -16 | 1 | 19 |
| Schubert Op. 90/3 | 43 | -51 | 1 | 60 |
| Mozart K. 545 | 37 | -7 | 2 | 11 |
| Fantaisie-Impromptu | 20 | -29 | 6 | 28 |
| Rachmaninoff Prelude | 29 | -3 | 7 | 26 |
| Pathétique II | 47 | -41 | 8 | 30 |
| Brahms Op. 118/2 | 28 | -59 | 10 | 45 |
| Ravel Pavane | 33 | -38 | 10 | 30 |
| Träumerei | 31 | -50 | 11 | 59 |
| Gymnopédie 1 | 23 | -49 | 15 | 58 |
A Disklavier capture — the pianist’s own key sensors, no microphone — was rendered to audio, transcribed as if it were a recording, and re-measured. The error the transcription step introduces, as a multiple of how far pianists actually differ on this dial, is 0.35. solid This dial survives transcription intact: where one recording sits on it can be argued from.