The biomechanical characteristics of the middle ear system measured by a new method. II: Clinical application and normal material.

An instrument for measuring the pressure-volume relationship of the middle ear system was introduced earlier. This paper describes the practical application of the instrument and presents a normal material of 45 healthy young adults. Reflecting a slight increase in pressure in the ear canal during the measuring procedure, a series of curves is obtained, each representing a different position of the tympanic membrane. From these curves the zero curve is defined, representing the zero position of the drum. This curve is used to determine the variables of the pressure-volume relationship of the middle ear system: hysteresis, pressure range, Pec0, and compliance. The variables express objective and dynamic measures of the mechanical properties of the middle ear. The method had an acceptable repeatability and was found to be consistent with earlier investigations. It is easy to perform and causes the subject no discomfort. It is therefore considered useful for further investigation of middle ear physiology and pathophysiology.