Turbulent traffic, screaming sirens, constant chatter at a coffee shop… It can be difficult to find our own peace and quiet in the midst of the noise-polluted cities we live in, but is the quietest room in the world as peacefully sane as you would think? The Guinness World Records acknowledged in 2012 the Anechoic Test Chamber at the Orfield Laboratories, located in Minnesota, USA, to be the quietest place on Earth; with its background noise reaching record low -13 decibels and absorbing an astounding 99.9% of sound produced within or outside the room.
The OL Anechoic (from Latin meaning non-echoing) Test Chamber, as any anechoic chamber, is an externally insulated room in which every interior panel is covered with special material that scatters and absorbs so much travelling energy, that it can simulate “free-field” conditions (conditions with zero sound reflections). Specifically, the OL Anechoic Chambers contain specially designed foam wedges as the absorbent component within the room. The wedges “trap” low frequency waves between the troughs in the wedges and then dissipate that wave energy through the air, and absorb higher frequency waves into the wedges themselves, thus overall reducing the amount of waves being reflected back into the room to a miniscule 0.1%. Generally, anechoic chambers are constructed to carry out acoustic experiments such as measuring the response of audio equipment including microphones, loudspeakers and quiet objects in conditions which does not affect any measurements.
Apart from being recognised as the most silent place on Earth, the OL Anechoic Test Chamber has gained a strong reputation for driving people crazy within a single hour, with the longest time a person being able to remain in the room being only 45 minutes! However, people such as the science youtuber, Veritasium, have demonstrated that it is possible to remain sane, and even enjoy being within a very similar anechoic chamber for a myth-busting 60 minutes.
So the question is, how does the human behaviour REALLY change within an anechoic chamber? Although being within the chamber most likely won’t drive you insane immediately, it will make you feel uncomfortable as the time goes on. People who have experienced the anechoic chamber report firstly hearing the rustling of clothes followed by auto-emissive noises, sounds produced by their own bodies such as the wheezing of a breath, gulping of bodily fluids and so on. Ultimately people within the chambers start hearing their own pulse and even start feeling their blood being pumped through their bodily parts!
Nevertheless, anechoic chambers do prove to induce unsettling psychosis-like behaviour. A study carried out by researchers at the University College London investigated the effects of brief 25 minute sensory (light and noise) deprivation on 36 individuals that differed in trait hallucination proneness. The researchers discovered that, essentially, both groups of people who are more and less prone to experiencing hallucinations, experienced consistent psychosis-like symptoms, such as irritability, incorrect comprehension and cognitive disorganisation.
And yet, why is the human behaviour affected so drastically within, what is basically, a soundproof room? The human ear is an extremely specialised and sensitive piece of equipment, a “biologically adapted microphone” if you like, that has evolved to detect a specific range of sound frequencies and act as spatial awareness indicators. So upon entering the LO Anechoic Test Chamber, a person would perceive the room to be absent of sound. All of the bodily function noises, the whooshing of the blood, the wheeze of a breath or swallowing of your saliva in your mouth, would suddenly become distinctly audible within the anechoic chamber.
It is the decrease in intensity of sound pressure to levels that are abnormal to humans, which produces a shock-response within a person. And this shock-response is expressed as the induced psychosis-like behaviour to the lack of environmental noise feedback, which we are so used to in our everyday lives. So city inhabitants, be warned upon entering the anechoic chambers, they are known to cause mental irritation and confusion, but hearing your own heartbeat does compensate for all the unrest!