quartertone

Quartertone is a term used in music to describe a microtonal interval of 50 cents, lying between two adjacent semitones in standard 12-tone equal temperament. It is also used to refer to pitches, scales, or tunings that subdivide the octave into 24 equal steps, with each step corresponding to 50 cents. Quartertones enable pitches that are not available in conventional Western tuning, expanding melodic and harmonic possibilities.

Notation and tuning: Quartertones are typically indicated with specialized accidentals such as half-sharps and half-flats, or with dedicated microtonal symbols. Some systems use 24-TET, in which quarter-tone steps are ordinary notes; others employ custom tunings and electronic synthesis. The practice appears in both experimental contemporary music and in genres that incorporate traditional microtonal scales, such as certain Middle Eastern and South Asian musical traditions, where intervals similar to quartertones occur in practice.

History and usage: The exploration of quartertones formed part of the broader early 20th-century microtonal movement. Pioneers such as Julián Carrillo and Ivan Wyschgradsky investigated continuous pitch systems and introduced notation and performance techniques for microtonal music. In modern times, quartertones appear in contemporary classical, electronic, and improvised music, and are used to approximate vocal and instrumental microtonality in various styles.

Performance and realization: Creating quartertones can involve retuning instruments, using electronic synthesis, or employing keyboards and instruments designed to play microtonal scales. Singers and instrumentalists may execute expressively altered intonation, while composers may use quarter-tones to achieve subtle color and tension beyond the standard 12-tone framework.

See also microtonal music, 24-tone equal temperament, half-sharp, half-flat.