Mechanical Properties of the Middle Ear System Investigated by Its Pressure-Volume Relationship

A new method is presented for the measurement of ear canal pressure changes in response to tympanic membrane volume displacements, i.e. the pressure-volume relationship (PVR) of the middle ear system. This method has several advantages when compared to tympanometry; for example, it avoids phase delay and hysteresis can be used as a variable thanks to bidirectional recordings. Moreover, dynamic compliance is registered physically as changes in volume relative to pressure. Normative data for 39 subjects are summarized along with preliminary data from patients exhibiting various clinical conditions. The major findings are that secretory otitis media with middle ear effusion results in significantly increased hysteresis (leading to large errors when middle ear pressure is determined by tympanometry), two types of ossicular discontinuity may be distinguished by this method and that myringoplasty leads to a linear PVR in contrast to the nonlinearity found in normal subjects.