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

摘要： 我们的耳朵很容易受到强烈的声音（> 130 dB SPL），这可能会损害中耳和内耳 结构和产生暂时或永久性听力损失。先前的研究集中在研究损害 但是对于中耳是如何传递极高强度的破坏性声音的， 到耳蜗。而由高强度稳态声引起的中耳肌反射则可降低声音 由于它不能传递到耳蜗，因此在短暂的脉冲声音期间不能保护耳朵。非线性机制 已经观察到中耳可以为脉冲声音提供保护。然而， 中耳非线性过程的定量研究，和非线性机制的贡献， 中耳声音传递的频率和电平依赖性没有得到很好的描述。此外，病因 由强烈声音引起的中耳结构破坏的原因知之甚少， 功能这种知识的缺乏限制了我们防止这种失败的能力。此外，还缺乏知识， 如何手术重建中耳被动假体或移植的工作和他们的失败率高， 水平的声音。为了解决这些问题，我们在本研究中提出了三个目标。Aim 1将使用人尸体 颞骨在时域和频域中系统地表征中耳非线性过程. 高强度，在正常和重建的中耳，以获得关键的新知识，中耳结构 并在高音量下工作。目标2将扩大声音强度的水平，可以打破鼓膜 膜和其他软组织，以调查正常和重建失败的原因和时间历史 中耳对于目标3，我们建议开发有限元中耳非线性模型， 多个中耳非线性机制，包括脉冲时域模型和连续音 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， 开发新的耳部保护策略，改进受损中耳的手术修复 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.