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{{short description|Human ability to detect surroundings using sounds}}
'''Human echolocation''' is the ability of humans to detect objects in their environment by sensing echoes from those objects. This ability is used by some [[blindness|blind]] people to navigate within their environment. They actively create sounds, such as by tapping their [[white cane|canes]], lightly stomping their foot or by making clicking noises with their mouths. It can however also be fed in to the human nervous system as a new sensory experience. Human echolocation is similar in principle to active [[sonar]] and to the [[animal echolocation]] employed by some animals, including bats and dolphins.
'''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 [[white cane|canes]], lightly stomping their foot, snapping their fingers, or making clicking noises with their mouths. People trained to orient by echolocation can interpret the [[sound]] waves reflected by nearby objects, accurately identifying their location and size.

By interpreting the [[sound]] waves reflected by nearby objects, a person trained to orientate with echolocation can accurately identify the location and sometimes size of nearby objects and not only use this information to steer around obstacles and travel from place to place, but also detect small movements relative to objects.

However, in the case of human clicking, since humans make sounds with much lower frequencies and slower click rates, such human echolocation can only picture much larger objects than can other echolocating animals.


==Background==
==Background==
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{{see also|Animal echolocation}}
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The term "echolocation" was coined by zoologist Donald Griffin in 1944. But the phenomena was known about earlier, for example, [[Denis Diderot]] reported in 1749 that blind people could locate silent objects.<ref name=":0">{{Cite journal |last1=Kolarik |first1=Andrew J. |last2=Cirstea |first2=Silvia |last3=Pardhan |first3=Shahina |author-link3=Shahina Pardhan |last4=Moore |first4=Brian C. J. |date=2014-04-01 |title=A summary of research investigating echolocation abilities of blind and sighted humans |url=https://zenodo.org/record/853235 |journal=Hearing Research |volume=310 |pages=60–68 |doi=10.1016/j.heares.2014.01.010 |pmid=24524865 |s2cid=21785505}}</ref> Human echolocation has been known and formally studied since at least the 1950s.<ref>Richard L. Welsh, Bruce B. Blasch, ''[https://books.google.com/books?id=HezicsYdVysC&pg=PA150 online Foundations of Orientation and Mobility]'', American Foundation for the Blind, 1997; which cites S. O. Myers and C. G. E. G. Jones, "Obstable experiments: second report", ''Teacher for the Blind'' 46, 47–62, 1958.</ref> In earlier times, human echolocation was sometimes described as "facial vision" or "obstacle sense", as it was believed that the proximity of nearby objects caused pressure changes on the skin.<ref>Raymond J Corsini, ''The Dictionary of Psychology'', Psychology Press (UK), 1999, {{ISBN|1-58391-028-X}}.</ref><ref>M. Supa, M. Cotzin, and K. M. Dallenbach. ''[https://www.jstor.org/pss/1416946 "Facial Vision" - The Perception of Obstacles by the Blind].'' The American Journal of Psychology, April 1944.</ref><ref>Cotzin and Dallenbach. ''[https://www.jstor.org/pss/1418868 "Facial Vision": The Role of Pitch and Loudness in the Location of Obstacles by the Blind].'' The American Journal of Psychology, October 1950.</ref> Only in the 1940s did a series of experiments performed in the Cornell Psychological Laboratory show that sound and hearing, rather than pressure changes on the skin, were the mechanisms driving this ability.<ref name=":0" /> The field of human and animal echolocation was surveyed in book form as early as 1959<ref name=Griffin59>Griffin, Donald R., ''Echos of Bats and Men,'' Anchor Press, 1959 (Science and Study Series, Seeing With Sound Waves)</ref> (see also White, et al. (1970)<ref name=White70>White, J. C., Saunders, F. A., Scadden, L., Bach-y-Rita, P., & Collins, C. C. (1970). Seeing with the skin. Perception & Psychophysics, 7, 23-27.</ref>).


Many blind individuals passively use natural environmental echoes to sense details about their environment; however, others actively produce mouth clicks and are able to gauge information about their environment using the echoes from those clicks.<ref>{{Cite journal|url=http://www.psychologicalscience.org/index.php/publications/observer/2015/december-15/using-sound-to-get-around.html|title=Using Sound to Get Around - Association for Psychological Science|issue=10|journal=Aps Observer|volume=28|access-date=2016-04-22|date=2015-11-25|last1=Thaler|first1=Lore}}</ref> Both passive and active echolocation help blind individuals sense their environments.
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Human echolocation has been known and formally studied since at least the 1950s.<ref>Richard L. Welsh, Bruce B. Blasch, ''[http://books.google.com/books?vid=ISBN0891289461&id=HezicsYdVysC&pg=PA150&lpg=PA150&dq=echolocation+cane&sig=gqPdcmdlQzGTniUQ6PhHgrF_A2Y online Foundations of Orientation and Mobility]'', American Foundation for the Blind, 1997; which cites S. O. Myers and C. G. E. G. Jones, "Obstable experiments: second report", ''Teacher for the Blind'' 46, 47–62, 1958.</ref> In earlier times, human echolocation was sometimes described as "facial vision".<ref>Raymond J Corsini, ''The Dictionary of Psychology'', Psychology Press (UK), 1999, ISBN 1-58391-028-X.</ref><ref>M. Supa, M. Cotzin, and K. M. Dallenbach. ''[http://www.jstor.org/pss/1416946 "Facial Vision" - The Perception of Obstacles by the Blind].'' The American Journal of Psychology, April 1944.</ref><ref>Cotzin and Dallenbach. ''[http://www.jstor.org/pss/1418868 "Facial Vision": The Role of Pitch and Loudness in the Location of Obstacles by the Blind].'' The American Journal of Psychology, October 1950.</ref> The field of human and animal echolocation was surveyed in book form as early as 1959.<ref>Griffin, Donald R., ''Echos of Bats and Men,'' Anchor Press, 1959 (Science and Study Series, Seeing With Sound Waves)</ref> See also White, et al., (1970)<ref>White, J. C., Saunders, F. A., Scadden, L., Bach-y-Rita, P., & Collins, C. C. (1970). Seeing with the skin. Perception & Psychophysics, 7, 23-27.</ref>


