ABSTRACT
OBJECTIVE: To analyze the effect of noise exposure on the hearing ability at different frequency in workers.METHODS: A total of 2 411 workers in a mechanical plant in Guangzhou were chosen as the study subjects by using judgment sampling method. The pure tone audiometry threshold test was carried out to analyze the status of hearing loss at different frequencies and its relationship with the length of service of workers. RESULTS: Among the 2 411 workers,883 workers had different degrees of decreased hearing thresholds,the detection rate was 36. 6%. Among them,the single unilateral hearing loss accounted for 19. 6%( 472/2 411),and the binaural hearing loss was 17. 0%( 411/2 411). The hearing loss detection rate of left ear was higher than that of the right ear( P < 0. 05). The decreased threshold of left ear at 0. 5,3. 0 and 6. 0 kHz was higher than that of the right ear at the same frequencies( P < 0. 05). The decreased threshold in both the left and the right ear increased with the increase of the frequency( P < 0. 01). The decreased hearing threshold was the highest at the frequency of 6. 0 kHz. The auditory threshold of left ear in 0. 5,1. 0,2. 0,3. 0 and 6. 0 kHz were higher than that of right ear at the same frequencies( P < 0. 05). The detection rate of hearing loss increased with the increase of service length( P < 0. 01). The decreased threshold of 1. 0-6. 0 kHz increased with the increased length of service except for the frequency of 0. 5 kHz( P < 0. 05). CONCLUSION: There is a significant decreased threshold in workers exposed to noise frequency of 6. 0 kHz. The hearing ability of left ear is more easily impaired than the right ear.There is a dose-response relationship for the length of noise exposure and hearing loss.