What the quietest room in the world looks like (4 photos + 1 video)
To be in absolute silence in a place where no one can reach one sound and where there is no echo is not a test for everyone. They say that for some people, being in an anechoic chamber can even cause hallucinations! Well, let's look at the room that is listed in The Guinness Book of Records as the quietest in the world. 
This room is located in the Microsoft Audio Lab at Redmond, USA and is considered exceptional. Its noise level is -20.35 dBA. The room drowns out all external noise, making any sound published inside, absolutely creepy. 
“As soon as a person enters a room, he immediately experiences a strange and unique feeling that is difficult to describe, says Khundraj Gopal, speech and hearing specialist and designer Microsoft anechoic chamber. Most people perceive the absence sound like something deafening, feel fullness or ringing in the ears. Even the faintest sounds become clear and distinct as the level ambient noise is exceptionally low. When you turn your head, you you can hear this movement. You can hear your own breathing - and it's a pretty loud sound."
Of course, if you focus on the sound of your breath, then it can be heard anywhere, but this is usually interfered with by background noises. They cause our hearing organs to ignore minor sounds. However, in anechoic chamber, the ears adapt again and begin to pick up any rustle. And so very quickly there is a strange feeling. 
“The longest time spent in a cell on today is about 55 minutes,” adds Gopal. — Some of our employees may be continuously inside during 30 minutes or so. But many ask to be released within the first a few seconds."
It turns out that the ability to clearly hear the work of their internal organs is not the most pleasant feeling, but being in the very a quiet room in a world with the lights off is even scarier. Why? Yes because the lack of sound makes people lose their balance. So better to stand still. 
What better way to imagine how quiet it is make one comparison. When we are in an ordinary room in which no one makes noise, then one of the quietest sounds for our ear is calm breathing, and its level is about 10 dB. Noise level in Microsoft anechoic chamber is rated at -20.35 dB, which means that ambient noise in it is 20.35 dB below the threshold of human hearing.
The chamber consists of six layers of concrete and steel and is located on an array of vibration damping springs. The walls and ceiling inside are covered with wedges fiberglass with high absorbency. The floor consists of hanging sound-absorbing cables. All this place is cut off as far as possible from the rest of the building and the outside world to reduce the chance that any sound will penetrate inside.
There are no tours of the Microsoft anechoic chamber. Company uses it to test various audio devices - microphones, receivers and speakers, as well as to check the noise level from computing devices.
