Middle Ear Nonlinearity in High Intensity Sound: Impact on Hearing Damage and Protection

摘要： 我们的耳朵容易受到强烈的声音(&gt；130分贝SPL)的影响，这些声音会损害中耳和内耳 并造成暂时性或永久性的听力损失。以前的研究主要集中在研究损害。 但人们对中耳如何传递极高水平的破坏性声音知之甚少 送到耳蜗处。而由高水平的稳态声音引起的中耳肌肉反射则会降低声音 传输到耳蜗处，它在短暂的脉冲声音中不能保护耳朵。结构的非线性机理 人们已经观察到中耳可以为冲动的声音提供保护。然而，几乎没有 对中耳非线性过程的定量研究，以及非线性机制对中耳运动的贡献 中耳声音传递的频率和水平相关性没有得到很好的描述。此外，病因还包括 由强烈的声音引起的中耳结构故障，以及它们对中耳的影响，人们知之甚少 功能。这种知识的缺乏限制了我们防止此类失败的能力。此外，还缺乏对 被动假体或移植物手术重建中耳的效果和失败率高 水平的声音。针对这些问题，我们在本研究中提出了三个目标。目标1将使用人类身体 颞骨在时间和频率域中系统地表征中耳的非线性过程 高强度，在正常中耳和再造中耳，以获得关于中耳结构的关键新知识 并在高音量下发挥作用。目标2将把声音强度扩大到可以打破鼓膜的水平 膜和其他软组织研究正常和重建失败的原因和时间历史 中耳。对于目标3，我们建议建立有限元中耳非线性模型 多种中耳非线性机制，包括脉冲时域模型和连续音调 频域模型。这项研究将影响我们预测噪音引起的听力损伤的能力， 保护耳朵的新策略的发展和中耳损伤外科修复的改进 耳朵。

ABSTRACT: Our ears are vulnerable to intense sounds (> 130 dB SPL) that can damage middle- and inner-ear structures and produce temporary or permanent hearing loss. Prior research has focused on studying damage to the cochlea, but relatively little is known of how the middle ear transmits extremely high-level damaging sounds to the cochlea. While the middle ear muscle reflex elicited by high level steady state sounds can reduce sound transmission to the cochlea, it cannot protect the ear during brief impulsive sounds. Nonlinear mechanisms of the middle ear that can provide protection for impulsive sounds have been observed. However, there are few quantitative studies of middle ear nonlinear processes, and the contributions of nonlinear mechanisms to the frequency and level dependence of middle ear sound transfer are not well described. Furthermore, the etiologies of middle ear structural failures produced by intense sounds are poorly known, as are their effects on middle ear function. This lack of knowledge limits our ability to prevent such failures. There is also a lack of knowledge of how surgically reconstructed middle ears with a passive prosthesis or graft work and their failure rate at high level sounds. To tackle these questions, we propose three aims in this study. Aim 1 will use human cadaveric temporal bones to systematically characterize middle ear nonlinear processes in time and frequency domains at high intensity, in normal and reconstructed middle ears, to gain critical new knowledge on middle ear structure and function at high sound levels. Aim 2 will extend the sound intensity to levels that can rupture the tympanic membrane and other soft tissues to investigate the cause and time history of failures in normal and reconstructed middle ears. For Aim 3, we propose to develop finite element middle ear nonlinear models that incorporate multiple middle ear nonlinear mechanisms, including impulsive time-domain models and continuous tone frequency-domain models. This study will impact our ability to predict noise-induced hearing damage, development of new strategies for ear protection and improvements in the surgical repair of damaged middle ears.