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About Audiology

 

Tell me about Cochlear Implants

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, the doorbell, or telephone ringing, traffic noise, kitchen utensils, dogs barking and background music.
  • Increased ability to recognise speech with lip-reading.
  • An improved ability to understand speech using hearing alone.
  • Improvement in voice monitoring and speech production.
  • 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:

  1. Age of onset of deafness.
  2. Previous experience of hearing.
  3. Duration of profound deafness.
  4. 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.
  5. 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.

Nucleus CI24RE(CA) Implant
Click to enlarge

The speech processor is worn externally. Pictured below are the Freedom BTE and Freedom Babyworn speech processors.


Nucleus 5
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Freedom Babyworn
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 it is 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.

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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