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Tell me about Cochlear Implants
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What is a Cochlear Implant?
A cochlear implant is a device that provides hearing sensations for severely and profoundly
deaf individuals who derive no significant benefit from hearing aids.
The NZ Cochlear Implant Programme
This was established in 1986 with funding provided by the Deafness Research Foundation (Inc).
The programme was based at the Auckland District Health Board with a satellite clinic in
Christchurch (as of 1988). It has provided cochlear implants for adults and children
throughout NZ.
In 2003, a North Island and Southern Cochlear Implant Programme became established to
better meet the needs of an increasing number of potential and actual cochlear implant recipients.
These two programmes function independently of each other but there are still strong links
between the two groups.
What are the benefits of a Cochlear Implant?
Recipients of a cochlear implant obtain a wide range of sound information and auditory
experience including:
- Improvement in the detection of environmental sounds, such as a knock on the door, t
he doorbell, or telephone ringing, traffic noise, kitchen utensils, dogs barking and
background music.
- Increased ability to recognise speech with lip-reading.
- Improvement in voice monitoring and speech production.
- About 70% of cochlear implant users are able to understand speech using hearing alone,
- Most implant users report increased ease
and enjoyment in communication with family and friends.
Expectations
Following successful implantation of the device, the degree of benefit varies depending on:
- Age of onset of deafness.
- Previous experience of hearing.
- Duration of profound deafness.
- The commitment and involvement of the individual/parents is vital. A cochlear implant
provides severe-to-profoundly deaf individuals with the opportunity to hear the important
sounds of speech. A lot of personal commitment is required to work on how to listen
and to make sense of the sounds.
- On-going habilitation; this includes
attending appointments with the CI team and local professsionals.
What does the cochlear implant consist of?
The entire device consists of two main parts, the implanted electrode array and the externally
worn speech processor equipment.
The cochlear implant is surgically placed in the ear. The package sits under the skin behind
the ear. The fine electrode array is placed into the cochlea.
 Click to enlarge
The speech processor is worn externally. Pictured below are the behind the ear ESPrit 3G and
the body worn SPRint speech processors. These are worn by most implantees as of 2005;
however in mid 2005 the processor and internal device will be replaced with new technology.
Behind-the-ear ESPrit 3G
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Body-worn SPRint
Click to enlarge |
How does it work?
Speech and environmental sounds are picked up by the sensitive microphone of the external
speech processor. The sound is converted into a digital signal by the processor and sent to
the implant via the transmitting coil. The coil sits over the implant package and is held in place
by magnet attraction between the internal and external magnets. The digital signal is received
by the implant package and a code of electrical signals is sent to the active electrode array in
the cochlea. The sensory hearing cells in the cochlea (spiral ganglion cells) are electrically
stimulated and a nerve impulse is sent along the auditory nerve which is perceived in the
auditory cortex as a sound.
Who is a candidate?
A cochlear implant may be considered when a hearing loss is so great that no significant
benefit is obtained from a hearing aid. There is no minimum age for implantation; however,
there is a minimum weight restriction due to the nature of the surgical procedure involved.
In general, the shorter the period of auditory deprivation, the better. Once is it established,
through methodical audiological testing, that no benefit is being obtained from a hearing aid,
a cochlear implant should be considered as soon as possible.
Congenitively deaf children, who are three years of age or more, need to have been fitted
with hearing aids and started to develop speech and language in order to benefit from a
cochlear implant and may not be considered a suitable candidate for a cochlear implant.
How can I get referred?
A referral to the programme can be made by any of the professionals listed below:
- Audiologist
- Ear, Nose, and Throat (E.N.T.) Specialist or Otolaryngologist (ORL)
- Adviser on Deaf Children
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