Blind as a Bat

September 5, 2011

Torah Kachur

Bats are famous for their use echolocation to navigate in the pitch black and, despite the old wives' tale, will not come close to your nicely quaffed mullet.   The premise is simple, bats can emit sounds (like those heard here) over a wide range or within a single frequency and they simply wait for the echo off of a solid object to determine how far and how fast that object is from the bat.



If you want to test your own echolocation abilities - stand in a public place so everyone can watch and laugh at you, yell as loud as you can at a wall that is close and wait for the echo, repeat towards a wall that is further away.  The further the wall, the longer it takes for the sound to get back to you....and the people around you will still have time to point and laugh.

Both bats and some whales use echolocation, or sonar, to fly at night or swim through murky water but can humans use it?  The requirements for successfully 'seeing' the environment using sound includes a tongue and two ears (looking like Christian Bale is sadly not a prereq).  Some blind people have been taught to use echolocation to listen to the echo off the clicks of the tongue and do away with the white cane.  Both early-blind and late-blind can be taught to use echolocation and their brains adapt to the new technique easily by using regions of the brain normally devoted to vision in order to interpret the new sensory information.  In particular, the researchers found that the calcarine sulcus, a region of the brain normally dedicated to vision, is stimulated in both the early blind and late blind participants during echolocation. 


Of course, the human use of echolocation isn't as precise or accurate as that of a bat or whale and becomes considerably more difficult for those blind people ripping up the noisy D floor on a saturday night.  Now, a new device called the Tacit sonar locator will help the blind use the concept of echolocation much more efficiently.  The premise of this device is exceedingly simple - emit ultrasonic pulses off the device and the sensor detects the bounceback and you get a 'picture' of the surroundings.  And it doubles as a hot new fashion accessory.


Using either natural tongue clicks for echolocation or the Tacit takes a bit of practice and is easier for people that are early-blind but requires almost no training and is easily adapted into someone's life.  And it also makes you a bit closer to becoming Batman.


Thaler L, Arnott SR, & Goodale MA (2011). Neural correlates of natural human echolocation in early and late blind echolocation experts. PloS one, 6 (5) PMID: 21633496



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