[Course of the audiometric threshold in relation to the age in chronic acoustic trauma]

Until now the relationship between auditory threshold and age has been evaluated in normal subjects only. In this study the Author reports results obtained in a cross-sectional study on 416 subjects suffering from noise-induced hearing loss who were exposed to noise for 10 years at least. The results show that hearing loss over time was more correlated to age than to noise exposure. Moreover, the evolution of hearing loss over time had a linear shape while in noise-induced hearing loss evolution has a logarithmic shape and in presbyacusis it has an exponential shape. The differential threshold between 30 and 60 years obtained by applying the linear regression model was, at higher frequencies, significantly reduced compared to normal subjects. These results suggest that threshold values related to age obtained in normal subjects can not be applied in subjects affected by noise-induced hearing loss.