Syzygys

Xenharmonic music is music that uses tuning systems other than 12‑tone equal temperament (12‑TET). The term was coined by American microtonalist Ivor Darreg, drawing on the Greek xenos, meaning both "foreign" and "hospitable." In Darreg’s formulation, xenharmonic explicitly welcomes just intonation and equal temperaments such as 5‑, 7‑, 11‑, 19‑, 22‑, 24‑, 31‑EDO (equal divisions of the octave) and far beyond, as well as non‑octave and alternative interval cycles. In practice, xenharmonic music emphasizes scales, chords, and melodic gestures that arise naturally from these tunings rather than attempting to imitate 12‑TET. It includes everything from pure, beating‑free JI harmonies to vividly "alien" sonorities from non‑octave and higher‑prime temperaments, realized on acoustic, electronic, and hybrid instruments.

Avant-garde music is an umbrella term for boundary-pushing practices that challenge prevailing norms of harmony, rhythm, timbre, form, and performance. It privileges experimentation, conceptual rigor, and a willingness to reframe what counts as music at all. Historically tied to early 20th‑century artistic modernism, avant-garde music introduced atonality, the emancipation of noise, and new forms of notation and process. It embraces indeterminacy, extended techniques, electronics, spatialization, and multimedia performance, treating sound as material to be sculpted, questioned, and reinvented.

Microtonal classical is a stream of Western art music that organizes pitch using intervals smaller than the conventional 12-tone equal temperament. Composers employ alternative equal temperaments (such as 19, 24, 31, or 72 tones per octave), just intonation, and other tuning systems to expand harmony, melody, and timbre beyond the familiar semitone grid. The genre foregrounds novel intervals, complex chordal spectra, continuous pitch (glissandi), and fine-grained intonational nuance. It can sound otherworldly, tense, or delicately shimmering, and often requires specially retuned instruments, extended techniques, or custom-built instruments to realize its pitch language.

Microtonal music is music that uses microtones—pitches that fall between the notes of the Western 12‑tone equal temperament (12‑TET). In practical terms, it employs intervals smaller than a semitone or uses alternative tuning systems that do not align with the customary twelve equal divisions of the octave. Beyond simple “quarter‑tone” writing, microtonality encompasses historical and global pitch systems (such as those of Arabic, Persian, Turkish, Indian, and Southeast Asian traditions), just‑intonation lattices, and equal divisions of the octave with many steps (e.g., 19‑EDO, 24‑EDO, 31‑EDO, 53‑EDO, 72‑EDO). It may be realized on retuned acoustic instruments, specially built or modified instruments, voice, or digital synthesis/samplers. Aesthetic results range from delicate, shimmering pitch colors and continuous glissandi to rugged, “in‑between” harmonies and new modalities—often creating sensations that sound ‘between the keys’ of a piano.