Department of Family Medicine
Noise Induced Hearing Loss
Did you know that:
· Prolonged exposure to noise greater than 85-90 dBA (decibels measured on the A-scale) may cause hearing loss?
· Prolonged exposure to levels of 90-100 dBA causes loss of hearing?
· Brief exposures to noise sources of 100-130 dBA can cause hearing loss?
· A single exposure to a level of 140 dBA or higher can cause hearing loss?
DO I NEED TO BE CONCERNED ABOUT PROTECTING MY HEARING?
Yes. Especially if a doctor has diagnosed hearing loss, or you work with noisy equipment, or you have to raise your voice at work just to communicate with someone 2-3 feet away.
DON'T WE ALL LOSE SOME HEARING AS WE GROW OLDER?
Yes, but prolonged exposure to loud noise can accelerate hearing loss. Men lose hearing earlier than women; this may be due to more unprotected noise exposure among men.
IS NIHL (NOISE INDUCED HEARING LOSS) A COMMON PROBLEM AT WORK?
NIHL has been studied extensively in the military and industry. Federal regulations require hearing conservation programs for industry. Smaller employers and agriculture are exempt from these requirements. Research on exposure to agricultural noise sources is more important than ever. The role of agricultural noise in NIHL is not new; the University of Nebraska has been studying tractor noise since 1970.
HOW DOES NIHL OCCUR?
NIHL occurs in several ways. The first stage is a temporary threshold shift in the pattern of hearing. The shift raises the level of loudness required to hear sounds and is accompanied by tinnitus (ringing or buzzing in the ears) and a mild hearing loss at the higher frequencies. Hearing returns to normal within a few hours or one - two days after the ear has had time to rest.
A permanent threshold shift in the pattern of hearing may occur after repeated temporary threshold shifts, or it may occur after a single acute exposure of high intensity such as having a gun fired close to the ear.
Continued exposure to loud noise sources will lead to greater loss of hearing and tinnitus may become a permanent symptom. Sounds may also appear to be muffled. NIHL causes permanent damage to the ear. There is no medical or surgical cure to restore hearing. Partial hearing loss can be helped with a hearing aid.
WHAT ABOUT LOUD MUSIC AND ROCK BANDS?
Live rock bands typically have dBA levels from 100 to 130. Prolonged exposure under these conditions will damage hearing. Temporary hearing loss with ringing or buzzing in the ears (tinnitus) are warning signs.
WHAT IF I AM EXPOSED TO LOUD NOISE FOR ONLY SHORT PERIODS OF TIME?
The following table lists the standards for allowable noise levels in industry. Safe noise levels are determined by a combination of duration of exposure and the intensity of the noise.
Hours Per Day Noise Level (dBA)
*For example a person who does not use hearing protectors cannot be exposed to a noise level of 100 dBA for more than two hours per day. If the job requires exposure to 100 dBA for more than two hours, personal hearing protectors must be worn. This is a federal regulation.
DON'T PERSONAL HEARING PROTECTORS INTERFERE WITH HOW I LISTEN TO THE EQUIPMENT I AM OPERATING?
Ear plugs and muffs reduce the total amount of noise that reaches your inner ear. You quickly adapt to any change in the sound of your machinery.
DOESN'T A PERSON GET USED TO NOISY WORK SITUATIONS?
Yes, but if you get used to a noisy work environment, it may mean that you have already lost some of your hearing. You may not be aware of how much you have lost.
IS IT TOO LATE TO START USING PERSONAL HEARING PROTECTORS?
The use of protectors will prevent further NIHL, whether the loss has occurred in one or both ears.
WHICH ARE BEST, EAR PLUGS OR EAR MUFFS?
Ear plugs have advantages: low cost, easy to carry, comfortable to use in hot weather, and they do not restrict head movement.
Ear muffs generally offer greater protection and may be worn with minor ear infections when ear plugs would be irritating or painful.
Protectors can be purchased at safety supply houses, firearm/hunting supply stores, most hardware stores and many pharmacies. Ear plugs or ear muffs will reduce the amount of noise that reaches the inner ear by 10 to 30 decibels depending upon the type.
Prevention of NIHL
· Wear personal hearing protectors (ear muffs or ear plugs) when working around noisy equipment for prolonged periods. Make sure the hearing protector is properly fitted. Maintain and wear them according to the manufacturer's instructions.
· Keep all machinery properly lubricated.
· Keep the exhaust systems of all engines in good repair. Replace worn mufflers.
· Reduce the amount of time you are exposed to high noise sources, especially if you do not have personal hearing protectors. Frequent breaks help the ears to recover from noise stress.
· Remember, recreational noise sources can be as damaging as industrial noise. Motorboat engines, ATVs, target practice, stereos, and live bands are a few examples. Reduce exposure when possible: turn down the stereo, keep away from the amplified speakers at rock concerts, and wear hearing protectors while target shooting, cutting grass, or while using a leaf blower or a chain saw.
· Do not use the music from head-sets to "protect" yourself against noise. It is distracting and adds to the total noise level. When using headsets, keep the volume at a comfortable level at all times.
· Home made hearing protectors such as cotton balls are not effective.
· Have your hearing tested at your next check-up by a qualified examiner.
· Good hearing insures better communication and improved quality of life. It's never too late to save the hearing you have remaining.