for National Geographic News
With just a click of the tongue, anyone can learn to "see" with their ears, according to a new study of human echolocation.
Several animals, such as bats, dolphins, whales, and some shrews, are known to use echolocation—sound waves bounced off nearby objects—to sense what's around them.
Inspired by a blind man who also navigates using sound, a team of Spanish scientists has found evidence that suggests most humans can learn to echolocate.
The team also confirmed that the so-called palate click—a sharp click made by depressing the tip of the tongue against the roof of the mouth—is the most effective noise for people to use.
Daniel Kish, executive director of World Access for the Blind in Huntington Beach, California, was born blind. He taught himself to "see" using palate clicks when he was a small child.
Kish is able to mountain bike, hike in the wilderness, and play ball games without traditional aids.
To better understand Kish's skill, Juan Antonio Martínez and his colleagues at the University of Alcalá in Madrid trained ten sighted students to echolocate.
"It was very difficult to persuade some people to take part in the experiments, because most [of our] colleagues though that our idea was absurd," Martínez said.
The students were asked to close their eyes and make sounds until they could tell whether any objects were nearby.
After just a few days of training, the students had all acquired basic echolocation skills, the scientists report in the March/April 2009 issue of the journal Acta Acustica.
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