Your refrigerator could be the culprit. Not kidding.
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!!!