Prevalence and an Analysis of Noise- Induced Hearing Loss in Army Helicopter Pilots and Aircraft Mechanics

The effect of long term exposure to excessive levels of aircraft noise have been considered to be one of the major factors causing permanent hearing loss of the military Background and Objective: Hearing impairment from noise exposure has been reported in fix-wing pilots, especially in civilized countries. However, there are few studies on rotary wing aviators and aircraft mechanics, especially in developing countries whose hearing conservative program is not well established. The present study, therefore, was done to evaluate the prevalence of noise induced hearing loss and the contributing factors that may effect both groups of noise-exposed population. Material and Method: Report questionnaires were reviewed and physical examination combined with audiometric records of 34 pilots and 42 mechanics in the Royal Thai Army Aviation Center, Lobburi, were examined. Hearing loss was studied using four categories of significant threshold shift (STS). Amplitude of noise radiated by aircraft was also measured at different distances. Results: No significant difference was found in prevalence of hearing loss in aviators (32.4%) and aircraft mechanics (47.6%), but in the aircraft mechanics group there were more damage of frequency involvemen