A cochlear implant is a small electronic device that can help improve the hearing of people with severe, irreversible hearing loss. A surgeon places the implant in the inner ear, and it is activated by a component worn outside the ear.
Although cochlear implants don't fully restore hearing, they can allow a person to hear and understand more sounds than what a hearing aid makes possible. For a child who is deaf or hard of hearing, having cochlear implants could provide them with the opportunity to go to school alongside hearing students and develop listening and speech skills. For an adult with moderate to profound hearing loss, cochlear implants can improve their quality of life by allowing them to keep up with conversations and hear alerts and alarms.
In normal hearing, parts of the inner ear, or cochlea, convert soundwaves into electrical impulses. These impulses travel to the brain, which recognizes them as sound.
In most people who develop hearing loss, the hairs in the cochlea have become damaged or missing, usually as a result of aging and repeated exposure to loud noises, or for genetic reasons. That disrupts the efficient transmission of electrical signals to the brain, resulting in hearing loss. A cochlear implant bypasses damaged parts of the cochlea and stimulates the auditory nerve directly.
The Cochlear Implant System
● Microphone and transmitter: The transmitter, worn outside the ear, is approximately the size of a quarter. It picks up sounds, which then travel to a speech processor.
● Speech processor: A person with a cochlear implant wears their speech processor externally, either hooked to a belt like a badge or behind their ear like a hearing aid, to convert sound into a digital code that gets transmitted to an implanted stimulator.
● Implanted stimulator: The implanted stimulator is a small component placed under the skin behind the ear. It receives information from the speech processor and sends it to the auditory nerve. The brain interprets this signal and recognizes it as sound.
A magnet coupled to the implanted stimulator holds the transmitter in place on the wearer's head, behind the ear where the implanted stimulator is located.
How Does the Cochlear Implant Work?
Cochlear implants allow people to hear by receiving and processing sounds and speech. The internal and external devices work together to change sound into electrical signals that stimulate the hearing nerve.
● First, the microphone on the external device picks up the sound energy. The speech processor then filters, analyzes and converts the soundwaves into a digital code.
● That signal travels through the cable to the headpiece, which transmits it across the skin to the internal receiver via radio frequencies.
● Then, the internal receiver sends the signal to the electrodes implanted inside the cochlea.
● The electrodes transmit small electrical pulses that stimulate the auditory nerve, which attaches to the cochlea. By triggering the auditory nerve directly, the cochlear implant circumvents the damaged parts of the cochlea that lead to hearing loss.
● The auditory nerve then carries the electrical signals to the brain, which interprets them as sound. This entire process occurs so quickly that the listener will hear speech and other sounds without any noticeable time lag.
Cochlear Implant Candidates
In general, the best candidates for cochlear implants share these characteristics:
● Being in good overall health
●Having realistic expectations for the results of their surgery
● Experiencing profound hearing loss in both ears
●Are no longer benefiting from conventional hearing aids
●No medical conditions that would make surgery too risky
●A willingness to participate in listening and speech therapy
Frequently Asked Questions About Cochlear Implants
If you're exploring cochlear implants for yourself or your child, our guide to cochlear implant surgery can help.
Will cochlear implants fully restore hearing for deaf people?
No, a cochlear implant is a valuable communication tool, but not a cure for deafness. When hearing functions normally, parts of the inner ear convert soundwaves into electrical impulses. These impulses travel to the brain, which interprets them as sound. A cochlear implant replicates that process. Implants, coupled with listening therapy, can help people recognize sound, including speech.
What differentiates cochlear implants from hearing aids?
Hearing aids work to amplify sound, but people with severe to profound hearing loss may have trouble understanding speech and other sounds, even with powerful hearing aids. Cochlear implants bypass the damaged part of the ear and send sound directly to the hearing nerve.
Given time and training, most cochlear implant recipients demonstrate improvement in their ability to understand speech, even in noisy surroundings, compared to people who wear hearing aids. They may even be able to talk on the phone or listen to music.
Are cochlear implants safe?
Cochlear implants have been in use since the 1970s, and several types of devices have received FDA approval for use in children and adults.
What happens during cochlear implant surgery?
Cochlear implant surgery is fairly routine and typically performed under general anesthesia. The surgeon will make a small incision behind the ear, and will sometimes need to shave a tiny patch of hair away from the incision site.
Next, the surgeon places the implant under the skin and inserts the electrode into the inner ear. The surgeon will close the incisions, often with disposable stitches, so there may be no need to return later to have your stitches taken out. Following cochlear implant surgery, the surgical team will perform tests to measure your response to the implant.
How long does a cochlear implant operation take?
In most cases, getting a cochlear implant is an outpatient procedure that takes around two hours per ear.
Are there risks in cochlear implant surgery?
Risk is inherent in any surgery. However, the surgical risks associated with cochlear implantation are minimal.
If new advances in hearing technology become available, will I need follow-up surgery to replace my cochlear implants?
The implanted unit is a lifetime device. The externally worn speech processor, which is responsible for translating soundwaves into code and sending the information to an internal implanted simulator, relies on software that you can have upgraded as technology improves.
Will my child outgrow the internal implant and need a new one?
No. Babies are born with fully formed cochleas, and the skull structures attain almost complete growth by age 2. The design of the electrode array accounts for skull growth in younger patients.
Should I wait for cochlear implant technology to improve?
No, the design of the surgically implanted receiver and electrode array has changed relatively little during the history of cochlear implants. However, speech-coding strategies, which are responsible for delivering the signal to the internal unit and are stored in the externally worn speech processor, have improved significantly over the years. The speech processor can incorporate new technology when available.
Are there any activity restrictions people who have cochlear implants should be aware of?
People with implants can shower, swim and enjoy playing virtually any sport when they are not wearing the external components of their system. The only restrictions are participating in scuba diving and skydiving, due to the pressure changes associated with these activities.
You can resume airline travel within a week or two of getting surgery, as long as you don't experience any surgical complications. However, the equipment may activate the metal detectors at the airport, so you'll need to carry your cochlear implant medical ID to help you clear the security screening.