Study on Combined Effect of Noise and Heat Exposure on Hearing Loss of Tunnellers

Objective To study the combined effect of noise and heat exposure on hearing loss of tunnellers.Methods Four groups with equivalent environment conditions were selected,and their noise and heat stress levels were measured.Differences in the level of hearing loss were analyzed.Results There was no significant difference in the speech hearing threshold and high frequency hearing threshold of the group of heat exposure only in comparing with the control(P0 05).However,there did have significant difference both in the group of noise only and in the group with noise and heat exposure(P0 01).Both speech hearing threshold and high frequency hearing threshold of the noise and heat group were obviously higher than those of the group with noise exposure only,and the difference was significant(P0 01).Conclusions Heat stress did not have any effect on speech hearing threshold and high frequency hearing threshold,however,the combined effect of noise and heat would enhance the hearing loss.