Cochlear Implant

Cochlear Implant

Welcome.

You may be wondering whether a cochlear implant is the best choice for you or someone in your life. This brochure is designed to address many of the questions you may have and to offer basic information on hearing, hearing loss and the stages of the cochlear implant journey.

Cochlear Implant

About Hearing

How Hearing Works

  1. The outer ear collects sound waves and directs them to the eardrum.
  2. The eardrum vibrates with sound.
  3. Sound vibrations move through the ossicles to the cochlea.
  4. Sound vibrations cause the fluid in the cochlea to move. Fluid movement causes the hair cells to bend. Neural signals are created which are picked up by the auditory nerve. Hair cells at one end of the cochlea send low‑pitch sound information, and hair cells at the other end send high‑pitch sound information.
  5. The auditory nerve sends signals to the brain, where they are interpreted as sounds.

About Hearing Loss

The Audiogram

Cochlear Implant

An audiogram is a graph illustrating a person’s usable hearing. It is a measure of the amount of hearing loss that an individual has for each ear. Along the top of the graph, the numbers, which correspond to frequencies, range from 125 to 8000 Hz.

Frequency is expressed in cycles per second, or Hertz. The higher the frequency, the higher the pitch of the sound, for example, 250 Hertz (Hz) sounds like the dripping of a faucet, while the high‑pitched ringing of the telephone is about 8000 Hz.

Loudness is measured in units called decibels. Zero decibels (0 dB) don’t mean “no sound”. It is just very soft. Conversational voice level is around 55 dB, and 120 dB is extremely loud – about as loud as a jet taking off when you are standing just 25 meters away. The numbers along the side of the graph are hearing levels in decibels

During a hearing test, an audiologist presents sounds one frequency at a time. The softest tone at which a person can hear at each frequency is marked on the audiogram at that frequency and intensity. This is called the “hearing threshold”.

Your audiogram is a “picture” of your hearing. It indicates how much your hearing varies from normal. It also indicates if there is a hearing loss, what kind of hearing loss there may be and where the problem might be located.

Conductive Hearing Loss

Any problem in the outer or middle ear that prevents sound from being conducted properly is known as a conductive hearing loss. Conductive hearing losses are usually mild or moderate in degree, ranging from 10 to 70 decibels.

In some cases, a conductive hearing loss can be temporary. Depending on the specific cause of the problem, medication or surgery may be a solution. A conductive hearing loss may also be helped with hearing aids or a middle ear implant.

A blockage or deformity in the middle ear can prevent the bones from vibrating properly.

Sensorineural Hearing Loss

Cochlear Implant

Sensorineural hearing loss results from missing or damaged sensory cells (hair cells) in the cochlea and is usually permanent. Also known as “nerve deafness”, Sensorineural hearing loss can be mild, moderate, severe or profound

Mild to severe sensorineural hearing loss can usually be helped with hearing aids or a middle ear implant. Severe or profound hearing loss can usually be helped with a cochlear implant.

The cochlea does not function properly and is unable to change sounds into the electrical pulses that the auditory nerve needs.

Mixed Hearing Loss

A mixed hearing loss is a combination of a sensorineural and conductive hearing loss. It results from problems in both the inner and middle ear. Treatment options may include medication, surgery, hearing aids or a middle ear implant.

A mixed hearing loss is a combination of a sensorineural and conductive hearing loss.

Neural Hearing Loss

A problem that results in the absence of or damage to the auditory nerve can cause a neural hearing loss. Neural hearing loss is a profound hearing loss and is permanent.

Hearing aids and cochlear implants cannot help, because the nerve is not able to pass on sound information to the brain. In some cases, an auditory brainstem implant (ABI) may help.

The auditory nerve is damaged or missing. Neural impulses cannot be transmitted to the brain.

About Cochlear Implants

What is a Cochlear Implant System?

A cochlear implant system is a medical device for individuals with severe to profound sensorineural hearing loss. For individuals with this type of hearing impairment, hearing aids provide little or no benefit. A cochlear implant system bypasses the non‑‑ functioning part of the cochlea and delivers electrical signals directly to the auditory nerve. Cochlear implant systems can be used effectively by both prelingually and postlingually deafened children and adults.

Implant

Internal – surgically placed under the skin

The implant consists of a housing, which contains the electronics, and the electrode array as well as the receiving antenna and a magnet that holds the coil in place behind the ear.

Audio processor

External – worn behind the ear

The audio processor consists of a control unit, a battery pack, and a coil that transmits information through the skin to the implant.

How a Cochlear Implant System Works

Cochlear Implant

Cochlear implant systems convert everyday sounds into coded electrical pulses. These electrical pulses stimulate nerve fibers in the cochlea. The auditory (hearing) nerve transmits the signals to the brain where they are interpreted as sound. The implant continuously stimulates at very high speed. As the brain receives sound information instantaneously, sounds are heard as they occur.

  • Sounds are picked up by the microphone in the audio processor.
  • The audio processor analyses and codes sounds into a special pattern of digital information.
  • This information is sent to the coil and is transmitted across the skin to the implant.
  • The implant interprets the code and sends electrical pulses to the electrodes in the cochlea.
  • The auditory nerve picks up the signals and sends them to the auditory centre in the brain. The brain recognizes these signals as sound.

Who Can Benefit from a Cochlear Implant System?

Cochlear implants are used successfully in over 90 countries worldwide by both prelingually and postlingually deafened children and adults. While it is not possible to predict exact benefits for each cochlear implant user, the following guidelines are helpful:

Implantation at a young age is highly recommended because hearing is important for language development and because research has shown better outcomes for children implanted at an early age.

Older children and adults with previous speech and language development generally perform better with a cochlear implant.

A long period of profound hearing loss may limit the benefits of a cochlear implant.