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The new buzz: Echolocation

india Updated: Feb 17, 2008 21:35 IST
Prakash Chandra

The Biblical phrase, “... And the blind shall see” could soon become a reality — at a mere click of your tongue. Scientists in Britain are using the technique of echolocation to teach visually challenged children to ‘see’ their surroundings by clicking their tongues — much like bats, dolphins and whales do.

Echolocation uses reflected ultra-high frequency sound waves to measure the distance, size and density of objects around a blind person. The louder the echo, the bigger the object. The position is determined by which ear the echo reaches first (if it reaches the right ear first, the object is obviously to the right). A lower-pitched echo indicates a receding object, while a higher pitch shows its movement towards you. You could try this out by putting on a blindfold and asking someone to move, say, a dinner plate in front of your face. Click your tongue, or make any noise: with practice, you’ll be able to tell when the plate is close to you.

In nature, echolocation helps toothed whales and dolphins navigate and feed in deep or murky waters. Since sound travels four-and-a-half times faster in water than in air, the dolphin’s brain is adapted to rapidly analyse the echoes. The echolocating beam is directional, and can be moved with a slight turn of the animal’s head. This enables dolphins to detect a target the size of a golf ball from a football field away. The Sonar (SOund NAvigation And Ranging) system used in ships and submarines works on this principle.

Bats echolocate by sending out ultrasonic squeaks up to 200,000 times per second from their noses. These bounce off insects or branches and are picked up by the bat’s sensitive ears. The echoes describe the landscape, the prey, and its movement. Research proves that humans adapt very well to the bat’s echolocation system. So next up could be navigation devices that emit ultrasonic bat-like calls and convert the echoes into sounds that can be heard by blind people using the device.