Robert Snider, MD
What did you say?
Hearing loss is something that most of us will face sometime in our lives to a degree. The types of hearing loss are divided into two groups. Those that involve the outer ear, ear canal, eardrum, ear bones and middle ear space are called conductive losses. Those that involve the hearing organ with its contained hair cells and nerve fibers and the nerves leaving the ears are called nerve losses.
Nerve losses may be temporary from exposure to machinery noise, music, gunshots or other loud sounds without adequate ear protection. Hearing may improve after a few days, but in many cases, nerve loss leaves some residual damage. As time goes on, each additional instance of noise trauma compounds the damage, eventually leading to permanent hearing loss.
However, there are many other causes of permanent hearing loss, such as physical blows to the head and ear area that occur in automobile, industrial and other types of accidents. Infections that are severe or recurrent can also cause permanent loss of hearing. There are hereditary influences on hearing, as well.
In some families, these influences may cause hearing to be absent or poor at birth or to decline rapidly beginning early in life. In other cases, a hereditary susceptibility to damage from noise trauma leads to hearing loss later in life. Even the normal aging process usually results in a decline in hearing due to loss of the hair cells and nerve fibers that produce the tiny electrical currents our brains process as sounds.
Hearing works by sensing sound waves, also known as sound vibrations, in the air. The sound vibrations are concentrated slightly by the outer ear and funneled to the ear drumhead which vibrates a bone called the malleus (hammer) which then vibrates the incus (anvil) which then vibrates the stapes (stirrup). As this innermost bone moves, it sets up waves in the fluid of the inner ear that move hair-like cells which are also in the inner ear. As these hair-like cells bend and rebound, they send tiny electric current messages through the nerves to the brain. Here, the messages can be compared to stored memories that let us understand the world of sound that surrounds us.
The sense of hearing relies on a fairly complex sequence of events, but it can be protected through simple steps. It is important that we prevent the causes of hearing damage we can control. We can minimize noise trauma by avoiding loud noise whenever possible, and taking precautions such as using adequate ear protection and limiting the duration of exposure when avoidance of the noise is not possible. It is also important to treat infections adequately to minimize the permanent loss these can cause.
We can restore many of the conductive losses with surgery or medications, but nerve losses require replacement with assistive therapies such as hearing aids which make sounds louder or surgical implants which replace some of the functions of the hearing organ (cochlea). These surgeries and therapies are done by specially trained physicians called otolaryngologists and by specially trained individuals called audiologists.
If your hearing suddenly declines, you should see your physician immediately so any longterm loss can be minimized. The more common problem is a gradual loss of hearing that sneaks up on us. We may not realize the loss is troublesome until some says, “That TV is too loud!” or, “ I’m talking to you!” If this happens, bring it up during your next physical or contact your otolaryngologist so it can be evaluated. Your doctor will try to restore and preserve as much of this important function as long and as much as possible.