Human Echolocation is the ability of humans to use sound echoes to help determine their immediate and nearby surroundings. Using methods such as tapping a cane on the ground, stamping their feet, or making clicking sounds with their mouths they are able to interpret the resulting echoes/reflections to provide them with an internal “map” of their surroundings.
Similar in principle to sonar used by bats, toothed whales and dolphins, reflecting sound waves returning to the ears provide important clues such as proximity, density, shape and size of nearby objects.
Working Mechanics of Human Echolocation
The auditory system processes sound waves as they reflect off surrounding surfaces and enter the ears, much like the visual system with light waves reflecting off objects and into our eyes.
“The auditory system has the amazing ability to detect faint differences in volume, frequency and timing between the left and right ears of incoming reflections. It is these subtle differences that make human echolocation possible.”
With echoes, a blind traveler can perceive specific information from far beyond their immediate surroundings. Echoes provide information about the nature and placement of objects such as walls, doors, stairs, ceilings, overhangs, cars, poles etc. Echoes can then provide further information such as location (proximity), dimension (size and shape), and density (how thick or thin). By interpreting the interrelatedness of these qualities, blind people can perceive much about the nature of their surroundings.
Whether visually impaired or not, all humans (with operational auditory systems) use sound clues to understand their surroundings. Make a noise in a large enclosed space and you can hear the delay in reflections as the sound repeatedly bounces around the room, have a friend yell out your name from a distance and you can fairly easily determine the direction your friend is calling you from. However when it comes to the visually impaired, they seem to have the ability to tap into this phenomenon with much greater ability.
How Echolocation in the Blind is Interpreted in the Brain
Studies using Functional magnetic resonance imaging (fMRI) techniques have shown that parts of the brain associated with visual processing are modified for the new skill of echolocation. This phenomenon is known as cortical remapping, whereby the brain has remapped itself to make use of a section of the brain otherwise reserved for another function. This helps explain why the blind are able better develop their echolocation abilities compared to those with a fully operational visual system.
Further studies suggest that the secret to echolocation isn’t just super sensitive ears. Instead, the entire body, neck and head are key in “seeing” with sound. Humans interpret sound waves not just through their ears, but also through interactions with their upper body. Sound waves are absorbed through the torso, skull, and reflected off the shoulders and into the ears. As each person is of different size and shape, everyone will experience a unique pattern of incoming echoes. Head movements are also important in determining object information. Making slight head adjustments in conjunction with clicking sounds can better help blind echolocation experts sense an object’s contours.
Notable Echolocation Experts
Blind from infancy due to retinal caner, Daniel Kish or otherwise known as “real-life Batman” learnt as a young boy to judge his surroundings by making rapid clicking noises with his mouth and listening for their echoes. Amazingly no one taught him this technique which is now recognised as echolocation. Kish undertakes a variety of everyday activities which many would deem impossible for blind people, including biking and hiking.
Kish now devotes the majority of his time teaching other blind people his technique which he calls FlashSonar. Over 500 students from around the world have taken the course which is run by non-profit organisation, World Access for the Blind. Kish and fellow researchers are developing a range of protocols to allow beginners to start practicing, and improving their echolocation abilities.
Ben Underwood also lost his eyes to cancer at age 3, leaving him with no vision at all. Like Kish, he taught himself to see with sound. Underwood never had a guide dog, never used a cane (unlike Kish), and rarely used his hands to navigate; instead like Kish, he produced clicking sounds using his mouth at regular intervals while listening intently to the resulting echoes. Underwood starred in the documentary “The Boy Who Sees Without Eyes” in 2007, chronicling his life and abilities. Unfortunately Underwood died on January 19, 2009 at the age of 16, from the same cancer that took his vision.
Innovations in Echolocation
Although research remains in early stages, it is easy to foresee future utilisation of virtual reality (VR) technologies to help train blind people on how to use echolocation in the safety of their own home. Such technologies could create programs that help train the various aspects of human echolocation such as object distance, location and size. The trainee would experience different sound reflections determined by their head position, and given verbal instruction through the software on their virtual environment and their task within the exercise. This is could greatly reduce anxiety by participants who fear training in public, while providing them with a decent skill base before utilising the technique in the real world.
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