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June 12, 2004

Early implants for hearing problems

From: The St. Louis Post-Dispatch, MO - Jun 12, 2004

By Florence Shinkle
Of the Post-Dispatch

A few months after his first birthday, it became obvious to Patrick Barton's parents and therapists that the hearing aids Patrick wore weren't providing him with enough access to sound for speech to develop.

"He started babbling, making all those prelinguistic noises, b-b-b, m-m-m - and then he stopped," recalled his mother, Ginger Barton, 34.

Silence, the enemy, was back in their midst.

The Bartons, along with therapists from St. Joseph Institute for the Deaf in Chesterfield, agreed that Patrick should have a cochlear implant - a man-made hearing system that bypasses a flawed natural one.

First given federal approval in 1988, the cochlear implant now is approved for use in children a year old, and even younger in special cases. There are no clear predictors yet of how fluent these babies will become. If they prove to have no additional learning disabilities, St. Joseph therapists hope to mainstream them into regular classes by kindergarten or the primary grades.

New requirements

Born on June 15, 2002, Patrick was identified at birth with a hearing defect, under state laws implemented six months earlier in both Illinois and Missouri requiring auditory screening of newborns before they leave the hospital. Both states provide support for medical and educational services to the children identified.

Debby Wilson, president of St. Joseph, says the school's population of infants and toddlers is "exploding" as a result of the new requirements.

Missouri will fund testing and therapy for children from birth to 3 years who are identified with a hearing defect. The income of the parents is not a factor. Every child with a need qualifies.

St. Joseph, founded in St. Louis in 1837, is an approved provider of those services, as well as an accredited private school for the hearing-disabled in grades one through eight. It has four other campuses, including downstate Illinois' only such school, in Champaign-Urbana, plus campuses in Kansas City, Oklahoma City and Indianapolis. In Chesterfield, enrollment of babies and toddlers in the early intervention center has grown from 16 to 27 since the beginning of the year.

The school teaches more children fitted with the cochlear implants than any other school in the United States, with an enrollment of 71 older children in Chesterfield. Children from 13 states and seven countries come to Chesterfield to learn speech with this new hearing device.

In place of his own misfiring transmission system, Patrick was wired with a microphone to collect sounds, a speech processor to analyze the sounds and code them into electric impulses, and an implant - surgically placed in the mastoid bone behind the ear - to send the impulses via electrodes to the auditory nerve.

Each of the 12 electrodes would be assigned a different set of frequencies. For instance, one electrode would carry the high frequencies that allow the brain to hear letters such as "s" and "h." Another electrode would carry the lower frequencies of the guttural consonants. All 400,000 sounds that the natural auditory system can distinguish would be available to Patrick synthetically.

On the journey

Thirty years ago, children like Patrick Barton would have spent their lives on the margins of the hearing world, practicing lip reading and speaking only with great struggle.

Patrick has a deep-seated dysfunction of the inner ear, probably a short circuit in the signal transmitting patterns from the cochleus to the auditory nerve that relays impulses to the brain. Generally, adults with this type of profound hearing loss cannot discriminate sounds enough to understand speech, according to a recent paper on the disorder.

But technological innovations hold promise, for the very young more than any. The aim now is to intervene medically as soon as a hearing loss is confirmed - before any biological deterioration can occur from lack of neural stimulation and at the developmental stage when the brain is most receptive to learning language.

Patrick got his implant at 14 months. While he waited for the surgery appointment at Children's Hospital, his mom removed his hearing aids altogether. "They were useless," she said. Hope resided with the cochlear implant.

Six weeks after the operation, it was time for the new system to be turned on. Patrick's parents were there for the climactic moment when he crossed from the soundless world to the hearing one.

"Nothing happened," Jeff Barton recalled. "He just kind of looked at us a little funny. I thought, 'My God, I've let them drill a hole in my son's head for nothing.'"

It turned out Patrick's quizzical response was typical - he was a person lost in the wilderness without a map. The cochlear implant was providing sound information to the child, but access to sound is not the same thing as hearing.

Hearing is the process of distinguishing sounds and attaching meaning to them. From birth, the infant with normal hearing is building up a store of understanding about what various sounds mean and which ones are more or less important and how to concentrate on one rather than the other. Long before that child can talk, his glossary of understood words and sounds is expansive.

Beverly Fears, Patrick's audiologist at St. Joseph, gave him a good portion of the audible universe all at once, via the computer program she wrote for his cochlear implant. Now he had to learn how to sift and prioritize specific sounds; he had to build up his auditory memory of their meanings and then reach to imitate them - the beginning of speech.

And so the Bartons' two-story house became a forest, and Ginger and Patrick became hunters, zeroing in on specific sounds and words and matching them with the things they were connected to, conquering the sounds and displaying them like trophies of war.

"Here's your airplane, Patrick. What does the airplane sound like? It goes hm-m-m, hm-m-m-m-m-m," Ginger Barton says. She makes her voice tone wavy, and she moves the airplane in an undulating pattern.

"Now you make the sound how the airplane goes." She holds the airplane stock still, its gratifying motion dependent on Patrick's showing he has heard the voice oscillations.

"Hm-m-m-m-m-m," he says, and the voice variations are there, a precious melody.

"Yes, hmm-m-m-m-m. Yes!" She beams emphatic approval, a response both heartfelt and calculated.

"All day long I give him constant language, all day," she says. "I use everything here to bring on speech."

Fears believes Patrick now has access to all the sounds around him. "Of course, he has to identify them and associate meaning like any child, and he's delayed, from the months he lost, but he's under way; he's on the same journey now as a normal hearing child."

That afternoon was muggy. Thunder cracked. "Oooooh," Patrick said, and he touched his finger to the ear with his hearing device. Then he ran into the next room for a window with a view.

"Patrick, come here," his mom called to him after a bit.

And from the next room, he came.

© 2004 The St. Louis Post-Dispatch