Septimal chromatic semitone
In music, a septimal chromatic semitone or minor semitone is the interval 21:20. It is about 84.47 cents. The septimal chromatic semitone may be derived from the harmonic series as the interval between the twentieth and twenty-first harmonics.
The septimal chromatic semitone equals a just chromatic semitone plus a septimal semicomma.
When added to the 15:14 semitone, the 21:20 semitone and 28:27 semitone produce the 9:8 tone and 10:9 tone, respectively.
