UCL News


If these walls could talk, they would whisper

17 August 2005

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 UCL, 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 UCL Department of Phonetics & Linguistics, 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. …

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.

While most anechoic chambers are used for acoustic research, UCL's is used in phonetics - the scientific study of the human voice. Researchers make precise recordings of voices, using both microphones and laryngographs. This latter device, developed by one of the academics who used this chamber, measures the opening and closing of the voice box while the subject speaks. Linguists at UCL use the recordings to identify the root causes of speech abnormalities in children.

Another device in the crowded control room is a spectrum analyser. "The spectrum analyser looks at the different frequencies in a voice," Cushing says. Using high-quality digital recordings, researchers employ the analyser to examine the minute details of speech, furthering our understanding of human expression. Other research in the department has investigated the hearing of people who have had ear surgery.

Oli Usher, 'The Guardian'