Cochlear Implants


Cochlear Implants

Cochlear implants are small hearing devices fitted under the skin behind your ear during surgery. A cochlear implant is a small, complex electronic device that can help to provide a sense of sound to a person who is profoundly deaf or severely hard-of-hearing

They have an external sound processor and internal parts including an electronics package with an electrode array. The external processor takes in sound, analyses it and then converts it to signals which are transmitted across the skin to an internal receiver-stimulator, which sends the signals along the electrode array into a part of the inner ear called the cochlea. The signal is then sent to the brain along the hearing nerve as normal. This means that cochlear implants are only suitable for people whose hearing nerves are functioning normally.

A cochlear implant is sometimes recommended for adults or children who have profound sensorineural hearing loss in both ears which is not helped by hearing aids.

Before a cochlear implant is recommended, you will be assessed to find out whether it will help improve your hearing. If a cochlear implant is recommended, it will be inserted into your ear (or both ears) during an operation and will be switched on three weeks later. An implant does not restore normal hearing. Instead, it can give a person a useful representation of sounds in the environment and help him or her to understand speech.

How does a cochlear implant work?

Besides Hair cells there are many usable nerve fibers within the auditory nerve that can be stimulated by the cochlear implant’s electrical signals. A cochlear implant is different from a hearing aid. A hearing aid makes sound louder – called amplification whereas a cochlear implant bypasses the normal outer and middle ear. It directly electrically stimulates the nerve responsible for hearing.

There are two main components to a cochlear implant:
  • 1. The internal receiver/stimulator (implant) which is surgically placed under the skin and in the ear.
  • 2. The external speech processor (headpiece) which is not implanted and is worn either behind the ear (ear-level speech processor) or on the belt (body-worn processor).

Sound is picked up by the microphone on the speech processor, which converts the sound into an electrical signal. This signal is then “encoded” or converted to specific patterns or pulses that is then sent to the transmitting coil of the speech processor. The signal is then sent across the skin inductively (i.e. there is no direct connection with the implant) to the receiving coil of the internal receiver/stimulator (the implant).

The implant then sends the encoded electrical signal to the electrode array which has been implanted into the cochlea (inner ear). Multiple channels and points of stimulation now fire in a pattern that the cochlea can recognize stimulating the auditory nerve. The auditory nerve picks up these signals and transmits them to the brain (auditory cortex) where they are perceived as sound.

Cochlear implant mapping & Programming

Cochlear Implant Mapping is the term used for programming cochlear implant to the specifications and needs of its user. It is a necessary step in the post-operative aural rehabilitation of the Cochlear Implant patient.

In another words Cochlear Implant Mapping is a program that help to optimize the cochlear implant user’s access to sound by adjusting the input to the electrodes on the array that is implanted into the cochlea.

The primary goal of the programming or say follow-up sessions is to set the maximum loudness, based on the subjective report of the patient.

Benefits of Cochlear Implants

Benefits of cochlear implants may range from improved sound awareness to hearing and understanding speech in noise and also can vary from individual to individual. Here we require a surgeon and an audiologist who can recommend patients cochlear implants after going through certain facts like length of hearing loss, motivation and degree of rehabilitation and it varies person to person.

  • Sound awareness
  • Hearing everyday sounds
  • Improved lip reading
  • Hearing and understanding speech
  • Improving the user’s own speech
  • Listening in background noise
  • Using a telephone