Trying to identify rhythmic humming in home
I don't know if this is the same issue but I'll mention it because &quot;WUm-WUm-WUm-WUm-WUm&quot; is exactly how I would describe it.  When I moved into my first home, I would sometimes hear a low resonating sound like you said &quot;WUm-WUm-WUm-WUm-WUm&quot;.  It really scared me because I thought maybe it was my furnace or something but it would happen even when the furnace wasn't running.  I finally just got used to it but I couldn't figure out where it was coming from.  It sounded kind of like how I would imagine a UFO hovering over my house might sound (no UFOs were sighted.)  I checked an 80Hz test frequency video just now and it was similar in tone.
A few years later, we had a gas fireplace put in and after a while I noticed that this sound was gone.
So here's my best guess as to what it was: there's a train yard a few miles away from where I live.  When the diesels come through, they are going very slow/idling and they make a low &quot;WUm-WUm-WUm-WUm-WUm&quot; sound.  Around a certain frequency, this sound was resonating in the chimney.  When the fireplace was installed, two insulated liners were added (intake and outtake) which changed the resonant frequency of the chimney and eliminated the sound.