THIS WEEK:                                                           31 Jan 98
 #21  Singing sirens could save the blind.

   By ROB EDWARDES
If you cannot see, you may not be able to find your way out of a burning
building-and that could be fatal. A company in Leeds could change all that
with directional sound alarms capable of guiding you to the exit.
Sound Alert, a company set up by the University of Leeds, is installing the
alarms in a residential home for blind people in Somerset and a resource
centre for the visually impaired in Cumbria. The alarms produce a wide range
of frequencies that enable the brain to determine where the sound is coming
from.
Deborah Withington of Sound Alert says that the alarms use most of the
frequencies that can be heard by humans. 'It is a burst of white noise that
people say sounds like static on the radio,' she says. 'Its life-saving
potential is great.'
She conducted an experiment in which people were filmed by thermal-imaging
cameras trying to find their way out of a large smoke-filled room. It took
them nearly four minutes to find the door without a sound alarm, but only 15
seconds with one.
Withington studies how the brain processes sound at the university. She says
that the source of a wide band of frequencies can be pinpointed more easily
than the source of a narrow band. Sirens based on the same concept have
already been installed on emergency vehicles (This Week, 23 September 1995,
p 11).
The alarms will also include rising or falling frequencies to indicate
whether people should go up and down stairs. They were developed with the
aid of a Pounds Sterling 215 000 grant from British Nuclear Fuels.

New Scientist
Volume  157.   Issue   2119.
Copyright (C) IPC Magazines Ltd, 1985-1997


Bud Kennedy
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