[guide.chat] blind man goes around the world using echos
- From: "harold kitching" <harold.kitching01@xxxxxxxxxxxxxx>
- To: "guide chat" <guide.chat@xxxxxxxxxxxxx>
- Date: Thu, 13 Sep 2012 12:01:15 +0100
go down past the bbc bumf, to the start of the artical.
BBC News - Human echolocation: Using tongue-clicks to navigate the world -
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12 September 2012 Last updated at 09:12
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Human echolocation: Using tongue-clicks to navigate the world. By William
Kremer BBC World Service
Daniel Kish
Daniel Kish has been blind since he was a baby but that hasn't stopped him
living an incredibly active life that includes hiking and mountain-biking. To
do this, he has perfected a form of human echolocation, using reflected sound
waves to build a mental picture of his surroundings.
When Daniel Kish clicks his tongue, the world answers back.
Cars, trees, doorways, bollards on the pavement. all are identified and mapped
in his brain using information gleaned from a series of sharp little taps of
his tongue against the roof of his mouth, two or three times a second.
From an early age, the Californian developed a sonar technique which allowed
him to navigate using echoes from repeated tongue-clicks. The skill has led to
him being dubbed a "real-life Batman" - a description he welcomes.
Find out more.
Daniel Kish cycling
Daniel Kish spoke to Outlook on the BBC World Service
"It is the same process bats use," he says. "You send out a sound or a call and
sound waves are physical waves - they bounce back from physical surfaces.
"So if a person is clicking and they're listening to surfaces around them they
do get an instantaneous sense of the positioning of these surfaces."
The echoes from his clicks inform Kish about an object's distance, size,
texture and density. It's enough for him to differentiate between, say, a metal
fence and a wooden fence.
"It's not that I can really tell metal from wood, but I can tell the difference
between the arrangement of structures," he says.
"For example, a wooden fence is likely to have thicker structures than a metal
fence and when the area is very quiet, wood tends to reflect a warmer, duller
sound than metal."
But, he adds, conditions really have to be right to discern this reliably.
Kish worked with British boy Lucas Murray, who plays basketball and rock climbs
using echolocation
Echolocation has allowed Kish to pursue outdoor hobbies such as hiking, despite
being totally blind. Kish also says echolocation allows him to engage
aesthetically with the world.
"The sense of imagery is very rich for an experienced user. One can get a sense
of beauty or starkness or whatever - from sound as well as echo," he says.
"Even architecture has some distinction. One can click at a building, for
example, and hear whether or not the building is ornamented or featureless."
Is echolocation a form of seeing?.
Graphic showing activation of visual brain
In 2011, a team of scientists in Canada scanned the brains of two blind
volunteers who said they could echolocate and two sighted non-echolocators.
As they were scanned, the participants listened to two sets of sound recordings
- ones which contained echoes and ones in which the echoes had been removed.
The scans showed activity in the calcarine cortex - the part of the brain
associated with processing vision for sighted people. However, this was only
the case for those participants who said they could echolocate. Most
interestingly, the activity in the calcarine cortex was stronger when these
participants were played recordings with the echoes intact.
No special activity was noted in the auditory cortex of these participants.
One of the scientists, Lore Thaler, says: "We don't know to what extent they're
"seeing" but they're certainly using the part of the brain that sighted people
use for vision."
Kish now devotes almost all his time to training other blind people in his
technique, which he calls FlashSonar. More than 500 students in at least 25
countries have taken the course which is run by not-for-profit organisation,
World Access for the Blind.
On one level, there is nothing revolutionary in human echolocation. Emma
Tracey, who writes for the and has been blind since birth, says all blind
people use sound as they move around in their daily lives.
This can vary between "passive echolocation", in which incidental echoes are
used to help navigate, and "active echolocation", in which the subject emits a
noise in order to produce echoes - whether it be a click of a tongue or a tap
of a cane.
"You find yourself using your footsteps a bit loudly sometimes to just get your
bearings," says Tracey. "Sometimes you click your fingers, almost without
thinking."
She says that the echoes created by the sounds she makes vary depending on
whether she is in a wide open space or around dense objects, and this helps to
inform her movements.
But, she says, using sound to navigate has its limitations. "If it's snowing
it's very difficult to get around, very difficult," she says.
Fiona Sandford, who runs Glasgow-based blind support charity Visibility,
invited Kish over to train her outreach staff in FlashSonar several years ago.
"Many people who are blind do use a form of echolocation," she Sandford. "And
what Daniel Kish does, he takes that ability and hones it."
She likens the impact of his training to a piano student progressing from the
ability to play a simple tune to performing a concerto.
And yet it seems that relatively few blind people use active echolocation to
the extent advocated by Kish and a few others around the world.
"In many instances it's discouraged," says Kish. "I personally have worked with
students who've come from schools for the blind, for whom clicking was actively
discouraged.
Blind football players In blind football there are boards around the pitch to
reflect the sound
"I believe it's discouraged because it's seen as a 'blindism' - if you're
clicking then you're drawing undue or negative attention to yourself."
Fiona Sandford admits that the clicking noise is a barrier for some of her more
self-conscious clients, particularly the adults.
"What we've found is the people that are most receptive to echolocation are
young people."
Much of Daniel Kish's work is focused on training children - some as young as
toddlers - to gain confidence and independence by using a long cane together
with echolocation.
The Royal London Society for Blind People's Dr Tom Pey believes that blind
people should be introduced to the technique, but agrees that some people may
resist it.
Echolocation in nature.
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