Common questions about cochlear implants
What is cochlear implant?
A cochlear implant is a device designed to help severe to profoundly deaf individuals who gain little or no benefit from hearing aids.
With their cochlear implant they gain awareness of environmental sounds, most can understand speech without lip-reading and some can use the telephone.
The cochlear implant system converts acoustic sound waves into weak electric currents, which are delivered to the immediate vicinity of the auditory nerve in the inner ear or cochlea.
The auditory nerve is stimulated by these electric currents and transmits nerve impulses to the brain, where they are understood as acoustic sensations.
- If a patient suffers from nerve deafness, does this mean that his hearing or auditory nerve is destroyed?
No, the auditory nerve may still potentially function even in cases of nerve deafness; in most cases the auditory nerve is intact (or partially functional), but the hair cells in the cochlea are damaged or destroyed.
Normally, when sound waves reach the ear they are converted into electric currents by tiny sensory hair cells. The auditory nerve responds to the electric current and passes it on to the brain. We experience this as "hearing".
If the hair cells are damaged, there is no mechanism to convert the sound waves into electric currents, and without electric current the nerve is not stimulated. As a result nothing can be heard.
- How can the cochlear implant help?
The cochlear implant conveys weak electric stimuli to the vicinity of the auditory nerve. The electric stimulus activates the nerve, which then transmits a signal to the brain.
The brain recognizes this signal and we experience this as "hearing".
The cochlear implant has the same function as the hair cells, in that it transforms sound into an electric current that stimulates the auditory nerve.
- How many parts are there to a cochlear implant system?
A cochlear implant consists of two main components:
- The internal component, Cochlear Implant, which is implanted surgically, and
- The external components, Speech Processor, Microphone & Transmitter Coil, which are worn outside the body.
- What does the internal component consist of?
The inner component or implant package contains an induction coil and an electrode array.
With surgery this implant package is implanted in the temporal bone behind the ear. The electrode array is introduced into the inner ear (cochlea).
An electric current across the electrode array activates the auditory nerve and the result is that you "hear".
- What is the purpose of the external component of the cochlear implant?
The external part converts sound waves into electric signals.
It consists of a microphone, a small speech processor and an external coil.
- The microphone picks up the sound waves and transforms them into weak electric signals.
- The speech processor modifies these electric signals.
- The external coil receives the electric signals via a cable. If the external coil is placed over the internal coil, signals will be transmitted through the intact skin to the implant and electrode array
In this way the auditory nerve is stimulated, which results in acoustic sensations.
- Can the speech processor be removed at night?
Yes, the speech processor can be removed at night. However, it should then be switched off, so as not to exhaust the battery.
The speech processor may be worn through the night if desired - some users like to 'keep in touch' with the hearing world even when asleep.
- Is hearing absolutely normal with a cochlear implant?
No. From individuals who could hear before they were deafened we know that the acoustic impressions from a cochlear implant differ from "normal hearing".
Users initially describe the sound characteristics with words like "mechanical", "technical", and "synthetic".
This perception changes over time, most users do not notice this artificial sound quality after a few weeks.
- How long does it take before the user derives the maximum benefit from a cochlear implant?
From research we know that the performance of individuals can be quite different. However benefits start immediately.
For adults, performance reaches a plateau at about 3 months after the initial tuning sessions and continues to improve at a slower rate.
In children improvement is at a slower pace. A lot of training is needed after implantation to help the child use the new ‘hearing’ he/she now has.
- What acoustic signals can be perceived with a cochlear implant?
With a cochlear implant most acoustic signals of medium and high intensity can be perceived as well as quieter sounds.
Patients report that they can perceive footsteps, slamming of doors, sounds of engines, ringing of the telephone, barking of dogs, whistling of the kettle, rustling of leaves, the sound of a light switch being switched on and off, and so on.
- Are users able to understand what is being said without looking at the speaker?
A large number of users are able to understand speech without lip-reading. However, even in cases where this is not possible, there is some improvement in lip-reading with the implant.
- Does the cochlear implant facilitate lip-reading?
Yes, users are able to perceive characteristic sound patterns of speech, the addition of these impressions to the observation of movements of the mouth and face facilitates lip-reading.
