> There was an episode of Cowboy Bebop, where a mechanic held a wrench against an engine cowling to see how much it vibrated (likely a real thing people do with real engines?)

I was watching a documentary about dirt track racing and they showed one of the mechanics on the team who was blind.

He would put a long screwdriver on the engine and hold the handle to his ear. He could debug timing issues by hearing the vibrations.

There is also the case of the water leak detectors in the UK who use basically a long stick with one end on the ground and the other in their ear. e.g. https://www.youtube.com/watch?v=gVeEoWTsiiw