Noise levels in over-the-road tractors

Noise levels in eight over-the-road tractors were measured under actual driving conditions to quantify the noise exposures of the drivers. Decibel readings were taken for a range of individual frequencies and weighting scales under standardized conditions. Readings were also taken under non-standardized conditions and continuous monitoring dosimeters were used. Spectral analysis of the noise indicated that high sound pressure levels were associated with low frequency noise. Differences were observed between the A scale readings on the sound level meter and those calculated from the dosimeter. These differences are attributed to non-standardized conditions experienced during normal vehicle operation and indicate that truck drivers are exposed to potentially harmful noise levels, often in excess of 90 dBA.