In music, a pentatonic scale is a notes per octave. Pentatonic scales are very common, and found all over the world: in the tuning of the Ethiopian krar and the Indonesian gamelan, in the melodies of African-American spirituals and of French composer Claude Debussy.

One of the most common pentatonic scales, sometimes called a major pentatonic scale, can be constructed in many ways. A simple construction takes five consecutive pitches from the circle of fifths; starting on C, these are C, G, D, A, and E. Transposing the pitches to fit into one octave rearranges the pitches into the major pentatonic scale: C, D, E, G, A:

Another construction, derived from Western European classical music, begins with a major scale and omits the fourth and the seventh scale degrees: a C major scale is {C, D, E, F, G, A, B}, so omitting the F and B again results in the sequence {C, D, E, G, A}. The major pentatonic scale can also be seen as all the pitches that are not present in the major scale: in C major, the remaining pitches are G flat, A flat, B flat, D flat, and E flat, the notes in the G flat major pentatonic scale. These notes are also the black keys on the piano keyboard.

A minor version of the pentatonic scale is obtained by using the same notes as in the major pentatonic scale, but starting one step lower to obtain the tonic note; an A minor pentatonic scale is A, C, D, E, G:

Only certain divisions of the octave, 12 and 20 included, allow uniqueness, coherence, and transpositional simplicity, and that only the diatonic and pentatonic subsets of the 12 tone chromatic set follow these constraints (Balzano, 1980, 1982).

The pentatonic blues scale is the minor pentatonic with a lowered fifth:

Tuning

Deriving the pitches in a pentatonic scale from stacked fifths leads to a Pythagorean scale of {1/1, 9/8, 81/64, 3/2, 27/16}. Deriving the pitches from the major scale leads to a just scale of either {1/1, 9/8, 5/4, 3/2, 5/3} (a 5-limit pentatonic) or {1/1, 9/8, 21/16, 3/2, 7/4} with blue notes of the flatted fourth and flatted seventh.

Further pentatonic musical traditions

The pentatonic scale is very common in Scottish music. Some scholars believe that English folk music was likewise at one time a pentatonic tradition; for the reasoning behind this claim, see Folk music.

The major pentatonic scale is the basic scale of the music of China; the minor pentatonic is used in Appalachian folk music. Both the major and the minor pentatonic scale are commonly used scales in jazz.

The pentatonic scales used in Indonesian gamelan music are called slendro and pelog.

Composers of Western classical music have occasionally used the pentatonic scale for special effects. Maurice Ravel used it as a pastiche of Chinese music in "Laideronette, Emperatrice des Pagodes", a movement from his "Ma Mère l'Oye" (Mother Goose) suite for orchestra. Frédéric Chopin wrote the right hand piano part of his Etude Op. 10 no. 5 in the major G flat pentatonic scale--hence, using only the black keys.

Blackfoot music is most often pentatonic or hexatonic.

Hemitonic or anhemitonic

Pentatonic scales may be described as hemitonic or anhemitonic. Hemitonic scales contain one or more semitones and anhemitonic scales do not contain semitones.

Further reading

• Tran van Khe (1977). "Le pentatonique est-il universel? Quelques rEflexions sur le pentatonisme", The World of Music 19, nos. 1-2:85-91. English translation p.76-84
• Kurt Reinhard, On the problem of pre-pentatonic scales: particularly the third-second nucleus, Journal of the International Folk Music Council 10, 1958