OBSERVING AUDITORY MECHANICS WITH PRESSURE MEASUREMENTS

这项拟议的项目通过测量耳蜗声压、耳道声压和中耳腔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的、基本的探索。大部分研究工作将花在耳蜗研究上；中耳工作是一个相关的、较小的研究。耳蜗对单个频率的声压有选择性，在物理极限允许的情况下非常敏感，并能瞬间适应广泛的刺激水平。耳蜗术的核心是一个流体/组织和压力/运动波，它将声音能量沿着耳蜗传到Corti器官上依赖频率的位置。关于耳蜗机械的许多问题仍然存在。这些问题涉及基本未知数，如频率映射和调谐的物理基础，以及更精细的问题，如非线性的基础。拟议的实验通过使用压力图来同时测量耳蜗波的压力和运动分量，来检查耳蜗行波的组织和液体成分。压力将被映射到靠近基底膜的液体中，同时用传递到耳道的声音或电流(在激活耳蜗自然的机电转换的水平)来刺激耳蜗。结果将用于量化和探索调谐、频率映射和非线性的核心元素：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中注入能量。了解耳蜗的机制是一个至关重要且难以实现的目标。许多研究人员的进步以及技术和计算创新正在使这一目标变得触手可及。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，声音以行波的形式通过中耳传播。例如，相对于耳道内的声压(中耳的输入)，在距骨(中耳的输出)处的耳蜗内的声压的相变频率行为在2到40 kHz之间是延迟的。增益(耳蜗压/耳道压)在这些频率上几乎是平坦的。因此，声音中的时间和频率信息都由中耳高保真地传输到耳蜗处。中耳是怎么做到的？为了解决这个问题，声音将被传送到耳道，并将在耳道、耳蜗前庭阶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对耳朵的变化将被分析，以了解鼓膜和听骨是如何将声音传递到耳蜗处的。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.