The Orfield Laboratories in Minnesota, the USA, known as the quietest place in the world, was established to test hearing aids. While the lowest intensity that a human ear can hear is 0 decibels, the sound intensity in this room is -9.4 decibels.
Every sound wave in the room is absorbed and completely extinguished by acoustic materials specially placed in the room. In this quiet room, you can easily hear your heartbeat, and if you are careful, you can even hear the sounds of wrinkles on your clothes.
