Mechanism of Hearing Disturbance due to Alteration of Atmospheric Pressure

Abstract

The mechanism of deterioration in bone conduction due to changes in atmospheric pressure was examined in 20 normal subjects using a sound-proof pressure chamber. The subjects wore special ear plugs with which the external auditory canal was connected to a pressure gauge and and a small pump placed outside the chamber. Subjects were in structed not to swallow to avoid active opening of the Eustachian tube. The chamber pressure was decreased (or increased) to± 500 mmH₂O at a speed of 30 mmH₂O/sec. Then pressure in the external auditory canal was decreased (or increased) gradually after the chamber pressure had reached ±500 mmH₂O. However, the level of bone conduction did not recover the level before decrease (or increase) in the chamber pressure. These findings suggest that at a least minor part of the deterioration in bone conduction after changes in the chamber pressure was caused by displacement of the round window membrane.