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June 22, 2012

Sympyrean — a generative audio sequencer built using Web Audio API


Sympyrean, a generative audio sequencer, uses a stellar system you create to produce music. The motion of the planets and moons within the system, as well as their distance from the star determine what notes you hear and when.

The app was inspired by a concept called Musica Universalis (also known as the music of the spheres) which dates all the way back to ancient Greece. The story begins with the greek mathematician Pyathagoras who apparently loved to play with strings. What he discovered was that if he stretched a string between two points and placed his finger on that string and plucked it, the pitch (or note) it produced was determined by the length of the segment he plucked. More importantly, he found the notes which sounded the clearest were at interval ratios between the length of the plucked segment and the total length of the string. This is, in fact, where we get the system of tuning used in music today. For instance, the interval of a perfect fifth has a ratio of 3:2. If we take the note E4 which has a frequency of about 659Hz, and divide it by the frequency of the note a perfect fifth below, A4 at 440Hz, we end up with about 1.5 which is three halves or, you guessed it: a ratio of 3:2.

Quite interesting and fun, once you get the hang of the interface.  And the audio functions were built entirely using Web Audio API!