Those who can see their environments often do not readily perceive echoes from nearby objects, due to an echo suppression phenomenon brought on by the [[precedence effect]]. However, with training, sighted individuals with normal hearing can learn to avoid obstacles using only sound, showing that echolocation is a general human ability.<ref name=":1">{{Cite journal|last1=Wallmeier|first1=Ludwig|last2=Geßele|first2=Nikodemus|last3=Wiegrebe|first3=Lutz|date=2013-10-22|title=Echolocation versus echo suppression in humans|journal=Proceedings of the Royal Society of London B: Biological Sciences|language=en|volume=280|issue=1769|pages=20131428|doi=10.1098/rspb.2013.1428|issn=0962-8452|pmc=3768302|pmid=23986105}}</ref>
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== Mechanics ==
{{No footnotes|date=October 2008}}


Lore Thaler led researchers at [[Durham University]] to determine if they could teach echolocation to people. Over a ten-week period, they taught it to 12 blind people and 14 others who were not blind.<ref>{{Cite web |last=Machemer |first=Theresa |title=People Can Learn Echolocation in Ten Weeks |date=June 4, 2021 |url=https://www.smithsonianmag.com/smart-news/study-shows-people-can-learn-echolocation-ten-weeks-180977889/ |access-date=2023-06-06 |website=Smithsonian Magazine |language=en}}</ref>
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[[Visual perception|Vision]] and [[hearing (sense)|hearing]] 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.{{Clarify|date=October 2010|reason=needs better way to express idea without misleading mention of "energy"}} In the case of sound, these waves of reflected energy are called "[[Echo (phenomenon)|echoes]]".


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==Mechanics==
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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).
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[[Visual perception|Vision]] and [[hearing (sense)|hearing]] are akin in that each entails detection of reflected waves of energy. Vision processes light waves that 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 neural systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that their sense organs receive. In the case of sound these waves of reflected energy are referred to as [[Echo (phenomenon)|echoes]].


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Echoes and other sounds can convey spatial data that are comparable in many respects to those conveyed by light.<ref name=Rosenblum2000>{{cite journal |journal=Ecol. Psychol. |year=2000 |volume=12 |issue=3 |pages=181–206 |title=Echolocating distance by moving and stationary listeners|vauthors=Rosenblum LD, Gordon MS, Jarquin L |doi=10.1207/S15326969ECO1203_1|citeseerx=10.1.1.540.5965 |s2cid=30936808 }}</ref> A blind traveler using echoes can perceive very complex, detailed, and specific features of the world from distances far beyond the reach of the longest cane or arm. Echoes can 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).
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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.


⚫
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.<ref name=Kish2000>{{cite thesis|year=1982|title=Evaluation of an echo-mobility training program for young blind people: Master's Thesis, University of Southern California |author=Kish D.}}</ref>
- "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.


===Brain areas associated with echolocation===
- "Evaluation of an echo-Mobility training program for Young blind people", Daniel Kish, Master Thesis. 1982, University of Southern California.
[[Image:Brain image of blind echolocator.tif|thumb|right|400px|Echo-related activity in the brain of an early-blind, trained echolocator is shown on the left. There is no activity evident in the brain of a sighted person not so trained (shown on the right) listening to the same echoes]] Some blind people are skilled at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes. Although few studies have been performed on the neural basis of human echolocation, those studies report activation of [[primary visual cortex]] during echolocation in blind expert echolocators.<ref name=":0" /><ref name="Thaler2011">{{cite journal|year=2011|title=Neural correlates of natural human echolocation in early and late blind echolocation experts|journal=PLOS ONE|volume=6|issue=5|pages=e20162|bibcode=2011PLoSO...620162T|doi=10.1371/journal.pone.0020162|pmc=3102086|pmid=21633496|vauthors=Thaler L, Arnott SR, Goodale MA |doi-access=free}}</ref><ref name="Reader">{{citation|title=Bat Man|date=June 2012|url=http://www.uwo.ca/bmi/news/bmi_news/bat_man.html|publisher=Reader's Digest|access-date=March 14, 2014|archive-date=March 15, 2014|archive-url=https://web.archive.org/web/20140315184642/http://www.uwo.ca/bmi/news/bmi_news/bat_man.html|url-status=dead}}</ref> The driving mechanism of this brain region remapping phenomenon is known as [[neuroplasticity]].


