Effects of Lifetime Noise Exposure Viewed Through the Brainstem Reflex Bifocals: Middle Ear Muscle Reflex and Medial Olivocochlear Reflex

项目摘要 噪声性听力损失（NIHL）影响美国近四分之一的成年人。最近的发现- 一系列有关耳蜗突触病和外毛细胞（OHC）损失的扩展高频率，它 很明显，早期的NIHL在传统的听力学检查下仍然是“隐藏”的。如果没有早期的- 如果不加以保护和干预，这种损害可能会发展成更严重的听力损失。因此， 治疗/生活方式改变可能未被利用。然而，目前还没有可行的工具可以识别 早期听力损伤以前的研究测试听觉传入通路的完整性没有产生 结论性的结果然而，短期和长期的噪声暴露相关的外周损伤与以下因素相关： 听觉传出系统的变化。具体而言，内侧橄榄耳蜗反射（MOCR）和 已经报道了中耳肌反射（MEMR）的阈值升高。鉴于保护作用， 通过抑制外周输入的MOCR和MEMR，以及它们的差异随损伤的变化，我们 认为MOCR和MEMR的联合检测可以作为人类早期听力损伤的标志。 使用一种新的基于耳声发射（OAE）的传出检测，在拟议的研究中，我们的目标是（1）评估- 评估噪声暴露引起的传出和传入功能的长期年龄特异性变化;（2）评估 噪声暴露引起的传出和传入功能的短期变化。我们会调查 通过招募个人，在广泛的年龄范围（18-50岁）和噪音暴露中对两种反应进行研究 从高噪声暴露（音乐家，退伍军人，建筑工人，农民）和低噪声暴露- 学生（学生，教授）。为了评估噪音暴露引起的短期变化，我们将对参与者进行测试， 在他们典型的工作日前后。为了进行可靠的暴露分层，噪声暴露将客观地 使用5天声音剂量测定法定量艾德。我们还将使用最敏感的传入措施，以允许比较- 子与子的关系。将采用机器学习方法来确定 耳蜗，传入和传出功能的短期和长期的噪声暴露。 项目1的研究结果将揭示MOCR和MEMR组合指标是否可以描述噪声暴露 老化的影响，并强调耳蜗，传入和传出措施之间的关系。的结果 项目2将揭示长期噪声暴露是否预测噪声暴露后的短期变化， 亦然更好地了解噪声暴露后听觉系统的短期和长期变化 将有助于发展（1）一个客观的快速筛选测试的听觉传出，能够检测 噪声干扰相关的听力损伤和（2）统计模型，以使预测即将发生的损害的基础上 关于传出功能总之，这些工具将有助于早期发现和促进听力保护。

Project Summary Noise-induced hearing loss (NIHL) affects nearly one in four adults in the United States. With recent discov- eries pertaining to cochlear synaptopathy and outer hair cell (OHC) loss in the extended high frequencies, it is clear that much of the early NIHL remains `hidden' under traditional audiological scrutiny. Without early de- tection and intervention, such damage can progress into more severe hearing loss. Thus a critical window for therapeutics/lifestyle changes may go unutilized. However, there are currently no feasible tools that can identify early hearing damage. Prior studies that test the integrity of the auditory afferent pathway have not produced conclusive results. However, short- and long-term noise exposure-related peripheral damage are correlated with changes in the auditory efferent system. Specifically, hyperactivity in the medial olivocochlear reflex (MOCR) and threshold elevation of the middle ear muscle reflex (MEMR) have been reported. Given the protective roles of the MOCR and the MEMR through inhibition of peripheral inputs, and their differential changes with damage, we argue that a combined assay of MOCR and MEMR may serve as a marker for early hearing damage in humans. Using a novel otoacoustic emission (OAE)-based efferent assay, in the proposed studies we aim to (1) eval- uate long-term age-specific changes in efferent and afferent function due to noise exposure and (2) evaluate short-term changes in efferent and afferent function due to noise exposure. We will investigate the concurrent working of the two reflexes across a wide age range (18-50 years) and noise exposure by recruiting individuals from high noise exposure (musicians, veterans, construction workers, farmer) and low noise exposure occupa- tions (students, professors). To evaluate short-term changes due to noise exposure, we will test participants before and after their typical work day. For reliable exposure stratification, noise exposure will be objectively quantified using 5-day sound dosimetry. We will also use the most sensitive afferent measures to allow compari- son with efferent measures. Machine learning approaches will be employed to ascertain relationships among the cochlear, afferent, and efferent function for short- and long-term noise exposures. Findings from project 1 will reveal if the combined MOCR and MEMR metrics can delineate noise exposure effects from aging, and highlight the relationships among cochlear, afferent, and efferent measures. Findings from project 2 will reveal if long-term noise exposure predicts short-term changes following noise exposure and vice- versa. A better understanding of short- and long-term changes in the auditory system following noise exposure will aid in the development of (1) an objective rapid screening test of the auditory efferents capable of detecting noise exposure-related hearing damage and (2) a statistical model to enable predicting impending damage based on efferent function. Together, these tools will contribute to early detection and promote hearing conservation.