Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Biophysics and Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Hear Res. 2021 Feb;400:108116. doi: 10.1016/j.heares.2020.108116. Epub 2020 Dec 1.
The vibration response of the middle ear (ME) to sound changes when static pressure gradients are applied across the tympanic membrane (TM). To date, it has not been well understood which mechanisms lead to these changes in ME vibration response. In this study, a 3D finite-element model of the human ME was developed that simulates the sound-induced ME vibration response when positive and negative static pressures of up to 4 kPa are applied to the TM. Hyperelasticity of the soft-tissue components was considered to simulate large deformations under static pressure. Some ME components were treated as viscoelastic materials to capture the difference between their static and dynamic stiffness, which was needed to replicate both static and dynamic ME behavior. The change in dynamic stiffness with static preload was simulated by linearization of the hyperelastic constitutive model around the predeformed state. For the preloaded harmonic response, we found that the statically deformed ME geometry introduced asymmetry in the vibration loss between positive and negative pressure, which was due to the TM cone shape. As opposed to previous assumptions, the prestress in the ME due to static pressure had a substantial impact on the vibration response. We also found that material nonlinearity led to a higher stiffening at the umbo but a less pronounced stiffening at the footplate compared to the linear elastic condition. The results suggest that flexibility of the incudomalleolar joint (IMJ) enhances the decoupling of static umbo and footplate displacements, and that viscosity and viscoelasticity of the IMJ could play a role in the transfer of sound-induced vibrations from the umbo to the footplate. The components of the incudostapedial joint had minimal effect on ME mechanical behavior.
当鼓膜（TM）上施加静态压力梯度时，中耳（ME）对声音的振动响应会发生变化。迄今为止，人们还不太清楚是什么机制导致了中耳振动响应的这些变化。在这项研究中，开发了一个人体 ME 的三维有限元模型，该模型模拟了当 TM 上施加高达 4 kPa 的正、负静态压力时，声音引起的 ME 振动响应。软组织成分的超弹性被认为是模拟静态压力下的大变形。一些 ME 成分被视为粘弹性材料，以捕捉其静态和动态刚度之间的差异，这是复制静态和动态 ME 行为所必需的。通过围绕预变形状态对超弹性本构模型进行线性化，模拟了静态预载对动态刚度的影响。对于预加载的谐波响应，我们发现，静态变形 ME 几何形状导致正、负压力之间的振动损耗不对称，这是由于 TM 锥形形状所致。与之前的假设相反，静态压力引起的 ME 预应力对振动响应有很大影响。我们还发现，与线性弹性条件相比，材料非线性导致在鼓岬处的刚度增加，但在基板处的刚度增加不明显。结果表明，镫骨砧关节（IMJ）的灵活性增强了静态鼓岬和基板位移的解耦，而 IMJ 的粘性和粘弹性可能在声音引起的振动从鼓岬传递到基板方面发挥作用。镫骨-砧骨关节的组件对 ME 的机械行为影响最小。