In a 2014 study by Thaler and colleagues,<ref>Thaler, L., Milne, J. L., Arnott, S. R., Kish, D., & Goodale, M. A. (2014). Neural correlates of motion processing through echolocation, source hearing, and vision in blind echolocation experts and sighted echolocation novices. Journal of Neurophysiology, 111(1), 112-127.</ref> the researchers first made recordings of the clicks and their very faint echoes using tiny microphones placed in the ears of the blind echolocators as they stood outside and tried to identify different objects such as a car, a flag pole, and a tree. The researchers then played the recorded sounds back to the echolocators while their brain activity was being measured using [[functional magnetic resonance imaging]]. Remarkably, when the echolocation recordings were played back to the blind experts, not only did they perceive the objects based on the echoes, but they also showed activity in those areas of their brain that normally process visual information in sighted people, primarily the [[primary visual cortex]] or V1. This result is surprising, as visual areas are normally only active during visual tasks. The brain areas that process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed. Importantly, when the same experiment was carried out with sighted people who did not echolocate, these individuals could not perceive the objects and there was no echo-related activity anywhere in the brain. This suggests that the cortex of blind echolocators is plastic and reorganizes such that primary visual cortex, rather than any auditory area, becomes involved in the computation of echolocation tasks.
==Notable individuals who employ echolocation==


Despite this evidence, the extent to which activation in the visual cortex in blind echolocators contributes to echolocation abilities is unclear.<ref name=":1" /> As previously mentioned, sighted individuals have the ability to echolocate; however, they do not show comparable activation in visual cortex. This would suggest that sighted individuals use areas beyond visual cortex for echolocation.
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[[Image:Ben underwood.jpg|thumb|right|Ben Underwood]]


===James Holman===
==Notable cases==

One of the earliest documented cases of echolocation was "the blind traveler" [[James Holman]] (1786–1857), who used the sound of a tapping cane to travel the world. Journalist William Jerdan wrote, "From [[Marco Polo]] to [[Mungo Park (explorer)|Mungo Park]], no three of the most famous travelers, grouped together, would exceed the extent and variety of countries traversed by our blind countryman."{{Citation needed|date=November 2009}}


===Daniel Kish===
===Daniel Kish===
{{main|Daniel Kish}}
Echolocation has been further developed by Daniel Kish, who works with the blind through the non-profit organization [[World Access for the Blind]].<ref>{{cite web|url=http://www.worldaccessfortheblind.org/|title=World Access Online}}</ref> He leads blind teenagers hiking and mountain-biking through the wilderness, and teaches them how to navigate new locations safely, with a technique that he calls "FlashSonar".<ref name=BBC/> Kish had his eyes removed at the age of 13 months due to [[retinoblastoma|retinal cancer]]. He learned to make [[palatal click]]s with his tongue when he was still a child, and now trains other blind people in the use of echolocation and in what he calls "Perceptual Mobility".<ref name=autogenerated1>{{citation|last=Kish|first=Daniel|year=1995|title=Evaluation of an Echo-Mobility Program for Young Blind People|version=Master's thesis|location=San Bernardino, CA|publisher=Department of Psychology, California State University|page=277|url=http://worldaccessfortheblind.org/thesis.txt|archive-url=https://web.archive.org/web/20020202195520/http://worldaccessfortheblind.org/thesis.txt|archive-date=February 2, 2002}}</ref> Though at first resistant to using a cane for mobility, seeing it as a "handicapped" device, and considering himself "not handicapped at all", Kish developed a technique using his white cane combined with echolocation to further expand his mobility.<ref name=autogenerated1 />


Kish reports that "The sense of imagery is very rich for an experienced user. One can get a sense of beauty or starkness or whatever—from sound as well as echo."<ref name=BBC>{{cite web | url=https://www.bbc.co.uk/news/magazine-19524962 | title=Human echolocation: Using tongue-clicks to navigate the world | publisher=BBC | date=12 September 2012 | access-date=September 12, 2012 | author=Kremer, William}}</ref> He is able to distinguish a metal fence from a wooden one by the information returned by the echoes on the arrangement of the fence structures; in extremely quiet conditions, he can also hear the warmer and duller quality of the echoes from wood compared to metal.<ref name=BBC/>
Echolocation has been further developed by Daniel Kish, 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 [http://www.worldaccessfortheblind.org World Access for The Blind].<ref>[http://www.worldaccessfortheblind.org/ World Access for the Blind<!-- Bot generated title -->]</ref> Kish had his eyes removed at the age of 13 months due to retinal cancer.<ref>Interview with him on Derren Brown; how to be a psychic spy</ref> He has developed a click-emitting device and trains other blind people in the use of echolocation and in what he calls "Perceptual Mobility".<ref>[http://www.youtube.com/watch?v=3Px-aPnk4ZU YouTube - Extraordinary People - The boy who sees without eyes [4/5&#93;<!-- Bot generated title -->]</ref><ref name=autogenerated3>[http://www.youtube.com/watch?v=uobuBc2GO0o YouTube - Dan Kish using and explaining Echolocation<!-- Bot generated title -->]</ref><ref name=autogenerated1>http://www.worldaccessfortheblind.org/docs/der_spiegel-en.txt</ref>


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===Thomas Tajo===
<ref name=autogenerated1 /><ref name="
Thomas Tajo was born in the remote Himalayan village of [[Chayangtajo]] in the state of [[Arunachal Pradesh]] in the north-east India. He became blind around the age of 7 or 8 due to optic nerve atrophy and taught himself to echolocate. Today he lives in Belgium and works with Visioneers or World Access to impart independent navigational skills to blind individuals across the world. Tajo is also an independent researcher. He researches the cultural and biological evolutionary history of the senses and presents his findings to scientific conferences around the world.<ref>{{Cite web |date=2017-11-20 |title=Thomas Tajo |url=https://visioneers.org/thomas-tajo/ |access-date=2023-01-22 |website=Visioneers.org |language=en-US}}</ref>
autogenerated3" /><ref name=autogenerated2>[http://www.youtube.com/watch?v=MNkJ1diTxOE YouTube - Extraordinary People - The boy who sees without eyes [5/5&#93;<!-- Bot generated title -->]</ref>


