Need help with unusual noise
Dearest helpful ones, I am losing the few marbles I have left because I am unable to pinpoint the origin of an unusual noise in my home that I've been hearing for two years.
It goes on any time of day, but isn't an every day occurrence. I can go days without hearing it. It has nothing to do with time of year or weather. It has nothing to do with the furnace, which is only nine months old. It has nothing to do with the sump pumps because I have gone into the basement to observe the pumps when I hear the noise begin. This is not related to toilets being flushed. Or water running in sinks or tubs. Or running a washing machine. I can be sitting quietly reading a book alone in my home and will suddenly hear a noise like something is kicking on. It's a little like hearing an old sump pump go on when it's about to break, if that makes sense, only it's not the sump pumps. It makes a loud noise while it "runs" for perhaps a minute, and halfway through I'll hear something that sounds like pipes in the house are vibrating.
Some additional notes:
I do not have tinnitus.
This is not the hum being heard by people in various countries.
It happens in all weather and all seasons and is not related to the ground being wet.
It can be heard inside the house on the first floor only, is quite muffled sounding when in the basement, and cannot be heard at all from the yard just outside the room where I can hear it.
Do any of you have any idea what may be causing this?