Time-domain "wave" model of the human tympanic membrane

Middle ear models have been successfully developed for many years. Most of those are implemented in the frequency domain, where physical equations are more easily derived. This is problematic, however, when it comes to model non-linear phenomena, especially in the cochlea, and because a frequency-domain implementation may be less intuitive. This research explores a different approach, based on a time-domain implementation, fitted to impedance data. It is adapted from a previous work for the cat and focuses here on the human ear: volume velocity samples are distributed uniformly in space and updated periodically to simulate the propagation of the sound wave in the ear. The modeling approach is simple, yet it can quantitatively reproduce the major characteristics of the human middle ear transmission, and can qualitatively capture forward and reverse power transmission - a key feature of this time-domain implementation. These results suggest that complex, multi-modal propagation observed on the TM may not be critical to proper sound transmission along the ear. Besides, model predictions reveal that impedance and velocimetry measurements may be inconsistent with each other, hypothetically because velocimetry protocols could alter the middle ear. (C) 2009 Elsevier B.V. All rights reserved.