Ever feel like your office is a little too loud and distracting? Or have those moments when you're at home and you think it's quiet, but then you start to hear the hum of the refrigerator and the low rumble of distant traffic? Maybe you'd like a holiday to the quietest place in the world - though be warned, you're probably not prepared for what total silence does to the human brain.

Shhh. Hear that? No? That's surprising. Odds are, you can hear something right now: A siren, the hum of a fan, the blur of background conversations, the ticking of a watch. It's seldom our worlds are fully silent -- so seldom that complete silence feels shocking.