Backward and Forward Driven Eardrum Motions

描述（由申请人提供）：声音诱导的鼓膜位移（TM）是环境声在耳蜗内正向转化为声音的第一个阶段，而听骨链机械运动诱导的鼓膜位移是耳蜗产生的声音向耳道内测量的具有临床价值的耳声发射（oae）反向转化的最后一个阶段。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。虽然最近的研究表明，高频耳道声对TM表面的复杂运动响应与TM表面存在多个波相一致，但不同的TM位移波对听骨链的激发和随后的声音向内耳传递的贡献尚不清楚。此外，对于中耳膜如何响应由内耳产生的声音或听骨的机械刺激所产生的听骨运动，我们知之甚少。尽管已知声压运动在正向和反向传播中都存在显著的不均匀性，但也缺乏描述在TM附近和远离TM的空间声压分布的数据。本研究旨在：(1)表征TM表面运动对耳道内声音正向刺激和主动中耳植入物反向机械刺激的响应；(2)生成离TM近、远声压的详细空间剖面，该剖面将与TM正、反向刺激时的详细地表运动相关联；(3)量化(a) TM表面运动与中耳对耳蜗刺激的声能传递和(b)听骨运动与TM在反向刺激下的声音转换之间的关系。我们采用新开发的频频全息干涉仪来测量TM表面上超过30万个点在不同刺激下的位移幅度和相位，以及计算机控制的麦克风定位系统来系统地采样离TM表面近（1毫米内）和远（10毫米）的耳道内的声压。实现这些目标将：(i)量化正、反向刺激产生的TM表面运动的不同波型、波幅和波长；（ii）更好地界定不同TM表面波对双向声音传播的贡献；（iii）更好地描述TM在临床上有用的耳声发射测量中的作用；（iv）研究后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中的临床应用。

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.