Blind man uses sonar to 'see'
A Californian man who has been blind for most of his life can 'see' using sound, and is in Australia to help teach the technique to others.
Daniel Kish, who lost his sight to retinal cancer when he was just 13 months old, has dubbed his bat-like technique "flash sonar".
He uses sounds to detect objects in his environment by sensing echoes from those objects.
"It's an active form of echolocation that allows a blind individual to see using flashes of sound, instead of flashes of light," he told ABC News Breakfast.
"An individual emits flashes of sound - and they may be in the form of a tongue click - and uses those flashes to illuminate the environment and extract information from the returning soundwaves, that return from surfaces in the environment.
"And then we can construct images based on the information we have extracted."
Mr Kish combines echolocation with the use of his cane to boost his mobility, and leads groups on hiking and mountain bike adventures.
"I've always been able to do this. I think it has to do with how I was raised. I was raised to pretty much be involved in all of the other things that kids were doing," he said.
"I went to regular school, I played with sighted children, I had to have an equaliser.
"As I've grown older, my interest has turned more to developing methods of teaching it and helping blind people to learn it."
The Centre for Brain and Mind in the US has studied the activity in Mr Kish's brain as he listened to the sounds he uses in flash sonar.
Researchers found that instead of activating the area of the brain responsible for interpreting sound, the sounds activated Mr Kish's visual cortex - supporting the idea that sounds provide a visual effect that allows Mr Kish to 'see'.
Mr Kish, who heads non-profit organisation World Access for the Blind, is currently holding a series of workshops with Australian students to teach them to see in new ways.
He says many blind people use echolocation to a certain degree but are unaware of it.
"Our hope is to help blind people become more aware of it so that they can become conscious of developing and refining it and integrating it more naturally into their daily lives," he said.
"It generally helps people become more confident. They're more aware of their surroundings, they're more aware of the options they have within their surroundings.
"It enables people to interact with their environment more quickly, with more precision, with more grace.
"People can participate in a wider range of activities with greater levels of comfort and confidence. They can conduct themselves with more poise.
"It just basically adds a dimension to a person's ability to interact with the environment effectively."