The Effects of Chronical Noise-Exposure on Hearing Ability, Psychological and Mental Attitude of Workers in Automotive Industry

Introduction: Noise is considered as a physical hazard that seriously threatens human health in industrial environments. It is also the most important and influential harmful physical factor in workplace that can affect the individuals’ lifestyle and job. The present study aimed to determine the effects of chronic noise on the hearing ability as well as psychological and mental attitudes of workers in the workplace. Methods: This descriptive-analytical study was carried out to measure the sound intensity received by the individuals' ears at an 8-hour equivalent level based on ISO 9612: 2009 standard, using the Testo device (model CEL-815). Annoyance (negative mental attitude to work environment) was also measured using a questionnaire containing 11 questions.  Furthermore, the Stroop and Tower of London (TOL) tests were applied to investigate the cognitive performance.  Results: A total of 300 people with the mean age of 36.03 ± 3.79 were included in this study. The results clearly showed a significant relationship between cognitive indicators and hearing loss (P < 0/05 ). A significant relationship was also observed between annoyance and hearing level at different sound frequencies (P < 0/05). Besides, the results of the Stroop, Tower of London, and cognitive performance tests had a significant relationship with the annoyance caused by chronic exposure to noise (P < 0/05). Conclusion: The results of this study clearly showed the positive effect of hearing loss on annoyance and cognitive performance indicators among the workers exposed to chronic noise.