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Directional Sound:
A Public Radio Commentary
by Bill Hammack
Listen using RealAudio
One women believes that a special sound she's developed may save
thousands of lives every year. Her name is Deborah Withington,
and she's a scientist at Leeds University in England.
She's developed a special sound that, when heard can be located
quickly and accurately by the listener.
Her Eureka moment came when she was sitting in her car and heard
a fire engine's siren. "I realized," she said, "I had not the
faintest idea where it was coming from. Because of that, I was
still in danger." Most people would let this drop, but Withington
is a neuroscientist who specializes in how people hear sounds.
She first did some research to see if others also couldn't locate
the sound. Her studies showed that more than half the time,
motorists couldn't tell whether an approaching siren was directly
behind or in front of them. This percentage is worse than if
people were to just guess.
To solve this problem, she used her understanding of the brain to
invent a sound that lets humans locate it easily.
It works by using a rich mixture of pitches. For a human to
identify the direction of sound, a lot of information is
required. When a sound comes from, say, the right side, it
arrives first at the right ear, and is louder than in the left
ear. But for us to perceive this difference in loudness we need a
sound with lots of different pitches. For example, a rushing
river or a waterfall. With this wide range of pitches, our brains
have the maximum number of cues available to locate the sound.
So, what exactly does Withington's sound, sound like? Here it is,
although it probably won't have much potency because of the small
speakers of your radio.
Withington tested it out in a siren, and while it worked so that
people could locate it, that sound just didn't have the authority
of the old one. but she combined it was the whirl of a
traditional siren and it worked perfectly.
And there are other uses for it. For example, she claims that
people will look toward the sound involuntarily. So, the Munich
airport is testing it in their fire alarms, hoping that people
will be attracted to the sound of the alarm and thus able to
navigate through smoke.
And in its most novel use, Withington hopes it can be used on
security cameras. When a bank is robbed, she envisions the
security camera emitting her new sound. This would force the
thief to look straight at the camera, giving the police a good
look a the culprit.
Still, to me the pinnacle of western technology would be to add
this sound to my pager. I'm always setting it down somewhere, and
to find it again I have to listen to it buzz and slowly home in
on it. It would be nice to be directionally drawn toward it.
Copyright 2002 William S. Hammack Enterprises
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