two pitches close together produce a third rhythm ·
the interference of their waves, audible as a pulse
A440 + A443 = 3 beats/sec · what a string player hears when tuning slightly off · in unison mode both voices are pure sines, so what you hear is unison beating · in dyad mode each tone has 8 harmonics and the chord beats where its partials meet · in dyad mode the interval presets play the chord itself (A4 and the ET upper note)