The effect of oxygen inhalation on temporary threshold shift in humans

To examine the effects of an increased oxygen supply on the establishment of noise-induced TTS in humans, 20 Ss were exposed for 10 min to a narrow band of noise centered at 3 kc/s at 100 db SPL, while inhaling either a 60% or a 90% oxygen-air mixture. In a control condition, these Ss inhaled air only while being subjected to the same noise. In the 10 Ss who had inhaled the 90% mixture, TTS was less than when they had inhaled air (delta TTS - 2.06 db, p less than 0.25). Delta TTS (0.07 db) for the 10 Ss who inhaled the 60% mixture was not significant. A further 5 Ss inhaled the 90% mixture for 10 min with no noise exposure; there was no effect on the hearing threshold levels. It was concluded that inhalation of at least 90% oxygen-air for 10 min does not affect HTLs but does reduce TTS. A re-examination was suggested of the possibility that there is a relationship between auditory fatigue and supply of oxygen to cochlear structures.