If you stand in it for long enough, you start to hear your heartbeat. A ringing in your ears becomes deafening. When you move, your bones make a grinding noise. Eventually, you lose your balance because the absolute lack of reverberation sabotages your spatial awareness.

In this room, surrounded by six layers of concrete and steel, located at Microsoft's headquarters in Redmond, Washington, all sound from the outside world is locked out and any sound produced inside is stopped cold. It's called an "anechoic" chamber because it creates no echo at all -- which makes the sound of clapping hands downright eerie.

The background noise in the room is so low that it approaches the lowest threshold theorized by mathematicians, the absolute zero of sound -- the next step down is a vacuum or the absence of sound.

Inside, the measured noise level is negative decibels -- to be precise, -20.3 decibels, which is 20.3 dB below the threshold of human hearing. For context, calm breathing can be heard at 10dB in a normal room, and a soft whisper at 30dB.

This is the world's quietest place.

The concrete bunker currently holds the Guinness World Record for the world’s quietest place after swiping the title from another chamber in Minneapolis, Minnesota which has noise levels of -9.4 dB. The Orfield Laboratories, once dubbed “the quietest place on earth” is now open to the public and has become a tourist hot spot.

More Info: www.bbc.com