Noise exposure in the rural setting.

Noise levels of 155 tractors on 36 farms were studied. The range of noise levels at the driver's ear level with radios off and windows closed (if so equipped) was from 78 to 103 dB. Seventy-five percent of tractors without cabs had noise levels in excess of 90 dB, compared to only 18% of tractors with cabs. The use of a radio adds an average of 3.1 dB of noise. When some cab windows are open and the radio is on, an average of 4.2 dB is added to the cab noise. From the results of this study, the authors recommend hearing protection when time on a tractor with a cab approaches 3 to 4 hours and when time on a tractor without a cab approaches 1.5 to 2 hours. Limited use of the radio is also recommended.