What is a Cochlear Implant?

It is an electronic device that transforms acoustic signals into electrical signals that stimulate the auditory nerve, thus correcting the hearing deficit.

How does it work?

The sounds are picked up by the speech processor’s microphone. It analyzes and digitizes this sound into coded signals.
Different cochlear implants have different ways of processing sound. This is what we call speech coding strategies.
The two main ways to digitize sound are:
1. Extraction of sound characteristics: digitizes the selected parts of the sound signal.
2. Whole sound strategies: digitize all sound information.

Once encoded, the signals are sent from the speech processor to the transmitting antenna.
The transmitting antenna sends these signals to the inner (implanted) part by means of radio frequency waves.
This internal part activates the electrodes and these stimulate the auditory nerve. The excited nerve fibers carry the signal to the cortex that interprets it.

This entire process is carried out through the different parts of the Cochlear Implant, which are divided into External and Internal.

  • External:
  • Microphone: Picks up the sounds.
  • Processor: Selects and encodes the most useful sounds for language comprehension.
  • Coil: Sends the encoded sounds to the inner part by radio frequency.
  • Receptor-Stimulator: Sends electrical signals to the electrodes. It is implanted in the temporal bone, behind the pinna.
  • Electrodes: They are inserted inside the cochlea (inner ear) and stimulate the nerve cells that are still functioning. These stimuli pass through the auditory nerve to the brain, which recognizes them as sounds and then has the sensation of hearing.

Who benefits from the cochlear implant?

  • Those who have profound sensorineural hearing impairments and some severe loss of both ears (bilateral).
  • Patients in whom the use of conventional hearing aids is not useful or who obtain little improvement with them.
  • The maximum benefit is obtained in cases of postlingual deafness (those patients in whom the deafness occurs after having acquired language).
  • In cases of prelingual deafness (before the acquisition of language) it is advisable to apply the cochlear implant to children as soon as possible, preferably between the first and second year of life.
  • The candidate for a cochlear implant must not suffer from any serious disease or significant general pathology that prevents the operation.
  • It is very important that the patient has a real interest and hope in hearing again, and that he or she has the support of family, friends, etc.
  • It is useful in both children and adults.

Cochlear implant surgery

It consists of the implantation of electrodes and the fixation of the implant recipient. The external part will be placed one month after the operation as healing is necessary. The operation is quite safe, however, as in any operation, some problems such as infections or poor healing may be encountered.

Cochlear implant programming

How does the Cochlear Implant help the patient?

  • Recovers the ability to feel auditory.
  • The ear distinguishes different sounds or noises.
  • Initially, everyday sounds and noises are better perceived, such as the doorbell, the telephone ring, ambient music, the noise of cars and horns, ambulance sirens, dog barking, etc., and in some cases the understanding of the word.
  • Improves the follow-up of normal conversations, with lip reading initially supported. Then it will be complementary help.
  • With good training you can get to use the phone.

Pre-implant clinical tests

Before placing a cochlear implant, a series of tests must be carried out to determine to what extent the patient’s hearing can be restored.

Some of these tests are:

  • Tonal audiometry (pure tones) and vocal audiometry (words), to know the patient’s degree of hearing and the level of discrimination of the conversation.
  • Otoacoustic emissions and auditory evoked potentials.
  • Hearing aid effectiveness assessment.
  • X-ray: a radiological study by means of a CT scan of the cochlea is required to know its state of permeability and if there is any degree of malformation of the same and/or Brain Magnetic Resonance to see the auditory nerve and cochlea.
  • Psychological study and degree of motivation to solve their deafness, neurological and speech therapy, genetic study and blood tests, etc.

Cochlear Implant Placement

It is performed by means of a surgical intervention, under general anesthesia. It is currently performed with little surgical risk.

The patient remains normally hospitalized for one or two days in the clinic, being able to return home on his own, and with few postoperative problems.

Possible risks and complications

They are normal for any surgical intervention under general anesthesia.

The possibility of not being able to implant is very low. One of these cases is when the cochlea does not exist or there is no auditory nerve.

After the intervention

A month after the intervention, the speech processor is programmed with the help of a computer.

It is important to know that the sounds, after the placement of the Cochlear Implant, do not “sound” as before. For this reason, and for there to be a perfect adaptation on the part of the patient, post-operative speech therapy rehabilitation is essential.

Cochlear Implant Rehabilitation

Its purpose is to ensure that the patient gets the most out of their Cochlear Implant. To do this, they must become familiar with it and learn to use a new sound code that will lead them to better communication with the environment.

This learning is carried out during several weekly sessions, the first months after the placement of the Cochlear Implant, and is carried out by personnel specialized in rehabilitation with Cochlear Implants.


implante coclear