 thumb|right|250px|composer charles ives chose the chord above as a good candidate for a "fundamental" chord in the quarter tone scale, akin not to the tonic but to the major chord of traditional tonality .  or  microtonal music is music using microtonesâintervals of less than an equally spaced semitone. microtonal music can also refer to music which uses intervals not found in the western system of 12 equal intervals to the octave. ==terminology==  microtonal music can refer to all music which contains intervals smaller than the conventional contemporary western semitone. the term usually refers to music containing very small intervals but can include any tuning that differs from the western 12-tone equal temperament. traditional indian systems of 22 Åruti; indonesian gamelan music; thai, burmese, and african music, and music using just intonation, meantone temperament or other alternative tunings may be considered microtonal (; ). microtonal variation of intervals is standard practice in the african-american musical forms of spirituals, blues and jazz . many microtonal equal divisions of the octave have been proposed, usually (but not always) in order to achieve approximation to the intervals of just intonation (; ). terminology other than "microtonal" is used by theorists and composers. ivan wyschnegradsky used the term ultra-chromatic for intervals smaller than the semitone and infra-chromatic for intervals larger than the semitone . ivor darreg proposed the term xenharmonic. (see xenharmonic music). ==history==  the hellenic civilizations of ancient greece left fragmentary records of their musicâe.g. the delphic hymns. the ancient greeks approached the creation of different musical intervals and modes by dividing and combining tetrachords, recognizing three genera of tetrachords: the enhar
Ancient_Greek_music Microtonality Post-tonal_music_theory