Anechoic chamber: The room that 'sucks out' sound
What is it like to spend time in one of the quietest rooms in the world?
For The Why Factor on the BBC World Service, the BBC's Mike Williams set out to investigate what role silence plays in our increasingly noisy lives.
As part of his research he went into an anechoic chamber at the University College of London to get as close as possible to experiencing what true silence sounds like.
Although tiny amounts of sound leak into the room the levels are so quiet that they are not audible to the human ear.
Hear more on The Why Factor on the BBC World Service on Friday 8th March at 19.30.