A two-click confirmation for copy, save, or any action that quietly worked: the same small click twice, 70 ms apart, the second one quieter. Both clicks sit on one pitch, so it reads as a thing that was done twice rather than a switch going up or down. Use it for copy buttons, saved drafts, applied settings, or a checkbox that finally agreed.
click 1: sine 1480 Hz, 18 ms long, 2 ms attack, 12 ms to -60 dB click 2: the same 1480 Hz at 70 ms, 3 dB quieter (level 0.35 against 0.5), 20 ms long, 2 ms attack, 14 ms to -60 dB transient: 3 ms of white noise band-passed at 3.6 kHz (Q 1.6) on each click, at 18% level no room, no tail (the buffer is 160 ms and both clicks are gone before 100 ms)