A study of noise exposures aboard an oceangoing hopper dredge was conducted. Personal noise dosimeters were attached to an unspecified number of watchtenders serving aboard a 30 year old dredge operating in the Delaware River. Personal noise exposures during the 4 or 6 hour watches were monitored. Watchtenders whose 8 hour equivalent continuous sound level exposures (Leq8) exceeded 83 A-weighted decibels (dBA) were asked to describe their work activities. Noise levels in the areas of the ship where these exposures occurred were measured. Noise levels in quiet areas such as staterooms, crew quarters, messes, and recreation areas ranged from 45 to 65dBA. Noise exposures of around 93dBA were experienced by the bintender while on the hopper deck during dredging operations. A fireman who operated the boilers was exposed to noise levels that were generally below 85dBA. He was exposed to 94dBA noise whenever he entered the lower engine room. Engine room noise originated from feed pumps, turbine reduction gear casings, and lubricating oil piping. A watch engineer received Leq8s of 84 to 94dBA in the engine operating flat. Major noise generating sources in the flat included the turbine reduction gear casing, turbine lubricating oil pumps and piping, main condenser and distilling unit air ejectors, and steam pressure reducing stations. The oiler who assisted the watch engineer was exposed to 78 to 94dBA noise. The authors conclude that worker noise exposures aboard the dredge consist of work related and off duty exposures. Recommendations for reducing noise exposures included enclosing the engine room equipment, installing an acoustically isolated enclosed operating station, replacing feed pump motors in the engine rooms, and implementing a hearing conservation program.
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