Hearing protection devices decrease the intensity of sound that reaches the eardrum. They come in two forms: earplugs and earmuffs.

Earplugs: Earplugs are small inserts that fit into the outer ear canal. To be effective they must totally block the ear canal with an airtight seal. They are available in a variety of shapes and sizes to fit individual ear canals and can be custom made. For people who have trouble keeping them in their ears, they can be fitted to a headband.

Earmuffs: Earmuffs fit over the entire outer ear to form an air seal. They are held in place by an adjustable band. Earmuffs must be snugly sealed so the entire circumference of the ear canal is blocked.

Properly fitted earplugs or muffs reduce noise by 15 to 30 dB of sound. The better earplugs and earmuffs are approximately equally effective in sound reduction. However, earplugs are better protection against low frequency noise (such as noise from a jackhammer), and earmuffs are better protection against high frequency noise, (such as noise from an airplane taking off).

Simultaneous use of earplugs and muffs usually adds 10 to 15 dB more protection than either used along. Combined use should be considered when the noise exceeds 105 dB. It is important to understand that ordinary cotton balls or tissue paper wads stuffed into the ear canals are very poor protectors since they only reduce noise by approximately 7 dB.

Studies have shown that one-half of the workers wearing hearing protectors receive one-half or less of 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.

Medica Consulting has a wide range of hearing protectors. Our friendly, professional team are happy to assist you in the selection of the correct protectors to suit your environment. For contact phone details, please click HERE.


© 2005 Medica Consulting Limited.