The keyboard keys are clicking (ever notice how the backspace and spacebar make different sounds from the rest of the keys?).
The chair I'm sitting on is creaking.
The one that my feet are on is uneven so a leg hits the ground when I shift.
The cat is scratching herself somewhere in the house and I can hear her collar bell tinkle.
The fridge just switched on.
Audrey just turned over in her creaky bed.
I just took a snorty breath through my nose. Damned allergies.
My neck just made a crackly sound as I turned my head around. Ugh... that didn't make me feel old.
My mouse clicks as I search for a photo to insert.
Those are the sounds I hear at 11:52pm in my "quiet" house.