It is a room within a room within a room; the innermost chamber is lined with 3.3-foot-thick fiberglass acoustic wedges and floats on I-beams and springs. Both inner rooms have double walls of insulated steel; the outside walls are foot-thick concrete. The background noise level is minus 9.4 decibels. In this room, even a dog is deaf to the world outside.
The total absence of sound outside your body makes you keenly aware of what's going on inside your body. Your heart pumps. Your lungs inflate and deflate. Your ears buzz. Your blood pulses. In an anechoic chamber, you are one noisy organism. With no reverberation in the room, you have no spatial orientation cues. After about half an hour in the dark, you can become disoriented. Eventually, you might experience visual and aural hallucinations.