What does silence sound like in an empty theatre?

I’ve been thinking about it since I walked through the back doors of the old civic hall this morning. No one else was there, just dust motes dancing in the slant of light from the high windows. The floorboards creaked under my feet like they remembered me — and then, after I stopped moving, the silence wasn’t empty at all. It hummed. Like a note held too long by someone who forgot to let go. What’s your version of that?