What is a cochlear implant?
A cochlear implant is an electronic medical device that replaces the function of the damaged inner ear. Unlike hearing aids, which make sounds louder, cochlear implants bypass the damaged hair cells of the inner ear (cochlea) to provide sound signals to the brain.
Who can they help?
The cochlear implant technology can help people who:
have moderate to profound hearing loss in both ears
receive little or no benefit from hearing aids
score 50% or less on sentence recognition tests done by hearing professionals in the ear to be implanted
score 60% or less on sentence recognition tests done by hearing professionals in the non-implanted ear or in both ears with hearing aids.
Many people have cochlear devices in both ears (bilateral). Listening with two ears can improve your ability to identify the direction of sound and separate the sounds you want to hear from those you don’t.
Many people suffer hearing loss because their hair cells in the inner ear or (or cochlea) are damaged. The cochlear implant enables the sound to be transferred to your hearing nerve and enables you to hear. The process is described below:
1. A sound processor worn behind the ear or on the body, captures sound and turns it into digital code. The sound processor has a battery that powers the entire system
2. The sound processor transmits the digitally-coded sound through the coil on the outside of your head to the implant.
3. The cochlear implant converts the digitally-coded sound into electrical impulses and sends them along the electrode array placed in the cochlea (the inner ear).
4. The implant's electrodes stimulate the cochlea's hearing nerve, which then sends the impulses to the brain where they are interpreted as sound.
What are the benefits of a cochlear implant?
Many adults with cochlear implants report that they:
Hear better with a cochlear implant than with a hearing aid
A previous study has shown that people with a cochlear implant achieve an average of 80% sentence understanding, compared with 10% sentence understanding for hearing aids1.
Can focus better when in noisy environments.
Find it easier to have conversations with people across meeting tables, in restaurants and other crowded places.
Reconnect with missed sounds that they could not hear before their cochlear implant.
Feel safer in the world as they can hear alarms, people calling out and approaching vehicles.
Talk and hear on the phone.
What factors can affect these benefits?
The benefits of cochlear ear implants are often different for different individuals. These differences are often due to:
how long they have had hearing loss before receiving a cochlear implant
how severe their hearing loss is
the condition of their cochlea (inner ear)
the presence of other medical conditions
how much practice they include in everyday life when using their cochlear implant system.
What is the process for getting an implant?
A potential cochlear implant candidate should visit an ENT physician or an audiologist for a referral to a cochlear implant center. At the center, the candidate will undergo audiological and psychological testing, a medical exam and imaging studies to determine if they will benefit from a cochlear implant. There will also be counseling for the candidate, to make sure he or she - or parents, for a child - understand the large follow-up commitment required after the implant surgery, as well as what to expect regarding device performance and limitations.
After a child or adult is considered a viable candidate, he or she will undergo the implantation surgery, which is done under general anesthesia. It typically takes between two and four hours and most people spend one night in the hospital afterward. When they leave the hospital, the person will not be able to hear yet. Although the internal components have been placed, the surgical site must heal before the external device is placed.
About four to six weeks after the surgery, the patient will return to the cochlear implantation center to be fitted with the external device. At this appointment, the audiologist will activate the cochlear implant and begin the process of mapping the processor for the individual's specific needs. When the cochlear implant is "turned on," this is the first time many children and adults are experiencing sound. Whether first hearing a spouse's voice, their own voice, a parent's voice or the audiologist, it's quite an emotional and memorable milestone for the patient or parent.
This first appointment will be followed by other fine-tuning and adjustments to the cochlear implant map as the patient begins his or her new hearing journey. Many individuals need several follow-up visits over a few months to adjust the mapping of the signals to the electrodes, as well as to help the person become accustomed to his or her device. Especially for those who've never heard sound before, an auditory training program is necessary to help the brain learn how to process the new auditory stimulation. Much like hearing aids, individuals will want to schedule regular visits with their audiologist for occasional adjustments and hearing tests.