Hearing loss is the most prevalent disease among miners. A study of U.S. western hardrockmines revealed that 96% of machine operators were overexposed to noise, withjackleg drill operators having the most rapid noise dose accumulation. Traditionally,jackleg drills have been driven by pneumatic power. However, there are currentlyavailable rotary hammer drills powered by electricity. This paper presents an acousticassessment of pneumatic and electric jackleg drills that involved Noise SourceIdentification (NSID), penetration rate measurements, operator’s cumulative noise dosemeasurements, and the determination of sound power levels. NSID using beamformingarray technology revealed two dominant noise sources for the electric drill, one located atthe drill and one located at the drill steel-rock interaction place. In contrast, NSID for thepneumatic drill showed only one dominant noise source located at the drill. Penetrationrate and noise dose measurements were combined to estimate the accumulated dose andtime required to drill a reference depth hole. Sound power level measurements whiledrilling into granite yielded overall levels of 115.3 dB(A) and 123.4 dB(A) for the electricand pneumatic drills, respectively. The results show that from an occupational noiseexposure perspective the acoustic performance of the electric drill, despite its slowerpenetration rates, overcomes the benefits of traditional pneumatic drills.
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