Human echolocation

Human echolocation

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Human echolocation is the ability of humans to detect objects in their environment by sensing echoes from those objects. By actively creating sounds – for example, by tapping their canes
White cane
A white cane is used by many people who are blind or visually impaired, both as a mobility tool and as a courtesy to others. Not all modern white canes are designed to fulfill the same primary function, however: There are at least five varieties of this tool, each serving a slightly different...

, lightly stomping their foot or making clicking noises with their mouths – people trained to orientate with echolocation can interpret the sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 waves reflected by nearby objects, accurately identifying their location and size. This ability is used by some blind
Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness...

 people for acoustic wayfinding
Acoustic wayfinding
Acoustic wayfinding is the practice of using the auditory system to orient oneself and navigate physical space. It is commonly used by the visually impaired, allowing them to retain their mobility without relying on visual cues from their environment....

, or navigating within their environment using auditory rather than visual cues. It is similar in principle to active sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 and to the animal echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...

 employed by some animals, including bats and dolphins.


Human echolocation has been known and formally studied since at least the 1950s. In earlier times, human echolocation was sometimes described as "facial vision". The field of human and animal echolocation was surveyed in book form as early as 1959. See also White, et al., (1970)


Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

 and hearing
Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...

 are closely related in that they can process reflected waves of energy. Vision processes light waves as they travel from their source, bounce off surfaces throughout the environment and enter the eyes. Similarly, the auditory system processes sound waves as they travel from their source, bounce off surfaces and enter the ears. Both systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that they receive. In the case of sound, these waves of reflected energy are called "echoes
Echo (phenomenon)
In audio signal processing and acoustics, an echo is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single...


Echoes and other sounds can convey spatial information that is comparable in many respects to that conveyed by light. With echoes, a blind traveler can perceive very complex, detailed, and specific information from distances far beyond the reach of the longest cane or arm. Echoes make information available about the nature and arrangement of objects and environmental features such as overhangs, walls, doorways and recesses, poles, ascending curbs and steps, planter boxes, pedestrians, fire hydrants, parked or moving vehicles, trees and other foliage, and much more. Echoes can give detailed information about location (where objects are), dimension (how big they are and their general shape), and density (how solid they are). Location is generally broken down into distance from the observer and direction (left/right, front/back, high/low). Dimension refers to the object's height (tall or short) and breadth (wide or narrow).

By understanding the interrelationships of these qualities, much can be perceived about the nature of an object or multiple objects. For example, an object that is tall and narrow may be recognized quickly as a pole. An object that is tall and narrow near the bottom while broad near the top would be a tree. Something that is tall and very broad registers as a wall or building. Something that is broad and tall in the middle, while being shorter at either end may be identified as a parked car. An object that is low and broad may be a planter, retaining wall, or curb. And finally, something that starts out close and very low but recedes into the distance as it gets higher is a set of steps. Density refers to the solidity of the object (solid/sparse, hard/soft). Awareness of density adds richness and complexity to one's available information. For instance, an object that is low and solid may be recognized as a table, while something low and sparse sounds like a bush; but an object that is tall and broad and very sparse is probably a fence.

- "Echolocating Distance by Moving and Stationary Listeners", Lawrence D. Rosenblum, Michael S. Gordon and Luis Jarquin‌, in Ecological Psychology, 2000, Vol. 12, No. 3, pages 181-206.

- "Evaluation of an echo-Mobility training program for Young blind people", Daniel Kish, Master Thesis. 1982, University of Southern California.

Notable individuals who employ echolocation

Daniel Kish

Echolocation has been further developed by Daniel Kish
Daniel Kish
Daniel Kish is an American expert in human echolocation and President of World Access for the Blind, a non-profit founded in 2000 to facilitate "the self-directed achievement of people with all forms of blindness" and increase public awareness about their strengths and capabilities, which has...

, who works with the blind, leading blind teenagers hiking and mountain-biking through the wilderness and teaching them how to navigate new locations safely, through the non-profit organization World Access for The Blind. Kish had his eyes removed at the age of 13 months due to retinal cancer
Retinoblastoma is a rapidly developing cancer that develops in the cells of retina, the light-detecting tissue of the eye. In the developed world, Rb has one of the best cure rates of all childhood cancers , with more than nine out of every ten sufferers surviving into...

