Cochlear Implant - A guide to Hearing Loss

This surgical procedure can improve hearing in adults and children who have severe hearing loss or are completely deaf. It uses a series of electrodes which are implanted into the inner ear to enable electrical impulses to be sent to the brain. These impulses are interpreted by the brain as sound.

Cochlea damage

This is an option for those people who have sensorineural hearing loss as a result of damage to the hair cells within the cochlea. These hair cells normally allow sound waves to be transmitted to the brain but if they become damaged or die then this process is affected which results in hearing loss. The cochlea is a shell-like structure within the inner ear which sends signals via the auditory nerve to the brain. The brain then recognises these as sounds and what we know as hearing. A cochlear implant can bypass this damage by stimulating the auditory nerve to send electrical signals to the brain which are interpreted as sound.

What does a cochlear implant consist of?

A cochlear implant is an electronic package comprised of four parts:

  • Electrodes which are implanted inside the cochlea
  • Microphone and headpiece which sits outside the ear
  • Speech processor which chooses and arranges sounds
  • Transmitter plus receiver which converts these sounds into electrical signals to be sent through the auditory nerve.

Basically there is an internal section which is inserted within the inner ear and an external section which sits just behind the ear.

Microphone: outside the ear

Headpiece: outside the ear

Speech processor: outside the ear Transmitter plus receiver: inside the ear

Electrodes: inside the ear

How does a cochlear implant work?

To summarise: it performs the job of the cochlear and works as follows:

Step 1: the microphone detects sounds from outside.

Step 2: these sounds are sent via a cord to the speech processor which selects and organises these sounds. These sounds are organised according to the wearer’s needs.

Step 3: the transmitter receives this sounds from the speech processor and converts them into electrical signals.

Step 4: these electrical signals are picked up by the electrodes which send these to different areas of the auditory nerve. This are then sent to the brain which recognises these as sounds.

The speech processor has a series of controls which enable the wearer to set the sound levels to their own requirements.

Please note that this does NOT restore your hearing to normal. But what it can do is to enable you to hear sounds and take part in a normal conversation. It also means you can hear the telephone.

How does this differ from a hearing aid?

The main difference is that a hearing aid amplifies sounds whereas a cochlear implant means that you hear everyday sounds and human speech. However it does take a bit of time to adjust to this although children adapt quicker than adults. The reason for this is that the sounds heard via the implant are different to those compared to normal hearing. You will have to get used to the sound sensitivity controls on the speech processor as well as learning (or re-learning) to interpret the sounds heard through the implant. But most people find that they get used to their new form of hearing after a period of time which also boosts their self-confidence.

So, who would benefit from a cochlear implant?

Children who are born deaf, adults who have hearing loss later on in life and anyone not suitable for a hearing aid would gain from having a cochlear implant.

What has been found is that children who are born deaf have benefited from this to the extent that they are able to participate in mainstream education. (Source: Deafness Research UK)

Researchers are currently looking at ways of utilising implants for other types of hearing loss.

Treatments : A guide to Hearing Loss

Hearing Loss

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