Kr. Williams et al., MODE SHAPES OF A DAMAGED AND REPAIRED TYMPANIC MEMBRANE AS ANALYZED BY THE FINITE-ELEMENT METHOD, Clinical otolaryngology and allied sciences, 22(2), 1997, pp. 126-131
This work makes use of recent finite element discretization of the hum
an tympanic membrane where the known anisotropy of the tympanic membra
ne is implemented by a series of thin beam elements superimposed on th
in shell membrane elements. These thin beam elements were introduced i
n order to simulate the fibre structure of the tympanic membrane. The
onset of tympanosclerosis has been modelled as a gradual increase in t
ympanic membrane density and modulus in the affected area. This increa
sed density results in a fall of 55% of the first natural frequency fo
r only a 16% area of drum sclerosis. Additionally the amplitude respon
se is significantly reduced. Repair of the membrane was simulated by r
emoval-of the fibre system from the affected area. Under these circums
tances the natural frequencies virtually return to the healthy state b
ut the mode shapes of vibration do not. The repair to tile membrane, a
lthough not significantly altering frequency values, has resulted in a
disruption to the normal mode shape patterns with consequences in the
movements conveyed to the stapes and cochlear fluids.