You know the TV ad: “Can you hear me now?” Thinking about those words puts an image of a Verizon technician into my head. There are many people who could not hear him no matter where he stood. But, in the 1950s a new technology called a cochlear implant began to emerge that can bring sounds to some of them.
The implant is different from a hearing aid. Instead of merely amplifying sounds, it uses an external signal processor to change sound into electrical impulses that travel along the auditory nerve to the brain. The implants were meant to bring sound to the soundless.
Early devices were not very useful. Surgeons originally implanted only a single electrode, which did not stimulate much of the auditory nerve. Also, the devices did not act like the auditory nerve and cochlea which, in conjunction, separate frequencies of sound into low, medium, and high ranges. Those who volunteered for the surgery were given the ability to distinguish variable pitch of sounds in the world around them, and became better at lip reading. But, they did not gain the ability to understand spoken words.
The devices have improved considerably over time. More electrodes have been added (current devices utilize 24), increasing the amount of information traveling to the brain. Like individual wires in a telephone cable, there are 30,000 fibers that make up the auditory nerve. Each fiber can carry information. Some of the external receivers now have more than one microphone, so sound can become more directional. The microphones are more sensitive to tone, pitch, and frequency.
Implants aren’t meant for everyone. They aren’t nearly as accurate as the shell-shaped cochlea inside the ear. As in all surgeries, results vary from one individual to the next. Some end up able to hear a doorbell. One or two recipients have reported the ability to carry on telephone conversations.
Implants are not recommended for people who can function with a hearing aid. They aren’t an option for someone who has suffered from hearing loss for a protracted period of time; check with your doctor to see if your auditory nerves are intact and can be stimulated. An implant cannot help if your hearing problem comes from somewhere other than the inner ear. For those looking into getting an implant, there is a cost. While they work wonders to accentuate high frequency sounds, low frequency hearing—if you currently have any—is lost.
For some, the cochlear implant carries a stigma. The device is usually big and bulky. Those who wear them are noticed. Future devices will not be as obtrusive. One being developed by the Massachusetts Institute of Technology will be completely implantable. It will have the ability to process more impulses faster, than current devices. And, its battery will only need recharging every two weeks.
Another device is being put through its paces by Dr. Bruce Gantz at the University of Iowa. Ten years ago, Gantz decided to do something about the frequency gap between hearing aids and implants. He’s developed a device that combines the best features of both technologies, giving users access to both the low frequencies hearing aids can pick up and the high frequencies that implants are best used for (Click here for more information on Dr. Bruce Gantz's device).
If you would like to know more about hearing loss in general, visit the website for the Hearing Loss Association of America. For more specifics about advances in cochlear implants, one of the best places is the Cochlear Implant Research Lab at the Massachusetts Institute of Technology. Finally, to participate in a study examining the effectiveness of a fully implantable device under development, contact Otologics,Inc.
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