1) You can tell a reader by how they approach you when you're reading. It's simple - they don't.
2) Finding absolute silence is very difficult. Bugs. Heaters. Cars. Your own heartbeat if you're paying attention. In my case, the snot percolating in your nostrils. Dear God. It's never quiet anywhere.
3) You also don't realize how much your body moves involuntarily. I got a new iPhone 5 with the compass app and was holding utterly still while trying to hit true North. Almost impossible. Try it sometime. You'll go insane.