Diagnosing Noise-Induced Hearing Loss Sustained During Military Service for Men Aged Between 61 and 80 Years

A recently described method (rM-NIHL) for diagnosing noise-induced hearing loss (NIHL) sustained during military service for men aged up to 60 years was developed based on the shapes of the audiograms of noise-exposed military personnel and a control group matched in age but without known noise exposure. Here, the applicability of the rM-NIHL method to men aged 61 to 80 years was evaluated, based on a database including 329 military noise-exposed men (ExpDB) and a database including 123 non-exposed men (ContDB). The method had high sensitivity but poor specificity. For further analysis, ExpDB was randomly split into ExpDB1 and ExpDB2, and ContDB was randomly split into ContDB1 and ContDB2. ExpDB1 and ContDB1 were used for the development of new methods and ExpDB2 and ContDB2 were used for evaluation. Modification of the criteria used in the rM-NIHL method led to a better balance between sensitivity and specificity, but the overall diagnostic performance was only moderate. A new method, denoted M-NIHL60+, was developed based on a weighted average of the age-corrected hearing thresholds across all frequencies from 1 to 8 kHz. This method gave a reasonable balance between sensitivity and specificity and gave higher diagnostic performance than the original rM-NIHL method or the rM-NIHL method with modified criteria. Comparison of data for older and younger exposed groups (assessed previously) supported the hypothesis that the rate of change of thresholds with age for noise-exposed individuals is greater for frequencies where the initial NIHL is small than for frequencies where it is large.