Sound levels on Manitoba farms and reduction of windrower noise

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Baker, Gordon D.
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More than three hundred tests were made to determine typical sound levels of many types of farm machinery used by farm workers in Manitoba. Sound pressure levels were measured at the operator's ear with portable measuring and recording equipment. Only twenty percent of the tractors tested produced sound levels of less than 90 dBA at high idle when loaded. The sound level at the operator's ear for eight forage choppers ranged from 95 to 109 dBA. Most self-propelled swathers, power-take-off combines, grinder-mixers, forage blowers, balers, vegetable harvesters, grain dryers and even small riding garden tractors produced sound levels in excess of 90 dBA. Very few farm machines had sound levels of 90 dBA or less and therefore a risk of hearing impairment is possible for operators exposed to eight or more hours per day on a continuous basis. Tests were perfomred on a water cooled self-propelled windrower to determine its dominant noise sources. Various engine, exhaust, and hydrostatic transmission treatments were tried to reduce the sound level at the operator's ear. The exhaust and transmission treatments were very beneficial.