Can You Hear Me Now? Loud Noise Causes Hearing Loss!

I was talking on the phone with my friend Tim the other day and every few minutes he kept asking me to talk louder. The line was clear, no cell phones were used, I was talking just as I am right now and we were both in the comfort of our own homes. So it got me thinking, is it me or can he just not hear me? Well, the truth is that according to National Institute on Deafness and other Communicative Disorders, over 30 million Americans are exposed to hazardous sounds on a daily basis. And that constant exposure is giving way to a serious health problem called Noise Induced Hearing Loss.

Today we will learn about the National Health Problem sweeping the nations, begin to comprehend how the ear works and how we as humans hear, we will then break down sound in its relationship to hearing while figuring just how loud is too loud.

Loud music has long been attributed to Noise Induced hearing loss, but until recently it flew under the radar as a health issue for adults and elderly people. In the April 2005 edition of Pediatrics magazine, they state that an estimated 12.5% of children aged 6 to 19 years of age have noise-induced thresh-hold shifts. Noise-induced threshold shifts can range from needing to turn up the volume on your stereo to the beginnings of NIHL. The article also mentions that the previously cited percentage is almost a 40% increase since 1985. Although the statistics are alarming, Americans are still unaware because of a lack of information on Noise Induced Hearing Loss.

Noise Induced Hearing Loss as documented at nidcd.nih.gov says that "Noise-Induced Hearing Loss can be caused by a one-time exposure to loud sound as well as by repeated exposure to sounds at various loudness levels over an extended period of time." This means that one time of listening to something as loud as an explosion, or years of listening to loud music can have the same effect on our hearing. What is also alarming is that the symptoms of NIHL increase gradually over a period of time but I'll get into that a little bit later.

NIHL has several different forms ranging from partial deafness, tinnitus and total deafness. A person with partial deafness may never lose their hearing completely, and are often greatly helped with the use of a hearing aid. Tinnitus on the other hand is much more of an impairment. The National Institute on Deafness previously mentioned states that "Tinnitus is a constant ringing, roaring, clicking or hissing in the ears." To say the least, it's a bothersome condition. The American Tinnitus Association has reported that at least 12 million Americans have Tinnitus and 1 million experience it to the point that it interferes with their daily activities. There are many ways that people with Tinnitus can cope. The National Institute on Deafness says that, like partial deafness it can be treated with hearing aids, but for more serious cases it is treated with a series of prescription drugs are taken daily.

To begin to understand Noise Induced hearing loss and how it affects us we must first understand how the ear works. Contrary to popular belief there is much more to your ear than what is visible from the outside. The February 23rd edition of Science World in an article by Bob Nugel describes the ear with this diagram. Start with the outer ear, where sound is funneled into the eardrum. The sound then enters the inner ear, which contains a snail-shaped area called the cochlea, which is filled with fluid. The fluid vibrates with the sound, in turn causing tiny hair like structures called cilia to vibrate as well. The cilia transmit the vibration in the form of nerve impulses to the auditory nerve. The Auditory nerve then takes the message to the brain, which tells you that, your hearing.

So now that we understand how we understand sound, what does it mean? Well the article in Science World also explains that "Intense sound waves damage the cilia causing them to bend and sometimes break. Once cilia are damaged, even a small bit, they never recover 100% and are weaker, therefore less powerful vibrations can damage them even more. Eventually cells attached to the cilia die, and the result ranges from Tinnitus, which as we know IS curable to total deafness for which there is no cure.

I would like to direct your attention to the current slide, which is are 2 Scanning Electron pictures of what the inside of the Cochlea look like with and without damage. This picture shows how the ear is, devoid of any cilical damage. Notice that the cilia are in neat bundles within the basilar membrane and the smaller cilia are not visible. This picture on the other hand is representative of someone whose hearing is definitely damaged. Notice that the cilia are longer in this picture and some are bending in odd directions. The smaller cilia that were originally hidden are out and the basilar membrane has expanded considerably. This ear is incredibly damaged beyond repair and this person should be having trouble hearing.

Now the real issue as mentioned above is that no one knows how long it can take for this kind of hearing impairment to begin. Holly Kaplan of the American Speech-Language Hearing Association says that for some people, listening to ear splitting music just once can trigger hearing damage. In short, a single concert can rob you of your ability to hear. The NIDCD says that "The cilia can be injured by two kinds of noise: loud impulse noise, such as an explosion, or loud continuous noise, such as that of an iPod Nano."

Now you may be saying to yourself, "How do I know whether something is too loud or not."