The choice of hearing protectors is a very personal one and depends on a number of factors including level of noise, comfort, and the suitability of the hearing protector for both the worker and his environment. Most importantly, the hearing protector should provide the desired noise reduction. If the noise exposure is intermittent, ear muffs are more desirable, since it may be inconvenient to remove and reinsert earplugs.
Earplugs are inserted to block the ear canal. They may be premolded (preformed) or moldable (foam ear plugs). Ear plugs are sold as disposable products or reusable plugs. Custom molded ear plugs are also available. Earplugs are a popular choice in the workplace because they are simple th use, less expensive, and are more comfortable in hot or damp work ares. However, earplugs must be properly inserted to provide adequate protection and should not be used in areas having noise levels over 105dB.
Earmuffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a headband. Ear muffs can vary with respect to the material and depth of the dome, and the force of the headband. The deeper and heavier the dome, the greater the low-frequency attenuation provided by the protector. The headband must fit tightly enough to maintain a proper seal, yet not be too tight for comfort. Ear muffs can usually provide greater protection than plugs, although this is not always true. They are easier to fit, generally more durable than plugs, and they have replaceable parts.
Hearing protectors have a noise reduction rating (NRR) printed on the package. Noise is measured in decibels (dB); each 10 dB jump reflects a doubling of the noise level. The idea is to get the noise reduced to a safe and comfortable level; for a two-hour stint in your workshop, that should be less than 90 dB. Foam plugs offer an NRR of about 30 dB; earmuffs about 25 dB; molded plugs slightly less than 25 dB. For extremely loud operations, wear both plugs and muffs to attain an NRR of 35 db or more.
Did you know?
The 30,000 tiny hair cells arranged in our inner ear’s snail-shaped cochlea are responsible for transmitting sound. The hairs nearest the opening are responsible for transmitting high-frequency noises and are the first ones damaged by loud noise. That’s why people with hearing damage can hear a low-pitched male voice with better clarity than a higher-pitched female voice.
The human aspects of hearing protection are particularly important since the only useful kind of protection is the protection that is actually worn. Some people do not accept particular kinds of protectors; every human being is different, and the anatomy of the ear and ear canal can vary significantly from person to person. The bottom line on hearing protection is worker preference. If the workers do not like the type of protection (for example, if it is uncomfortable, does not fit well, or is impractical), they will not wear it.