My Eaton Supercharger turns at 18,800 rpm'* at redline. The whine is remarkable. We've often been under the impression that the whine is the sound of the gears (straight-cut gears like an Indy-Car gearbox, remarkable similarity to that sound.
But this frequency lies outside the perception of humans.
To make it more difficult, each supercharger rotor has 3 lobes, so the frequency of that (if they actually make sound) is tripled.
What are we hearing?
Why does my dog hate riding in the 93 when I romp the throttle?