Hearing Better in the Dark
Blind people are better at locating distant sounds than people who can see.
Where is that noise coming from? Not sure? Try living with your eyes closed for a few years.
Blind people are better at locating sounds than people who can see, a new study says. Without the benefits of vision, the ears seem to work much better.
Parts of the brain that normally deal with visual information become active in locating sound in people who are blind by age 11.
|Courtesy FONAR Corporation|
Previous studies have shown that blind people are better than others at reaching out and touching the sources of sounds that are close by. Researchers from the University of Montreal wanted to see if blind people were also better at locating sounds that are far away.
Twenty-three blind people participated in the study. All had been sightless for at least 20 years. Fourteen of them had lost their vision before age 11. The rest went blind after age 16. The experiment also included 10 people who could see but were wearing blindfolds.
In one task, volunteers had to pick the direction of a sound coming from about 3 meters away. When the sound was in front of them or slightly off center in front, both groups performed equally well.
When sounds came from the side or the back, however, the blind group performed much better then the blindfolded group. The participants who had been blind since childhood did slightly better than those who lost their sight later.
Recognizing the locations of distant sounds can be a matter of life-or-death for blind people, say the researchers. Crossing the street, for instance, is much harder when you can’t see the cars coming.
Still, the researchers were surprised by how well the blind participants did, especially those who went blind after age 16. In another experiment, the scientists also found that parts of the brain that normally deal with visual information became active in locating sound in the people who were blind by age 11. These brain parts didn’t show sound-location activity in the other group of blind people or in the sighted people. The scientists now want to learn more about the workings of brains of “late-onset” blind people.
It takes a while for the brain to boost its hearing skills, so simply blindfolding yourself (if you can see) probably won’t make your ears more powerful. On the other hand, spending a day wearing a blindfold might be an eye-opening experience, so to speak. If nothing else, you might better appreciate how challenging it can be to get around without sight.—E. Sohn
Bower, Bruce. 2004. Hearing better in the dark: Blindness fuels ability to place distant sounds. Science News 166(Oct. 16):245. Available at http://www.sciencenews.org/articles/20041016/fob5.asp .
You can learn more about the brain and blindness at faculty.washington.edu/chudler/visblind.html (Neuroscience for Kids).