Longitudinal changes in hearing ability among Swedish conscripts.

An analysis of a military database of about 36,000 tone audiograms from male Swedish conscripts aged 18 to 19 and recorded from 1969 to 1977 demonstrates a successively decreasing prevalence of hearing loss during this period. This might reflect improved therapy during the 1950s and 1960s of ear disorders causing hearing loss in small children. If observations in other studies on a reverse trend during the 1980s are confirmed, they indicate, together with the present study, that around 1980 young people began to be harmfully exposed to an environmental factor causing hearing loss. If this is the case, the causative factor would probably be non-occupational exposure to electronically amplified sounds from loudspeakers and headphones.