Minor sixth

Minor sixth Play (help·info)

A minor sixth is the smaller of two commonly occurring musical intervals that span six diatonic scale degrees. The prefix 'minor' identifies it as being the smaller of the two (by a chromatic semitone); its larger counterpart being a major sixth. The minor 6th is abbreviated as m6, its inversion is the major third and in equal temperament is enharmonically equivalent to the augmented fifth. Its most common occurrence is between the third and (upper) root of major chords.

A minor sixth in just intonation most often corresponds to a pitch ratio of 8:5 or 1:1.6 ( play (help·info)), or various other ratios including the 27:32 subminor sixth^[1] (possibly 63:40^[2]) of 906 cents (the Pythagorean major sixth), and the 14:9 septimal minor sixth^[3] of 764.9 cents^[4], while in an equal tempered tuning, a minor sixth is equal to eight semitones, a ratio of 2^2/3:1 (about 1.587), or 800 cents, 13.69 cents smaller. The ratios of both major and minor sixths are corresponding numbers of the Fibonacci sequence, 5 and 8 for a minor sixth and 3 and 5 for a major. The 11:7 undecimal minor sixth is 782.492 cents ( Play (help·info)).

The minor sixth is one of consonances of common practice music, along with the unison, octave, perfect fifth, major and minor thirds, major sixth and (sometimes) the perfect fourth. In the common practice period, sixths were considered interesting and dynamic consonances along with their inverses the thirds, but in medieval times they were considered dissonances unusable in a stable final sonority; however it should be noted that in that period they were tuned very flat, to the Pythagorean minor sixth of 128/81. In just intonation, the minor sixth is classed as a consonance of the 5-limit.

Any note will only appear in major scales from any of its minor sixth major scale notes (for example, C is the minor sixth note from E and E will only appear in C, D, E, F, G, A and B major scales).

See also

• musical tuning
• list of meantone intervals

Sources