Noise controls for drills in the dimension stone industry

Abstract

Drills in the dimension stone industry have proven to be a problem when it comes to overexposures to noise. These drills include, but are not limited to slot drills, down-hole drills, and horizontal lift-hole drills. Although drills with acoustically treated operator cabs exist for this industry, most drills encountered do not have them. Considerable effort has been made by both the Mine Safety and Health Administration (MSHA) and industry to achieve compliance with the noise standards stated in Code of Federal Regulations (CFR) Title 30, part 62 for the drills without operator cabs. Several individual noise controls are available for these drills. They include exhaust mufflers, operator control barriers, hammer covers, face shields, and three-sided enclosures. A joint noise study was conducted by MSHA and a cooperative mining company to determine the effectiveness of these individual noise controls alone and in various combinations. Previously, these noise controls were studied separately under varying conditions and some found to provide significant noise reductions. The study was conducted to determine their effectiveness under the same conditions and to quantify not only their reduction in sound level, but also overall noise dose.