May 24, 2002

Roaring Tractors Will Damage Your Hearing!

A familiar sound has returned to the prairies this spring, farm tractors and other machinery are roaring to life as field work resumes. According to a North Dakota State University agricultural safety specialist, that roaring poses a serious threat to farm workers’ hearing.

"Safety and health researchers have thoroughly studied the effects of noise on hearing loss, so the safe limits for exposure to levels of noise are well known. Ninety decibels is the loudest sound that workers should be exposed to for eight hours or more," says George Maher of the NDSU Extension Service. Because most farmers work much more than eight hours a day during the crop production season, their exposure to noise levels should be less than 90 decibels at any given time.

According to Maher, exposure to excess noise levels can have health impacts beyond hearing loss. High noise levels aggravate fatigue and stress, two key factors that can cause accidents. Increased fatigue slows reactions to sudden hazards and changes in the immediate work environment. Workers exposed to excessive noise levels will be more fatigued than those whose hearing is protected.

"Too much exposure to loud noise results in increased levels of stress. Agriculture has enough stress associated with it, anything contributing to the stress should be controlled. Tests have shown that hearing protection does reduce worker stress," Maher says.

"Whenever the noise level gets close to the maximum permissible levels, hearing protection should be worn," Maher says. Measuring noise levels is not an easy task, it requires the careful use of precision equipment, so a worker’s first sensing of loud noise levels is an acceptable indication that hearing protection should be worn.

Hearing loss is less obvious than a loss of other senses, making it harder to detect. A "ringing" noise or somewhat muffled sense of hearing is one sign. Loss of the ability to hear some sounds, especially the higher pitched frequencies is another sign. Initial hearing loss from temporary excessive noise levels may return overnight, but continued exposure to these levels will cause hearing loss to become permanent.

Operating a newer tractor with a 'sound-engineered' cab can result in less exposure to harmful noise levels. Wearing ear muffs or ear plugs is another way. According to Maher, stuffing wads of cotton in the ears is not safe hearing protection, the noise may be muffled but it is still getting through, and will damage your hearing. The design and manufacture of safe, effective hearing protective equipment is a precision process.

Many brands, styles, and models of plugs and muffs are available, so selecting protective equipment for your hearing protection can be confusing. Do not depend on price alone. Price is usually a good indicator of quality, but not always, Maher says.

The noise reduction rating (NRR) should help you in making a decision. A higher NRR value indicates more protection, at a noise level of 100 decibels your hearing protection with a NRR of 25, will reduce your exposure to 75 decibels.

Protective equipment must be test fitted to the individual. Ear muffs can usually be tried on and checked for comfort and effectiveness. "They must fit properly if they are to do the job," Maher says.

You should also test the equipment with a loud noise present. "Testing them in a silent room tells you nothing," Maher says "There must be some noise present. If there is a significant reduction in the noise volume and perhaps elimination of some frequencies then they offer some protection."

Ear muffs should be snug enough that they do not slip from position, but not so snug that they cause discomfort. The muff should have direct contact around the ears they may not seal properly against your head if you wear your hair long and over the ears. Some ear muffs are more effective in certain positions, the way you wear them will affect how well they work. Those that are affected by position offer the most protection when the strap is over the top of your head. The NRR rating may be lower when the strap is worn around the back of the head or under the chin.

Ear plugs should fit in the outer ear canal comfortably. They may take some getting used to, but should not be painful. Some kinds of plugs are rolled down to a smaller diameter, inserted carefully in the outer ear canal, and allowed to expand; filling the outer canal. With other kinds, you simply wiggle them in.

"If you can still hear the tractor, even for just a few hours after work, that is a strong indication of hearing loss," Maher said. "Get your hearing checked soon and learn how bad your loss is, maybe you should be wearing some hearing protection."

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Writer: Stephanie Renner
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu
Source: George Maher, (701) 231-8288, gmaher@ndsuext.nodak.edu