microtones

Microtones are pitch intervals smaller than the standard Western semitone. They arise when a musical system divides the octave into more than 12 equal steps or when tunings reflect harmonic series and listener perception rather than conventional keyboard pitch names. Microtonal practice appears in numerous traditions and in modern experimental music, enabling melodic and harmonic nuance beyond 12‑tone equal temperament.

In traditional music, microtones are often essential. Arabic, Persian, and Turkish classical repertoires employ makam or maqam systems with intervals that lie between Western semitones. Indian classical music uses shrutis, a theoretical set of microtonal pitches within an octave, guiding intonation and ornamentation. Indonesian gamelan scales such as sléndro and pelog produce pitches not aligned with Western semitone divisions, contributing distinctive timbres and melodies.

Western theory has developed several microtonal frameworks. Dividing the octave into 24, 31, or 53 equal steps creates quarter-tone, stepped, or finer tunings. Just intonation uses pure intervals drawn from the harmonic series and can generate microtonal pitches. Notation often employs quarter- or half-sharp symbols, special accidentals, or alternative systems to indicate precise cent values; some composers use continuous or nonstandard notation.

In performance and instrument design, microtonality is supported by extended keyboards, fret systems, and electronic synthesis. Composers and performers also work with nonwestern tuning practices, exploring perceptual color and spatial hearing challenges.

Prominent figures include Julián Carrillo (Sonido 13), Alois Hába (quarter-tone systems), Harry Partch (custom microtonal instruments), and Ivan Wyschnegradsky (53‑ET). Microtones continue to influence contemporary composition, ethnomusicology, and sonic experimentation. See also microtonality, tunings, just intonation, maqam, raga.

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