===Ben Underwood===
===Ben Underwood===
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[[File:Ben underwood.jpg|thumb|right|Ben Underwood]]
Ben Underwood was a blind American who was born on January 26, 1992, in [[Riverside, California]]. He was diagnosed with [[retinal cancer]] at the age of two, and had his eyes removed at the age of three.<ref>morgan isdell aleks petcova even white thomas cian
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[https://abcnews.go.com/Primetime/story?id=2283048&page=1 Humans With Amazing Senses] — ABC News.</ref>


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He taught himself echolocation at the age of five, becoming able to detect the location of objects by making frequent clicking noises with his tongue. This case was explained in ''20/20: Medical Mysteries''.<ref>{{cite news | url = https://www.theguardian.com/family/story/0,,1999283,00.html | location=London | work=The Guardian | first=Joanna | last=Moorhead | title=Seeing with sound | date=January 27, 2007}}</ref> He used it to accomplish such feats as running, playing basketball, riding a bicycle, rollerblading, playing football, and skateboarding.<ref>{{cite news | url = https://www.cbsnews.com/news/how-a-blind-teen-sees-with-sound/ | work=CBS News | title=How A Blind Teen 'Sees' With Sound | date=July 19, 2006}}</ref><ref>[https://people.com/archive/the-boy-who-sees-with-sound-vol-66-no-4/ The Boy Who Sees with Sound] — People Magazine</ref> Underwood's childhood eye doctor claimed that Underwood was one of the most proficient human echolocators.
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Diagnosed with [[retinal cancer]] at the age of two, American Ben Underwood had his eyes removed at the age of three.<ref>[http://abcnews.go.com/Primetime/story?id=2283048&page=1 Humans With Amazing Senses] — ABC News.</ref>


He inspired other blind people to follow his lead. He died of cancer in 2009.
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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''.<ref>{{cite news | url = http://www.guardian.co.uk/family/story/0,,1999283,00.html | location=London | work=The Guardian | first=Joanna | last=Moorhead | title=Seeing with sound | date=January 27, 2007}}</ref> He used it to accomplish such feats as running, playing basketball, rollerblading, playing [[foosball]], and skateboarding.<ref>{{cite news | url = http://www.cbsnews.com/stories/2006/07/19/earlyshow/main1817689.shtml | work=CBS News | title=How A Blind Teen 'Sees' With Sound | date=July 19, 2006}}</ref><ref>[http://www.people.com/people/article/0,26334,1212568,00.html The Boy Who Sees with Sound] — People magazine</ref>


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===Lawrence Scadden===
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 demonstrated to Underwood how he used his white cane combined with echolocation to further expand his mobility, though Underwood never adopted this method.<ref name=autogenerated2 />


Lawrence Scadden lost his sight as a child due to illness, but learned to use echolocation well enough to ride a bicycle in traffic. (His parents thought that he still had some sight remaining.)<ref>[https://www.amazon.com/Surpassing-Expectations-Life-without-Sight/dp/1425797229/ ''Surpassing Expectations: Life Without Sight''] Scadden, Lawrence]</ref> In 1998, he was interviewed at the Auditory Neuroethology Laboratory at the [[University of Maryland]] about his experience with echolocation.<ref name=White70/> The researchers were aware of the ''Wiederorientierung'' phenomenon described by Griffin<ref name=Griffin59/> where bats, despite continuing to emit echolocation calls, use [[path integration]] in familiar acoustic space. Scadden said he did the same, as echolocation required extra effort.
Underwood died on January 19, 2009 at the age of 16, from the same cancer that took his vision.<ref>[http://www.benunderwood.com/index.html] Ben Underwood Website</ref>


The National Science Teachers Association created the "Lawrence A. Scadden Outstanding Teacher Award of the Year for Students With Disabilities" in his honor.<ref>{{Cite web |title=Recognizing excellence—The Lawrence Scadden Teacher of the Year Award {{!}} NSTA |url=https://www.nsta.org/blog/recognizing-excellence-lawrence-scadden-teacher-year-award |access-date=2023-09-21 |website=www.nsta.org |language=en}}</ref>
===Tom De Witte===


===Lucas Murray===
Tom De Witte was born in 1979 in Belgium with [[wikt:bilateral|bilateral]] [[congenital]] [[glaucoma]] 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.
'''Lucas Murray''', from [[Poole, Dorset]], was born blind, and is one of the first British people to have learned human echolocation, having learned it from [[Daniel Kish]].<ref name="echo">{{Cite news|url=http://www.bournemouthecho.co.uk/news/4666030.Lucas_learns_echo_technique_to____see___/|title=Lucas learns echo technique to 'see'|date=7 October 2009|publisher=Daily Echo|access-date=8 October 2009}}</ref> Lucas' parents saw a documentary about Daniel Kish teaching Ben Underwood echolocation.<ref>{{Cite web|url=http://www.benunderwood.com/|title=Ben Underwood &#124; Blind Boy Who Could See}}</ref><ref name="BBC2">{{Cite news|url=http://news.bbc.co.uk/1/hi/england/dorset/8291573.stm|title=Blind boy uses his ears to 'see' |date=5 October 2009|work=BBC News|access-date=8 October 2009}}</ref> Months later, they learned that Daniel would be visiting a Scottish charity called Visibility<ref>{{Cite web|url=https://visibilityscotland.org.uk/|title=Visibility Scotland - Listening and responding to people affected by sight loss across Scotland|website=Visibility Scotland}}</ref> and contacted him. Kish taught the five-year-old Lucas the basics of echolocation over four days. By age seven, Lucas was proficient enough to not only accurately tell the distance of objects, but also their material, and could play with other children in sports such as rock climbing and basketball.<ref name="telegraph">{{Cite news |last=Irvine |first=Chris |date=5 October 2009 |title=Seven year old blind boy uses echoes to see |work=The Daily Telegraph |location=London |url=https://www.telegraph.co.uk/news/uknews/6260515/Seven-year-old-blind-boy-uses-echoes-to-see.html |access-date=8 October 2009}}</ref><ref>{{Cite web|url=https://www.rnib.org.uk/who-we-are/action-for-blind-people|title=Action for Blind People merged with RNIB|date=23 March 2017|website=RNIB - See differently}}</ref> In 2019, he enjoyed a week's [[work experience]] with [[South Western Railway (train operating company)|South Western Railway]].<ref name="cartlidge">{{cite news |last1=Cartlidge |first1=Sarah |title="The best work experience ever": Blind teenager enjoys "phenomenal" placement |url=https://www.bournemouthecho.co.uk/news/17649733.the-best-work-experience-ever-blind-teenager-enjoys-phenomenal-placement/ |access-date=28 May 2020 |work=Bournemouth Echo |date=19 May 2019 |language=en}}</ref>


