Comment on cindi0398's post
In my case I think that it's a low level frequency in the ground, because I can hear it in my garage (and the house) which is 3 walls of concrete in the hill with only the door and the roof that's wood. I also heard this in a house miles away.
Comment on thedarkseid007's post
Thanks Dark. I am going to have a look around even though the sound is not heard outside.
Comment on cindi0398's post
"Has anyone considered the idea that this has just become more prevalent since more and more cell phone towers have been installed?" This is what I believe it to be. But proving it & doing something about it would be next to impossible...
Comment on speedball1's post
Thanks Tom. I hear a mixture of motors while outside so it is hard to determine where this one is coming from. Some Will it rule out plumbing if I shut off the main water valve coming into the house and still hear the noise?