24ET

24 equal temperament (24-ET), also called 24 equal divisions of the octave or 24-EDO, is a musical tuning in which the octave is divided into 24 equal steps. Each step measures 50 cents, so there are two steps for each traditional 12-ET semitone. This creates a dense set of pitches between the familiar notes of standard Western tuning and enables the performance of quarter-tone intervals and other microtonal sonorities without adopting an entirely different tuning system.

Relation to 12-ET and tonal possibilities: In 24-ET, the notes of 12-ET appear as every other step, meaning 12-ET is embedded within 24-ET. This allows musicians to approximate many intervals from just intonation more closely than in some coarser tunings, while still offering distinct microtonal options. The system supports scales and chords that lie outside the standard 12-tone repertoire and provides a straightforward framework for composing and analyzing music with 50-cent step sizes.

Notation and practice: Notation often uses specialized accidentals to indicate 50-cent steps, such as half-sharps or context-dependent symbols, since standard sharp/flat signs do not capture the microtonal nuance. Instruments and software that support 24-ET include microtonal keyboards, multi-timbral synthesizers, and digital audio workstations with adjustable tunings. Performers may choose intonation schemes within 24-ET to fit a particular musical language, from closer approximations to just intonation to entirely new sonorities.

History and usage: 24-ET has been explored in microtonal music since the early 20th century and features in the work and theory of composers such as Ivan Wyschnegradsky. It remains a common reference point in discussions of non-12-tone tunings and continues to appear in experimental, academic, and electronic music contexts.