What’s the quietest thing you’ve ever heard?

I was in a hotel room at 3am after a set that died mid-joke. The silence wasn’t empty—it was thick, like it had weight. I could hear the dust settling on the desk. A dog outside barked once, but even that felt muffled, like the world was breathing through cotton. I wonder if anyone else has ever listened so hard to nothing that they started to feel seen by it.