COMMA (MUSIC)

In music theory, a 'comma' is a small or very small interval between two enharmonic notes tuned in different ways. For example, an A flat tuned as a major third below C in just intonation, and a G sharp tuned as a major third above E, will not be exactly the same note. The difference between those notes, the diesis, is almost a quarter tone, easily audible.
All of the intervals mentioned below are presumed to be tuned in just intonation.
There are many commas, notably :

★ Pythagorean comma or ditonic comma (difference between 7 octaves and 12 perfect fifths)

★ syntonic comma, the difference between four perfect fifths and one major third plus two octaves

★ schisma, the difference between 8 perfect fifths plus one major third and 5 octaves (equal to the interval between Pythagorean comma and syntonic comma)

★ diaschisma, the difference between 4 fifths plus 2 thirds and 3 octaves
Commas are frequently used in the description of musical temperaments, where they describe minute tuning differences that are eliminated by that tuning system. For instance, twelve-tone equal temperament ''tempers out'' the Pythagorean comma by narrowing each fifth slightly.
There are also several intervals called commas, which are not technically commas because they are not rational fractions like those above, but are irrational approximations of them. These include the Holdrian comma and Mercator's comma.

Contents

See also

See also

★ List of musical intervals