1997 Volume 40 Issue 1 Pages 46-51
When the tympanic membrane (TM) is perforated by trauma or otitis media, hearing threshold rises. Although the dynamic behavior of the middle ear with TM perforation is expected to be different from that with a normal TM, that with TM perforation has not been well analyzed. Therefore, in this paper, first, applying our own finite-element method (FEM) program, a three-dimensional FEM model of the human middle ear with TM perforation was established. Then, using this model, the dynamic behavior of the TM and ossicles was analyzed. Results are as follows: The effect of the TM perforation on the vibration patterns of the TM and ossicles depended on location and size of the TM perforation, the maximum decrease of the sound pressure in the cochlear was about 15dB. Therefore, a large hearing loss detected in clinical study would be caused by the cancellation effect in the cochlear or the middle ear pathology except for the TM perforation.
