"The Hum"

Where are you located?
I know I'm not crazy, but I hear a constant hum inside my house. First time I really became aware of this was when we lost power for days last february. I heard it then too. Never payed it much attention until then. With no power available there were no appliances operating in the home. So that rules any of that out as a source. It's at that time I also heard it outside. I just figured people were running generators to keep their heat on. However I still hear it. It's a low pitched thrumming kind of noise like a generator continuously running at a steady speed. Wife told me its tinnitus. I say bullshit. My 9 year old hears it too. He actually came to me this morning and mentioned hearing this. He says it sounds like a truck just sitting and running. I wouldent think a 9 year old would have tinnitus. I looked it up online and apparently I'm not the only one. Anybody else here this?