A twelve-year longitudinal study of hearing thresholds among professional divers.

In this prospective study over twelve years, we have studied 30 young professional divers. The aim of the study was to see if changes in hearing thresholds were related to cumulative diving exposure. The study started at the beginning of the divers' education to become professional divers. Over the follow-up period the divers performed air-dives to shallow sea levels with a median number of 477 dives (range: 40-4458). The examination was performed by measuring air conduction thresholds in a sound treated booth. During follow-up, a significant reduction in auditory function was found at 0.25, 0.5, 2, 3 and 6 kHz for the right ear and 3, 4 and 6 kHz for the left ear. A reduction in hearing function associated with diving was found at 4 and 8 kHz (p < 0.01) both ears combined. Hearing impairment among this group of professional divers, with possible noise exposure, shows that hearing impairment is associated with their profession.