Navy Hearing Conservation Program: threshold shifts in enlisted personnel, 1995-1999

This study presents audiometric information from 54,057 Navy enlisted personnel in the Navy and Marine Corps Hearing Conservation Program database from 1995 to 1999. The purpose was to compare current threshold shift patterns for Navy enlisted population with historical literature and review programmatic effectiveness issues. The data suggest that 82% of the population did not display significant threshold shift (STS) on the "annual" and "termination" audiograms, which increased to 94% after the "follow-up 2" examination. Compared with historical data, STS rates were significantly lower for the most junior enlisted personnel (E1-E3) (odds ratio = 0.34, p = 0.00, 95% confidence interval = 0.30-0.39) but not significantly different for more senior enlisted personnel (odds ratio = 0.96, p = 0.22, 95% confidence interval = 0.90-1.03). STS rates did not appear to correlate with expected "high" and "low" noise exposure Navy enlisted occupations. This suggests further investigation to readdress the possible risk factors other than noise intensity/duration.