This is a "Skyline" representation (as suggested by Gottschewski) of Griegs 1903 recording of 'Butterfly'. Click on any bar to hear the corresponding extract from the recording. Hovering on any bar will highlight the corresponding bit in the score. On the left side, a metronome can be started, that follows precisely Grieg's tempo inflections.
The score of the first section, where width and height of every measure are proportional to the real duration in the 1903 recording.