Sometimes silence is not golden

Hearing: Early detection of problems is important to learning development.

April 30, 2000|By Rosie Mestel | Rosie Mestel,los angeles times

Why are they advertising the Cleveland Symphony Orchestra all over the Philadelphia airport? Carren Stika wondered as she traipsed toward baggage claim. She stopped at a pay phone and noticed the area code: 216.

"That's when I realized -- oh, no! I'm in Ohio!" she says.

Stika hadn't heard the garbled buzz of the in-flight announcement, so she hadn't known about the unscheduled touchdown in Cleveland. A fuzzy speech signal and the fuzzy ability of her ears to hear combined to confound her again.

"Every one of us has stories like that," says Stika, who, years after the airport incident, is a director of research for a San Diego rehabilitation center for people with hearing problems.

By "us," Stika means the hard of hearing, a condition she first knew she had at age 20.

But her hearing loss likely dates back much further. That's why her school report cards would come home with comments like "Needs to listen more carefully." Hearing loss is why she had a lisp as a kid, why college friends would tell her she sometimes seemed stuck-up or out of it, because she would "ignore" folks, fail to laugh at jokes or chime in on conversations in off-kilter ways.

"People attribute those kinds of mistakes to everything but hearing loss," she says.

About 28 million Americans have hearing problems, ranging from the mild to profound. For some people, the losses were always there, or swooped down overnight from a viral infection or some other cause. For Stika and most others, the losses build up slowly over years.

Scientists estimate that more than half of all childhood cases of deafness are inherited (as well as many cases in which hearing loss sets in later).

Estimates for the average age at which a serious hearing impairment is diagnosed range from 14 months to 2 1/2 years. This may sound early enough, but it's not.

"In the past, we haven't really appreciated that even when babies were just lying there, a few weeks old, their brains were already developing the capacity for language," says Jim Battey, director of the National Institute on Deafness and Other Communication Disorders, in Bethesda.

"If they receive no language input during a critical window of time -- a time that stretches back to birth -- they lose an opportunity to learn language."

Thus, while early detection gives a child a good chance of communicating normally -- either in sign or spoken language -- by the time he or she begins school, late detection and intervention mean a child has a long, dreary game of catch-up ahead. And some kids can never catch up.

In studies of preschoolers, those whose problems were detected after 6 months of age were more likely to have developmental delays than those whose problems were detected earlier. They lagged behind in their ability to use and understand expressive language; in their social and emotional growth; and in the scope of their vocabulary.

This doesn't mean there's no hope if a child's problem is discovered late, says Christine Yoshinaga-Itano, professor at the University of Colorado at Boulder and lead author of the studies. "But it's harder."

That is why hearing advocates have been pressing for across-the-board screening for hearing problems in newborns.

"Screening is extremely important," says Jim Potter, director of government relations for the American Speech-Language-Hearing Association, a professional group that advocates early screening. "We want to give children every chance that we can."

Such advocates are making headway. Today, 27 states, including Maryland, have enacted legislation for universal newborn screening programs -- twice as many states as a year ago. Legislation is pending in at least a dozen states to establish or build on existing laws.

And last year, Congress passed a bill to provide grants to help states set up screening programs and provide the necessary follow-up care.

It's relatively straightforward to test the hearing of an adult: Audiologists put people in a booth and have them press buttons and parrot back phrases in response to the sounds they hear. It's another matter to test the hearing of a baby.

Luckily, if a baby's mouth can't tell you, his or her ears can do the talking instead, due to an odd property of hearing that has only been appreciated in the past few decades. Ears, it seems, not only receive sounds, they emit them as well.

The source of these sounds are "outer hair cells" in our ears that move around in response to noises, somehow sharpening our hearing. As a byproduct, the movements vibrate the eardrum, sending noises back out into the world.

The noises an ear normally makes when exposed to sound are so quiet we can't hear them. They're loud enough for instruments to detect, though, unless there's significant hearing impairment. Then the outer hair cells don't jiggle. The sounds aren't generated. And that is the essence of how to screen for hearing problems in newborns.

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