Yeah, I'm not trying to be mean to the OP, but that was my thought as well. Or its either sound that you normally wouldn't hear because other sounds overpower it, but in the middle of the night, it becomes much more discernible. I have a mini-fridge that occasionally makes a weird sound (like a popping followed by like a whirring). Since they mentioned hearing issues, I wonder if it might even be a hearing aid that is amplifying certain frequencies exacerbating it, or they maybe should have a hearing aid to balance things out and their hearing deficiencies are making those noises much more discernible).
Lots of people use white noise generators (or other that serves same purpose, fans, etc) to help mask sounds when sleeping.
I've even seen speakers that you put under your pillow (basically a flat bluetooth speaker, but I believe it can also provide vibrations which can help with say alarm clock like functions; I actually am surprised we haven't seen a boon of like vibrating blankets or something, acting sorta like how rocking cribs or driving helps babies fall asleep quicker with some vibrations).