Sounds like trouble

Hearing loss occurs mostly with age. A breakdown of nerve cells in the inner ear or changes in the eardrum or bones of the middle ear makes it difficult to hear some sounds.

High blood pressure, diabetes and heart disease can also contribute to hearing loss, according to WebMD. Allergies, head colds, infections, trauma and some medications may cause a loss of hearing.

According to Steve Brown, an audiologist with Brown and Willen Audiology Center in Cape Girardeau, the major cause of hearing loss outside of aging is noise.

The federal Occupational Safety and Health Administration (OSHA) developed stringent guidelines for protecting industrial workers from noise, requiring ear protectors and an annual hearing test. But small companies and farmers are exempt from those guidelines.

Even in precautions are taken in the workplace, damage to hearing can take place at home.

"Sometimes people get off work and take their ear protection off and go home and get out the chain saw or shoot a gun and don't protect themselves," Brown said.

The best ear protectors, he said, are "ones that are used."

Hearing loss can happen as a result of not only the number of decibels (dB) registered by a given sound, but by the length a person is exposed to a sound -- the sound pressure level (spl). OSHA has determined that anything over 85 decibels is potentially dangerous. A ringing telephone gives off 85 decibels, but Brown said it would take eight hours of continuous ringing for damage to occur.

As the decibel level increases, the amount of time one can be exposed to it without harm decreases. A lawn mower gives off between 100 and 110 decibels, Brown said. The time it takes to mow the average lawn probably wouldn't hurt anyone's hearing. But a landscaper who mows lawns all day, or a homeowner with a really large yard might be in some danger.

Brown said his son put himself in a bad situation recently when he wanted to mow the lawn while listening to a CD on his headset.

"Once he got it loud enough to hear over the lawn mower he would be up into the dangerous level of sound," he said.

A shotgun or rifle report measures between 140 and 160 decibels. So it's possible to work in a factory for eight hours at a level of 95 to 100 decibels and cause little damage, Brown said, but to go home and fire a shotgun once and do some permanent nerve damage.

Most people who have some hearing loss don't realize it because it is gradual, Brown said, and because only the high frequencies of sound are lost.

"Someone may say they can hear a dog barking four blocks away but that does not mean there's no damage," Brown said.

A person who can hear the dog barking, or hear someone knock on the back door, loses his ability to hear consonant sounds because they occur at a higher frequency. As a result, it sounds like people are mumbling only the vowel sounds.

Hearing loss from noise trauma is irrevocable, Brown said, but entirely preventable. It is also treatable with hearing instruments, and other means of amplification. Modern hearing instruments, he said, are digital and can be programmed to fit a patient's specific needs, unlike older models that amplified everything.

Brown advises anyone who suspects a hearing loss in himself or a family member to consult a trained audiologist. Most hearing aid centers offer tests and sell hearing aids, but Brown pointed out that there are no state requirements mandating that people who work there be licensed.

An audiologist, he said, is able to determine if a hearing loss is the result of a medical problem, and if so will refer the patient to a medical doctor. If no medical problem exists, then the audiologist can offer the patient options for correcting the problem.

lredeffer@semissourian.com

335-6611, extension 160