This study empharizes on noise-induced hearing loss of aircraft mechanics who repaired jet aircraft (A310), light propeller aircraft (T-41D), medium propeller aircraft (G-222), heavy propeller aircraft (C-130H) and helicopter (UH-1H). The audiological analysis was conducted for 94 aircraft mechanics who worked at Wing 6, Royal Thai Air Force. The noise levels were measured for five types of aircraft and in their workplaces. The result indicates that hearing thresholds of aircraft mechanics were significantly related to aircraft noise (X2 = 11.95, p < 0.05). Although average of hearing threshold of aircraft mechanics was not found to be higher than normal hearing threshold but there were incidences of hearing loss among jet, light propeller, medium propeller, heavy propeller and helicopter mechanics in range of 500-8000 Hz at 41.7, 20.8, 21.1, 36.4 and 40.0 percent of each type respectively. The ability to hear at 6000 Hz was the most impaired. The comparison of hearing threshold between each type of aircraft mechanics and control group showed that all types of aircraft mechanics had higher hearing threshold than control group and there was no significantly different between each type of aircraft mechanics. There was no incidence of hearing loss in the range of speech frequencies (500-2000 Hz). Age and time duration of work were likely to affect hearing threshold of aircraft mechanics.
