Long-term effect of noise exposure during military service in South Korea.

OBJECTIVE: Most Korean men spend at least two years in the military service usually in their early twenties. The aim of this study was to identify the long-term effect of exposure to military noise during military service by comparing two regressions of age-related hearing loss between groups with and without exposure to military noise. DESIGN: Cross-sectional observational study. STUDY SAMPLE: Finally, 4079 subjects were included, among 10,286 data of men's audiogram from January 2004 to April 2010. We excluded repeated testers and any subjects who had other known external causes or had an asymmetric audiogram. We grouped subjects with exposure to military noise (N = 3163) and those without as the control group (N = 916). RESULTS: There was a significant effect of exposure to military noise at 4 and 8 kHz after controlling for the effect of age. The annual threshold deterioration rates were faster in the military noise exposed group than in the control group at 1, 2 and 4 kHz (p < 0.05). CONCLUSION: The long-term effect of exposure to military noise on age-related hearing loss showed an adding effect at 8 kHz and an accelerating effect in the frequency region from 1 to 4 kHz.