ACTUALIDAD | DW
The blind "come" with an echo sounder
Blind people can orient themselves in space or measure the distance of obstacles by emitting sounds and tracking the echo they produce. That is a technique frequently used by dolphins and bats. When walking short distances, Eskandar Abadi, an Iranian journalist who was born without the sense of sight, is oriented in space emitting sounds, a sort of click that, when hitting the objects around it, generates an echo. This secondary noise lets you know how far away the possible obstacles are. When the paths are larger, Abadi clicks his fingers to create a louder sound. "Thanks to the echoes I can recognize if what I have in front is a wall or a tree because the echoes are different," he says.
Abadi works since 2002 in the Persian language of Deutsche Welle and moves smoothly through its facilities thanks to the echo sounder. To discover what happens in the neurological system when a blind person is oriented with the sense of hearing, a group of scientists have initiated an experiment in which the brain activity of several volunteers is measured. Small microphones are inserted into their ears to record the sound of the clicks that they emit for orientation and the echoes they produce.
Sounds that allow to see
"Study participants listen to the recording of these clicks while measuring their brain activity," explains Lore Thaler, a German scientist who collaborated with an experiment at the University of Western Ontario focused on the echo sounder as a "vision" resource for blind people. When the researchers compared the registered brain activity patterns with and without echoes, they realized that there was activity in the visual areas of the brain and not in the auditory areas.
“As soon as the blind heard the echoes of the clicks, the visual cortex of the brain was activated; that is the part of the brain that digests the visual impressions of people who can see and not the auditory impressions, ”says Thaler, clarifying that the ability to orient in space through the sense of hearing can also be developed by the people who see . However, those who are accustomed to moving with the help of the echo sounder have learned to recognize surfaces and structures, as well as distances.
Corners and edges with right or rounded angles generate a different echo; hence the ear serves them to obtain such an accurate picture of the environment, says Thaler, who works simultaneously in another study dedicated to the echo sounder at the University of Durham, United Kingdom.
Authors: Gudrun Heise / Evan Romero-Castillo
Publisher: Enrique López