I wish it was that simple.
Absolutely, positively not originating from within my house. I can ‘hear’ it at various points outside, but with infrasound it’s difficult to isolate. It does come & go and I’m convinced it’s probably somebody’s HVAC in the area, but it could be anything.
Ironically, it literally JUST NOW ceased while typing (no joke).
Maddening, but the traffic noise is WELCOME!!!
I’m not an acoustics expert but it could TWO sources of sound converging at your house. Have you asked any neighbors if they hear the same thing or would that cause them to think you are crazy?
Nearby major powerlines?