Music to Her Ears

When a deaf toddler gets cochlear implants, a whole new world opens up.
At 16 months, she played the piano and ?sang.?
At 16 months, she played the piano
and "sang."

Four-year-old Mecaden Bennett likes to give a running commentary whenever she watches her mother change her little brother's diaper. She exclaims, "Ew, Mommy, Levi stinks!" or "All clean!" -- neither of which would be worth noting except that Mecaden is deaf. When she was a baby, she couldn't hear a sound unless it was as loud as a jet engine blaring in her ear.

Had she been born earlier, the Raleigh, North Carolina, preschooler would probably be delivering her diaper play-by-play in sign language, if at all. But her parents, Emily and Todd, chose to get her cochlear implants -- surgically implanted electronic devices -- so now she's learning to speak and understand just like a hearing child. Mecaden got an implant in one ear when she was a year old, and then one in her other ear 17 months later, during a critical window for her language development. "We were beyond thrilled to have the option of implants," says Emily, stressing that she and her husband never felt they were "fixing" their daughter. "We wanted Mecaden to be able to communicate with us and the rest of our family, and we felt that if we could give her the gift of hearing, why wouldn't we?"

The Bennetts' attitude reflects a major shift within the deaf culture. Ironically, while it's trendy for parents to teach sign language to their hearing babies, parents of deaf children are helping them avoid speaking with their hands. Approximately 10,000 deaf children are born in the United States every year, and more than half of those who are diagnosed as a baby now get an implant before their second birthday. Within five years, more than 90 percent of deaf children born to hearing parents will have at least one implant by the time they are 18 months old, predicts John Niparko, M.D., a cochlear-implant surgeon at Johns Hopkins Hospital, in Baltimore.

Amazing Technology

In order for a child to hear, sound must travel down the ear canal to the cochlea, the snail-shaped organ that connects the auditory nerve to the brain. The cochlea is lined with microscopic hair cells that vibrate when they're stimulated by sounds. When the hair cells vibrate, the nerve fibers at their base carry electrical signals to the brain, which interprets them as language or environmental sounds, such as a dog barking, rain hitting the roof, or a mother's voice. When a child like Mecaden has extensive sensorineural hearing loss, the hair cells don't work -- so the implants bypass them.

At the heart of each device is an electrode array that a surgeon inserts into the cochlea. A receiver is implanted under the skin on the mastoid bone, which is behind the ear, and then the electrodes and receiver are connected. A child wears other parts of the device outside her body, including a speech processor that looks like a hearing aid. It's connected to a radio coil, which resembles a small steering wheel, and is held in place by a magnet that attaches to the receiver under the skin. A microphone in the speech processor picks up sounds, converts them to an electrical code, and sends them to the coil, which delivers them to the receiver. From the receiver, they travel to the electrode array and then to the brain.

Early models in the 1970s made it possible for deaf people to hear some sounds, but because the devices had only one electrode instead of an array, it was hard for users to understand what they heard. The first implant recipients were adults who had lost their hearing after learning to speak and listen. They were ideal candidates because they already knew what things sounded like. By 1990, as more electrodes were added and the technology was fine-tuned, the FDA approved implants for children ages 2 and older. In 1998, the age was lowered to 18 months, and in 2002, it was lowered to 1 year. The popularity of cochlear implants has grown steadily since then.

Although one implant has been proven to help a child learn to speak and listen, studies show that having two makes it much easier to hear in noisy environments and to figure out where sounds are coming from. Recent research from UT Southwestern Medical Center, in Dallas, has also found that children with implants report having the same quality of life as kids with normal hearing. The surgery and follow-up therapy costs between $40,000 and $60,000 per implant and is usually covered by insurance -- although some insurers resist paying for a second implant.

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