Dynamic Properties of Human Tympanic Membrane After Exposure to Blast Waves.

Abstract

Blast overpressure causes dynamic damage to middle ear components, and tympanic membrane (TM) rupture is the most frequent middle ear injury. However, it is unclear how the blast waves change mechanical properties of the TM and affect sound transmission through the ear. This paper reports the current study on dynamic properties of the TM after exposure to blast waves by using acoustic loading and laser Doppler vibrometry (LDV). The TM specimens were prepared from human temporal bones following exposures to blast overpressure. Vibration of the TM specimen induced by acoustic loading was measured by LDV over a frequency range of 200-8000Hz. An inverse-problem solving method with finite element modeling was used to determine the complex modulus of the TM specimen. The post-blast storage modulus ranged from 23.1 to 26.9MPa, and loss modulus ranged from 0.09 to 3.78MPa as frequency increased from 200 to 8000Hz. Compared to the complex modulus of normal TM reported in the literature, the post-blast storage and loss modulus decreased significantly across the frequency range. The scanning electron microscopy (SEM) images of the post-blast TM samples showed microstructural changes of the tissue, which explained the alteration of mechanical properties of the TM samples.