AN ARTICLE IN yesterday’s Daily Mail reported on an anechoic chamber owned by a company in South Minneapolis, and it’s got some choice quotes:
The chamber is lined with wedge-shaped baffles to absorb virtually all the energy from any sound waves produced inside. Uses include hiring it out to manufacturers striving to design the sounds their products make. It also allows sensory-deprivation training for astronauts, hence the article’s exciting sub-head Visitors see hallucinations after a short while. Being blindfolded and suspended in a tank of warm water probably helps. You can read the whole article here.
The quietest place I’ve been to in London was Chislehurst limestone caves, where this recording was made:
That’s only in one part of the cave system, where a shaft extends upwards to just beneath someone’s back-garden pond, hence the water dripping down. Elsewhere it’s deathly quiet. The owners of Chislehurst caves used to run an annual competition which challenged anyone to spend the night inside alone. Like the astronauts in the anechoic chamber, some contestants ended up having hallucinations and fleeing before dawn.
One reported how he saw a white spectral figure rush towards him. Sensory deprivation seems to produce visual hallucinations over auditory ones. A policeman won the contest in the 1950s, but a later attempt ended in someone else knocking himself out on a low beam as he tried escaping from an imagined horror. The cave challenge was stopped after that.
The National Physical Laboratory at Teddington in south-west London has its own anechoic chamber for hire, as well as other intriguing acoustic environments, including a reverberation room and a listening room done up like a domestic living room.