Anechoic chamber, Copenhagen, Denmark

© Alastair Philip Wiper/Science Photo Library

Anechoic chamber, Copenhagen, Denmark

Anechoic chambers are most commonly used to test the noise levels made by electronic and mechanical devices during normal operation. The pyramid-like foam protrusions on the walls and ceiling are designed to reduce the reflection of sound waves so that when the chamber is closed, any sound occurring within the chamber can be recorded and measured as accurately as possible.

But these chambers aren’t ideal spots for a quick nap or a moment of “me time.” Humans who have spent more than a few minutes inside a closed anechoic chamber report that once their brains adjusted to the total silence, they were soon able to hear the blood flowing through their own veins.