Another device in the crowded control room is a spectrum analyzer. "The spectrum analyzer looks at the different frequencies in a voice," Cushing says. Using high-quality digital recordings,researchers employ the analyzer to examine the minute details of speech, furthering our understanding of human expression.
Elsewhere, scientists and engineers mainly use anechoic rooms for routine acoustic research, such as testing equipment and modelling sound propagation. But one complex technology developed in the chamber features finds a practical application in the nation's living rooms.
"Head-related transfer functions" (HRTFs) underpin the surround sound effects in many computer games. Audio systems using this technology create their 3D sound effects using only a pair of normal stereo speakers. The illusion is created using a detailed acoustic model of the human head, developed in an anechoic chamber, to subtly tweak the sound so as to mimic the realism of five-speaker systems.
The silence of the anechoic room has inspired musicians, too. The American composer John Cage visited Harvard University's facility in the late 1940s. Cage discovered that total silence is not actually possible: he claims he heard two sounds, "one high, my nervous system in operation, one low, my blood in circulation." After this experience, he was inspired to write his "silent" piece, 4'33", in which the "music" is made by the ambient sounds of the concert hall alone.
Some people, standing in an anechoic chamber, have lost their balance. Professor Linda Luxon, an audiologist at the Institute of Child Health, questions why this might be. "I can't give you any rational explanation of why people would lose their balance in an anechoic chamber," she says. But she does agree that people find orientation easier if they have full use of all five senses.
As I step out of the anechoic chamber and back into the control room, my sensory deprivation ends. Before going into the chamber, I had thought the control room was quiet, but I now hear the fans of the computer systems, the echoes of students chatting outside. The shock of hearing all this is as great as was the shock of hearing nothing.
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