Inside the world’s quietest room, the anechoic chamber

Steve Orefield, founder of Orefield Laboratories, discusses the experience of sitting in an anechoic chamber, one of the quietest rooms on earth. Inside, all external sounds are absorbed, leaving only the sounds from one's own body, such as ear buzzing, joint movements, and heartbeats. These sounds become significantly louder, and the experience can be either relaxing or claustrophobic. Most people can only endure the chamber for about an hour and 15 minutes due to the intense silence.

What is the relationship between the sounds heard inside the chamber and the sounds heard outside?

How long do people usually last inside the anechoic chamber and what are the reasons for this duration?