Semicomma

Semicomma on C .

The semicomma, also Fokker's comma (after 31-TET pioneer Adriaan Fokker), is type of small musical interval, or comma, in microtonal music equivalent to 2109375:2097152, or $3^{3}\cdot 5^{7}:2^{21}$. This is a ratio of approximately 1:1.0058283805847168, or about 10.06 cents (). It is derived from the difference in pitch between three 75/64 just augmented seconds () and one 8/5 just minor sixth () begun on the same root ((3 × 274.58) - (1 × 813.69) = 823.74 - 813.69 = 10.05 cents).

See also

• Septimal kleisma
• Septimal semicomma