Sonorism (from the Latin sonorus — “resonant”) took shape in the Polish school of the 1960s. Composers focused on sound colour: dense tone clusters, glissandos of whole groups, playing behind the bridge, knocking on the instrument's body, the whisper and cry of a choir.
The style's manifesto is Threnody to the Victims of Hiroshima by Krzysztof Penderecki for 52 strings — a score of graphic symbols instead of ordinary notes. Sonoristic thinking expanded the very notion of what can be musical material, and fed the Ukrainian avant-garde (the early Silvestrov, Hrabovsky) of the “new folkloric wave” era.
