The sound of silence

How it works

An anechoic chamber is a room built to absorb sound. Its walls, floor, and ceiling are covered in deep foam wedges. They soak up almost all of the sound that hits them¹. There are no echoes. Outside noise is blocked by thick walls and springs under the floor.

Inside, your ears have nothing to hear from the room. So they hear you. Within a few minutes many people notice their heartbeat. Then the whoosh of blood in the neck and head. Then the hiss of breath and the creak of joints. Some people hear their stomach. The brain also turns up its own gain when input is low, so faint signals feel loud.

Many people also hear a thin, high ringing. In a small number of people, part of this may be the inner ear itself. The outer hair cells of the cochlea move and make faint sounds called otoacoustic emissions².

The quietest room ever measured is at Orfield Laboratories in Minneapolis. It reached -24.9 dBA in November 2021⁴. That is below the threshold of human hearing, which is about 0 dBA¹. From 2015 to 2021 the record belonged to a chamber at Microsoft in Redmond, Washington, at about -20 dBA¹⁴. Before that Orfield held it, with -9.4 dBA in 2004 and -13 dBA in 2012⁴.

How common it is

The first evidence came from a 1953 study by Heller and Bergman, in which most people with normal hearing reported ringing or buzzing inside a quiet room⁵. That is a small, old study rather than a large modern trial, but its result matches what visitors to anechoic chambers consistently describe today. Later studies found lower figures, from 64% to 83%⁵. In a 2022 study, 74% of 77 young adults with normal hearing heard sounds after four minutes in an anechoic room⁵. Hearing your own heartbeat and breath needs no special study, since a quiet enough room makes it easy for many people to notice.

Is it a problem?

No. Hearing your heartbeat, breath, or a faint ringing in a very quiet room is a normal effect of low background noise, not a sign of tinnitus or hearing damage⁵. The sounds stop being noticeable once you leave the room and ordinary background noise returns. Mention it to a doctor if a ringing or buzzing continues after you leave quiet surroundings, since that pattern is closer to true tinnitus³.

History and culture

A story says that nobody can stay in the Orfield chamber for more than 45 minutes⁴. This is a myth. People find the room strange, and some feel dizzy because they lose the sound cues they use for balance. But people have sat in anechoic chambers for hours. The room does not harm you. It only shows you how much noise your own body makes.