Occupational exposure to noise and the prevalence of hearing loss in a Belgian military population: a cross-sectional study

The armed forces are highly exposed to occupational noise. The aim of this study was to evaluate the prevalence and noise exposures associated with the severity of hearing loss (HL) in a Belgian military population. A cross-sectional study was carried out at the Centre for Medical Expertise (CME) and in four Units of Occupational Medicine (UOM). Hearing thresholds were determined by audiometry. The examination included a questionnaire on hearing-related medical history, and noise exposure in military and leisure time activity. A multinomial logistic regression model was used to assess the association of the severity of HL with tinnitus, with the military occupation, and with noise exposures. Of the 2055 subjects aged 18-55 years, 661 (32.2%) had a slight HL (25-40 dB), 280 (13.6%) had a moderate HL (45-60 dB) and 206 (10.0%) had a severe HL (> 60 dB) of 4 and 6 kHz for both ears. The prevalence of slight, moderate and severe HL increased significantly with age and was higher for subjects from Paracommando and infantry units. Fighting in Built-Up Area (FIBUA) training, shooting with large caliber weapons, and participation in military exercises were the best determinants of HL in this population. These results suggest that subjects from infantry and Paracommando units run the highest risk of HL because they are exposed to very loud noises in their professional life, like large caliber shooting and FIBUA training.