Your implicit assumption is that the hum is caused by something electrical; i.e. not a diesel engine or some natural cause.
Then we can turn off the electricity for the whole town and see if it stops! :D
"The University of Windsor report said the hum’s likely source was blast furnace operations on Zug Island" ... which is over the border in the United States.
Cutting off the power to that island would be a good thing to try, but apparently the US is uncooperative.
But that's exactly the point. It would rule out a ton of stuff.
But might have to turn off electricity for days if generators are used.