So what is echolocation exactly? Bats and dolphins aren’t the only mammals that use the ability to use sounds alone to identify objects and navigate unfamiliar surroundings. New research shows that blind people are also capable of using this build in mechanism.
Back in 2007 fourteen-year-old Ben Underwood of Sacramento, California appeared on the Oprah Winfrey Show, on the CBS Evening News, and in a number of print newspaper and magazine articles. Underwood navigates his neighborhood and high school by rapidly clicking his tongue and using the echoes from the sound to determine what is around him. Using this technique, he even zips around his neighborhood on roller blades.
Underwood’s seemingly uncanny ability to navigate exclusively by sound has been dubbed by the media “echolocation,” which is the name given by scientists to the ability of nocturnal creatures like bats to navigate by emitting sonar signals at frequencies that are too high for humans to hear and that allow them to locate and feed on flying insects.
Some dolphins also use echolocation to navigate through the water by making clicking sounds. With television cameras recording the spectacle, Underwood went swimming with dolphins at Sea World to compare their methods to his own.
The concept of using tongue clicks to navigate isn’t new; another Californian, Daniel Kish, has been doing it for years and even teaches the technique to other blind people to supplement their use of a white cane or dog guide.
Mel Goodale, director of the Centre for Brain and Mind at the University of Western Ontario and Canada Research Chair in Visual Neuroscience, said in a Public Library of Science news release commented:
“It is clear that echolocation enables blind people to do things that are otherwise thought to be impossible without vision, and in this way it can provide blind and vision-impaired people with a high degree of independence in their daily lives.”
The blind are believed to hear better than the sighted, which accounts for the musical talents of famous blind musicians like Ray Charles, Stevie Wonder, and Ronnie Milsap. It is also often assumed that the blind must naturally have extra-sensitive touch in order to read Braille.
Those hard of sight learn to make clicking noises and listening to the faint returning echoes, blind people are able to map out their environments, identifying objects such as a car, building or mailbox.
This new evidence suggests that blind people may be able to play team sports or find their own way around by fine tuning this talent.
Surprisingly, by measuring participants’ brain activity while they were echolocating, the investigators also found that the blind echolocators were actually using the “visual” part of their brains to process the sounds.
There are also two types of sonar processing, passive and active. Passive sonar is the most widely used type among humans. It relies on sounds in the environment or sounds casually produced by the listener, such as footsteps or cane taps. The images thus produced are relatively vague and out of focus. Passive sonar may be sufficient for detecting the presence of objects, but not for distinguishing detailed features. It’s a little like hearing the murmur of other people’s conversations around you. You catch bits and pieces, but the information contained therein may or may not be relevant or discernible.
Active sonar involves the use of a signal that is actively produced by the listener. It allows the perception of specific features as well as objects at greater distances than passive sonar. It’s more like engaging in active conversation with elements of the environment. One can ask specific questions of particular elements and receive clearer answers. In fact, scientists who study bats call the process of bat sonar “interrogating the environment.”
The bat is actively involved in querying features of the environment for specific information through an array of complex sonar calls almost as varied and strategic as a language. Only recently has it been made clear that humans can learn to do likewise.
Sources: The Public Library of Science and The National Federation of the Blind
Written by Sy Kraft