A heptatonic scale is a musical scale that has seven pitches, or tones, per octave. Examples include:
- the diatonic scale; including the major scale and its modes (notably the natural minor scale, or Aeolian mode)
- the melodic minor scale, like the Aeolian mode but with raised 6th and 7th ascending
- the harmonic minor scale, like the Aeolian mode but with raised 7th
- the harmonic major scale, like the major scale but with lowered 6th
Indian classical theory postulates seventy-two seven-tone scale types, collectively called melakarta or thaat, whereas others postulate twelve or ten (depending on the theorist) seven-tone scale types.
Several heptatonic scales in Western, Roman, Spanish, Hungarian, and Greek music can be analyzed as juxtapositions of tetrachords.[1] All heptatonic scales have all intervals present in their interval vector analysis,[2] and thus all heptatonic scales are both hemitonic and tritonic. There is a special affinity for heptatonic scales in the Western key signature system.