Alexander Chen, a Creative Director at Google Creative Lab, built pianophase.com, a tribute to Steve Reich’s 1967 composition, Piano Phase. 

True to form, the dueling, in-browser pianists begin by playing the twelve-note sequence in unison. The second piano gradually speeds up, shifting out of phase until the second is exactly a note ahead of the first in the pattern. This gradual shifting continues as the second piano moves further and further ahead, creating surprising and interesting variations of the repeating twelve notes.

What is truly wonderful is the visualization that Chen brings to Reich’s composition. To be able to watch along as your ears work to make sense of the rival tempos at play is a joy. There is some minor interactivity available as well, offering the user the chance to drag the dots around the circular scene with all the grace of a cat bounding across the keys. Simply letting go of the dots returns them to their regularly-scheduled process.

Bonus: A personal YouTube favorite, Steve Reich Looks at a Cake.