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, at age 51, Kish is an expert at human echolocation.
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."
As Kish, who has been dubbed a "real-life Batman," explains in this TED talk, echolocation allows him to discern not only an object's size and proximity but 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 work?
Kish co-authored a 2018 study 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.
In 2009, a Spanish study 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. A few years later, another study from 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.
Researchers also have learned that human echolocation can be taught and requires only a few weeks of practice. Kish, through his non-profit organization World Access for the Blind, hopes to do that by training sight-impaired individuals all over the world to become more independent in their environment.
WAFTB's slogan: Our Vision is Sound.
Editor's note: This article has been updated since it was originally published in October 2017.