Everyone knows what hearing is. Hearing loss, or deafness, is the partial or total inability to hear sound in one or both ears. The human ear is remarkable as is the smallest and most complex organ in the body. Considering the ear's delicacy, it is remarkably resilient. Nevertheless, illness or injury can impair our ability to hear properly.

It is possible that someone who has hearing loss may be able to hear some sounds or simply nothing at all. Often people also call it deaf, deafness, or hard of hearing when they're talking about hearing loss.

It has been observed that out of 1000 babies born, three may have hearing impairment. This is the most common birth defect. Although there is a possibility that hearing problem can also develop later in life, there are many types of hearing loss:

1. Conductive hearing loss: it is a problem with the part of the outer or middle ear. Most patients with conductive hearing loss have a mild hearing loss and it is usually temporary because in most cases medical treatment can help. It could be when one has middle ear infections, collection of fluid in the middle, blockage of the outer ear (by wax), damage to the eardrum by infection or an injury.

2. Sensory hearing loss: This happens when the cochlea is not working correctly because the tiny hair cells are damaged or destroyed. Depending on the loss, a patient may be able to hear most sounds (although they would be silent); only some sounds; or no sounds at all. Sensory hearing impairment is almost always permanent and a patient's ability to talk normally may be affected. It could be due to age-related hearing loss that people experience as they get older, injury caused by loud noise to the hair cells, viral infections of the inner ear (may be caused by viruses such as mumps or measles), Meniere's disease (abnormal pressure in the inner ear), a brain tumor or a stroke.

3. Mixed (conductive and sensory combined) hearing loss: this happens when the outer and middle ear is affected and also the tiny hair cells are damaged. This is a very critical case and cannot be cured fully.

4. Neural hearing loss: This happens when there is a problem with the connection from the cochlea to the brain. Neural means related to nerve, so neural hearing loss means the nerve that carries the messages from the cochlea to the brain is damaged. In recent years, substantial advances have made it possible to determine the cause of hearing impairment in nearly all cases, and to treat the hearing loss in many of them.