Types and Causes of Deafness

Types of Deafness

Conductive hearing loss occurs when sound vibrations don't go from the air around a person to the moving bones of the inner ear as well as they should. If something is blocking the ear canal, like ear wax, there is a conductive hearing loss. If there is fluid inside the inner ear where the bones are, like the fluid from an inner ear infection, there is a conductive hearing loss. If the bones of the ear get a buildup of calcium, from a disease perhaps, and they can't move as freely as they need to, there is a conductive hearing loss. Generally, conductive hearing loss doesn't cause a total inability to hear, but it does cause a loss of loudness and a loss of clarity. In other words, sounds are heard, but they are weak, muffled, and distorted.

Neural hearing loss (Nerve deafness) occurs when the auditory nerve, which goes from the inner ear to the brain, fails to carry the sound information to the brain. Neural hearing loss can cause a loss of loudness or a loss of clarity in sounds.

Mixed hearingloss is a combination of conductive and neural hearing losses.

Causes of Deafness

Heredity. Some people are born deaf. Usually the cause is unknown. Sometimes people will say it's because of something that happened to the mother during her pregnancy, but this is often just guessing. Although deafness does sometimes "run in families," deaf parents often have hearing children and hearing parents often have deaf children.

Diseases of the Ear

Ear infections are diseases which can cause fluid or mucus to build up inside the ear. If pressure builds up inside the ear, the eardrum is less flexible than it should be. As the ear heals, the fluids drain out of the ear or are absorbed into the body. Some hearing may be lost during the infection; it may or may not return when the infection is healed.

Otosclerosis is a common cause of hearing loss. Although in the past people have thought that it was caused by diseases such as scarlet fever, measles, and ear infections, in fact these have nothing to do with its development. It is a hereditary disease in which portions of the middle ear or inner ear develop growths like bony sponges. The disease can be in the middle ear, the inner ear, or both places. When it spreads to the inner ear a sensorineural hearing impairment may develop. Once this develops, it is permanent. If it is in the stapes bone, in the middle ear, it can cause a conductive hearing loss. The amount of hearing loss depends on the amount of otosclerosis in the area.

Meningitis is an inflammation of the membrane(called the meninges) that surrounds the brain and the spinal column. Meningitis itself doesn't cause deafness, but since the brain is so close to the ears, sometimes the inflammation of the meninges can cause the inner ear to become inflamed also, and this can result in deafness.

Injuries of the Ear

Punctures of the Eardrum. Hearing loss can be the result of a hole in the eardrum, which could be caused by either injury or disease. The eardrum is the thin membrane that separates the ear canal and the middle ear. The middle ear is connected to the throat by the eustachian tube, which relieves the pressure in the middle ear. So a hole in the eardrum causes a loss of hearing and sometimes fluids can drain from the ear. Luckily the eardrum usually heals itself, although it can take a few weeks or months. While the eardrum is healing, it must be protected from water and from further injuries. If the eardrum doesn't heal by itself, it may need surgery. The amount of hearing that is lost depends on the size of the hole in the eardrum and a lot of other things.

Injuries which can perforate the eardrum include:

• Foreign objects, such as Q-tips or hairpins, which are pushed too far into the ear canal.
• Explosions, which cause an abrupt and very big change in the air pressure, which can cause an eardrum to tear.
• Car wrecks, fights, and sporting injuries.

Nerve Damage. Damage to the auditory nerve can also be the result of an injury or a disease. Injuries can happen in auto accidents or falls. The result of nerve damage is that the electrical signals of sounds do not get transmitted from the ear to the brain.

Loud Noises. A very common cause of deafness is repeated or long-term exposure to loud noises. This is why heavy equipment operators, firefighters, factory workers, and especially rock musicians suffer hearing losses after years of their work. Usually a single incident of exposure to loud noises will not cause deafness, but a repeated exposure to loud noises over a period of time will often cause moderate to severe hearing loss.

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