Age-related hearing decline in individuals with and without occupational noise exposure

Abstract

This study was conducted to compare the pattern of age-related hearing decline in individuals with and without self-reported previous occupational noise exposure. This was a prospective, population-based, longitudinal study of individuals aged 70-75 years, from an epidemiological investigation, comprising three age cohorts. In total there were 1013 subjects (432 men and 581 women). Participants were tested with pure tone audiometry, and they answered a questionnaire to provide information regarding number of years of occupational noise exposure. There were no significant differences in hearing decline, at any frequency, for those aged 70-75 years between the noise-exposed (N= 62 men, 22 women) and the nonexposed groups (N = 96 men, 158 women). This study supports the additive model of noise-induced hearing loss (NIHL) and age-related hearing loss (ARHL). The concept of different patterns of hearing decline between persons exposed and not exposed to noise could not be verified.

Figure 1

Mean hearing threshold levels in the better ear, men (a-c) and women (d-f) At 70 and at 75 years of age. Subdivision by noise groups: Total group (a and b) No reported occupational noise exposure (c and d) and more than 10 years of occupational noise exposure (e and f)

Figure 2

(a and b) Mean annual threshold change in dB/year, in the better ear, from 70 years to 75 years of age, by gender and noise exposure groups: No reported noise (No N) or >10 years of reported occupational noise exposure (N) Adapted data for subjects of the same age for reference, from Lee et al. (2005) with negative or positive noise history, and from Pearson et al. (1995), are supplied. Mean values, rather than medians, are shown for illustrative purposes