ABSTRACT
Introduction In music theory, a comma is the tiny interval that results from tuning a note in two different ways. The classic example is the syntonic comma, the difference between tuning four pure perfect fifths (for example, C-G-D-A-E) and tuning two octaves plus a pure major third (C-C-C-E). In this case the interval between the two versions of the E will be 21.5 cents, or just over a fifth of a semitone (the former higher than the latter); a subtle difference, but big enough to matter. In historical tuning practice these commas, while theoretically straightforward, although they are of different types and sizes, were generally regarded as a nuisance, an impediment to playing in tune and to the use of certain harmonic procedures. With the adoption of 12-note equal temperament during the nineteenth century they vanished, the price being that as a result, no musical interval apart from the octave was actually in tune.
