Recently I have been hearing a low pitched rumbling/humming sound inside my house, everywhere in my house. I hear it on all floors and even the basement, with no change in volume as I migrate through the house.
We have ruled out electrical issues as I have had an electrician check all grounding and connections at the meter and in my service panel. Also, If I throw the main breaker off and kill power to everything, I still hear the rumbling. Electrical service is underground and my main panel has a grounding bond to the water supply line coming into the house.
My wife claims she doesn't hear anything, but I swear the sounds feels like its in my head. Before heading off to the doctor, I am wondering if plumbing can cause a resonant sound as I have described. I don't hear the sound outside, in my car, or at work.....but that maybe because my house is way quieter than the rest especially at night when I seem to notice it the most. I am not sure if that is simply because I'm trying to fall asleep and I am fixated in it.
I am on municipal water and sewer with your typical hot water heater and hot water baseboard heating systems.