Hearing losses among workers working in 80 to 85 dB noise environment

ObjectiveTo investigate hearing losses among workers working in noise environment with pressure level≥80 dB or < 85 dB and offer the basis for hearing care among this crowd.

MethodsTwo enterprises in Shanghai were chosen for the study, whose working environment was with equivalent A-weighted sound pressure level ≥80 dB or < 85 dB. By means of random sampling, a total of 1 360 workers were selected from the two enterprises, who were divided into two groups for hearing tests based on their noise exposure service length with their age and gender corrected.

ResultsThere were no obvious hearing losses found in the group with noise exposure service length≤20 years (average hearing thresholds in high frequency of both ears were less than 40 dB). There were 4 workers whose average hearing thresholds in high frequency of both ears were greater than or equal to 40 dB, and who were in the group where workers′ noise exposure service length was more than 20 years after correction of their age and gender, and 2 of them were accompanied with speech frequency hearing loss.There was no statistical significance in the difference between the two groups(χ_{exact method}²=3.10, P > 0.05).

ConclusionThere is no correlation between noise exposure service length and hearing losses in working under environment with sound pressure level ≥80 dB or < 85 dB. As there are a few cases of hearing losses occurring in the group with workers′ noise exposure service length over 20 years. It is advised that workers whose noise exposure service length is over 20 years should be the key targets in hearing care and supervisions.