In fact, true silence will make you insane. See: http://en.wikipedia.org/wiki/Sensory_deprivation

Can't find the article right now, but they once put people in a completely soundproof room; their minds started to make up sounds and increased their hearing sensitivity to the point where they could hear their own muscles move. I believe the longest one lasted 45 minutes.

This may be the article you were looking for: http://www.dailymail.co.uk/sciencetech/article-2124581/The-w...

True silence for long periods of time makes you insane. For a minute or two it's awesome how you start hearing "the sound of silence".