STRUCTURE-FUNCTION RELATIONS IN MIDDLE EARS

这项工作的长期目标是理解 外耳和中耳的结构及其在人体内的作用 听觉信号传输。方法是测量声学 表演是精选的物种，这些物种在听觉结构和 构造分析模型，其中的结构构件 在机械元素网络中明确表示。从… 这些测量和模型是结构的一般规则- 导出了函数关系。 在当前的赠款期间，关注的重点是CAT和 蜥蜴。在CAT测量中，外部和外部的性能 中耳决定了这些部位的表现 耳朵作为内耳的收集器和传送器。 蜥蜴的研究表明，通常的假设是 声音主要进入耳朵，但耳道必须 已修改；辅助声音路径通过大范围的 蜥蜴的皮肤也能将声音传递到中耳，这是最有效的 在低频率下。CAT和CAT的测量结果比较 蜥蜴显示鼓膜有明显的 不同的声学特性；在高频下，CAT TM是 而蜥蜴TM则呈块状。 这些结果表明，物种间的显著差异 存在于将声音刺激耦合到鼓膜的过程中- 膜运动。这里提出的项目主要集中在 这些过程以及这些变化的结构基础 不同脊椎动物门类之间的过程。三个领域将是 检查：1)哺乳动物外耳的表现， 既是作为声功率的收集器，也是 关于声源位置的信息，将被研究 通过对其外耳有 有趣的结构相似和不同之处。2) 通往中耳的辅助路径将在蜥蜴身上进行研究， 鸡，以及一些哺乳动物(猪和羊)中的 鼓膜结构不同于猫、豚鼠和 人类。猪和羊的一大块结构截然不同的部分 鼓膜是松弛的，而不是拉伸的。我们会 探索这样一种假设，即这种“软性部分”的功能是 通往中耳的副通路。3)两者之间的关系 猫、豚鼠鼓膜的结构和功能 将对猪、栗鼠、鳄鱼和鸡进行研究 通过测量他们的“机械变压器” 属性。由于鼓膜在脑部疾病中起着关键作用 产生了中耳和变形金刚的特性 它的结构在脊椎动物中差异很大，规格 TM的结构-功能关系是关键。 对这项工作所产生的声音接收的理解 对听力学学者诊断耳聋具有实际意义。 传导性听力障碍与外科耳科医生 耳畸形矫正术。

The long-term goal of this work is to understand the relationship the structure of external and middle ears and their function in auditory signal transmission. The approach is to measure acoustic performance is selected species that vary in aural structure and to construct analytical models in which structural components are explicitly represented in networks of mechanical elements. From these measurements and models general rules for structure- function relations are derived. During the current grant period attention was focused on cat and lizard. In cat measurements of the properties of the external and middle ear have determined the performance of these parts of the ear as collectors and transmitters acoustic power to the inner ear. The lizard studies have shown that the usual presumption that sound enters the ear primarily though the ear canal must be modified; accessory sound pathways through large areas of the lizard's skin also couple sound to the middle ear, most effectively at low frequencies. Comparison of the measurements on cat and lizard shows that the tympanic membranes have distinctly different acoustic properties; at high-frequencies the cat TM is resistive whereas the lizard TM is masslike. These results suggest that substantial interspecies differences exist in the processes that couple acoustic stimuli into tympanic- membrane motion. The projects proposed here are focused on these processes and on the structural basis of variations in these processes among different vertebrate classes. Three areas will be examined: 1) The performance of the mammalian external ear, both as a collector of acoustic power and as a source of information about the location of sound sources, will be studied through measurements in species whose external ears have interesting structural similarities and and differences. 2) Accessory pathways to the middle ear will be studied in lizard, chicken, and also in some mammals (pig and sheep) in which the tympanic-membrane structure differs from cat, guinea pig, and human. In pigs and sheep a large structurally-distinct section of the tympanic membrane is flaccid rather than stretched. We will explore the hypothesis that this "pars flaccida" functions as an accessory pathway to the middle ear. 3) The relationship between structure and function of the tympanic membranes of cat, guinea, pig, chinchilla, alligator lizard, and chicken will be studied through measurements of their "mechanical transformer" properties. Since the tympanic membrane plays a key role in producing the transformer-like properties of the middle ear and its structure varies dramatically among vertebrates, specification of the TM's structure-function relations is key. The understanding of sound reception that results from this work will be of practical significant to audiologists in the diagnosis of conductive hearing disorders and to otologists in the surgical correction of abnormalities of the ear.