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


The scientist [[Kevin Warwick]] experimented with feeding ultrasonic pulses into the brain (via electrical stimulation from a neural implant) as an additional sensory input. In tests he was able to discern distance to objects accurately and to detect small movements of those objects.<ref>Warwick K, Hutt B, [[Mark Gasson|Gasson M]], and Goodhew I. "An attempt to extend human sensory capabilities by means of implant technology". ''Proc. IEEE International Conference on Systems, Man. and Cybernetics - Hawaii'' October 2005. pp.1663-1668</ref>
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===Dr. Lawrence Scadden===


===Juan Ruiz===
Dr. Scadden has written of his experiences with blindness.<ref>[http://www.amazon.com/Surpassing-Expectations-Life-without-Sight/dp/1425797229/ Scadden, Lawrence]</ref> 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.


Blind from birth, Juan Ruiz lives in Los Angeles, California. He appeared in the first episode of ''[[Stan Lee's Superhumans]]'', titled "Electro Man". The episode showed him capable of riding a bicycle, avoiding parked cars and other obstacles, and identifying nearby objects. He entered and exited a cave, where he determined its length and other features.{{citation needed|date=January 2013}}<!-- The whole section -->
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===
==In popular media==
The 2017 video game ''[[Perception (video game)|Perception]]'' places the player in the role of a blind woman who must use echolocation to navigate the environment.<ref name=perception>{{cite web |last=Skrebels |first=Joe |date=May 25, 2017 |url=http://www.ign.com/articles/2017/05/25/perception-review |title=Perception Review |publisher=[[IGN]] |access-date=May 25, 2017}}</ref>


In the 2012 film ''[[Imagine (2012 film)|Imagine]]'', the main character teaches echolocation to students at a clinic for the visually impaired. This unconventional method spurs a controversy but helps students explore the world.<ref name=imagine>{{cite news|last1=Grierson|first1=Tim|title=Imagine|url=http://www.screendaily.com/reviews/the-latest/imagine/5046312.article|access-date=June 21, 2017|work=ScreenDaily}}</ref>
[[Lucas Murray]], 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.


In the 2007 children's fantasy novel ''[[Gregor and the Code of Claw]]'', protagonist Gregor learns echolocation. This skill proves useful for fighting in the Underland, an underground civilization which is the main setting of the book.<ref>{{Cite book |last=Collins |first=Suzanne |url=https://www.worldcat.org/oclc/74568049 |title=Gregor and the Code of Claw |date=2007 |isbn=978-0-439-79143-4 |edition=1st |location=New York |oclc=74568049}}</ref>
⚫
===Juan Ruiz===

Stan Lee's Superhumans
The Marvel character [[Daredevil (Marvel Comics character)|Daredevil]] is a superhero who uses his heightened senses paired with echolocation to perceive the world in extraordinary detail.<ref>{{Cite web |title=Daredevil (Matt Murdock) On Screen Powers, Enemies, History {{!}} Marvel |url=https://www.marvel.com/characters/daredevil-matthew-murdock/on-screen |access-date=2024-04-18 |website=www.marvel.com}}</ref>
<ref>http://www.history.com/shows/stan-lees-superhumans/bios/radar</ref> Blind from birth, Juan Ruiz–much like Daredevil–visualizes the world through a form of sonar that resembles echolocation, a technique used by bats and dolphins.


==See also==
==See also==
⚫
*[[Animal echolocation]]
*[[Acoustic location]]
*[[Acoustic location]]
*[[Sensory substitution]]
*[[Sensory substitution]]
*''[[Thaandavam]]'', a [[Tamil language|Tamil]] film involving human echolocation
*[[Daredevil (Marvel Comics)|Daredevil]]


==References==
==References==
{{reflist}}
{{reflist|33em}}
⚫
[http://adsence.kiev.ua/2009/10/22/ben-underwood-ekstraordinanaya-lichnost/ Ben Underwood]


