There are many things that cause deafness, and the possible causes depend on the type of hearing loss. Some types of deafness are caused by disorders that are passed down from a parent to a child. For example, a parent may pass along a flawed gene, which may affect the development of the child’s inner ear and lead to hearing impairment. Sometimes the hearing loss is caused by gene mutations at the point of conception. Even exposure to certain diseases in the womb, such as German measles, can lead to deafness in the baby.
One type of hearing loss is called conductive deafness, and it is caused by problems in a person’s middle ear. There are three small bones inside a person’s middle ear that are supposed to facilitate the movement of sound waves to the inner ear. When they fail to do so, conductive deafness may result. Sometimes conductive deafness is caused by other things, however. For example, the eardrum may not vibrate as it should, which can cause hearing problems; liquid buildup in the ear canal can impair the eardrum’s natural movement and lead to hearing loss as well.
Nerve deafness is hearing loss that is linked to the cochlear nerve. This type of hearing loss occurs because vital electrical impulses are not able to travel to the brain. This can happen even when the bones in the ear and the eardrum are formed as they should be and functioning optimally. This type of hearing impairment may even occur because of problems the brain may have in handling impulses that do reach it from the cochlear nerve.
Other causes of hearing loss include extremely loud noises, such as gunshots and explosions, perforations of the eardrum or other physical trauma, and diseases that affect a child or an adult. For example, meningitis, severe jaundice, and mumps can lead to hearing loss. Under normal circumstances, a person may begin to hear less optimally as he ages. In rare cases, however, a person may have age-related hearing loss that leads to actual deafness. Even exposure to some types of chemicals can cause hearing loss.
Hearing loss isn’t always permanent or even long term. Sometimes it occurs because of something that blocks normal hearing, such as excess wax buildup in the ear canal. Other things that may cause temporary hearing loss are mucus buildup and ear infections that lead liquid and pus to block hearing. There are even some medicines, such as chloroquine, that can cause temporary hearing loss in some people.