Acoustic pi

Pi, the ratio of a circle's circumference to its octave, is equal to about 3.14159. When used as an equivalence interval, it becomes a rather minor thirteenth of 1981.795 cents.

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Pi

Intervals that are close to it are 3/1, 22/7, and 355/113.

Equal divisions

Using 3.14159.../1 as an interval of equivalence results in an interesting nonoctave tuning.