== External links ==
==External links==
* [http://www.newscientist.com/article/mg20227031.400-how-to-see-with-sound.html?full=true How to see with sound] Article by Daniel Kish in the [[New Scientist]]
* [https://web.archive.org/web/20121018154104/https://www.newscientist.com/article/mg20227031.400-how-to-see-with-sound.html?full=true How to see with sound] Article by Daniel Kish in the [[New Scientist]]
* [http://www.hcs.harvard.edu/~husn/BRAIN/vol1/echo.html Harvard historical study and bibliography]
* [https://web.archive.org/web/20070112221744/http://www.hcs.harvard.edu/~husn/BRAIN/vol1/echo.html Harvard historical study and bibliography]
⚫
* [https://web.archive.org/web/20110811043212/http://adsence.kiev.ua/2009/10/22/ben-underwood-ekstraordinanaya-lichnost/ Ben Underwood]
* [http://www.seeingwithsound.com/voicefr1.htm Seeing with Sound project]
* [http://www.seeingwithsound.com/voicefr1.htm Seeing with Sound project]
* [http://www.mensjournal.com/the-blind-man-who-taught-himself-to-see The Blind Man Who Taught Himself To See] Men's Journal
* [https://web.archive.org/web/20121122060244/http://www.uwo.ca/its/brain/ReadersDigest_BatManStory.html Bat Man] Reader's Digest
* [http://www.humanecholocation.com Human Echolocation] {{Webarchive|url=https://web.archive.org/web/20140823101958/http://www.humanecholocation.com/ |date=2014-08-23 }} - Learn to See with your Ears - Free audio lesson for learning to click.
* [http://www.thisamericanlife.org/radio-archives/episode/544/batman This American Life: Batman] (audio)


{{DEFAULTSORT:Human Echolocation}}
{{DEFAULTSORT:Human Echolocation}}
[[Category:Blindness]]
[[Category:Blindness]]
[[Category:Listening]]
[[Category:Sonar]]
[[Category:Sonar]]

[[de:Menschliche Echoortung]]
[[fr:Écholocation humaine]]
[[hi:मानव एचोलोकातिओं]]

Latest revision as of 17:22, 31 October 2024

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, lightly stomping their foot, snapping their fingers, or making clicking noises with their mouths. People trained to orient by echolocation can interpret the sound waves reflected by nearby objects, accurately identifying their location and size.

Background

[edit]
See also: Animal echolocation

The term "echolocation" was coined by zoologist Donald Griffin in 1944. But the phenomena was known about earlier, for example, Denis Diderot reported in 1749 that blind people could locate silent objects.[1] Human echolocation has been known and formally studied since at least the 1950s.[2] In earlier times, human echolocation was sometimes described as "facial vision" or "obstacle sense", as it was believed that the proximity of nearby objects caused pressure changes on the skin.[3][4][5] Only in the 1940s did a series of experiments performed in the Cornell Psychological Laboratory show that sound and hearing, rather than pressure changes on the skin, were the mechanisms driving this ability.[1] The field of human and animal echolocation was surveyed in book form as early as 1959[6] (see also White, et al. (1970)[7]).

Many blind individuals passively use natural environmental echoes to sense details about their environment; however, others actively produce mouth clicks and are able to gauge information about their environment using the echoes from those clicks.[8] Both passive and active echolocation help blind individuals sense their environments.

Those who can see their environments often do not readily perceive echoes from nearby objects, due to an echo suppression phenomenon brought on by the precedence effect. However, with training, sighted individuals with normal hearing can learn to avoid obstacles using only sound, showing that echolocation is a general human ability.[9]

Lore Thaler led researchers at Durham University to determine if they could teach echolocation to people. Over a ten-week period, they taught it to 12 blind people and 14 others who were not blind.[10]

Mechanics

[edit]

Vision and hearing are akin in that each entails detection of reflected waves of energy. Vision processes light waves that 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 neural systems can extract a great deal of information about the environment by interpreting the complex patterns of reflected energy that their sense organs receive. In the case of sound these waves of reflected energy are referred to as echoes.

Echoes and other sounds can convey spatial data that are comparable in many respects to those conveyed by light.[11] A blind traveler using echoes can perceive very complex, detailed, and specific features of the world from distances far beyond the reach of the longest cane or arm. Echoes can 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.[12]

Brain areas associated with echolocation

[edit]
Echo-related activity in the brain of an early-blind, trained echolocator is shown on the left. There is no activity evident in the brain of a sighted person not so trained (shown on the right) listening to the same echoes

Some blind people are skilled at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes. Although few studies have been performed on the neural basis of human echolocation, those studies report activation of primary visual cortex during echolocation in blind expert echolocators.[1][13][14] The driving mechanism of this brain region remapping phenomenon is known as neuroplasticity.

In a 2014 study by Thaler and colleagues,[15] the researchers first made recordings of the clicks and their very faint echoes using tiny microphones placed in the ears of the blind echolocators as they stood outside and tried to identify different objects such as a car, a flag pole, and a tree. The researchers then played the recorded sounds back to the echolocators while their brain activity was being measured using functional magnetic resonance imaging. Remarkably, when the echolocation recordings were played back to the blind experts, not only did they perceive the objects based on the echoes, but they also showed activity in those areas of their brain that normally process visual information in sighted people, primarily the primary visual cortex or V1. This result is surprising, as visual areas are normally only active during visual tasks. The brain areas that process auditory information were no more activated by sound recordings of outdoor scenes containing echoes than they were by sound recordings of outdoor scenes with the echoes removed. Importantly, when the same experiment was carried out with sighted people who did not echolocate, these individuals could not perceive the objects and there was no echo-related activity anywhere in the brain. This suggests that the cortex of blind echolocators is plastic and reorganizes such that primary visual cortex, rather than any auditory area, becomes involved in the computation of echolocation tasks.

Despite this evidence, the extent to which activation in the visual cortex in blind echolocators contributes to echolocation abilities is unclear.[9] As previously mentioned, sighted individuals have the ability to echolocate; however, they do not show comparable activation in visual cortex. This would suggest that sighted individuals use areas beyond visual cortex for echolocation.