. He has developed a click-emitting device and trains other blind people in the use of echolocation and in what he calls "Perceptual Mobility".

Though at first resistant to using a cane for mobility, seeing it as a "handi-capped" device, and considering himself "not handicapped at all", Daniel Kish developed a technique using his white cane combined with echolocation to further expand his mobility.

Ben Underwood

Diagnosed with retinal cancer at the age of two, American Ben Underwood had his eyes removed at the age of three.

He discovered echolocation at the age of five. He was able to detect the location of objects by making frequent clicking noises with his tongue. This case was explained in 20/20:medical mysteries. He used it to accomplish such feats as running, playing basketball, rollerblading, playing foosball, and skateboarding.

Underwood died on January 19, 2009 at the age of 16, from the same cancer that took his vision.

Tom De Witte

Tom De Witte was born in 1979 in Belgium with bilateral congenital glaucoma
Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...

 in both eyes. It had seemed that De Witte would become a successful flautist until he had to give up playing music in 2005. De Witte has been completely blind since 2009 due to additional problems with his eyes.

He was taught echolocation by Daniel Kish and was given the nickname "Batman from Belgium" by the press.

Dr. Lawrence Scadden

Dr. Scadden has written of his experiences with blindness. He was not born blind, but lost his sight due to illness. As a child, he learned to use facial vision well enough to ride a bicycle in traffic. (His parents thought that he still had some sight remaining.) He later participated in experiments in facial vision (White, et al. 1970). About 1998, he visited the Auditory Neuroethology Laboratory at the University of Maryland and was interviewed about his experience with facial vision. The researchers in the lab study bat echolocation and were aware of the Wiederorientierung phenomenon described by Griffin (1959), where bats, despite continuing to emit echolocation calls, use dead reckoning in familiar acoustic space. Dr. Scadden indicated that he found echolocation effortful, and would not use it to navigate in familiar areas unless he were alert for obstacles, thus providing insight into the bat behavior.

The Regional Alliance of Science, Engineering and Mathematics for Students with Disabilities (RASEM) and the Science Education for Students With Disabilities (SESD), a Special Interest Group of the National Science Teachers Association (NSTA) have created the Lawrence A. Scadden Outstanding Teacher Award of the Year for Students With Disabilities in his honor.

Lucas Murray

Lucas Murray
Lucas Murray
Lucas Murray , from Poole, Dorset, was born blind, but is one of the first British people to learn to visualise his surroundings using a technique similar to bats and dolphins, called echolocation. By the echo caused by clicking his tongue on the roof of his mouth, Murray can identify how close...

, from Poole, Dorset, was born blind. He is believed to be one of the first British people to learn to visualise his surroundings using echolocation, and was taught by Daniel Kish.

Kevin Warwick

In this experimentation, the scientist, Kevin Warwick
Kevin Warwick
Kevin Warwick is a British scientist and professor of cybernetics at the University of Reading, Reading, Berkshire, United Kingdom...

 fed in ultrasonic pulses, as an extra sensory input, via a neural implant, through electrical stimulation. In tests he was able to accurately discern distance to objects and to detect small movements of those objects.

See also

  • Animal echolocation
    Animal echolocation
    Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...

  • Acoustic location
    Acoustic location
    Acoustic location is the science of using sound to determine the distance and direction of something. Location can be done actively or passively, and can take place in gases , liquids , and in solids .* Active acoustic location involves the creation of sound in order to produce an echo, which is...

  • Sensory substitution
    Sensory substitution
    Sensory substitution means to transform the characteristics of one sensory modality into stimuli of another sensory modality. It is hoped that sensory substitution systems can help handicapped people by restoring their ability to perceive a certain defective sensory modality by using sensory...

  • Daredevil
    Daredevil (Marvel Comics)
    Daredevil is a fictional character, a superhero in comic books published by Marvel Comics. The character was created by writer-editor Stan Lee and artist Bill Everett, with an unspecified amount of input from Jack Kirby, and first appeared in Daredevil #1 .Living in the Hell's Kitchen neighborhood...

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