ASU Research E-Magazine: Sounding Better All the Time

Kay Basham sits before a grand piano in ASU’s School of Music and performs a beautiful rendition of Andrew Lloyd-Webber’s “Music of the Night.” She makes few if any mistakes. Listening to her play, you would never guess that, technically, Basham is deaf. That fact is amazing in itself. Even more amazing is that the one time Basham does hit a sour note, it takes all of her willpower not to wince—she hears it as well as anyone else!

Ten years ago, Basham could not hear a single note she played. At the time, it seemed as if the piano teacher from Bettendorf, Iowa would have to give up the music career she adored. But today, with the help of six tiny electrodes implanted deep inside her inner ear, Basham can teach, perform, and enjoy music again.

Basham is one of eight patients working with Michael Dorman, an ASU professor of speech and hearing science. Each of these hearing-imparied patients received a cochlear implant about 10 years ago.

The cochlea is a tiny spiral-shaped chamber within the inner ear. It is the essential organ for hearing in humans. Millions of nerve endings within the cochlear spiral connect directly to the auditory nerve. Implants electrically stimulate these cochlear nerves.

Within the past two years, Dorman has refitted each patient with a new, improved processor. The new processors improve function of the implants.

“Implants have been around since the 1970s,” Dorman explains. “What’s interesting from the technology viewpoint is that we’re getting better at making them. As technology improves our patients do better. We want to know how much better they’re doing, and why they’re doing better.”

Several times a year, the eight individuals visit Dorman at his ASU laboratory. He uses a variety of hearing tests in a search for answers.

Dorman tests each person’s ability to recognize everything from single vowels and consonants to complete sentences. The results describe, quantitatively, how much better the patients hear with the new processor. The patients, however, describe the difference in a more qualitative sense.

“This one’s much more clear,” says Basham, describing her new device. “The processor can reproduce sound in a much more normal manner. Also, the microphone is so much better that I can hear things from a greater distance.”

Basham can also hear a wider range of sound. “What I do hear is much easier to sort out from the rest of the environment,” she adds.

“What really excites me about this new device is that I can use the telephone more efficiently,” says Bobby Hise, a minister from Lubbock, Texas. “I could make it work with the old device. I could hear the phone ring. I could say hello. And I could ask a question where I anticipated some part of the answer.” Using the new device, “I can get phone calls from anybody and talk about anything.”

An Austrian company called Med El manufactures the new, improved cochlear implants that Dorman is testing. A group at the Research Triangle Institute in North Carolina developed the underlying technology. Dorman collaborates with the group. Their work is supported by the National Institutes of Health.

Dorman tests the new device as part of a project aimed at getting approval from the Food and Drug Administration to market it in the United States. Without the new implant, Dorman’s patients would be stuck with 1970s technology. The original manufacturer of cochlear implants no longer supports the product.

“It’s a story about corporate greed,” Dorman explains. During the early 1970s, implant technology had gotten to a point where companies began to take an interest in manufacturing the devices for commercial use.

About 200 people received an implant devised and tested as part of a clinical trial for FDA approval. But the product was never approved.

“The principals in that particular company really thought that they would hold the company for a short time, and then sell it. They never put money into research and development,” Dorman says. While waiting for FDA approval, they sold the product to another medical company. Unable to get the hearing implant approved, the second company sold it to yet another company.

“But they too, literally had only money to lose, unless they could get FDA approval,” Dorman continues. They didn’t.

“There are 150 to 200 ‘orphan’ patients wandering around with a device that nobody wants to work on because they can’t make any money off of it. We decided to help ourselves and those patients by giving them a new implant as a ‘research only’ device.”

The original 200 patients are ideal for Dorman’s research because of the nature of their first implants. Most cochlear implant systems are subcutaneous, meaning that the device’s receiver is implanted completely under the skin. On the outside, a radio frequency transmitter is held against the implant with a magnet. The transmitter is connected by a thin cable to a processor that looks something like a Walkman(TM) radio.

Today, Dorman’s patients all use a percutaneous device. The connector to the implanted electrodes actually protrudes through the skin just above and behind the ear. All of the electronics for signal processing are housed outside of the body. The processing unit connects to the implant by “jacking in” to the connector, known as a pedestal, that protrudes through the skin.

