Echolocation: A Useful Tool for the BlindHuman

Jim Blackshear

Feburary 2002 Stephen F. Austin State University

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The term echolocation was first coined by Donald Griffin, who, in1938, discovered that bats navigate with the aid of high frequencysounds bouncing off obstacles in their environment (Uy,1994). When you say echolocation to most people, they immediatelythink of bats and dolphins as the only creatures with this talent. Itwas surprising to me, as well as others, that blind humans have beenusing a form of echolocation for quite a long time. There have beenmany attempts to aid in mobility for the blind. From 1944 to 1947 theCommittee on Sensory Devices of the National Academy of Sciencesdeveloped eighteen different portable devices to aid the blind inavoiding obstacles (Uy, 1994) none of which were very successful.Echolocation also has been observed in some forms of rodents, andsome nocturnal cave birds. The first recorded instance of a blindhuman using echolocation was in 1749 by Diderot, who observed theability of a blind person to determine the presence and even thedistance of some objects (Uy, 1994).

Some theories on how the blind "see" have to do with a phenomenoncalled facial vision. Some thought that the skin of the subjects,especially of the outer ear, could sense pressure changes in theenvironment due to obstacles. Others believed that the Subjects weresimply listening to the changes in the sound's echo, such as pitch,loudness, and even direction. Still others believed that the changesin pitch along with pressure sensitivity were needed in tandem toexplain facial vision. A study in was conducted in 1947 by Worcheland Dallenbach to determine the validity of these theories. Somefindings include: (1) the dermal surfaces of the external ears arenot sufficient for the perception of obstacles. (2) The pressuretheory of the "obstacle sense" is untenable. (3) Auditory stimulationis both a necessary and a sufficient condition for the perception ofobstacles by the blind. (4) The aural mechanism involved is audition.(5) The auditory theory should be regarded as an established fact(Worchel and Dallenbach, 1947). This tells us that echolocation istotally dependant on sound and not pressures on the skin.Echolocation is definitely the way by which these blind Subjects"see".

Another study, done by Cotzin and Dallenbach in 1950, was designedto determine if the changes in pitch or in loudness were bothrequired to echolocate. The study concluded that the changes in pitcha necessary and sufficient condition in echolocation. There is noevidence to suggest that loudness is a factor as long as the echoesare audible to the Subjects hearing (Cotzin and Dallenbach, 1950).Another study done some years later was designed to find if differentspectra of canes' tapping sounds made any difference in the Subjectsability to navigate. The 10 different cane types used were all foundto have identical effectiveness in echolocation, supporting theprevious research that pitch changes are used by Subjects and not theinitial pitches (Schenkman and Jansson, 1986). This partiallyexplains why different blind Subjects have different sound methodssuch as, cane tapping, hissing, lip smacking, and clicking.

In 1962 Dr. Kellogg determined in a laboratory setting that blind,and blindfolded sighted Subjects could determine with great accuracythe distance and size of objects(Uy, 1994). He found that the fartheraway the objects were or the closer in relative size they were, theharder it was for the subjects to distinguish between the two. In1965 Dr. Rice showed that percent correct detection of an object wasa function of the distance and size of the object from the observer(Uy, 1994). So, at a greater distance, objects needed to be larger indiameter to be detected by Subjects. As the object was placed fartherfrom a subject, the sound intensity of the echo became lower, andobject detection became more difficult. As object size increased, theSubjects ability to detect the object drastically improved. The typesof sounds preferred by human Subjects were also studied in Rice's1965 experiment. Subjects used a variety of self-produced sounds,including tongue clicks, hisses, and lip-smacks. (Uy, 1994). Thisstudy determined that whichever method the subjects preferred wasmost effective for that individual. This suggests that the method ofsound production is irrelevant but that it must have something to dowith the changes that occur to the sounds when they arereflected.

Echolocation is used by the blind to help them navigate throughtheir homes, along city streets, and even to help locate objects intheir environment. One of the major hindrances of the blindpopulation is their inability to "reach out" into their environment.Their inability to gather information at a distance and insteadhaving to tactilely navigate through their world. Echolocationprovides at least a rough way for the blind to "reach out" into theirenvironment and somewhat help make up for their loss or absence ofsight. Any method to improve on this visual compensation technique orto help teach it to others is well in need of future study. As I lackthe technical background needed to help improve on the methods ofecholocation in the blind, I have decided to focus on methods wherebycompetent blind echolocators could help teach these methods to othersin the blind community.

