What is a cochlear implant?

People have been having cochlear implants for decades now but like with all technology – there has been many advancements over the years with implants getting better and better.

There are two main parts to a cochlear implant – the internal part and the external part.

The External Part.

This is called a behind the ear (BTE) audio processor which collects the sound waves from next to the ear via a microphone and transfers this into electrical impulses and sends these down the wire to the transmitter which sits on the skin above the receiver using magnets. The sound is relayed to the receiver using radio waves.

The Internal Part.

The internal part is made up of a ‘package’ (the receiver) which is probably roughly the size of a two pound coin and a long thin silicon ‘tail’ which contains the electrodes at the end of it. This part of the cochlear implant can only be inserted via surgery. A cut is made behind the ear and the skull is shaved to create a nesting place for the package and the silicon tail is threaded through the skull to the cochlear and the end is coiled up inside the cochlear so that the electrodes are inside the cochlear.

The noise that has been translated into electrical impulses by the receiver travel down to the electrodes and these fire short electrical sparks which are picked up by the small nerve endings that should work with the hair cells in the cochlear normally (see here for more explanations on the anatomy of the ear). These then carry the electrical impulses up to the brain to be decoded into the brains interpretation of the noise.

The operation itself to fit the internal components only takes a couple of hours and is usually done as a day case. There are risks associated with surgery such as infections, meningitis, damage to the facial nerves and the normal risks associated with any kind of surgery under general anaesthetic. A couple of weeks recuperation is needed after major surgery and it is not until a few weeks later that the external part gets fitted and the person is ‘turned on’. Because the method of relaying the noise to the brain is different and the brain has never ‘heard’ this noise before it is unable to ‘recognise and identify’ the sound at first. Months and years of dedicated training is then needed to relearn all these beeps and electrical sounds into meaningful and possibly recognisable sounds. Day to day noises heard repeatedly are usually the first to be picked up such as things banging onto the table, zips, taps running etc. More complicated noises like speech take much longer and may never be fully learnt depending on the level of benefit the person is getting through the cochlear implant and how well they are able to recognise the sounds. Regular trips back to the centre to get checked out and to adjust the amount of information being fed through to the receiver from the processor. Upgrades of the external processor are possible over time just like upgrading a mobile phone. These may produce different sounds so is not always done.

The benefits of a cochlear implant vary from person to person and depends greatly on their background and their dedication to relearning these new sounds. Some such benefits are; improving their communication skills, being able to recognise sounds that help them in their daily lives, improve their safety and increase their independence.

There are some things that you are not able to do with a cochlear implant or need to avoid! A build up of static electricity may cause the electrical components to reset! So it is advised to avoid plastic slides! Deep sea diving, walking through airport body scanners, having an MRI (although this may be possible if the internal magnets are removed beforehand) and getting the external parts wet in the shower or swimming so need to be removed first! An ear infection may affect the effectiveness temporarily.