The influence of ageing on noise-induced hearing loss.

A lifetime of exposure to noise is likely to have negative effects on the hearing, but the interaction between noise-induced hearing loss (NIHL) and age-related hearing loss is difficult to determine. The most commonly accepted assumption is a simple accumulating effects of noise and ageing on the hearing. However, both a less than additive effect as well as a supraadditive effect has been proposed. Recently an interesting interaction between NIHL and age-related hearing loss has been reported (Gates et al., 2000). NIHL before old age reduces the effects of ageing at noise-associated frequencies, but accelerates the deterioration of hearing in adjacent frequencies. Findings from the longitudinal and cross-sectional gerontological and geriatric population study of 70-year-olds in Gothenburg, Sweden supports these observations. The incidence of tinnitus increases in old age, but not at the same high rate as presbyacusis. According to the gerontological and geriatric population study in Gothenburg tinnitus in old age is related more to hearing loss than to ageing. There are no simple correlations between exposure to noise during the active years and tinnitus in old age.