In 1996, NIOSH's National Occupational Research Agenda identified hearing loss as the most common job-related disease in the United States. Previous NIOSH health and safety investigative data of the mining industry indicate that at least 70 percent of mine workers, including those engaged in drilling activities, suffer noise-induced hearing loss severe enough to be classified as hearing disability. A recent NIOSH investigation was conducted on four different air-rotary drill rigs with cabs to determine the noise exposure of the operators. Sound level measurements were recorded around the rig and on the operator in the cab during production drilling. The results of these measurements indicate that, in all cases, the drill rig generates hazardous noise levels. The noise exposure for the operators varied from rig to rig and was dependent on rig/cab design and the operator's work behavior. Acknowledging these hazardous noise conditions and taking precautions can protect drill operators from suffering from noise-induced hearing loss (NIHL).