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Tuesday, 24 July, 2001, 14:27 GMT 15:27 UK
Noisy solution to crime problem
Security camera, AP
The noise should make people look at the camera
By BBC Science's Andrew Craig

Scientists in Britain have developed a new kind of noise that they hope will help to catch criminals.

Being able to pinpoint a sound is fundamental for survival for all animal species

Professor Deborah Withington
Leeds University
It is already being used to make security alarms more effective, and to stop mobile phone users being confused by other people's ringing phones.

The new sound has been developed by Professor Deborah Withington of Leeds University, UK, for use in conjunction with security cameras.

It works by using a rich mixture of frequencies that enables listeners to pinpoint exactly where it is coming from.

Facing the camera

Professor Withington says she has discovered that it is impossible for people who hear the sound not to turn and face it.

If it is emitted during a robbery, for example, from a speaker positioned next to a security camera, even the most disciplined criminal cannot help turning and giving the camera a nice clear shot of their face.

She says that, in tests, volunteers reacted without even knowing they were doing it.

Survival skills

"Being able to pinpoint a sound is fundamental for survival for all animal species, humans included," she said.

"Our sound has a massive range of frequencies in it," she added.

"As soon as you hear it, you can pinpoint exactly where the sound source is."

The noise is already used in alarms to help pedestrians tell which direction emergency vehicles or reversing trucks are approaching from, and to guide people towards emergency exits during fires.

Soon it could be helping to put criminals behind bars.

The BBC's Andrew Craig
"A rich mixture of frequencies"
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