OBSERVING AUDITORY MECHANICS WITH PRESSURE MEASUREMENTS

该项目通过测量耳蜗、耳道和中耳腔的声压来探索耳蜗和中耳的力学。实验和解释是听觉力学的直接、基本的探索。大部分的研究工作将花在耳蜗研究上；中耳研究是一项相关的小型研究。耳蜗对声压的不同频率有选择性，在物理极限允许的范围内敏感，并能立即适应广泛的刺激水平。耳蜗手术的核心是一种流体/组织-压力/运动波，它将声能沿耳蜗传输到耳蜗器官上与频率相关的位置。许多关于耳蜗力学的问题仍然存在。这些问题涉及基本的未知，例如频率映射和调谐的物理基础，以及更精细的问题，例如非线性的基础。提出的实验通过使用压力图来同时测量耳蜗行波的压力和运动分量来检查耳蜗行波的组织和流体成分。压力会在靠近基底膜的液体中被绘制出来，同时用传递到耳道的声音或电流（在激活耳蜗自然机电转导的水平上）刺激耳蜗。结果将用于量化和探索调谐、频率映射和非线性的核心要素：波的有效流体质量和Corti器官的机械阻抗，基底膜运动中的模式变化以及向行波注入的能量。了解耳蜗的机制是一个重要而难以捉摸的目标。许多研究人员的进步以及技术和计算创新使这一目标触手可及。更好地了解耳蜗的机械操作将对耳聋的预防和治疗产生影响，特别是数字助听器和人工耳蜗的设计。越来越多的证据表明声音是以行波的形式通过中耳传播的。例如，相对于耳道（中耳的输入）的声压，镫子（中耳的输出）的耳蜗内声压的相位-频率行为在2到40千赫之间呈延迟状。增益（耳蜗压力/耳道压力）在这些频率上几乎持平。因此，声音的时间和频率信息都由中耳高保真地传递到耳蜗。中耳是怎么做到的呢？为了解决这个问题，声音将被传递到耳道，并在耳道、耳蜗前庭阶梯和中耳空间进行压力测量。这些压力，以及它们在可逆和不可逆操作后的变化将被分析，以了解鼓膜和听小骨如何将声音传递到耳蜗。这些结果将对中耳的治疗和中耳假体的设计产生影响。

The proposed project explores the mechanics of the cochlea and middle ear via measurements of sound pressure in the cochlea, the ear canal and the middle ear cavity. The experiments and interpretation are direct, basic probes of auditory mechanics. The majority of the research effort will be spent on the cochlear study; the middle ear work is a related, smaller study. The cochlea is selective to individual frequencies of sound pressure, as sensitive as physical limits allow, and instantaneously adaptive to a wide range of stimulus levels. At the heart of cochlear operation is a fluid/tissue -and- pressure/motion wave which transports sound energy down the cochlea to frequency-dependent locations on the organ of Corti. Many questions about cochlear mechanics remain. These questions concern fundamental unknowns, such as the physical basis for frequency mapping and tuning, as well as more refined issues, such as the basis for nonlinearity. The proposed experiments examine both the tissue and fluid components of the cochlear traveling wave by using pressure maps to simultaneously measure the wave's pressure and motion components. Pressure will be mapped in the fluid close to the basilar membrane while stimulating the cochlea with sound delivered to the ear canal, or with electric current (at levels which activate the cochlea's natural electro-mechanical transduction). The results will be used to quantify and explore elements central to tuning, frequency mapping and nonlinearity: the wave's effective fluid mass and the mechanical impedance of the organ of Corti, mode changes in the motion of the basilar membrane and energy injection into the traveling wave. Understanding the mechanics of the cochlea is a vital and elusive goal. The progress of many researchers, and technical and computing innovations are bringing this goal within reach. Better understanding the cochlea's mechanical operation will impact on deafness prevention and treatment, especially the design of digital hearing aids and cochlear implants. Accumulating evidence indicates that sound is transmitted through the middle ear as a traveling wave. For example, the phase-vs- frequency behavior of the sound pressure inside the cochlea at the stapes (the output of the middle ear), relative to that in the ear canal (the input to the middle ear) is delay-like between 2 and 40 kHz. The gain (cochlear pressure/ear canal pressure) is nearly flat over these frequencies. Thus, both the temporal and the frequency information in sound is transmitted by the middle ear to the cochlea with high fidelity. How does the middle ear do it? To address this question, sound will be delivered to the ear canal and pressure measurements will be made in the ear canal, the cochlea's scala vestibuli, and the middle ear space. These pressures, and their changes following reversible and irreversible manipulations to the ear will be analyzed to understand how the tympanic membrane and ossicles deliver sound to the cochlea. These results will impact on the treatment of the middle ear and the design of middle ear prostheses.