Investigation of analog models of the human middle ear

Abstract

Many working principles developed in engineering sciences are also very useful for other sciences. One of these methods is modeling which is a very useful tool to describe complex systems and to make their analysis easier. For a better Understanding of the ear models, a brief anatomy of the human ear is given first, then the concept of impedance is developed and some dynamical analogies are presented. Four analog models of the middle ear are described and investigated. Olson uses strictly dynamical analogies, Onchi developed a mechanical model and gives the Lagrangian equations of motions for the vibration system of the middle ear. Miller uses a pure physical method to measure the input impedance of the ear at the eardrum. His network models of the middle ear have the same input impedance as the measured ears, but the elements of his models are only vaguely related to the elements of the ear. Zwislocki gives a block diagram of the middle ear and tries to make a one-to-one relation between the model elements and the ear. His models match the input impedance also very closely. All models investigated only simulate the input impedance of the ear. The main function of the middle ear, transforming the acoustic impedance of sound waves in air to the impedance of sound waves in fluid, can not be seen on these models