The Study of High Frequence Hearing Loss in Pilots

BACKGROUND: Hearing loss is associated with environmental noises. Not only the strength of the noise but also the exposure time of that seems important. We investigated to find the factors associated with hearing loss in pilots. METHOD: For the anlysis of hearing loss in pilots in the air force, we performed an audiometiric test on 563 pilots from 2000 to 2001 and analysed the results. REUSLT: The type of aircraft or regiment is not associated with hearing loss. The age, tenure and total flight time are the factors associated with hearing loss, especially in the high frequency zone. The flight time in the recent six months is shown not to be associated with hearing loss which means an exposure to noise in a longer term is important. In this study, the hearing threshold increased at 6,000 Hz regardless of age. CONCLUSION: The reason may be due to the noise environment of pilots. Therefore an additional study about pilots' normal limits of hearing threshold at 6,000 Hz and clinical meanings of that is necessary.

The Changes of the Left Ventricular Contractility and the Cardiac Vector of the Pilot by the Flight Time

To study on the left ventricular contractility and the cardiac vector of fighter pilots, 56 pilots and 15 normal cadets were selected and they were divided into six groups by flight time (hours). To evaluate the left ventricu-lar contractility of subjects, R amplitude of chest V1 , V5 , V6 lead were recorded by ECG, and R-Z interval were recorded by ICG (impedance cardiography). And, to evaluate the cardiac vector of subjects, mean QRS vec-tor of I, II, V2 , V6 lead were recored by ECG. Results of this study are following, 1) Systolic and diastolic blood pressure were decreased against flight time. 2) Sv1 +Rv5 was decreased against flight time; Sv1 +Rv5 was 27.8 mm in 50 hr Group that is the longest among the group, and 23.7 mm in 2,000 hr Group that is the shortest among the groups. V6 /V5 was no significant difference among the groups. 3) R-Z interval was decreased against flight time; R-Z interval was 166.8 X10(-3) sec in 50 hr Group that is the longest among the group, and 154.4 X10(-3) sec in 2,000 hr Group that is the shortest among the groups. 4) In frontal plan, the range of QRS vector axis was +57.3 degrees ~ +78.2 degrees that was deviated to left of body center according to the flight time. In horizon-tal plan, the range of QRS vector axis was -29.6 degrees ~ +47.2 degrees that was deviated to back of body center according to the flight time. In both plan, the amplitude of QRS vector was tend to decreasing against the flight time. Results of this study indicate that the cardiac function of fighter pilots was doubted to degenerate or weaken. Conclusionally, fighter pilots have to increase their cardioventricular fitness by the aerobic training and other methods.

Effect of Age and Flight time on the Audition of Pilots in Asiana Airlines

BACKGROUND: This is to evaluate the noisy environment, and to improve the hearing conservation program by analyzing the status of hearing loss and risk factors which cause hearing loss of Airlines pilots. METHODS: We reviewed Audiometric, Medical and Flying records of total 92 pilots under 55 years old . These subjects selected after excluding pilots with history of ear disease and ototoxic drug administration. The significance of the factors was analyzed by ANOVA and Regression test. RESULT: The mean age of pilots was 39.96 years old and the mean flight time was 5665.39 hours. The noise levels by aircrafts were mean 76.9dB and maximum 144.4dB in B737, mean 78.5dB and maximum 143.2dB in B747. The noise levels by headset were mean 72.1dB and maximum 144.1dB. The mean hearing threshold level was different with age groups. The older in age, the higher in the mean hearing threshold level at high frequency and left ear. It was increased the mean hearing threshold level (dB) at high frequency (4,000 Hz) by total flight time The effect on hearing threshold level at high frequency in left ear was statistically significant in total flight time (p=0.032). CONCLUSION: The noise level of aircrafts could cause noise-induced hearing loss in some pilots. Age and total flight time are within the range of possibility of hearing loss. The result of this study ascertained the possibility of hearing loss due to monaural-headsets on the left ear at 4,000 Hz. It is recommended that an effective hearing conservation program should be provided for the headset-wearing communication pilots.