Not sure if this is the proper venue for this but here goes.
I have just recently noticed a humming noise in one of the walls of a bathroom. My hearing isn't all that good, so it may have been there all along.
There is "nothing" on that wall in the bathroom or the closet on the other side of the wall.
I'm baffled. I may try to contact the gentleman who built it if I still have his phone number.
Beyond that, there is another higher pitched hum on the hall wall. On that wall is the doorbell ringer, and a thermostat for the furnace/ac. I know it's been there all along, but still wonder about it.
I don't want those poltergeists breathing up my oxygen, lol.