The degree of help for lip-reading depends on the patient's practice in dealing with acoustic signals and speech.
- Are users able to make a telephone call?
Many users are able to make telephone calls and understand familiar voices over the telephone. Some good performers are able to make normal telephone calls and even understand an unfamiliar speaker. However, not all users are able to use the phone.
- Does the cochlear implant help in watching TV or in listening to the radio?
For many users the cochlear implant does make watching TV easier - especially when you can also see the speaker's face. The radio is more difficult as there are no visual cues available.
- Can a user listen to music?
Some users are able to enjoy music. Some enjoy the sound of certain instruments (piano or guitar, for example) and certain voices.
For others, the information transmitted by the implant may be insufficient to allow them to fully enjoy music.
- Are there any unpleasant sounds?
During the speech processor tuning the clinician will perform certain tests to find out when a patient experiences acoustic signals as being unpleasantly LOUD .The speech processor is then adjusted so that no acoustic signal reaches this point.
- Does the cochlear implant influence tinnitus?
Many users find that tinnitus decreases while their device is operating. Usually tinnitus decreases only on the implanted side, and for many users it remains reduced even when the speech processor is not switched on.
Most users experience a lessening of tinnitus, in some cases it remains unchanged and there have been reports of rare cases where it is worse.
- Since when have cochlear implants been in use?
The first experiment with electrical stimulation was undertaken in France in 1950. From the late 1970s there have been an increasing number of cochlear implantation's each year. The first truly commercial devices were available from the early 1980s.
- Do those who have an implant system use it?
The great majority of implanted persons use their processor regularly from morning to night.
- What can children receiving a cochlear implant be expected to achieve?
Since children are better able to utilize new information than adults, they can also be expected to benefit more from a cochlear implant.
A very limited hearing can have a considerable influence on a child's ability to learn to talk and on overall development. The speech of most children with cochlear implants is of better quality and more intelligible than their peers using acoustic hearing aids.
- Is there a difference between the results of implantation in adults and children?
Children who are implanted at a very young age or adults who became deaf after learning to talk - i.e. with post lingual deafness - respond better to the implant than adults with congenital deafness (born deaf) or pre lingual deafness.
- How can I help my child to use the cochlear implant profitably?
The best way of helping children to use their cochlear implant is to make hearing as interesting as possible for them.
This requires a great deal of patience and training. They have to be shown how they can consciously use and evaluate the acoustic information that they receive from their cochlear implant.
- What other requirements have to be fulfilled prior to an implantation?
A medical examination is necessary to ensure that the patient is appropriate to undergo surgery.
The patient is likely to have scans of their head to ensure that the cochlear implant array can be inserted.
Many Audiology tests are also required to rule out the possibility that the patient could not benefit from a change in hearing aids or additional counselling.
- Can the patient hear immediately after the operation?
No. Without the external coil and the speech processor the patient cannot hear. These components are fitted about a month after the operation, at the initial tuning session.
- Why is it necessary to wait 3 to 6 weeks after the operation before beginning the training?
A waiting period is necessary for the operative incision to heal completely. This usually takes 3 to 6 weeks. When the swelling has subsided, the initial fitting or programming of the processor can be done.
- What happens during the basic program?
The basic program consists of 3 phases:
- During the speech processor tuning the clinician will perform certain tests to find out when a patient experiences acoustic signals as being unpleasantly LOUD .The speech processor is then adjusted so that no acoustic signal reaches this point.
- Audiology tests are necessary to check whether the adjustment is correct and to find out what the patient perceives, before training is begun.
- Familiarization with the use of the device and aural training.
- How important is the active cooperation of the patient?
The patient's readiness to experience new and more detailed acoustic impressions and active cooperation in the training program are of decisive importance for the degree of success. The extent and the duration of the training differ from patient to patient.
- Is it beneficial if someone who is close to the patient takes part in the training program?
If possible, yes. This person should be included in the training program so as to be able to help the patient with the exercises. Such a person should also know how to handle the processor.
The information on this website is for educational purposes, and is not intended to replace medical advice. Please consult a hearing healthcare professional to diagnose or treat a hearing or health problem.
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- If a patient suffers from nerve deafness, does this mean that his hearing or auditory nerve is destroyed?