Estimated sound power radiated by surfaces on a continuous miner tail section using vibration measurements.
NOISE-CON 2003: Proceedings of the 2003 National Conference on Noise Control Engineering, Cleveland, Ohio, June 23-25, 2003. Holger DK, Maling Jr. GC, eds., Ames, IA: Institute of Noise Control Engineering of the USA, 2003 Jun; :1-9
Miners in underground coal mines experience prolonged exposure to high noise levels, often with A-weighted sound levels in excess of 90 dB. Fields tests have shown that the continuous miner conveyor is a dominant noise source. This paper identifies the most significant noise-radiating surfaces on the continuous miner tail section using vibration levels and surface areas to estimate the sound power levels of each surface. In addition, using five test cases, this study will examine the effects of three engineering noise controls on the surface-averaged vibration levels and average sound levels measured with four microphones located 2 m from the tail section. The noise-radiating surfaces of the conveyor's tail section include the top and bottom decks, the sideboards, and the flex plates. Emphasis is placed on the changes in the estimated sound power levels in the 500-2,500 Hz 1/3-octave bands, since this frequency range accounts for 80%-85% of the sound energy near the tail section. The results show that the bottom deck is the most significant noise radiator for the untreated miner. Installing a coated bottom deck reduces the estimated sound power level radiated from the bottom deck by 11 dB and the average sound level by 2 dB. Using a coated tail roller results in reductions of the estimated sound power levels for individual components from 1 to 4 dB and educes the average sound level by 2 dB. Coating the slide plate has little effect on both the estimated radiated sound power levels and the average sound level. The test results indicate that modifications that reduce flex plate vibration and reduce energy transfer from the tail roller into the tail section will be effective in reducing noise when combined with a coated tail roller and coated return deck.
Hearing-loss; Noise; Noise-exposure; Noise-induced-hearing-loss; Noise-levels; Engineering-controls; Mining-equipment; Underground-mining; Coal-mining; Control-technology
NIOSH, Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Holger-DK; Maling-GC Jr.
Research Tools and Approaches: Control Technology and Personal Protective Equipment
NOISE-CON 2003: Proceedings of the 2003 National Conference on Noise Control Engineering, Cleveland, Ohio, June 23-25, 2003