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See Inside Scientific American Mind Volume 25, Issue 4

MIND Reviews: I Can Hear You Whisper: An Intimate Journey Through the Science of Sound and Language




I Can Hear You Whisper: An Intimate Journey through the Science of Sound and Language
by Lydia Denworth
Dutton Adult, 2014 ($26.95)

Language, it is often said, is what makes us human. So what happens when the acquisition of language is impeded? Without language, how does one fully participate in the great drama of human life, let alone function in society?

These questions lie at the heart of Denworth's new book. Her youngest son, Alex, is nearly two when she discovers he has almost completely lost his hearing. The revelation prompts an avalanche of maternal anxiety. Can he have a normal life? What are the best ways to help him? And maybe most important, will he recover from the time he spent, unbeknownst to her, in near silence?

A former reporter and editor for Newsweek and People, Denworth attacks these questions as both mother and science journalist. The result is part memoir, part expository science writing and part history of the political intricacies of deafness. It is also, ultimately, a somewhat harrowing experiment.

Denworth finds she is racing against time. Although we continue to generate neurons throughout life, the brain undergoes a dramatic pruning process early on. Neural connections that are not used are deleted, whereas those that are retained become stronger. If the brain lacks sensory input early in life, not only may those connections fail to form, but regions normally used in, say, parsing auditory information may get co-opted for another job. Co-option is not necessarily problematic. There is some evidence, in fact, that deaf people who use sign language see better than hearing people do. A problem arises, however, if the brain-wide networks underlying language comprehension, be it sign or heard language, are not created at all.

Rather cruel animal experiments illustrate the underlying principle, which scientists often express as “use it or lose it.” In one study, scientists sewed kittens' eyes shut and removed the stitches after three months. Despite having perfectly good eyes, the cats remained forever blind. Deprived of visual stimuli during a critical period of brain development, their visual cortices now failed them. Their eyes could see fine, essentially, but their brains could not. As with the kittens, the worry with any child who lacks sensory input is that without early-life stimulation, the neural networks that enable perception simply will not develop.

So Denworth chooses to give her son a cochlear implant in his completely deaf ear before age three—theoretically still within that window of neural malleability. This means surgically implanting wires in the spiral-shaped cochlea of the inner ear, which connect to a “receiver” under the scalp. That receiver communicates with a hearing device worn behind the ear. The implant works essentially as an artificial ear with a near-direct line to the brain.

You would think that the deaf community would embrace such technology. But as Denworth explains, the community views cochlear implants with great ambivalence. (The sign for the implants in American Sign Language—ASL—is two fingers stabbing the back of the neck, like a vampire's bite.) This antipathy stems in part from the historical view of deafness as a defect. In recent decades a deaf civil-rights movement has pushed back against these kinds of assumptions. The deaf aren't defective, the counterargument goes, just different. They don't need fixing. Indeed, just because you can't hear doesn't mean you can't have language. As sign languages make plain, sound is not required for the fundamental linguistic process of linking meaning with symbols.

Which brings us to the conundrum Denworth faces: Should Alex focus on pursuing membership, however marginal, in the hearing world? Or should he master ASL, a system that he may more fully inhabit but that may also limit the scope of his world?

Denworth ultimately decides on the former. After his implant—and a stint at a school geared toward the hearing impaired—Alex attends a hearing school in Brooklyn, where, with extra help, he does quite well. But Denworth also hedges; she and Alex eventually study ASL.

At the end of the book, Denworth's family moves to Hong Kong. Alex, now past his seventh birthday, is talking, reading and thriving. Everyone's hard work has paid off. In their willingness to strike off on adventure (which Alex insists on), a reader senses that the motherly anxiety evident at the book's outset has subsided somewhat. She seems to have absorbed the notion that perfect hearing is not required for a full, rich life.

Denworth does a fine job interweaving the different elements of this historically fraught, scientifically complex and personally trying story. Major determinants of success among deaf and hard-of-hearing children include parents who care, access to resources and plenty of practice early in life. These fairly basic requirements highlight one way the deaf and hearing are actually more similar than different.

This article was originally published with the title "Sound Barrier."

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