So many things emit 50Hz noise, or a harmonic of it..
Pretty much used to that, but for odd ones.....
The one gadget that winds me up in our house is the Wii, if the kids have left it on you can hear it upstairs! (It's on a rigid built in MDF unit under the TV, right under our room, and the vibration from the disk drive travels right up the chimney breast.).
I am afflicted with "engineers ears" though, I blame my grandad. For example I can tell if just one the revolving arms in the dishwasher isn't spinning, just from the noise it makes.....
Biting the hand that feeds IT
