Silence holds a paradoxical place in science and in human consciousness. In science, the quietest conditions that modern technology allow are invariably used to research sound.
And our own search for “peace and quiet” never extends as far as wanting no noise at all. Real silence is strange and disturbing, not relaxing. Most people cannot sleep without at least some background sound.
The closest humankind can get to complete silence is the inside of a heavily soundproofed anechoic chamber, a handful of which exist in universities and labs across Britain. These are used for a range of interesting research – but they also have a profound effect on the people who go into them.
My search for one leads me to University College London, whose anechoic (“without echo”) room is in an anonymous, windowless building. In one of the busiest parts of campus, and next to the low hum of an electricity substation, it is hard to believe the unassuming walls can block out all sounds. Dave Cushing, a technician in the phonetics and linguistics department, which owns the facility, shows me the stacks of equipment used in the chamber, and the extensive precautions taken to keep sound pollution inside to a minimum.
Stepping into the chamber is a strange experience, “like being in a field in the middle of the night” according to John Fithyan who runs Southampton University’s facility. The silence is profound and the room looks unusual too, with jagged sound-cancelling spikes covering the walls and ceiling that take on a menacing look in the dim light. A 70s-style padded armchair sits incongruously in this other-worldly environment. As I sit on the chair, I try to speak. My voice sounds quiet and dead, and yet I am conscious of the sound of my breathing. As I hold my breath and try to experience the silence without the sound of my breath, I begin to hear a whistling noise in my ears. The experience is disconcerting.
Unpleasant or not, complete silence is incredibly difficult to achieve. Insulate a room, build it within thick brick walls, and vibrations will still get in. Mount the whole thing on springs, and the vibrations will stop – but the echoes won’t. Anechoic chambers eliminate this problem by covering walls, ceiling and floor with wedges of fibreglass which stick out 18in into the room. These absorb virtually all the sound, meaning that measurements of sound levels typically weigh in far below zero decibels, the threshold of human hearing. The Bell Labs chamber, the first ever built, featured in the Guinness Book of Records as the “quietest place on earth” after its construction in 1940.
Once you have a silent room, you don’t want to ruin it. So the chamber at UCL has specially designed silent air conditioning, and the walls contain coils to cancel out the hum of the substation. The chamber is lit with light bulbs instead of noisy fluorescent tubes. And users must walk on a platform, raised above the soundproofed floor. Even the steel door is covered with a foot and a half of fibreglass.
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