When I press on this fidget spinner, the noise gets louder and higher pitched. But when I drag it across the surface, the opposite happens.
Seems to happen on any resonant surface, like a wooden desk top or (here) the lid of a washing machine.
Why does the sound change?
(May require headphones, but turn the volume down first!)
I think I understand why *pressing* on the fidget spinner changes the sound. By causing a stronger mechanical coupling to the surface, more vibration is transmitted to the surface, and so the volume increases (as the surface acts like a sounding board). And maybe the pitch drops because my finger and the surface are absorbing the higher frequency components.
But why does *dragging* the fidget spinner with constant pressure cause the sounds to change back again?
Huh, that's weird...