There are many obstacles in the blind learning echolocation fromother echolocators. "Mobility instructors discourage echolocation,especially clicking. While training with my first dog, I forgotmyself and clicked to determine if I was near a pole. The instructortold me that my dog would be taken from me if I continued to make"those sounds," that they served no purpose, they made blind peopleobjects of ridicule. And furthermore, I'd confuse the dog. I stoppedclicking&emdash;until I returned home!" (Feinstein,2001, p. 1) These are the types of problems the blind who try toutilize echolocation are up against in their adaptation to theirenvironment. Many who are born blind are told in their young schoollives not to click, tap their canes loudly, or stomp slightly. Theseare all echolocation methods and are all looked down upon as makingthe blind seem more helpless or ungainly. The view of theseinstructors is that the blind need to sort of hide themselves in theseeing community to try to "fit in" without causing too many waves.Until these sorts of obstacles are removed many in the blindcommunity may never be able to use echolocation, or even be aware ofit.

This area has not been it the spotlight of study recently. I wasunable to find any research articles in the last five years. The mostrecent article published was in 1995. The authors argue thatecholocation may be a basic ability of humans. They reviewed studiesthat suggest both blind and sighted humans are capable of precisionin the perception of properties of some objects, such as distance,size, and shape. Relations were analyzed between sound pulse and echothat may provide information to support these arguments (Stoffregenand Pittenger, 1995). I was unable to find any articles, or even webbased material, about teaching echolocation to the blind. I suggest astudy to attempt to figure out what exact methods are used byecholocators. Then find out how to translate those methods so that ablind subject, that has no prior knowledge or experience with thephenomenon, might be able to learn. These studies would have to bedone over a broad range of established echolocators to try to findthe easiest or most teachable method for use in a school or programfor the blind. After these methods are refined, if in fact they canbe at all, then a school or program for the blind in our societycould be instituted to help aid in their navigation through ourworld. Any attempt to help blind individuals better cope with theirdisability is well worth the efforts that we might put intoresearching the topic.

One problem that might arise in teaching echolocation is thedifficulties that new blind Subjects run into. An experimentconducted in 1986 concluded that Subjects born blind had a muchgreater ability to identify obstacles correctly than did Subjectsthat were sighted and blindfolded (Boehm, 1986). This poses a problemwhen you attempt to teach echolocation to newly blind individuals.When you lose a sense you become more sensitive to your remainingsenses to help compensate for that loss. During the period betweenloss of sight and this heightening of the senses, namely hearing,echolocation might be hard to teach to a newly blind subject. Wewould need to find out about this time of adjustment in newly blindsubjects and determine when they would be sensitive enough to startto use echolocation effectively. The fact that even blindfolded,sighted, subjects can learn to use echolocation, while difficult andnot as effective, is still a good sign that possibly all blindindividuals will be able to learn to echolocate.

In conclusion, I would like to say that reading some of theaccounts by echolocators, and how effective their "sight" is, is veryastonishing. The detail that they report and how much easier it isfor them to navigate in the world makes me wonder why there is nosort of formal educative process by which individuals could learnthis skill. This is definitely an area that needs further attentionfor the aid of the blind community. The fact that young children bornblind are discouraged from different echolocation methods must firstbe addressed before any sort of formal schooling be implemented forthe blind community.


Boehm, Richard. (1986). The use of echolocation as a mobility aidfor blind persons. Journal of Visual Impairment & Blindness, Vol80(9): 953-954.


Cotzin, Milton., Dallenbach, Karl M. (1950). "Facial vision:" therole that pitch and loudness play in the perception of obstacles bythe blind. American Journal of Psychology, 63: 485-515.


Feinstein, Robert. (2001). Feinstein_click.html.


Schenkman, Bo N., Jansson, Gunnar. (1986). The detection andlocalization of objects by the blind with the aid of long canetapping sounds. Human Factors, Vol 28(5): 607-618.


Stoffegen, Thomas A., Pittenger, John B. (1995). Humanecholocation as a basic form of perception and action. EcologicalPsychology, Vol 7(3): 181-216.


Cotzin, Milton., Dallenbach, Karl M. (1950). "Facial vision:" therole that pitch and loudness play in the perception of obstacles bythe blind. American Journal of Psychology, 63: 485-515.


Uy, C., (1994). "Seeing" Sounds: Echolocation by Blind Humans.


Worchel, Philip., Dallenbach, Karl M. (1947). "Facial vision,"perception of obstacles by the deaf-blind. American Journal ofPsychology, 60: 502-553.