Semicomma

The semicomma^[1], 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^[1], or . This is a ratio of approximately 1:1.0058283805847168, or about 10.06 cents^[2] . It is derived from the difference in pitch between three justly tuned perfect fifths and seven just minor thirds (begun on the same root). An equal definition is that it is the difference between four minor thirds and three minor thirds. In equal temperament, however, the resulting notes are enharmonic equivalents (A♮=C♭♭♭) and there is no difference.

See also

• Septimal kleisma
• Septimal semicomma

Sources

1. ^ ^{a b} Haluska, Jan (2003). The Mathematical Theory of Tone Systems, p.xxix. ISBN 8088683289.
2. ^ "List of Intervals", Huygens-Fokker.org.