[The hearing function and vegetative reactions in airport technicians using individual hearing protectors].

The objective of the present study was to evaluate the hearing function in the airport technical personnel and estimate the effectiveness of multicomponent anti-noise hearing protectors used by the specialists engaged in the aircraft maintenance. The tonal threshold audiometry was carried out before and after a shiftwork. The extra-aural effect of noise was assessed from the characteristics of cardiac rhythm variability. The study included two groups of subjects: in one of them (n=8) they used ordinary flight headsets (control) in the other the protection was ensured with the help of multi-insert hearing protectors (n=16). The initial hearing thresholds were found to be increased up to 70 and 60 dB at the frequencies of 4 and 8 kHz respectively. The regression analysis revealed the relationship between these parameters and the duration of aerodrome work experience. Temporary threshold shifts were observed only in the control group. An increase in the tone of the sympathetic nervous system was observed in the control subjects but was absent in the study group. It is concluded that the multi-component hearing protectors employed in the present study are highly efficacious anti-noise devices. The mechanisms of noise-induced hearing loss are discussed.