Madrid, Spain – You may have heard of Daniel Kish or Ben Underwood, two blind people who learned to detect objects through echolocation – but you can do it too, according to Spanish researchers.
A team from the University of Alcalá de Henares (UAH) has shown that echolocation, used by dolphins and bats to explore their surroundings, can be taught.
Producing certain kinds of tongue clicks helps people to identify objects around them without seeing them – a useful tool for the blind, but also for people lost in fog or in the dark. By using echolocation, it is possible to measure the distance of an object based on the time that elapses between the emission of a sound wave and an echo being received.
“In certain circumstances, we humans could rival bats in our echolocation or biosonar capacity,” claimed Juan Antonio Martínez, lead author of the study and a researcher at the Superior Polytechnic School of the UAH.
The team first analysed the physical properties of various sounds. “The almost ideal sound is the ‘palate click’, a click made by placing the tip of the tongue on the palate, just behind the teeth, and moving it quickly backwards,” Martínez explained.
In order to learn how to emit, receive and interpret sounds, the scientists are developing a series of protocols. The first step is for the individual to know how to make and identify his or her own sounds – they are different for each person – and then to learn how to use them to distinguish between objects according to their geometrical properties.
Some blind people have taught themselves echolocation by trial and error. The best-known cases are the Americans Daniel Kish, the only blind person to have been authorized to act as a guide for other blind people, and Ben Underwood, considered to be the world’s best echolocator until he died early this year.
However, no special physical skills are required, say the researchers. “Two hours per day for a couple of weeks are enough to distinguish whether you have an object in front of you, and within another two weeks you can tell the difference between trees and a pavement”, said Martínez. The researchers say they can now detect certain internal structures, such as bones, and even objects inside a bag.
Martínez recommends starting with the ‘sh’ sound used to make someone be quiet. Moving a pen in front of the mouth can be noticed straightaway. The next level is to master the palate clicks.
The scientists recognise that they are still at the very early stages. But, they say, this technique could be very useful not only for the blind, but also for professionals such as firemen or rescue teams, enabling them to find exit points through smoke.
The research is published in the journal Acta Acustica united with Acustica.