Effect of anterior tympanomeatal angle blunting on the middle ear transfer function using a finite element ear model.

The anterior tympanomeatal angle (ATA) blunting is clinically defined as a certain degree of the ATA obliteration due to excessive fibrous tissue formation, which is a relatively common complication of external auditory canal (EAC) related operations. The aim of this study was to examine the effect of ATA blunting on the middle ear transfer function using a finite element (FE) model. Results showed that the displacements at the tympanic membrane (TM), at the manubrium and at the stapes footplate, and also the ratio of stapes footplate velocity to the sound pressure in the EAC were decreased to various degrees from ATA blunting of Grades 1-4. This was more significant with TM thickening at the frequencies below 3.2kHz, particularly in Grades 3 and 4 when analyzing the anterior region of the TM. The phase differences of TM and stapes footplate increased with the ATA blunting from Grades 1 to 4 in relation to normal ATA. It is noteworthy that the vibration mode of the malleus does not show obvious change, compared to the displacement reduction at the TM with ATA blunting Grades 1-4. These results suggest that FE analysis of ATA blunting effect appears to be effective.