Tagged: Permanent hearing loss

It’s a Noisy World

January 25, 2016

Beauty is in the “ear” of the beholder. What may be noise to one person may be a beautiful melody to another. In fact, I distinctly remember my mother saying, “turn that racket off!” when all I wanted to do was turn the music up louder. I wish I would have listened. Now, I have a constant ringing sound, called tinnitus in my ears. The average person doesn’t realize that there are other noises, not just music, that occur in our daily lives that can be dangerous to our ears.

According to the Better Hearing Institute, 30 million Americans are exposed to dangerous noise levels each day and 10 million Americans have already suffered irreversible hearing damage from exposure to noise. And, according to the National Center for Health Statistics, nearly 15% of American teens suffer from some measure of hearing loss. The sad part is that this type of hearing loss is completely preventable.

How loud is too loud?

Normal conversational speech occurs at approximately 60 decibels. A good rule of thumb is, if you have to raise your voice to be heard over the sound, it’s probably too loud to listen to for a long period of time. The length of time you can be exposed to a loud sound before permanent damage occurs depends on the volume of the sound. As the volume gets louder, the amount of time you are exposed to the sound should decrease in order to keep your ears safe. For example, exposure to 110 decibels (the volume of a chain saw) for only a few minutes without ear protection can be as damaging as an exposure to 85 decibels (the volume level of the typical lawn mower) for 8 hours.

What are the symptoms of noise induced hearing loss?

Noise induced hearing loss (NIHL) usually develops gradually over time. It’s possible for someone to lose a significant amount of hearing before becoming aware of its presence. Often, the first sign of NIHL is a slight ringing sound in the ears that may only be noticeable in a very quiet environment, like when you are trying to go to sleep at night. If noise exposure continues over time, you might begin to notice that the high-pitched sounds are not as clear. I will often hear, “I can hear just fine, I just can’t understand what people are saying.” The high frequencies are responsible for the majority of the clarity of speech. NIHL affects the high frequencies.

People fail to notice the impact of unsafe noise exposure because it causes few symptoms and for most people, occurs gradually over time. Hearing loss is rarely painful. At first, the ringing sounds may go away several minutes or hours after the noise exposure ends. You might assume that if the symptoms disappear, the ears have returned to normal. Even in the absence of symptoms, some of the cells in the inner ear that are necessary for hearing clearly may have been permanently damaged or destroyed by the noise. With repeated noise exposure, more cells are destroyed and a permanent hearing loss is likely to develop.

How can I prevent noise induced hearing loss?
Hearing loss caused by excessive noise exposure is not reversible, but NIHL is preventable.
There are three general rules for preventing permanent hearing loss due to noise:

1)      Understand what noises put you at risk. Remember, if you have to raise your voice to be heard, it’s probably too loud.
2)      Decrease the volume whenever possible.
3)      If in doubt, wear ear protection.

The American Academy of Audiology is leading the way to get the word out about noise induced hearing loss, especially to kids. The “Turn it to the left” campaign is educating kids and teens on the hazards of noise exposure in order to protect their hearing for a lifetime. To learn more about noise induced hearing loss or to determine whether noise exposure has damaged your hearing, contact your audiologist today.

How the Zebrafish May Cure Hearing Loss

February 16, 2015

 
“I’m sorry, your hearing loss is permanent.” For thousands of Americans each year, hearing loss that requires help for better communication becomes a reality. In fact, nearly one out of every ten people has a hearing loss in the United States. The most common hearing loss is damage to the inner ear hair cells, or cilia, that reside in the cochlea. The damage, called sensorineural hearing loss, can be caused by many things, including excessive noise exposure, disease processes, exposure to medications and due to the “accumulation of birthdays.” In fact, the prevalence of hearing loss increases exponentially in each decade after the age of 60.

Why is sensorineural hearing loss permanent?
Once hair cells die, they cannot be replaced. They do not regrow or regenerate. These cells are the single most important part of the mechanical working part of the ear. When a sound enters the ear, it passes down the ear canal to the eardrum, where the vibrations from the sound are passed on to the three smallest bones in the body: the malleus, incus and stapes. Or, hammer, anvil and stirrup, as they are more commonly called. This chain of bones works like a piston system, increasing the intensity of the sound and sending it in to the inner part of the ear where the hair cells reside. The hair cells bend when the third bone in the system pushes in to the cochlea. This bending action creates an electrical signal in the hearing nerve, which then sends a signal to the brain to be processed as sound. If the hair cells are damaged, the information cannot be passed on to the hearing nerve. When someone has damaged or missing hair cells, the result will be permanent hearing loss.

What’s being done about it?
In recent years, a research team at the University of Washington’s Merrill Bloedel Research Center has been working on finding a way to resolve the problem of permanent hearing loss. The most recent research involves the zebrafish. The zebrafish has hair cells running along the sides of its body that help sense vibrations in the water. The vibrations are converted to electrical information that is then sent to the brain. Sound familiar? Unlike human hair cells, though, the hair cells of the zebrafish are able to regenerate when damaged. Researchers hope to find out how the zebrafish regenerates their hair cells and use this information to develop a way for humans to regenerate damaged or missing hair cells. If they can do so, the researchers would, in effect, have a cure for the majority of permanent hearing loss sufferers.

A cure is still a long way away. But the research is promising and the researchers are dedicated to finding the answer for permanent hearing loss. To find out more about the research being conducted at the University of Washington’s Merrill Bloedel Research Center, visit depts.washington.edu/hearing.