Ability to hear depends on many structures
Hearing loss or congenital deafness is a condition which has a great impact on your social competencies. Without the ability to hear, it is easy to feel isolated, lonely, helpless and frustrated. Being able to hear noises is a process which involves several structures in the ear. Sounds are invisible vibrations, known as sound waves, which are sent through the air. These sound waves vary greatly, so each sound seems unique.
Sound waves travel from the outer ear to the middle ear, where they are transformed into pressure waves which are then transferred to fluid in the middle ear. These waves are then transmitted to the inner ear, called the cochlea, where thousands of microscopic fair fibres are put into motion, transforming the waves into electrical impulses. These impulses are then transmitted to the brain, which perceives them as sound.
Damage to the structures lead to different types of hearing loss
There are several types of hearing loss, depending on the structure in the ear which has been changed – congenital or acquired. These include.
- Conductive hearing loss: Mild to moderate hearing loss, as a result of defects in the outer ear or middle ear. This can e.g. be due to changes to the eardrum or the bones of the middle ear caused by trauma, inflammation of the middle ear or congenital defects.
- Sensorineural hearing loss: A mild to severe hearing loss. Here, parts of the inner ear have stopped working – for instance the cochlea or the hair fibres. This can be due to ageing, head traumas, certain medications, too much noise or it can be inherited from your parents.
- Neural hearing loss: A mild to severe hearing loss, where the auditory nerve doesn’t work, which can be due to head traumas, congenital defects or a tumour.
Deafness can be treated with implants
In people with moderate to severe hearing loss, which can’t be treated using a hearing aid and in people who score 50% or less on sentence recognition tests, there is a medical device which enables them to hear. This is called a cochlear implant. It is an electronic medical device which can replace the damaged parts of the inner ear. Regular hearing aids make sound from the surroundings louder, whereas a cochlear implant transforms sounds into digital code instead. The sound processor transmits the digitally-coded sound through the coil on the outside of your head to the implant, which converts the digitally-coded sound into electrical impulses which stimulate the cochlea's hearing nerve.
Studies have shown that the cochlear implant has been able to improve hearing abilities to a degree which nearly equals a fully normal hearing ability. Patients who had a 10 % sentence understanding with a hearing aid have acquired over 80 % sentence understanding after getting cochlear implants. The device can even focus your hearing in noisy surroundings, so you are able to speak to people across tables at gatherings, listen to music, talk on the phone, hear alarm signals and eliminate the feeling of isolation and helplessness.
In people with conductive hearing loss, single-sided deafness or mixed hearing loss, another device which can bring back hearing is available. When structures in the inner ear are unable to transmit soundwaves, hearing aids are rarely able to help the patient. In this situation, a concept called a bone conduction, which makes use of the bone’s ability to transmit sound, is available. Since the ear is surrounded by bones, sound can be transmitted through these and into the inner ear, thus avoiding the space between the outer ear and the middle ear, through which soundwaves usually travel. It is therefore possible to receive treatment using a bone conduction implant, which results in a natural sound with less distortion and feedback compared with conventional hearing aids. The equipment is called Cochlear’s Baha ® System, and you can even try it before undergoing surgery to experience the effect.
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