Computer-based Holography and Middle-Ear Function

描述（由申请人提供）：鼓膜（TM）（或鼓膜）是中耳将环境声音转化为内耳声音的声学力学的初始结构。虽然有很多关于中耳膜对耳朵其他部分的声音的假设，但很少有数据来验证这些假设。在过去的三年中，我们使用了新开发的激光全息技术来测量许多哺乳动物TM表面的声音诱导运动的大小和相位。这些测量结果表明，TM运动可以很好地描述为几种运动类型的总和，包括：相对波长较长的模态（二维驻波）运动和相对波长较短的行波。这项拨款将首先在广泛的声音频率和中耳类型范围内测试这一简单描述的普遍性，并利用行波速度的空间变化来比较多种哺乳动物中耳膜不同解剖可识别位置的力学特性。接下来，这些数据将与同时收集的声音诱发听骨运动的激光测振仪测量结果进行比较，以验证与中耳上的波传播相关的延迟导致中耳传导延迟的流行理论。利用改良耳道和人工耳道进行的额外的耳膜表面和听骨运动测量，通过确定耳膜在耳道内的位置和方向是否有助于耳膜上的声诱发表面波和听骨运动的延迟，验证了第二种理论。穿孔如何影响中耳道运动和中耳声音传递的其他几个理论将通过测量中耳道穿孔和穿孔前后中耳道和听小骨的声致运动来验证。最后，我们应用我们的技术来评估一种常见的中耳重建技术，即在中耳板上使用薄软骨片，如何影响中耳板和听骨运动。一个令人惊讶的初步结果需要进一步研究，即软骨片的放置可以大大减少TM上的行波，而听骨运动几乎没有变化。如果一般情况下是正确的，这个结果意味着我们在TM上看到的行波与中耳的声音传递无关。这一结果表明，受软骨影响较小的TM的长波模态位移决定了TM的功能，并反驳了多个短波响应的复杂相互作用驱动TM对高频声音响应的理论。

DESCRIPTION (provided by applicant): The tympanic membrane (TM) (or eardrum) is the initial structure in the middle-ear's acoustic-mechanical transformation of environmental sounds to sound within the inner ear. While there are many hypotheses of how the TM couples sound to the rest of the ear, there is little data to test these hypotheses. In the past three years we have used newly developed laser holography techniques to measure the magnitude and phase of sound-induced motions of the TM surface in a number of mammalian species. The results of those measurements suggest that TM motions can be well described by a summation of a few types of motion, including: relatively long-wavelength modal (2D standing-wave) motions and relatively short wavelength traveling waves. This grant will first test the generality of this simple description across a broad range of sound frequencies and middle-ear types, and use spatial variations in the velocity of the traveling waves to compare the mechanical properties of different anatomically identifiable locations of the TM in multiple mammalian species. Next, these data will be compared to simultaneously gathered laser-vibrometer measurements of sound-induced ossicular motion in order to test the popular theory that delays associated with wave-travel on the TM contribute to delays in sound-conduction through the middle ear. Additional TM surface and ossicular motion measurements made with modified and artificial ear canals test a second theory by determining whether the location and orientation of the TM within the ear canal contribute to sound- induced surface waves on the TM and delays in ossicular motion. Several other theories of how perforations affect TM motion and middle-ear sound transfer will be tested by measurements of the sound-induced motion of the TM and ossicles before and after controlled perforations and slits in the TM. Finally, we apply our techniques to assess how a common middle-ear reconstruction technique, the use of thin cartilage sheets on the TM, affects both TM and ossicular motion. A surprising preliminary result that requires further investigation is that the placement of cartilage sheets can greatly reduce traveling waves on the TM while producing little change in ossicular motion. If generally true, this result implies that the traveling waves we see on the TM are not relevant to sound transfer through the middle ear. Such a result would suggest that long-wave-length modal displacements of the TM, which are less affected by the cartilage, determine TM function, and refute theories that complex interactions of multiple short-wave-length responses drive the TM's response to higher frequency sounds.