What is a cochlear implant?
A cochlear implant is a surgically implanted device for the hearing-impaired. It is the first implantable technology able to restore a human sense - hearing. Unlike a hearing aid that amplifies sound to make it loud enough for an impaired ear, a cochlear implant bypasses the damaged area and sends sound signals directly to the auditory nerve.
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The internal component has two main parts (neither are visible from the outside):
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A receiver-stimulator [3] placed under the skin behind the ear
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An electrode array [4] sitting within the inner ear
- The external component has two main parts:
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A speech processor [1] which may be worn behind the ear or on the body
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A transmitter coil [2]
For some systems a remote assist device is also available to control the speech processor
How does a Cochlear Implant work?
Cochlear implants allow different parts of the inner ear to respond to different frequencies (pitch) of sound. The electrode array is placed within the inner ear. Each electrode of the array stimulates a different section of the inner ear corresponding to different frequencies.
When sound reaches the speech processor it is broken down into various components. This information is then passed to the transmitter coil and sent to the implanted receiver-stimulator. The receiver-stimulator sends this information to the appropriate electrodes in the inner ear. This signal stimulates the inner ear nerves and the information is passed to the brain.
Types of Cochlear Implant
Currently there are two main types of Cochlear Implant, a full array Cochlear Implant and a Hybrid Cochlear Implant.
Full array Cochlear Implant
In this particular implant the electrode array is advanced further into the inner ear allowing stimulation of a wide range of frequencies thus maximising the amount of information that can be provided electronically to the nerve of hearing.
Hybrid Cochlear Implant
This system utilises a shorter electrode array. As it is inserted a shorter distance into the inner ear it predominantly stimulates the nerves associated with mid and high frequency hearing. By using a shorter electrode array there is a greater possibility of preserving residual natural low frequency hearing in the operated ear. In this case a hearing aid is built into the speech processor allowing acoustic stimulation of the residual hearing. This combined electrical and acoustic stimulation confers advantages in some situations.
When is a Cochlear Implant considered?
A cochlear implant may benefit people who have a moderate to profound sensori-neural, or inner ear, hearing loss, particularly when conventional hearing aids no longer provide good understanding of speech. Such people may include those with a progressive or sudden hearing loss. Adults considering a cochlear implant usually need to have had some hearing in the past and have developed spoken language skills.
There are very few factors that contraindicate cochlear implantation. Frailty, other medical problems, language difficulties and previous surgery may be an impediment.
Our centre is structured to provide private cochlear implantation services to adults only. Public cochlear implantation services for adults are available through the Flinders Medical Centre. Children's cochlear implantation services are available through the Women’s and Children’s Hospital.
Read about the implant process and operation
Expected outcomes
A cochlear implant does not provide normal hearing and the degree of benefit varies considerably between individuals.
Generally the results are best when the potential recipient already has good spoken language skills. Most recipients develop the ability to understand speech well using a cochlear implant alone. Others find it a benefit if used in conjunction with either lipreading or a hearing aid in the opposite ear. Other advantages include an improved awareness of environmental sounds.
In ALL cases a successful outcome requires a strong commitment from both the recipient and their family and hard work through the switch-on and rehabilitation process. A cochlear implant is not a “plug in and switch on” device. There is a considerable learning process that needs to be undertaken.
This learning, training and improvement process is initially intensive and can continue throughout life.
View FAQ about cochlear implantation