tempo canon

A canon in which the voices move at different, fixed speeds simultaneously rather than entering at the same tempo at staggered intervals. The defining structural device of Nancarrow's mature output: one melodic line is superimposed on itself (or on a different melody) at a faster or slower tempo, creating a relationship of rhythmic counterpoint that unfolds and resolves according to mathematical proportion.

In performance or analytical listening, identify the tempo ratio first — then trace each voice independently before listening to their interaction. The 'convergence point' is the structural climax: the moment when voices moving at different speeds arrive simultaneously at the same place in their material.