Hearing Thresholds at Extended High Frequencies in Civilian Student Pilotswith Normal Hearing at Conventional Frequencies / 听力学及言语疾病杂志

ABSTRACT

Objective To study extended high frequency (EHF) audiometry for early detection of hearing loss in student pilots in civil aviation.Methods A total of 175 student pilots (all male,18~25 years old, mean 20.2±0.92 years) from a university flight academy were surveyed and underwent EHFA.All subjects had hearing thresholds ≤25 dB HL at conventional frequencies (0.25~8 kHz).The results were compared with the corresponding recommended standards in other countries.According to the use of personal listening devices, all the subjects were divided into the low risk group (non-use, 121 cases) and the high risk group (using>1 year, day>1 hour, 52 cases).The differences of hearing thresholds and detection rates at EHF between the two groups were compared.Results The hearing thresholds of 173 subjects (1 case of middle ear disease and 1 case with family history of hearing loss were excluded) at 9~20 kHz were slightly higher than the reference equivalent threshold sound pressure level (RETSPL) prescribed by American National Standardization Association and the age-matched thresholds recommended by a foreign literature (P<0.05 or P<0.01).The hearing thresholds in the high risk group elevated dramatically than that in the low risk group at 9,12.5,16 and 18 kHz(P<0.05 or P<0.01).As frequencies increased, the detection rate of hearing thresholds in the high risk group decreased gradually, and at 18 and 20 kHz it was significantly lower than that in the low risk group (P<0.01).Conclusion EHF audiometry is a helpful tool for early detection of noise-induced hearing loss in student pilots.Hearing health care should be emphasized in civilian student pilots.It is recommended to avoid the use of personal listening devices or reduce the use time of them.