Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
Hear Res. 2010 May;263(1-2):66-77. doi: 10.1016/j.heares.2009.12.024. Epub 2009 Dec 23.
Sound-induced motion of the surface of the human tympanic membrane (TM) was studied by stroboscopic holographic interferometery, which measures the amplitude and phase of the displacement at each of about 40,000 points on the surface of the TM. Measurements were made with tonal stimuli of 0.5, 1, 4 and 8 kHz. The magnitude and phase of the sinusoidal displacement of the TM at each driven frequency were derived from the fundamental Fourier component of the raw displacement data computed from stroboscopic holograms of the TM recorded at eight stimulus phases. The correlation between the Fourier estimates and measured motion data was generally above 0.9 over the entire TM surface. We used three data presentations: (i) plots of the phasic displacements along a single chord across the surface of the TM, (ii) phasic surface maps of the displacement of the entire TM surface, and (iii) plots of the Fourier derived amplitude and phase-angle of the surface displacement along four diameter lines that define and bisect each of the four quadrants of the TM. These displays led to some common conclusions: at 0.5 and 1kHz, the entire TM moved roughly in-phase with some small phase delay apparent between local areas of maximal displacement in the posterior half of the TM. At 4 and 8 kHz, the motion of the TM became more complicated with multiple local displacement maxima arranged in rings around the manubrium. The displacements at most of these maxima were roughly in-phase, while some moved out-of-phase. Superposed on this in- and out-of-phase behavior were significant cyclic variations in-phase with location of less than 0.2 cycles or occasionally rapid half-cycle step-like changes in-phase. The high frequency displacement amplitude and phase maps discovered in this study can not be explained by any single wave motion, but are consistent with a combination of low and higher order modal motions plus some small traveling-wave-like components. The observations of the dynamics of TM surface motion from this study will help us better understand the sound-receiving function of the TM and how it couples sound to the ossicular chain and inner ear.
采用频闪全息干涉法研究了人鼓膜（TM）表面的声致运动，该方法测量了 TM 表面约 40,000 个点的位移幅度和相位。测量使用 0.5、1、4 和 8 kHz 的音调刺激。从在八个刺激相位记录的 TM 频闪全息图中计算的原始位移数据的基本傅里叶分量中，推导出 TM 在每个激励频率下的正弦位移的幅度和相位。傅里叶估计值和测量运动数据之间的相关性在整个 TM 表面上通常大于 0.9。我们使用了三种数据表示形式：（i）沿 TM 表面的单个弦的相位位移图，（ii）整个 TM 表面的相位位移图，以及（iii）沿定义并平分 TM 的四个象限中的每一个的四个直径线的表面位移的傅里叶导出幅度和相位角的图。这些显示导致了一些共同的结论：在 0.5 和 1 kHz 时，整个 TM 大致同相移动，在后半部分 TM 中最大位移区域之间存在一些小的相位延迟。在 4 和 8 kHz 时，TM 的运动变得更加复杂，多个局部位移最大值围绕柄部排列成环。这些最大值中的大多数的位移大致同相，而有些则异相。在这种同相和异相行为之上，存在着与位置相差小于 0.2 个周期或偶尔快速半周期阶跃式同相变化的显著循环变化。在这项研究中发现的高频位移幅度和相位图不能用任何单一的波动运动来解释，而是与低阶和高阶模态运动的组合以及一些小的行波样成分一致。从这项研究中观察到的 TM 表面运动动力学将帮助我们更好地理解 TM 的声音接收功能以及它如何将声音耦合到听小骨链和内耳。
