Blast Production by a Shock Tube for Use in Studies of Exposure of the Tympanic Membrane to High-Intensity Sounds

Blast exposure can result in tympanic membrane (TM) rupture and middle ear and inner ear damage. However, the dynamics of the blast-induced TM rupture are unclear, leaving questions about how the blast-induced stresses and strains on the TM surface produce TM rupture unanswered. Our group is developing quantitative high-speed optical techniques for real-time characterization of the fracture mechanics of the TM. Here we describe our efforts to produce a shock tube acoustic loading device that produces repeatable and accurate supersonic blasts with peak pressures capable of rupturing TM samples. The design of the shock tube was decided through structural analysis, and the pressures produced by the blast waves were verified with multiple high-speed pressure sensors. Schlieren imaging combined with a high-speed camera is used to “visualize” blast waves emitted from the shock tube opening and analyze how they propagate and interact with testing samples. This information is necessary to understand the influence of these waves on the dynamic behavior of the TM and how they induce damage of the TM.