Self-Assessment of Hearing Status and Risk of Noise-Induced Hearing Loss in Workers in a Rolling Stock Plant

Abstract

Noise measurements and questionnaire inquiries were carried out for 124 workers of a rolling stock plant to develop a hearing conservation program. On the basis of that data, the risk of noise-induced hearing loss (NIHL) was evaluated. Additionally, the workers’ hearing ability was assessed with the (modified) Amsterdam inventory for auditory disability and handicap, (m)AIADH. The workers had been exposed to noise at A-weighted daily noise exposure levels of 74-110 dB for 1-40 years. Almost one third of the workers complained of hearing impairment and the (m)AIADH results showed some hearing difficulties in over half of them. The estimated risk of hearing loss over 25 dB in the frequency range of 3–6 kHz was 41–50% when the standard method of predicting NIHL specified in Standard No. ISO 1999:1990 was used. This risk increased to 50–67% when noise impulsiveness, coexposure to organic solvents, elevated blood pressure and smoking were included in calculations.