Does Occupational Noise Cause Asymmetric Hearing Loss?

In Brief Objective: Determine whether occupational noise exposure increases audiometric asymmetry. Design: Audiograms were performed on 2044 men from the Occupational Noise and Hearing Survey, representing four groups based on preliminary screening (for previous noise exposure, otologic history, and otoscopy) and current occupational noise exposure. The effects of current noise exposure on audiometric asymmetry were tested using ANCOVA, with binaural average thresholds as covariates. Results: There were no significant differences in asymmetry attributable to current occupational noise exposure. Results: Occupational noise exposure does not usually cause or exacerbate audiometric asymmetry. People claiming benefits for occupational noise-induced hearing loss often have asymmetric audiograms, but the cause of the asymmetry may be obscure. The Occupational Noise and Hearing Survey database allowed measurement of audiometric asymmetry in both noiseexposed and non-noise-exposed men. With appropriate controls for previous noise exposure, otologic history, abnormal otoscopy, and binaural average hearing levels, audiometric asymmetry was unaffected by current occupational noise exposure.