Bats and dolphins have long fascinated human beings with their ability to use a form of sonar or echolocation to navigate and find prey in areas where light is scarce. It’s a deceptively simple principle; the animal makes a series of high-pitched sounds, and its brain automatically calculates the distance of an object by the time it takes the sound to bounce back to its ears. Psychologist Lawrence D. Rosenblum, in his new book titled See What I’m Saying, makes the case that humans are also capable of echolocation to some degree, even when they are not conscious of using it.
Sound Navigation in the Blind
There is a common belief that people who have lost the use of one of their senses will generally compensate through heightened sensitivity in their other senses. As Rosenblum argues in his book, this certainly seems to be the case among the blind, many of whom use subtle sound cues to successfully maneuver around their environment.
He details the case of an experienced mountain biking guide who happens to be blind, and who uses sharp clicks of his tongue to navigate around trees, rocks, and other obstacles. The sounds he makes work much the same way as similar sounds made by bats or dolphins; the mountain biker can tell the distance and position of an obstacle by the timing and sound quality of the clicks as they bounce back to him. Additionally, when he is taking others on biking excursions, he fits their bike wheels with clicking mechanisms on the spokes, so he can tell where the other bicyclists are at all times.
Echolocation as a Common Human Ability
Of necessity, blind people are usually better at using echolocation than their sighted compatriots. However, Rosenblum is quick to point out that anyone can improve her own ability to echolocate with just a little practice.
In studies going back to the 1940s, it was found that sighted people wearing blindfolds were easily able to avoid walking into a wall they couldn’t see, and in other experiments most people were able to determine the shape and material of an object placed in front of a sound source, even when they couldn’t see it. In early tests, scientists were unsure whether the subjects were using sound to accomplish these feats, but when subjects’ ears were covered as well as their eyes, they were no longer able to avoid obstacles or perform other feats that had been easy for them when their ears were uncovered.
Humans Hear Better Than They Think
Evidently there is a lot more going on in the brain than humans realize when they hear something. Firstly, they are often reacting to minute sound wave interferences even when they are not aware of them, and can usually still navigate by echolocation even using almost nonexistent sound cues.
In addition, most humans have no trouble at all judging how large a room is or what its walls are made of, simply from listening to a sound recorded in the room. And even with no training or particular talent, almost all people tested were easily able to tell the length of a metal bar simply from hearing it drop to the floor, and could closely estimate the capacity of a wine glass just from the sound of the first pour. As Rosenblum explains in his book, humans’ hearing is clearly much more acute than is generally perceived, even if most of the magic happens well below conscious awareness.
Source:
Rosenblum, Lawrence D.. See What I'm Saying: The Extraordinary Powers of Our Five Senses. New York: W.W. Norton & Company, 2010.
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
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