The partial or total inability to hear is known as hearing impairment or hearing loss. It can be present at birth, or develop later in life.
There are a number of factors, which may cause hearing loss
1. Age - Age is the biggest factor when it comes to the loss of hearing, and you may lose the ability to hear as you age. This condition is known as presbycusis. It becomes difficult to understand high-frequency sounds like that of a child or a woman when you get old.
2. Noise - When you are exposed to loud noises for a prolonged period of time, it damages your ears. This leads to loss of hearing. 5% of the total population of the world is affected by noise (the degree of suffering varies). It may be a result of continuous exposure to loud music or a sudden exposure to a loud noise like an explosion.
3. Hereditary disorders - Hearing disorder may be inherited by the dominant or recessive genes of parents in the child. 70-80% of these cases inherit from the recessive genes, whereas 20-25% inherit hearing loss from the dominant genes.
4. Trauma - Serious injuries of the head/ears may cause loss of hearing, which may be either temporary or permanent. When damage is caused to the brain, the brain fails to process the message conveyed by the ears. So even if the ears are totally functional, a person may face the problem in hearing.
5. Perinatal problems - The ototoxic effects on the fetus due to excess intake of alcohol during pregnancy lead to hearing the loss in about 64% of the infants born to alcoholic mothers.