Noise-induced hearing loss is one of the 10 leading occupational diseases, and it affects as many as 10 million employees who work in noise above 85 dBA. A new study, "Changes Over Time in Audiometric Thresholds in a Group of Automobile Stamping and Assembly Workers With a Hearing Conservation Program" by LuAnn L. Brink et. al., used noise and hearing use measurements taken at the automobile assembly plant to construct average lifetime noise exposure and hearing protection compliance estimates. Published in the July/August 2002 American Industrial Hygiene Association's AIHA Journal, these estimates were then used to develop models predicting the workers' total hearing loss and onset of two accepted definitions of hearing loss.
"Hearing loss was proportional to lifetime average noise exposure estimates," wrote researchers, and "the use of hearing protection is inversely proportional to hearing loss, as expected."
They note that younger workers wore hearing protection "significantly" more often than older workers, adding, "A study of these protected workers will be needed to determine the effectiveness of hearing protection when used during the entirety of a worker's tenure."
Other than the percentage of time spent wearing hearing protection, other variables associated with hearing loss included lifetime average noise exposure, male gender, having transferred into the plant, older age and longer tenure at the facility.