An Investigation on Noise Level at Workplaces and Distribution of Hearing-loss Curve of Noise-exposed Workers

Objective To investigate the noise level at workplaces and the distribution of the hearing-loss curves of noise-exposed workers in a cane-sugar chemical plant.Methods 230 noise exposed workers and 144 non-noise exposed workers were examined hearing-loss by electronic audiometry.The distribution frequency of varied hearing-loss curve was analyzed.Results The noise levels represented by Leq(A) values at workplaces were all exceeded 8h-90db(A).The detection rates of V-shapes (wedge-shaped) and U-shaped hearing-loss curves of both ears were found higher in noise-exposed group compared with the controls(P0.01).Conclusion Noise levels with higher Leq(A) values caused not only hearing-loss,but also change of distribution of hearing-loss curves.This study suggested that necessity of noise control at workplaces and personal protection measures together with medical surveillance by regular electronic audiometry.