Noise-related hearing loss risk factors

Introduction: Hearing loss resulting from exposure to noise presents several onset degrees that depend on environmental conditions and on the individual himself or herself. These factors influence the lack of success associated to prevention programs and result in a cost to the individual and to the society. Cases and method: A total of 171 noise-induced hearing loss cases among metallurgical workers were analyzed retrospectively. The following parameters were considered in this analysis: age group, noise-exposure period in years, type of noise, smoking habits, audiometric thresholds and vocal discrimination indices. The audiometric thresholds set forth by ISO 1999 standard (1990)(4), in Annex A, were used as a control population. Result: It was observed that the auditory lesion manifestation times is shorter for younger individuals, indicative of greater susceptibility in younger age groups. The smoking habit associated to the professional activity influenced the vocal discrimination indices, although the smoking habit factor, analyzed isolatedly, did not affect the audiometric thresholds. The +40 age group exposed to impulsive noise presented worse audiometric thresholds when compared to those exposed to predominantly continuous noise. Conclusions: young individuals are more susceptible to noise exposure. The habit of smelting worsens the vocal discrimination levels. Exposure to impulsive noise causes the appearance of the worst audiometric thresholds as of the second decade of exposure and after the individual is 40 years old.