Published:  01:36 AM, 10 October 2019

Some blind people can 'see' with their ears

Daniel Kish and others use echolocation, just like bats do

Some blind people can 'see' with their ears

When Daniel Kish enters a room, he may not be able to see, but his ears give him a 360-degree view. Kish uses echolocation - just like bats or whales - to navigate the world. And it allows him to do everything from cycling in traffic to hiking, all on his own, without the benefit of sight.

Kish lost his vision as a toddler. He was diagnosed with retinal cancer and had to have both eyes removed before he was 13 months old. Amazingly, he taught himself that by making small noises he could listen for their echoes and learn what surrounded him. Today, Kish is an expert at human echolocation - and his organization is teaching other blind people how to do it, too.

Like many of those who use echoes, Kish makes clicking noises with his tongue and then listens for their feedback in the environment. "It is the same process bats use," Kish told BBC News. "You send out a sound or a call and sound waves are physical waves - they bounce back from physical surfaces."

Kish, who has been dubbed a "real-life Batman," explains in this TED talk that echolocation allows him to discern not only an object's size and proximity but also its texture and density.

So he can tell the difference between a tree, a wooden fence and a car, all with just a few clicks of his tongue. This ability has made Kish, and other human echolocaters, the subject of a number of studies aimed to better understand the process.

How does echolocation in humans work?

Kish co-authored a study published in the Proceedings of the Royal Society B showing that experienced "echolocators" can even increase the loudness and frequency of clicks for objects that are either beside or behind them. They will increase the intensity and number of clicks to adjust for the weaker reflection of sound for an object further away. This study is the first evidence on record that people who use echolocation will adjust their clicks to improve their senses.

An earlier study published in Acta Acustica analyzed the clicking noise that Kish used to navigate the world and found that his method of pulling his tongue backward instead of downward from the roof of his mouth created a noise that was sharp and clean and perfectly suited to echolocation.

Several teams of researchers have since taken a deeper dive on the neural architecture behind this skill with startling results. In one study published in PLOS One, researchers at the University of Western Ontario used brain mapping to determine that the area of the brain that a sighted person would use to interpret visual information is activated in a blind person who uses echolocation. Durham researchers took this idea one step further and found that the brain is incredibly flexible in this regard.

Even if the information doesn't come through the eyes, the part of the brain that's devoted to the initial stage of visual processing still works to digest spatial information, writes Science magazine.

This reaffirms that human echolocation can be taught and, in fact, only requires only a few weeks of practice. Kish, through his nonprofit World Access for the Blind (WAFTB) and Visioneers, hopes to do that by training sight-impaired individuals all over the world to become more independent in their environment.

The writer is a former national park ranger with a Masters Degree in Environmental Education.
The article appeared in Mother Nature Network

---Jenn Savedge

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