The Cochlear Implant Program
What is a cochlear implant?
A cochlear implant is a specialized technology that allows individuals with severe to profound hearing loss to hear and understand sound. The cochlear implant electrically stimulates nerve cells in the inner ear (cochlea) which then sends a signal up the hearing nerve to the brain. In doing so, the cochlear implant bypasses the problem affecting people with severe to profound hearing loss that prevents them from benefiting from hearing aids.
How does a cochlear implant work?
There are two parts to a cochlear implant; an external component which consists of a microphone, speech processor and transmitter, and an internal component which consists of a receiver/stimulator and electrode array.
The implant works in the following way.
- The microphone picks up sound and sends it to the speech processor.
- The speech processor analyzes and codes the signal
- The coded signal is sent to the transmitter
- The transmitter sends the signal across the skin via a magnet to the internal receiver/stimulator
- The internal receiver /stimulator sends the signal to the electrode array in the cochlea
- The electrode array stimulates the auditory nerve and the signal is sent to the brain.
The internal component is placed by a surgical procedure and is in position at all times under the skin. After surgery, the external component is programmed for the patient. It is worn similar to a hearing aid with the person placing the external device in the morning and removing at night before going to bed. The external device is usually worn as an ear level processor that sits behind the ear, or for very young children, a body worn processor may be used.
Who is a potential candidate for a cochlear implant?
- Children and adults with severe to profound hearing loss in both ears
- Individuals who use speech as their primary communication mode and receive insufficient benefit from hearing aids
- Children 12 months (younger in some cases) to 18 years and adults of any age
- Children who have appropriate educational resources and family commitment to success with cochlear implant
- Individuals with appropriate expectations of the benefits of cochlear implants and understanding of necessary follow-up and therapy needed
What steps are necessary to be considered for a cochlear implant?
- Specialized hearing tests completed by the implant audiologist
- For children, speech and language assessment by the implant speech pathologist
- Consultation with the cochlear implant surgeon (otologist)
- Radiology evaluation of the inner ear (CT scan/ MRI scan)
- Specialty consultations for individuals with other medical, developmental problems as needed
- Medical evaluation and clearance for surgery by primary care physician
Hearing aids are a common non-invasive treatment option for hearing loss. A hearing aid is a small electronic device worn in or behind the ear to amplify sounds. While hearing aids are useful in improving listening and communication, they do not cure hearing impairment of make the ear function normally.
A hearing aid is composed of three components: a microphone, an amplifier and a speaker. Sounds are received through the microphone, intensified by the amplifier, and transmitted to the ear through the speaker. The microphone, which picks up sounds from the air, converts them into electrical signals. Once these sounds have been made more powerful by the amplifier, they are changed back into acoustic signals to be heard by the person wearing the hearing aid. In addition to these three components of hearing aids, digital hearing aids also make use of a small computer.
As hearing aids amplify sounds, hair cells within the ear detect these sounds and convert them into signals to pass to the brain. Hearing aids do not work for every person with a hearing impairment. The issues of those with receptive hearing difficulties may not be resolved by hearing aids since the devices are only able to increase volume, not reception. For those individuals, the problem is akin to listening to a radio with static. No matter how loud you turn the volume up, the static remains.
Hearing Aid Styles
There are three basic styles of hearing aids that vary in size, placement and degree of amplification. Determining which style is best for the individual depends on the severity of the hearing loss.
- Behind the ear, or BTE - These hearing aids are worn behind the ear and connected to a plastic mold that is placed inside the outer ear. They are utilized by individuals with mild to profound hearing loss. New technology has introduced a smaller BTE aid consisting of only a small tube placed into the ear canal. This has the advantages of keeping the canal open and protecting the device from damage due to wax buildup. This smaller BTE also provides a clearer sound.
- In the ear, or ITE - These hearing aids are smaller devices that fit inside the outer ear. They can be used for mild to severe hearing loss but are not typically used for children since they will be quickly outgrown.
- Canal - Canal aids are the smallest type of aid and fit either in the canal, ITC, or completely in the canal, CIC. Because canal aids are so small, they may be hard to adjust and have very limited space for batteries and other devices. Canal aids, therefore, are most frequently recommended for individuals with mild to moderate hearing loss.
Individuals considering the purchase of hearing aids should consult with their doctors in order to make the most sensible choice. Since hearing aids are a costly investment, most manufacturers allow a 30-60 day trial period after purchase to make sure the devices are beneficial for the particular patient. To individuals for whom hearing aids work well, resulting in improved hearing and ability to communicate and socialize, they are a very worthwhile investment.