Test for Pressure Control Capacity of the Eustachian Tube

Abstract

Because the Eustachian tube controls middle ear pressure to maintain the best hearing level, we tested the equilibration capacity of the Eustachian tube by measuring hearing levels in a soundproof pressure chamber. The number of swallows to recover normal hearing after the chamber pressure reached -200 mm H₂O (an index of equilibration capacity for the static pressure differences across the eardrum) was less than 9 in normal subjects. The worst level of hearing and the time required to recover normal hearing from the beginning of alteration in the chamber pressure to -700 mm H₂O (indexes of equilibration capacity for dynamic pressure differences across the eardrum) were 0-17 dB and within 120 s in normal subjects. It was difficult to determine definitive normal ranges of the equilibrium capacity of the Eustachian tube when positive pressure was applied.

Key Words:

• pressure chamber
• control for static condition
• control for dynamic condition