poliritmia
Poliritmia is a musical concept describing the simultaneous use of two or more independent rhythmic streams within a piece. The term derives from Greek roots poly- (“many”) and rhythmos (“rhythm”). In practice, poliritmia creates a textured surface in which different voices or instruments emphasize different pulse groups or subdivisions, producing a larger rhythmic organization than any single line would alone. It is related to, but distinct from, hemiola (a temporary shift in metric accents, often 3 against 2) and cross-rhythm (the interaction of two or more conflicting meters).
Common examples include two patterns played in the same span but with different subdivisions, such as 3:2
Performance and notation: poliritmia is notated with separate rhythmic voices on multiple staff lines or with