In music theory, the kleisma
is an interval
important to temperaments
of the Bohlen-Pierce scale
. It is the difference between six minor thirds
and the "tritave" or perfect twelfth (an octave plus a perfect fifth), equal to a frequency ratio of 15625:15552, or approximately 8.1 cents
The interval was named by Shohé Tanaka, who noted that it was tempered to a unison by 53 equal temperament. Interestingly, it is not tempered out, despite its minute size, in 12 equal temperament where six minor thirds are 18 semitones while a perfect twelfth is 19 semitones.