There is no such thing as silence. Microsoft Sets Guinness World Record for Quietest Place on Earth.
There is no such thing as silence even on the quietest place on earth. Microsoft now holds the Guinness World Record for Quietest Place on Earth. You might think that a library reading room or well-insulated basement is a quiet place, but compared to the anechoic chamber in Microsoft’s audio lab, they’re about as quiet as a jumbo jet. The Eckel Anechoic Chamber at Microsoft set a new record at -20.6dB. Brownian motion (the random movement of particles in the air) is the quietest known sound outside the vacuum of space is measured at -23dB. To provide some context of how quiet this is, calm breathing is +10 dB; rustling leaves +20; normal conversation +60 and a jet plane take-off at +150 (at 25 meters). Click here to see a video on the Eckel Anechoic Chamber.
Microsoft and others including hearing aid manufacturers use anechoic chambers in a number of audio research and development applicatons and to test equipment and hearing aids.