Ok so the past several years I've noticed a humming sound when I'm in the house. It isn't anything in the house, like a fridge or tv or something; it's definitely coming from the outside. It's a low-toned hum, constant, steady, deep. I notice it most when the house is empty of people and is quiet, especially when the refrigerator is in self-defrost mode and is off. Even when the fridge is on I can still hear it. I hear it best in our family room, kitchen (both are in the back of the house), the garage (with the door closed and it's very noticeable in the car but I can still hear it if I'm standing the garage), and our bedroom and bathroom (bedroom is in the front of the house, bathroom is in the back of the house). It doesn't increase nor lessen if I open the windows, although outside noises (cars, trucks, kids playing, birds, etc) will often make me notice the hum less . . . . outside noises distract me from noticing I guess. I notice it less in other rooms of the house and don't hear it when I'm outside. Here's the thing . . I've also noticed it's absence. It goes off or stops at times, although I can't quite get a feel for a pattern. Over the summer I didn't notice it much at all but all the windows were open if nice or the A/C was on if hot and that was enough to mask the hum. Also, the kids were home and it's just generally noisier in the house in the summer. Since I notice it's absence --- there at times when it isn't there -- it would lead me to think that it's some type of machinery or electrical pulse or . . . ? I live quite near a nuke power plant and thought that maybe it has something to do with that but I have no idea. Or could it be a noise that the earth itself is emitting? If so, what is it and why/how does it start/stop? The hubs and my oldest have also heard it so I'm not imagining it nor is it something that is just going on with my ears/hearing. I've been looking around the internet and found this: More info at link: The Hum - Wikipedia, the free encyclopedia Does anyone else have any info/thoughts on this?