The most common cause of permanent hearing loss is noise exposure. That being said, unless you live in a perfectly quiet world, it is likely that you are exposing your hearing organ (cochlea) to excessive vibration. We hear through vibration and vibration is what causes the damage! It is a Catch-22.
The hearing organ is fragile.
The cochlea is the size of a green pea, curled like a snail and filled with fluid. Inside this tiny, sophisticated organ are rows of nerves that sit on a membrane that moves in response to sound. As the membrane is moved, individual nerves are set into motion, initiating the process of hearing sound. The process of hearing is dependent on healthy nerve cells in the cochlea and an intact pathway to the sound processing centers of the brain.
What does noise exposure do?
The nerve cells in the cochlea look like tiny flexible hairs standing erect in specific patterns along a membrane. The membrane is moved by sound vibration, which causes the hair cells (nerves) to respond by swaying, bobbing, contracting and expanding. If the sound is significantly loud, then they bump into each other. The hairs are not strong enough to withstand the rubbing and irritation from the nearby hair cells. This causes shearing, inflammation and breakage of the cells. A damaged hair cell may bend, swell into the next cell’s space or break off. Research has shown us that some of the damage impacts the ability of the cells to make the necessary chemicals to transmit the signal properly.
Why don’t I feel the damage occurring in my ears?
As the nerve cells are bumping into each other and breaking off, you really don’t experience pain or discomfort. It is after the noise stops that people will say that their ears feel stopped up. This is called temporary threshold shift. Usually, the next day the hearing will improve enough that you think your hearing returned to normal. Actually, it does not. The hearing will be less than it was before the noise exposure. You may also notice ringing in the ears, which may or may not fade after the noise exposure.
What does damage in the cochlea sound like?
Imagine taking a portable radio to the beach and getting a small amount of sand and water on the speaker. You would still be able to hear the music or speech but there would be some distortion. If you turn the radio volume up, you can hear a little more but the garbled, distorted sound is still there. You will notice this more as you listen to music and try to decipher the words to a song. A damaged cochlea has distortion because of the damage to the nerves. The nerves still vibrate but they send a less than perfect signal to the brain.
What type of hearing protection is best?
The most important aspect of hearing protection is the way it fits your ears. If you are outdoors wearing sunglasses and you want to put on earmuffs, you will notice that the glasses will not allow the muff to fit tight on your head all the way around the cushion. For this situation, it may be better to use in-the-ear plugs. The plugs come in a variety of shapes but the most important aspect is that they are tight and fully fill the ear canal. If you use foam plugs, squeeze them to a long, slender shape. Slide one into the canal and keep your finger on the end until the foam is finished moving or expanding. If you don’t hold it, it will expand outward, not inward to protect you. If your ears are very large or very small, you may need to invest in custom earplugs to make certain they fit properly.
Children need protection, too!
Teach children to use the earmuffs when they are watching you use the skill saw or chain saw. Often, concerts and sporting events are loud and can cause permanent damage to their tiny hearing organs. Children should wear earmuffs because they have tiny ear canals. It is important to wear them every time noise is around. Be consistent.
Custom hearing protection is a good idea.
For those people who need to wear hearing protection many times a week or engage in repeated activities, custom hearing protection is advised. Custom ear plugs are comfortable and fit the shape of the ear perfectly. If you have difficulty keeping plugs seated or they are not comfortable, have some made by your audiologist. QCBN
By Karon Lynn, Au.D.
More information at http://www.trinityhearing.net/