The absence of hearing loss in otologically asymptomatic recreational scuba divers

We undertook a retrospective cohort study of 16 experienced recreational scuba divers and 16 matched non-diver controls to determine the prevalence of hearing loss and, if present, the likely causes of this loss. Each subject was required to be aged 55 years or less and to have no history or likelihood of hearing loss. An audiologist, blinded to each subject's group status, undertook all examinations. There were no significant differences in group demographics. All divers were highly experienced (median number of dives 725). Comparison of mean hearing thresholds (range 250-8000 Hz) revealed no significant differences between divers and non-divers for both air and bone conduction studies. The only exception was at 6000 Hz where the air conduction threshold was significantly higher in divers than in non-divers (p = 0.03). However, there were no significant differences in Pure Tone and High Frequency averages. We conclude that experienced recreational scuba divers do not have elevated hearing threshold levels overall when compared to non-diver controls. This conclusion differs from that of investigators who have examined the hearing of experienced professional divers. Further investigation is indicated to further investigate this discrepancy and to determine whether the apparent hearing loss among the divers at 6000Hz was an isolated departure from normal hearing thresholds or, in fact, the result of diving.