Y'all.
Y'ALL

This sound has been bothering me all night and I just figured out what it was.

So, an aspect of my sensory processing issues is that I have trouble figuring out the direction, location, and distance of a sound.

I was hearing a low mechanical hum. I've heard it many nights.Thought it was something outside or in a neighbor's apartment.

But when I went to turn off the overhead fan, it stopped. Yes. The fan I use every evening. And apparently sometimes forget it makes a noise.