Field validation of a standard hearing loss prediction model in an Iranian textile industry

摘要

Background: Noise is the most frequent physical agent in workplace that effects on hearing loss. Purpose of the study: investigating the value of noise exposure in different jobs along with worker's noise induced permanent threshold shift and also prediction of hearing threshold alteration in relation to job and work experience using ISO 1999 standard and comparing with hearing loss measured by subjective method. Methods: The study was performed among 138 workers in a spinning factory in Yazd, Iran. Noise exposure level was measured in every work situation using task based method. An audiometric test was done in a standard sound proof room by an experienced audiologist. The noise induced hearing loss was identified after reduction of age related hearing loss. The needy program for worker’s hearing loss prediction was prepared using the ISO method. Finally the obtained data was analyzed by SPSS16 software. Results: Mean age and employment duration of participants were 36.58 ± 6.76 years and 11.08 ± 5.47 years, respectively. Mean noise exposure in office, spinning, baling, carding, combing and other parts was 45, 94, 95.5, 90, 85 and 88dBA, respectively. Mean measured hearing threshold was 16.69 ± 7.82dB in right ear and 17.59 ± 8.55 dB in left ear. Conclusion: There was a significant relationship between noise and employment duration with hearing loss. There was a significant different between the measured noise induced hearing loss and its predicted values. We concluded from this study that the proposed standard model is not a reliable predictor of hearing loss among the workers of the tested population.