Home' Trinidad and Tobago Guardian : June 11th 2013 Contents A32
body & soul
Guardian www.guardian.co.tt Tuesday, June 11, 2013
Bats are famous for using sound to navigate
successfully, and new research suggests we could
all use our "inner bat" to get around.
Blind people are aware of this technique. Some
click their tongue or tap their cane on the floor
and use the resulting echoes to help them move
Researchers in Southampton, England have found
that we could all make use of the soundscapes that
surround us, whether we can see or not.
The new study, which involved both sighted peo-
ple wearing blindfolds and blind people, looked at
the types of sound that were best to locate an
Lead researcher Dr Daniel Rowan, a lecturer in
audiology at the University of Southampton, said
in one test the longer sounds, lasting around half
a second, made things easier.
"What the experiment showed is that as the
duration of the sound got shorter and shorter, peo-
ple s ability to tell whether an object was to the
left or right got worse. Having a longer duration
signal appears better than a short one."
But if you want to know something different
about an object---like how close it is'---it may be
that a shorter duration, of just ten milliseconds,
could be better.
"Some bats that use echolocation. If they re
hunting prey, they change their call as they get
closer to the prey to reveal different sorts of infor-
Claire Randall, who has been virtually blind from
birth, uses echolocation.
"I think the first time I was aware of it was when
I was about five. I used to ride a bike and I developed
the ability to swerve past a lamp post and miss it
by millimetres, too regularly for it to be a coinci-
Her mother marvelled at her ability to miss obsta-
"One day my mum asked me how I always man-
aged to miss the lamp post, and the only way I
could explain it was, It goes dark past my ears. "
The history of echolocation is fascinating. Back
in the 1940s and 50s there was an idea that we
had a separate sense on the face specially for detect-
ing echoes. Now we know it s the hearing system
that does it and, although blind people seem to
have honed their skills, we are all capable of nav-
igating using sound.
One reason sighted people may not exploit this
ability so much is that their world is dominated by
This is seen in the "ventriloquism effect", where
sounds are attributed to a dummy because its mouth
is moving, overriding where the sound is really
coming from, the poker-faced ventriloquist.
Previous research has involved real-life locations.
But this study used "virtual obstacles", represented
by sounds mimicking echoes from those imaginary
objects in headphones worn by the study partic-
Dr Rowan said: "In using virtual objects there
were no other clues that someone might use: for
instance, the creaking as you move an object around
or the wafting of air across their face as you move
He has heard the reports of extraordinary feats.
"There are some expert echolocators who are
able to do some fairly amazing things, such as ride
a bike or play basketball, and World Access for the
Blind trains people to do this.
"But we know less about how blind people in
general use echoes."
The findings have just been published in the
journal Hearing Research. Dr Rowan hopes that
they will help to improve echolocation skills.
He said: "One of the things we
wanted to try to contribute to with
our research is to provide some
underpinning science that may
help the development of training
programmes, to help blind people
use echoes that arrive at their ears
Hugh Huddy, from the charity
VISION2020UK, said: "It s great
that scientists are starting to take
an interest in the way blind people
utilise sound to move around, but
comparing the way human spatial
hearing with that of bats, kind of
makes this whole subject less
human than it actually is.
"I don t feel that science needs
to prove that we hear in stereo,
but if this leads to more research
into the amazing and yet so ordi-
nary hearing ability within all of
us, helps sighted people see blind
people as more normal and helps
blind people make the most out
of their hearing, then this is a small
but very welcome development."
Using your 'inner bat' to navigate
YOUR DAILY HEALTH
News and Advice
Echolocation is the use of sound waves and echoes to
determine where objects are in space. Bats use echolocation
to navigate and find food in the dark.
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