Explain briefly how we can hear with our eyes.
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Although we depend on both vision and hearing to interact with our environment, we generally consider blindness a greater disability than deafness. At least when we’ve lost our hearing, we can still see to navigate through the world, and we can learn sign language or lip reading to communicate. While blindness leaves our language abilities intact, however, our mobility and independence are greatly impacted. So goes the received wisdom, but Daniel Kish doesn’t think of his blindness as a disability. Having lost both eyes to retinal cancer before the age of two, Kish has no memory of vision. He was also too young to understand that blindness was an impairment. So instead he taught himself to see by using his ears.
Kish makes clicking sounds as he moves through the world, and his brain uses the echoes to create a three-dimensional image of his environment. These images, he insists, are rich in shape in texture. He can’t perceive color, yet in another way his image of the world is more developed than those of sighted people. This is because he not only “sees” what’s in front of him but what’s behind him as well. In the following YouTube video, you can watch Kish riding his bicycle along a suburban street.
For sighted people as well, hearing takes the center stage of our attention when the visual input is unclear. Imagine you’re deep in a forest and it's getting dark. All you can see are trees and shadows, but a rich panoply of sounds will tell you what’s going on around you. I don’t know if it’s an illusion or reality, but the woods behind my house sound much noisier after dark.
We don’t experience our senses individually. Rather, our brain meshes with our vision and hearing to create our conscious experience of the world. What you see can influence what you hear, and likewise hearing can affect vision.
Although speech is perceived through the ears, what we see can change what we hear. In the following YouTube video, a man produces the same syllable over and over again. If you watch his mouth, you’ll hear the syllable “fah,” but if you look away you’ll hear “bah.” Although your ears hear “bah,” your eyes see “fah,” and even in speech your brain trusts vision over hearing. This phenomenon is known as the McGurk effect.