isopolyphony

Isopolyphony is a term used in music theory to describe a type of polyphonic texture in which the multiple voices operate within a shared rhythmic framework. The concept emphasizes alignment of metric accents and rhythmic values across parts, producing a relatively uniform temporal fabric even when the melodic lines differ in pitch. In isopolyphonic textures, voices may begin together or enter with closely coordinated rhythms, contributing to a cohesive, dense sound.

The terminology derives from iso-, meaning equal, and polyphony, the practice of multiple independent voices. Because the label is not universally standardized, its use varies among theorists. Some writers apply isopolyphony to historical repertoires—particularly contexts where voices display high degrees of rhythmic coherence—while others use the term more cautiously or not at all, preferring analyses based on parallel motion, canonic imitation, or tightly coupled voice-leading to describe similar textures.

Isopolyphony is distinct from isorhythm, which concerns repeating rhythmic talea or color that may be superimposed on varying melodies; it is also separate from heterophony, where voices ornament the same melodic line, and from true independent polyphony with divergent rhythmic structures. In practice, analysts identifying isopolyphonic features will examine how entrances, rests, and accents align across parts and whether rhythmic uniformity governs the texture as a whole.

See also: polyphony, parallel motion, canonic texture, isorhythm.