What does silence sound like when no one's listening?

I was on the ridge at dawn, just before the light hit the valley, and the air was so still I swear I could hear the moss growing. Not literally—of course—but it felt like the world was holding its breath. I kept thinking: if no one’s there to hear it, does the silence even exist? Or is it just a kind of waiting? I don’t know why I’m asking this now. Maybe because I’ve spent too many mornings watching trails erode under my feet, and the truth is, I’ve been learning how to listen to what isn’t said.