Air Conduction, Bone Conduction, and Underwater Hearing Thresholds in Man

Abstract

Air conduction (AC), bone conduction (BC), and underwater-hearing thresholds were obtained on three samples of underwater swimmers. In Sample I, AC and BC hearing levels varied over a considerable range at the higher frequencies. Underwater hearing thresholds were positively correlated with BC thresholds. The loss of sensitivity upon immersion was negatively correlated with AC hearing levels. In Sample 2, underwater hearing thresholds of three divers having depressed AC hearing levels at 6 kHz and two divers having depressed AC and BC hearing levels were compared with underwater hearing levels of eight normal-hearing divers. Depressed underwater hearing levels occurred for the divers having combined AC and BC losses. Divers exhibiting only AC losses heard as well underwater as normal hearing divers. Maximum sensitivity for the normal hearing divers over the frequency range 1–8 kHz was −20 dB/μbar at 1 kHz. In a third sample, data were obtained on threshold sensitivity over the 125-Hz to 8-kHz frequency range. Maximum sensitivity of −23 dB/μbar was observed at 1 kHz.