Field Validation of a Standard Hearing Loss Prediction Model in an Iranian Textile Industry

Noise is the most frequent physical agent in workplace that effects on hearing loss. This study aimed to investigate the value of noise exposure in different jobs along with noise induced permanent threshold shift of workers, prediction of hearing threshold alteration in relation to job and work experience using ISO 1999 standard and comparing with measured hearing loss. This study was performed among 138 Iranian workers in a Yazd spinning factory in 2014. Noise exposure level was measured using ISO 1999 method in any work conditions. An audiometric test was done in a standard soundproof room by an experienced audiologist. Noise induced hearing loss was identified after reduction of age related hearing loss. Necessary program for hearing loss prediction of workers was prepared using the ISO method. Finally, data were analyzed by SPSS16 software. Mean age and employment duration of participants were 36.58 ± 6.76 yr and 11.08 ± 5.47 yr, 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. The duration of employment and noise are two important factors in work-related hearing loss. There was a significant difference between the measured noise induced hearing loss and its predicted values (P<0.05). Better surveillance and prevention programs are recommended to reduce the prevalence of work-related hearing loss, such as perform pre-employment medical and periodic occupational health examinations.