To update a subcutaneous device, a doctor would have to surgically implant a new receiver. But updating the percutaneous device is easy—Dorman simply plugs the new processor into the existing pedestal.

Ironically, the pedestal that makes Dorman’s work possible may be the reason the original device never received FDA approval. Although nobody knows the exact reason the device was turned down, Dorman suspects that the FDA saw the pedestal as an infection hazard because it protrudes through the skin. If the new processor is approved, it will be marketed as a subcutaneous device.

“Companies have decided that it’s more cosmetically sellable to have nothing sticking through the skin,” says Dorman, noting that the skin around the pedestal can become red and irritated. “The skin can look a little messy.”

Based on the results of Dorman’s research, however, the FDA recently allowed patients fitted with the original implant to use the new processor with their existing pedestals. This will allow all of the original implant patients to benefit from findings made by Dorman’s research group.

“The new implant has really allowed me to live an independent life,” says Kay Howell-Ellis, a former nurse from Indian Hills, Colo. About two years before she received her implant, her husband was diagnosed with terminal brain cancer.

“Before he died I was aware that I was going to be living alone,” Howell-Ellis explains. “I didn’t have the cochlear implant at that time. I wondered how I was going to function. We decided to go ahead and have my implant while he was still alive. I think it was something of a boon to my late husband to know that I wasn’t going to become a total hermit.”

Today, Howell-Ellis enjoys the freedom that her hearing allows. “I still have my own home. I still do my own gardening. I can shop. I can make my own appointments,” she says.

The new implant technology has added even more independence to Howell-Ellis’ life. “I can talk on the phone now,” she says. “I can hear and understand people talking beside me or behind me most of the time. With the original implant, I pretty much had to stop what I was doing. I had to look at the speaker and use lip-reading a lot more than I do now.”

Dorman attributes the improvements in cochlear implant technology to a pair of factors. First, the new implants use more electrodes. These electrodes are implanted inside the cochlea deep within the inner ear itself. They create an electric signal in response to the vibrations of a sound. This impulse is carried along nerve fibers directly to the brain.

Each electrode is mapped to a certain range of frequencies. Original implant devices had six electrodes, but used only four. New devices take advantage of all six electrodes, allowing for reception of a greater range of frequencies.

Dorman is quick to point out, however, that more electrodes are not always better. “It turns out you only need about six or eight electrodes to reproduce speech perfectly well,” he says. “In fact, a person can understand sentences with only four electrodes. Part of what I do is an attempt to figure out why a person can do that at all. It doesn’t seem enough.”

Another benefit of the newer technology is the processor design. With older implants, the electrodes received signals simultaneously, causing interference between the currents.

New implant devices stagger the impulses so that no two electrodes are receiving signals at the same time. This method significantly reduces the interaction between the different current fields, according to Dorman.

Bobby Hise’s original cochlear implant allowed him to hear and recognize sounds. The new device has made them pleasant again, especially music.

“With the old box I couldn’t stand it,” he says. “Now I just listen to music all the time. I can’t think of any music I’ve listened to that I don’t like. Even rock! I’ve gotten into it.”

Hise never takes hearing for granted now. More difficult is encouraging his students to appreciate this ability. When he is asked to talk to kids about what it was like to regain his hearing, he has a ready response.

“You never will understand what I found unless you know what I lost,” he says.

To demonstrate how many sounds we take for granted, Hise assigns an exercise to the kids. As fast as you can, he tells them, write down every sound you have heard since waking up this morning.

“They’ll say they heard the alarm, they water running, dogs barking, friends talking, cars going by on the street,” he says.

Then he tells them, “You take all that, and you can put a hundred things between each of them. You say you heard the alarm. Did you roll over in bed? Did you hear the sheets ruffle? Did you hear your feet hit the floor?”

Usually, Hise says that eight out of every 10 sounds listed are environmental sounds—not people talking. He says that the loss of those sounds is what disconnects you from the world.

“I can have a relationship with my family and not hear them,” says Hise, who is an expert lip-reader. “But I can’t have a relationship with my world.” —Diane Boudreau