Estimating the effect of occupational noise exposure on hearing thresholds: The importance of adjusting for confounding variables

Objectives: To evaluate whether valid estimation of the effect of occupational noise exposure on hearing thresholds requires adjustment for factors other than age, sex, and race, which also influence hearing function. Design: Multivariate regression analyses were performed in the 1999-2002 National Health and Nutrition Examination Survey (N = 3527). Results: Occupational noise exposure was significantly associated with educational level, leisure time and firearm noise, and smoking. Incomplete adjustment for these factors leads to an overestimation of the effect of occupational noise exposure. Conclusions: Current methods of estimating the effect of occupational noise exposure (e.g., Annex C of American National Standards Institute S3.44) require better consideration of these confounding factors.