Noise like this is sometimes part of a TIs mysterious circumstances in any given location but it often occurs also as a new disturbing noise found coming from a neighbors apartment or in a living situation with more than one family.
Suddenly one day there's a pulsating, low hum coming from a neighbors house.
Have gotten this gotten this before and now again in this location-usually accompanied by being fried the shit out of by what seems like electromag or microwave.
I've learned one thing over.the years.
Dont Trust Anyone.