Scientists at Minneapolis’ Orfield Labs created their own soundless room, an anechoic chamber. Their studies have found that when putting subjects within the chamber, they begin to hallucinate within 30 minutes.
With an average quiet room having a sound level of 30 decibels, the anechoic chamber’s sound level is -9 decibels. The ceiling, floor, and walls of the chamber absorb sound rather than have it bounce off as normal objects do. The chamber is so quiet that the subjects can even hear their own organs functioning.
Although extremely interesting, the experience is rather unpleasant. Not one subject has spent more than 45 minutes in the chamber alone. Leaving a person to only their thoughts, the chamber could drive them insane.