It is an electronic device which helps in restoring partial hearing. It is implanted surgically in the inner ear and is activated using a device which is worn behind the ear. This device converts the sound impulses to electronic impulses which are thereafter transmitted to the hearing nerve which carries the auditory signals to the brain. The cochlear implant directly bypasses the damaged parts of auditory system, stimulating the hearing nerve and letting the individuals receive sound properly. Cochlear implant is the only efficient device for this group of patients and is widely accepted across the world.
A Human ear is divided into three parts, namely inner ear, middle ear and the external ear. The hearing mechanism involves two components. The conductive component allows the sound travel through the external ear canal which causes the eardrum to vibrate. There are 3 small bones in middle ear which conducts these vibrations from the eardrum to the cochlea which is the hearing organ situated inside the inner ear. The Sensorineural component reads these vibrations of bones and this result in the starting of waves of fluid in cochlea. These fluid waves stimulate sensitive hearing cells which are also known as hair cells. The soft motion of these hair cells thereon generates an electric current in the auditory nerve and it then travels to the brain.
Following are the two types of deafness:
- Conductive Deafness: A disease in middle or external ear results in conductive deafness. Medical treatments can cure this type of deafness.
- Sensorineural Deafness: This kind of impairment or nerve deafness occurs due to some problem in inner ear. It cannot be corrected with medicines. The hearing aid can help a person with moderate or severe hearing loss. This is done by amplifying the sound. However, if there is a bilateral severe sensorial hearing loss then the hearing aid cannot help much.
If a person is suffering from sensorial deafness, the hair cells are damaged. The nerve fibers become unresponsive because of the damaged hair cells. The nerve fibers can still transmit the electrical signals to the brain but this can be achieved only on stimulation. Cochlear implants helps in bypassing the damaged hair cells and then convert the auditory signals into electrical signals. These signals are then sent through hearing nerves to the receptor brain.