Cochlear implants actually consist of three linked components: a microphone placed behind the ear, which picks up sounds; a speech processor, often worn on the patient’s belt, which converts the sounds into electrical signals, and a surgically implanted receptor, which stimulates the groups of neurons in the cochlea, a seashell-shaped bone that sends nerve impulses to the brain. Cochlear implants first hit the market in 1985, but they were controversial through the mid-’90s, partly because they improved hearing in only 30 to 40 percent of patients. Today, advances in the technology have silenced most critics. Doctors say they can now significantly enhance hearing in 80 percent of patients, and even children born deaf are candidates for the procedure. But they should be treated within their first five years, before the brain loses its ability to process sound (children and adults who have been deaf for longer periods of time often fall into the other 20 percent). “It’s reaching a point where we can restore hearing to levels that approach the hearing of normal people–where we can actually cure deafness,” says Albert Maltan, a senior vice president of Advanced Bionics, which makes the Bionic Ear, the implant used by both Kleppe and talk-show host Rush Limbaugh, who had the surgery in December.
The idea of electrically stimulating the auditory system is nothing new. In the 18th century, Italian physicist Count Volta hooked two metal rods to his most famous invention, the battery, and inserted them into his healthy ears, generating a sound like the boiling of thick soup. By the 1970s, scientists had figured out that electrical pulses needed to be targeted to localized groups of hair cells, which convey different sets of tonal and pitch information to the brain. While the first generation of cochlear implants used a single, clumsy electrode to convey the entire spectrum of sound, today’s devices have up to 24 electrodes, each stimulating a different patch of neurons.
The results still aren’t perfect. People with the implant often say voices sound metallic, like a radio broadcast. And few are able to enjoy the tonal richness of music. Many also still lip-read to complement their new hearing, particularly in loud environments–though they are able to use the telephone, where there’s little background noise. The surgery costs up to $50,000, and most insurance policies will cover it.
For patients like Cora Jean Kleppe, it’s worth every penny. Last month Kleppe and her friend Melba drove to the University of California, San Francisco, Hospital, four weeks after her surgery, to have Kleppe’s implant programmed and activated. Kleppe was shown how to clip the microphone behind her ear and how to change the batteries in the speech processor. Then, right there in the hospital, her doctor remotely activated the implant. “It’s going to sound strange,” the doctor warned. Kleppe started to talk and then interrupted herself: “Does my voice sound like that?” Thirty minutes later she’s walking around the hospital lobby, looking at Melba with wonder every time her friend speaks. “We can talk,” she says. “We can gossip forever now.”
