What’s the quietest thing you’ve ever heard in a kitchen?

I was sharpening a chef’s paring knife yesterday—just before service—and the kitchen was so still, I swear I could hear the blade’s edge humming. Not literally, but like… the air around it had changed. No one else noticed. I stood there for two minutes, waiting for someone to say something. No one did. Just silence. What’s the quietest thing you’ve ever heard in a kitchen? Or maybe just the quietest moment?