LOL, my initial thought when I read the answers to the poll was that the last one was "My wife is too loud to hear it."
Seriously though, I believe I've only experienced true silence once, and I'll never forget it. It was on the top of (I believe) one of the highest mountains in Austria, near Hallstatt. I took a gondola partway up the mountain and then hiked to the very top, and I just happened to be alone on the summit for about 15 minutes. There was no wind. There were no animals. And obviously no people. It was then that I learned that the old saying "Silence is deafening" is actually true, in a sense. After a few moments, my brain couldn't seem to comprehend the complete and utter lack of sound, and I started "hearing" my own heartbeat and breathing roaring in my head. I have never since experienced silence like that.