Notable cases

[edit]

Daniel Kish

[edit]
Main article: Daniel Kish

Echolocation has been further developed by Daniel Kish, who works with the blind through the non-profit organization World Access for the Blind.[16] He leads blind teenagers hiking and mountain-biking through the wilderness, and teaches them how to navigate new locations safely, with a technique that he calls "FlashSonar".[17] Kish had his eyes removed at the age of 13 months due to retinal cancer. He learned to make palatal clicks with his tongue when he was still a child, and now trains other blind people in the use of echolocation and in what he calls "Perceptual Mobility".[18] Though at first resistant to using a cane for mobility, seeing it as a "handicapped" device, and considering himself "not handicapped at all", Kish developed a technique using his white cane combined with echolocation to further expand his mobility.[18]

Kish reports that "The sense of imagery is very rich for an experienced user. One can get a sense of beauty or starkness or whatever—from sound as well as echo."[17] He is able to distinguish a metal fence from a wooden one by the information returned by the echoes on the arrangement of the fence structures; in extremely quiet conditions, he can also hear the warmer and duller quality of the echoes from wood compared to metal.[17]

Thomas Tajo

[edit]

Thomas Tajo was born in the remote Himalayan village of Chayangtajo in the state of Arunachal Pradesh in the north-east India. He became blind around the age of 7 or 8 due to optic nerve atrophy and taught himself to echolocate. Today he lives in Belgium and works with Visioneers or World Access to impart independent navigational skills to blind individuals across the world. Tajo is also an independent researcher. He researches the cultural and biological evolutionary history of the senses and presents his findings to scientific conferences around the world.[19]

Ben Underwood

[edit]
Ben Underwood

Ben Underwood was a blind American who was born on January 26, 1992, in Riverside, California. He was diagnosed with retinal cancer at the age of two, and had his eyes removed at the age of three.[20]

He taught himself echolocation at the age of five, becoming able to detect the location of objects by making frequent clicking noises with his tongue. This case was explained in 20/20: Medical Mysteries.[21] He used it to accomplish such feats as running, playing basketball, riding a bicycle, rollerblading, playing football, and skateboarding.[22][23] Underwood's childhood eye doctor claimed that Underwood was one of the most proficient human echolocators.

He inspired other blind people to follow his lead. He died of cancer in 2009.

Lawrence Scadden

[edit]

Lawrence Scadden lost his sight as a child due to illness, but learned to use echolocation well enough to ride a bicycle in traffic. (His parents thought that he still had some sight remaining.)[24] In 1998, he was interviewed at the Auditory Neuroethology Laboratory at the University of Maryland about his experience with echolocation.[7] The researchers were aware of the Wiederorientierung phenomenon described by Griffin[6] where bats, despite continuing to emit echolocation calls, use path integration in familiar acoustic space. Scadden said he did the same, as echolocation required extra effort.

The National Science Teachers Association created the "Lawrence A. Scadden Outstanding Teacher Award of the Year for Students With Disabilities" in his honor.[25]

Lucas Murray

[edit]

Lucas Murray, from Poole, Dorset, was born blind, and is one of the first British people to have learned human echolocation, having learned it from Daniel Kish.[26] Lucas' parents saw a documentary about Daniel Kish teaching Ben Underwood echolocation.[27][28] Months later, they learned that Daniel would be visiting a Scottish charity called Visibility[29] and contacted him. Kish taught the five-year-old Lucas the basics of echolocation over four days. By age seven, Lucas was proficient enough to not only accurately tell the distance of objects, but also their material, and could play with other children in sports such as rock climbing and basketball.[30][31] In 2019, he enjoyed a week's work experience with South Western Railway.[32]

Kevin Warwick

[edit]

The scientist Kevin Warwick experimented with feeding ultrasonic pulses into the brain (via electrical stimulation from a neural implant) as an additional sensory input. In tests he was able to discern distance to objects accurately and to detect small movements of those objects.[33]

Juan Ruiz

[edit]

Blind from birth, Juan Ruiz lives in Los Angeles, California. He appeared in the first episode of Stan Lee's Superhumans, titled "Electro Man". The episode showed him capable of riding a bicycle, avoiding parked cars and other obstacles, and identifying nearby objects. He entered and exited a cave, where he determined its length and other features.[citation needed]

[edit]

The 2017 video game Perception places the player in the role of a blind woman who must use echolocation to navigate the environment.[34]

In the 2012 film Imagine, the main character teaches echolocation to students at a clinic for the visually impaired. This unconventional method spurs a controversy but helps students explore the world.[35]

In the 2007 children's fantasy novel Gregor and the Code of Claw, protagonist Gregor learns echolocation. This skill proves useful for fighting in the Underland, an underground civilization which is the main setting of the book.[36]

The Marvel character Daredevil is a superhero who uses his heightened senses paired with echolocation to perceive the world in extraordinary detail.[37]

See also

[edit]

