A cochlear implant is an electronic device that is partially implanted surgically into the cochlea, the hearing organ of the inner ear. The microphone, processor, and transmitter are worn externally.
Cochlear implants detect sounds via an ear level microphone that conveys these sounds to a wearable sound processor. The processor converts these sounds to tiny digital impulses that provide hearing sensations to the user. Some of the newest sound processors are small enough to fit behind a person’s ear. The electronic impulses from the processor are sent to a coil (half- dollar sized) worn externally behind the ear over the implant. The coil sends an FM signal to the implant receiver, located completely under the scalp.
The implant then directs these sound impulses to an array of tiny electrodes within the cochlea (inner ear). In these signals are information about the frequency and loudness of speech and other sounds. The responses to these signals are then conveyed along the auditory nerve to the cortex of the brain where they are interpreted as sound.
The sound processing units must be specially fitted for their users. Programming sound processors involves measurement of the individual’s sensitivity to the electronic impulses. Other sound quality such as pitch also may be assessed. These responses are used to customize each person’s implant system so that sound is as clear and comfortable as possible for them.
Because of the Cochlear implant, some profoundly deaf patients are able to communicate on the telephone the first day. Modern multichannel implants can provide very high levels of sound recognition to many recipients.
Cochlear Implant Surgery
Cochlear implant surgery frequently is conducted on an outpatient basis. After surgery, it generally takes three to five weeks for the incision to heal. Once healed, the implant recipient is fitted with the other components and the system is programmed to provide appropriate levels of stimulation.
Some patients with tinnitus (ringing in the ears) find that it is reduced after surgery, although it is not the goal of the surgery to reduce or eliminate tinnitus.
Who benefits from Cochlear Implants?
The patient likely to receive the most benefit from a cochlear implant is one who acquires profound deafness after developing verbal language skills and who is implanted within a few years of onset of deafness. Others who may benefit include:
Adults with severe to profound or profound sensorineural hearing loss (“nerve deafness”) in both ears, who receive limited benefit from hearing aids.
Children with a profound sensorineural hearing loss in both ears, who receive little or no useful benefit from hearing aids.
Patients who have no existing medical conditions that would prevent them from having a surgical procedure.
Patients who have the support of friends and family.
Patients who want to be part of the hearing world.
Children who can be enrolled in an educational program that stresses auditory and oral language development.
Patients who are willing and able to make a time commitment of up to one year for the necessary rehabilitation process.