NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
April 13, 2000
A familiar sound is returning to area fields. Farm tractors and other machinery are roaring to life as field activities resume. All that roaring may be costing some farm workers their hearing, warns a farm safety specialist at North Dakota State University.
Safe limits for exposure to levels of sound are well known to safety and health researchers, says George Maher of the NDSU Extension Service.For a duration of eight hours, the maximum level is 90 decibels. If the duration increases, the maximum permissible sound level decreases.
How loud is too loud? Measuring noise levels requires instruments that aren't usually available to farmers or implement dealers, but there are some common warning signs. If you've experienced a ringing noise or somewhat muffled sense of hearing, you've probably been exposed to excessive noise. You might also notice the loss of the ability to hear some sounds-- especially at higher frequencies.
"Initial hearing loss from temporary excessive noise levels may return overnight, but hearing loss from longer-term exposure will eventually become permanent," Maher warns. "Most farmers work much more than eight hours a day during the crop production season, so their exposure to noise levels should be less than 90 decibels at any given time. Excess noise levels aggravate fatigue and stress. That, in turn, increases the safety risk of the job by slowing workers' reactions to hazards and other changes in the work environment."
Using hearing protection can reduce the risk of hearing loss and cut stress and the risk of injury. Hearing protection should be worn in the workplace whenever the noise level approaches the maximum permissible levels. 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.
"Stuffing small wads of cotton in the ears is not safe hearing protection. Excessive noise can still damage your hearing. The design and engineering of safe, effective hearing protective equipment is a precision process," Maher says.
Selecting protective equipment to protect your hearing can be confusing. There are many brands, styles, and models of plugs and muffs are available. Which is the better buy? Don't depend on price alone, Maher advises. Look for the noise reduction rating (NRR) number. A higher NRR value indicates more protection if the protective device fits properly. If the noise level is 100 decibels and the NRR of your hearing protection is 25, then you will be exposed to a noise level of 75 decibels.
Also remember that for hearing protection devices, one size does not fit all. Protective ear muffs must be test fitted to the individual. Try them on and check them for comfort and effectiveness. They should fit snugly enough that they do not slip from position, but not so snug that they cause discomfort. Brush your hair to the back so the muff has direct contact around the ears. The position of the muffs 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.
How do you know if you will be protected by the particular equipment you are trying? Try them on with a loud noise present. If there is a significant reduction in the noise volume and perhaps elimination of some frequencies, they offer some protection.
Maher says ear plugs should not cause any pain. The feel of them may take some getting used to, but they should fit in the outer ear canal comfortably. Some kinds of plugs are to be rolled down to a smaller diameter, inserted carefully in the outer ear canal and allowed to expand to fill the outer canal. Others can simply be wiggled in.
A continuous roaring or rumbling noise lasting for hours after work is an indication of hearing loss. Maher says, "Have your hearing checked soon to determine how extensive your loss is and use hearing protection to protect yourself from further damage."
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Source: George Maher, (701) 231-8288
Editor: Tom Jirik, (701) 231-9629