Prevalence and an analysis of noise--induced hearing loss in army helicopter pilots and aircraft mechanics.
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.


METHODS
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 involvement including speech frequency and high frequency and more decibels loss than aviators. The type of hearing protection and smoking index were strongly correlated with hearing loss. Age, flight time and alcohol habit had no significant effect and ninety percent of the subjects had no self awareness of hearing loss.


CONCLUSIONS
Aircraft mechanics had more severity on hearing loss than aviators. Types of noise protector and cigarette smoking had significant association with hearing loss.
Jaruchinda
Pariyanan
P
Department of Otolaryngology, Phramongkutklao Hospital, Bangkok, Thailand. parybo@hotmail.com
Thongdeetae
Taninsak
T
Panichkul
Suthee
S
Hanchumpol
Pongtep
P
D000328:Adult; D000401:Aircraft; D006317:Hearing Loss, Noise-Induced / Q000453:epidemiology*; D006801:Humans; D008875:Middle Aged; D008889:Military Personnel; D009784:Occupational Diseases / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D013785:Thailand