Objective To compare the characteristics of hearing loss in helicopter pilots and fighter pilots, and provide evidence for hearing protection during aeromedical support service.
Methods Pure tone audiometry data from 316 qualified pilots for duties, who had no symptoms of tinnitus and hearing loss, were collected from July 2014 to September 2019 in the department of aviation medicine in the Air Force Hospital of Southern Theater Command, PLA. Among them, 186 cases were helicopter pilots, while 130 cases were fighter pilots. The incidence of auditory frequency threshold higher than 25 dB in 0.25, 0.5, 1, 2, 3, 4 and 6 kHz was calculated, respectively. Besides, the differences in the incidence of hearing loss in speech frequency (≤2 kHz) and high frequency (≥3 kHz) were analyzed.
Results The total incidence of hearing loss in helicopter pilots and fighter pilots was 16.4% and 12.3%, respectively (P > 0.05). The incidence of noise-induced hearing loss was 11.3% and 10.8%, respectively, without statistically significant difference (P > 0.05); The highest incidence of noise-induced hearing loss happened at the frequency of 4 kHz in both of the two groups. The incidence of hearing loss in speech frequency was 5.1% in helicopter pilots, statistically higher than 1.5% in fighter pilots (P < 0.05); The highest incidence of hearing loss happened at the frequency of 0.5 kHz for helicopter pilots and 2 kHz for fighter pilots.
Conclusion Pilots have a higher incidence of hearing loss, which is mainly caused by noise. However, the incidence of hearing loss at speech frequency in helicopter pilots is significantly higher than that in fighter pilots.
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