Backward and Forward Driven Eardrum Motions

说明书(申请人提供)：声致鼓膜位移(TM)是环境声在耳蜗内正向转化为声音的第一阶段，而听骨链机械运动引起的TM位移是耳蜗声向临床有价值的耳声发射(OAE)反向转化的最后阶段。然而，我们对TM在正向和反向声音传输中的工作原理的了解是有限的。尽管最近的研究表明，TM表面对高频声的复杂响应与TM表面上共存的多个波是一致的，但不同的TM位移波对听骨链的激发和随后的声音传输到内耳的贡献尚不清楚。此外，TM对内耳产生的声音或机械刺激听小骨产生的听骨运动的反应知之甚少。在TM附近和远离TM的空间声压分布方面也缺乏数据，尽管已知TM在正向和反向传播中的运动都存在显著的不均匀。这项研究的目的是：(1)表征TM表面运动对耳道内产生的声音的正向刺激和由活跃的中耳植入物产生的反向机械刺激的响应；(2)产生TM附近和远离TM的详细的声压的空间分布，这些空间分布将与TM的正向和反向刺激中的详细的TM表面运动相关联；(3)量化TM表面运动和通过中耳将声音能量传递到耳蜗区的关系；以及(B)听小骨运动和TM在反向刺激中的声音转换。我们使用最新开发的频闪全息干涉仪测量TM表面300000多个点上不同刺激的位移幅度和相位，并使用计算机控制的麦克风定位系统对TM表面附近(1 mm以内)和远离TM表面(最多10 mm)的耳道内的声压进行系统采样。实现这些目标将：(I)量化正向和反向刺激产生的TM表面运动的不同波类型、波幅和波长；(Ii)更好地定义不同TM表面波对双向声传输的贡献；(Iii)更好地描述TM在临床有用的耳声发射测量中的作用；以及(Iv)研究反向驱动耳道声压测量在评估驱动完整听骨链或圆窗的主动中耳假体方面的临床应用。 与公共健康相关：了解鼓膜对正向(正常)声音刺激和反向机械刺激(来自耳声发射或主动中耳植入)的反应将定义正常鼓膜的作用。一张鼓膜附近空间声压的详细图片将告诉我们：在正常刺激期间，鼓膜运动的不规则是否会显著影响耳道声场，以及这种不规则如何影响内耳或中耳产生的声音产生的耳道声压。后一个问题对于耳声发射在听力诊断和中耳植入物测试中的应用具有重要意义。

DESCRIPTION (provided by applicant): Sound-induced displacement of the Tympanic Membrane (TM) is the first stage in the forward transformation of environmental sound to sound within the cochlea, while displacement of the TM induced by mechanical motions of the ossicular chain is the last stage in the reverse transformation of cochlea generated sound to clinically valuable oto-acoustic emissions (OAEs) measured in the ear canal. However, our knowledge of the workings of the TM in both forward and reverse sound transmissions is limited. Although recent studies suggest complex TM surface motions in response to ear-canal sound at high frequency are consistent with multiple waves co-existing on the TM surface, the contributions of different TM displacement waves to excitation of the ossicular chain and subsequent sound transmission to inner ear are unclear. Furthermore, little is known of how the TM responds to ossicular motions produced by inner-ear generated sound or mechanical stimulation of the ossicles. There is also a lack of data describing spatial sound-pressure distributions near and far from the TM even though it is known that there are significant non-uniformities in TM motion in both forward and reverse sound transmission. This study aims to: (1) Characterize TM surface motions in response to forward stimulation by sound generated within the ear canal and reverse mechanical stimulation produced by an active middle-ear implant; (2) Produce detailed spatial profiles of sound pressure near and far from the TM that will be correlated with detailed TM surface motions in forward and reverse stimulation; and (3) Quantify the relationship between (a) TM surface motions and sound energy transmission through the middle ear to the cochlear excitations and (b) Ossicular motion and the sound transformation by the TM in reverse stimulation. We employ a newly developed stroboscopic holographic interferometer to measure displacement amplitude and phase in response to different stimuli at over 300000 points on the TM surface, together with a computer-controlled microphone positioning system to systematically sample the sound pressure within the ear canal both near (within 1 mm) and far (up to 10 mm) from the TM surface. Accomplishing these aims will: (i) Quantify the different wave types, wave amplitude and wavelength of TM surface motions produced by forward and reverse stimulation; (ii) Better define the contributions of different TM surface waves to sound transmissions in both directions; (iii) Better describe the action of the TM in clinically useful oto-acoustic emission measurements; and (iv) Investigate the clinical utility of backward driven ear-canal sound pressure measurements in the evaluation of active middle-ear prostheses that drive the intact ossicular chain or the round window. PUBLIC HEALTH RELEVANCE: Understanding how the eardrum responds to forward (normal) sound stimuli and reverse mechanical stimuli (from oto-acoustic emissions or active middle-ear implants) will define the role of the normal eardrum. A detailed picture of sound pressure in space near the eardrum will tell us: whether irregularities in eardrum motion significantly affect the ear-canal sound field during normal stimulation, and how such irregularities affect the ear-canal sound pressures produced by sound generated within the inner or middle ear. The later question is significant to the use of oto-acoustic emissions in hearing diagnosis and the tests of middle-ear implants.