References

[edit]
  1. ^ a b c Kolarik, Andrew J.; Cirstea, Silvia; Pardhan, Shahina; Moore, Brian C. J. (2014-04-01). "A summary of research investigating echolocation abilities of blind and sighted humans". Hearing Research. 310: 60–68. doi:10.1016/j.heares.2014.01.010. PMID 24524865. S2CID 21785505.
  2. ^ Richard L. Welsh, Bruce B. Blasch, online Foundations of Orientation and Mobility, American Foundation for the Blind, 1997; which cites S. O. Myers and C. G. E. G. Jones, "Obstable experiments: second report", Teacher for the Blind 46, 47–62, 1958.
  3. ^ Raymond J Corsini, The Dictionary of Psychology, Psychology Press (UK), 1999, ISBN 1-58391-028-X.
  4. ^ M. Supa, M. Cotzin, and K. M. Dallenbach. "Facial Vision" - The Perception of Obstacles by the Blind. The American Journal of Psychology, April 1944.
  5. ^ Cotzin and Dallenbach. "Facial Vision": The Role of Pitch and Loudness in the Location of Obstacles by the Blind. The American Journal of Psychology, October 1950.
  6. ^ a b Griffin, Donald R., Echos of Bats and Men, Anchor Press, 1959 (Science and Study Series, Seeing With Sound Waves)
  7. ^ a b White, J. C., Saunders, F. A., Scadden, L., Bach-y-Rita, P., & Collins, C. C. (1970). Seeing with the skin. Perception & Psychophysics, 7, 23-27.
  8. ^ Thaler, Lore (2015-11-25). "Using Sound to Get Around - Association for Psychological Science". Aps Observer. 28 (10). Retrieved 2016-04-22.
  9. ^ a b Wallmeier, Ludwig; Geßele, Nikodemus; Wiegrebe, Lutz (2013-10-22). "Echolocation versus echo suppression in humans". Proceedings of the Royal Society of London B: Biological Sciences. 280 (1769): 20131428. doi:10.1098/rspb.2013.1428. ISSN 0962-8452. PMC 3768302. PMID 23986105.
  10. ^ Machemer, Theresa (June 4, 2021). "People Can Learn Echolocation in Ten Weeks". Smithsonian Magazine. Retrieved 2023-06-06.
  11. ^ Rosenblum LD, Gordon MS, Jarquin L (2000). "Echolocating distance by moving and stationary listeners". Ecol. Psychol. 12 (3): 181–206. CiteSeerX 10.1.1.540.5965. doi:10.1207/S15326969ECO1203_1. S2CID 30936808.
  12. ^ Kish D. (1982). Evaluation of an echo-mobility training program for young blind people: Master's Thesis, University of Southern California (Thesis).
  13. ^ Thaler L, Arnott SR, Goodale MA (2011). "Neural correlates of natural human echolocation in early and late blind echolocation experts". PLOS ONE. 6 (5): e20162. Bibcode:2011PLoSO...620162T. doi:10.1371/journal.pone.0020162. PMC 3102086. PMID 21633496.
  14. ^ Bat Man, Reader's Digest, June 2012, archived from the original on March 15, 2014, retrieved March 14, 2014
  15. ^ Thaler, L., Milne, J. L., Arnott, S. R., Kish, D., & Goodale, M. A. (2014). Neural correlates of motion processing through echolocation, source hearing, and vision in blind echolocation experts and sighted echolocation novices. Journal of Neurophysiology, 111(1), 112-127.
  16. ^ "World Access Online".
  17. ^ a b c Kremer, William (12 September 2012). "Human echolocation: Using tongue-clicks to navigate the world". BBC. Retrieved September 12, 2012.
  18. ^ a b Kish, Daniel (1995), Evaluation of an Echo-Mobility Program for Young Blind People, Master's thesis, San Bernardino, CA: Department of Psychology, California State University, p. 277, archived from the original on February 2, 2002
  19. ^ "Thomas Tajo". Visioneers.org. 2017-11-20. Retrieved 2023-01-22.
  20. ^ morgan isdell aleks petcova even white thomas cian Humans With Amazing Senses — ABC News.
  21. ^ Moorhead, Joanna (January 27, 2007). "Seeing with sound". The Guardian. London.
  22. ^ "How A Blind Teen 'Sees' With Sound". CBS News. July 19, 2006.
  23. ^ The Boy Who Sees with Sound — People Magazine
  24. ^ Surpassing Expectations: Life Without Sight Scadden, Lawrence]
  25. ^ "Recognizing excellence—The Lawrence Scadden Teacher of the Year Award | NSTA". www.nsta.org. Retrieved 2023-09-21.
  26. ^ "Lucas learns echo technique to 'see'". Daily Echo. 7 October 2009. Retrieved 8 October 2009.
  27. ^ "Ben Underwood | Blind Boy Who Could See".
  28. ^ "Blind boy uses his ears to 'see'". BBC News. 5 October 2009. Retrieved 8 October 2009.
  29. ^ "Visibility Scotland - Listening and responding to people affected by sight loss across Scotland". Visibility Scotland.
  30. ^ Irvine, Chris (5 October 2009). "Seven year old blind boy uses echoes to see". The Daily Telegraph. London. Retrieved 8 October 2009.
  31. ^ "Action for Blind People merged with RNIB". RNIB - See differently. 23 March 2017.
  32. ^ Cartlidge, Sarah (19 May 2019). ""The best work experience ever": Blind teenager enjoys "phenomenal" placement". Bournemouth Echo. Retrieved 28 May 2020.
  33. ^ Warwick K, Hutt B, Gasson M, and Goodhew I. "An attempt to extend human sensory capabilities by means of implant technology". Proc. IEEE International Conference on Systems, Man. and Cybernetics - Hawaii October 2005. pp.1663-1668
  34. ^ Skrebels, Joe (May 25, 2017). "Perception Review". IGN. Retrieved May 25, 2017.
  35. ^ Grierson, Tim. "Imagine". ScreenDaily. Retrieved June 21, 2017.
  36. ^ Collins, Suzanne (2007). Gregor and the Code of Claw (1st ed.). New York. ISBN 978-0-439-79143-4. OCLC 74568049.{{cite book}}: CS1 maint: location missing publisher (link)
  37. ^ "Daredevil (Matt Murdock) On Screen Powers, Enemies, History | Marvel". www.marvel.com. Retrieved 2024-04-18.
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