Biomechanical characteristics of the middle ear system measured by a new method. III: Comparisons with tympanometric measurements.

A new method for studying middle ear mechanics is reported in which we measured ear canal pressure changes due to tympanic membrane volume displacements. One feature of this pressure-volume relationship (PVR) is the determination of dynamic compliance of the middle ear system (MES). We found a significant correlation between dynamic compliance expressed by the PVR and static acoustic compliance by tympanometry. Another feature of the PVR was determination of the mechanical zero position of the tympanic membrane (TM) defined in terms of minimum hysteresis, which correlated significantly with the neutral position of the TM determined by tympanometry, but indicates a retracted position of the TM relative to tympanometry. Finally the hysteresis effect of the MES measured with the PVR was compared and found to fall within the range of peak difference found in bidirectional tympanometric recordings, which is also influenced by phase delay and semi-dynamic conditions.