There is an anechoic chamber in Minneapolis, supposedly the "quietest place on earth", with isolated walls that absorb 99.99% of all echoes.
It is claimed that the world record for staying in this room is 45 minutes (one source claims 60 minutes). I find it hard to believe that the longest time someone can stand staying in such a room is such an absurdly low number, for a condition presumably similar to what deaf people experience all their life.
This room was features in another question here, which asks about the hallucinatory effects:
Does a -9 dB room cause hallucinations?
The answers to that question show that indeed such a room may induce hallucinations, but say nothing about the claimed world record.
Is the maximum time anyone has been able to stay in this or a similar room really been less than a couple hours?
Or has nobody tried for longer?
Examples for the claim:
Today.Com: The sound of silence: Sailor finds peace in world's quietest room (claims that someone beat the previous record of 45 minutes and stayed for an hour)