Test for Pressure Control Capacity of Eustachian Tube

Abstract

Considering that the Eustachian tube controls middle ear pressure to maintain the optimum hearing level, the equilibration capacity of the Eustachian tube was tested by measuring hearing levels in a sound-proof pressure chamber. As an index of equilibration capacity for static pressure differences across the ear drum, we counted the number of swallows required to recover normal hearing after the chamber pressure reached ± 200 mmH₂O. In normal subjects, less than approximately 8 swallows were necessary except in a few cases. As indices of equilibration capacity for dynamic pressure differences across the ear drum, the worst level of hearing and the time required to recover normal hearing from the beginning of the alteration in the chamber pressure to ± 700 mmH₂O were recorded. In normal subjects, the average worst level of hearing was 7.7-12.5 dB and hearing levels recovered within approximately 60 seconds except for a few cases.