Music theory: Harmony, Microtonal music, Aleatoric music, Inversion, Diatonic function, Neo-Riemannian theory, Algorithmic composition, Thummer keyboard, Klumpenhouwer network, Wicki-Hayden note layout, Transformational theory, Modulatory space

Source: Wikipedia. Pages: 50. Chapters: Harmony, Microtonal music, Aleatoric music, Inversion, Diatonic function, Neo-Riemannian theory, Algorithmic composition, Thummer keyboard, Klumpenhouwer network, Wicki-Hayden note layout, Transformational theory, Modulatory space, Chord-scale system, Pitch constellation, Progressive tonality, Diminution, Octave species, Spiral array model, Ohm's acoustic law, Augmentation, Treatise on Instrumentation, Centonization, Synthetic modes, Four-part harmony, Musivisual Language, Sonorism, Pythagorean hammers, Equivalence class, Similarity relation, Melodics, Danger music, Chromatic fourth, Musical tone, Lament bass, I-vi-ii-V, Constant structure, Descending tetrachord, Fragmentation, Tension, Musical similarity, Museme, Distance model, First octave, Rudiments of music, Aural space, Projected set, Privileged pattern, Musical cue, Order, Musical idea, Head-motif. Excerpt: Microtonal music is music using microtones¿intervals 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. Microtonal music can refer to all music which contains intervals smaller than the conventional contemporary Western semitone. The term implies music containing very small intervals but can include any tuning that differs from the western 12-tone equal temperament. Traditional Indian systems of 22 sruti; Indonesian gamelan music; Thai, Burmese, and African musics, and music using just intonation, meantone temperament, or other alternative tunings may be considered microtonal.(Griffiths and Lindley 1980; Griffiths, Lindley, and Zannos 2001). Microtonal variation of intervals is standard practice in the African-American musical forms of spirituals, blues and jazz (Cook and Pople 2004, 124¿26). 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. (Griffiths and Lindley 1980; Griffiths, Lindley, and Zannos 2001) 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 (Wyschnegradsky 1972, 84¿87). Ivor Darreg proposed the term xenharmonic. (See xenharmonic music). The Hellenic civilizations of ancient Greece left fragmentary records of their music¿c.f., 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 enharmonic, the chromatic, and the diatonic. Ancient Greek intervals were of many different sizes, including microtones. The enharmonic genus in particular featured intervals of a distinctly "microtonal" nature, which were sometimes smaller than 50 c