What’s the quietest thing you’ve ever noticed in a hospital?

Last week, I was refilling a pill dispenser and heard the faintest click—like a tiny door closing inside a medication fridge. It wasn’t part of any protocol, just… something mechanical settling. I stood there for a full minute, waiting for it to happen again. Not because it meant anything. Just because it felt like the building was breathing. What’s the smallest sound that ever caught your attention in a place like that?