Noise-induced hearing loss (NIHL) is the slow loss of hearing caused by exposure to too much noise. The damage caused is cumulative and permanent, effecting many facets of life.

Hearing protection devices decrease the intensity of sound that reaches the eardrum. However, studies have shown that one-half of the workers wearing hearing protectors receive less than half the noise reduction potential of their protectors because these devices are not worn continuously while in noise or because they do not fit properly.

A hearing protector that gives an average of 30 dB of noise reduction if worn continuously during an 8-hour work day becomes equivalent to only 9 dB of protection if taken off for one hour in the noise. This is because decibels are measured on a logarithmic scale, and there is a 10-fold increase in noise energy for each 10 dB increase.

During the hour with unprotected ears, the worker is exposed to 1,000 times more sound energy than if earplugs or muffs had been worn.

In addition, noise exposure is cumulative. So the noise at home or at play must be counted in the total exposure during any one day. A maximum allowable while on-the-job followed by exposure to a noisy lawnmower or loud music will definitely exceed the safe daily limit.

Even if earplugs and/or muffs are worn continuously while in noise, they do little good if there is an incomplete air seal between the hearing protector and the skin.

When using hearing protectors, you will hear your own voice as louder and deeper. This is a useful sign that the hearing protectors are properly positioned.

Just as sunglasses help vision in very bright light, so do hearing protectors enhance speech understanding in very noisy places. Even in a quiet setting, a normal-hearing person wearing hearing protectors should be able to understand a regular conversation.

Hearing protectors do slightly reduce the ability of those with damaged hearing or poor comprehension of language to understand normal conversation. However, it is essential that persons with impaired hearing wear earplugs or muffs to prevent further inner ear damage.

It has been argued that hearing protectors might REDUCE a worker's ability to hear the noises that signify an improperly functioning machine. However, most workers readily adjust to the quieter sounds and can still detect such problems.

What If My Hearing Is Already Damaged? How Can I Tell?

Hearing loss usually develops over a period of several years. Since it is painless and gradual, you might not notice it. What you might notice is a ringing or other sound in your ear (called tinnitus), which could be the result of long-term exposure to noise that has damaged the hearing nerve. Or, you may have trouble understanding what people say; they may seem to be mumbling, especially when you are in a noisy place such as in a crowd or at a party. This could be the beginning of high-frequency hearing loss; a hearing test will detect it.

If you have any of these symptoms, you may have nothing more serious than impacted wax or an ear infection, which might be simply corrected. However, it might be hearing loss from noise. In any case, take no chances with noise - the hearing loss it causes is permanent. If you suspect a hearing loss, please contact one of Medica Consulting's friendly, professional team for assistance. For contact telephone numbers, please click HERE.


© 2005 Medica Consulting Limited.


For futher information, you may wish to download the following documents published by OSH.

MESSAGE TO EMPLOYEES

HOW NOISE AFFECTS YOUR
HEARING