Tympanic membrane surface motions in forward and reverse middle ear transmissions

Characterization of Tympanic Membrane (TM) surface motions with forward and reverse stimulation is important to understanding how the TM transduces acoustical and mechanical energy in both directions. In this paper, stroboscopic opto-electronic holography is used to quantify motions of the entire TM surface induced by forward sound and reverse mechanical stimulation in human cadaveric ears from 0.25 to 18.4 kHz. The forward sound stimulus was coupled to an anatomically realistic artificial ear canal that allowed optical access to the entire TM surface, and the reverse mechanical stimulus was applied to the body of the incus by a piezo-electric stimulator. The results show clear differences in TM surface motions evoked by the two stimuli. In the forward case, TM motion is dominated by standing-wave-like modal motions that are consistent with a relatively uniform sound-pressure load over the entire TM surface. With reverse mechanical stimulation, the TM surface shows more traveling waves, consistent with a localized mechanical drive applied to the manubrium embedded in the TM. With both stimuli, the manubrium moves less than the rest of the TM, consistent with the TM acting like a compliant membrane rather than a stiff diaphragm, and also consistent with catenary behavior due to the TM's curved shape. (C) 2019 Acoustical Society of America.

对鼓膜（TM）表面在正向和反向刺激下的运动进行表征，对于理解鼓膜如何在两个方向上转换声能和机械能非常重要。在本文中，频闪光电全息术被用于量化在0.25至18.4 kHz频率范围内，正向声音和反向机械刺激在人体尸体耳朵中引起的整个鼓膜表面的运动。正向声音刺激耦合到一个符合解剖学实际的人工耳道，该耳道允许对整个鼓膜表面进行光学观测，反向机械刺激则通过压电刺激器施加到砧骨体上。结果显示，两种刺激引起的鼓膜表面运动存在明显差异。在正向情况下，鼓膜运动主要由类似驻波的模态运动主导，这与整个鼓膜表面相对均匀的声压负载是一致的。在反向机械刺激下，鼓膜表面呈现出更多的行波，这与施加在嵌入鼓膜的锤骨柄上的局部机械驱动是一致的。在两种刺激下，锤骨柄的运动幅度都小于鼓膜的其他部分，这与鼓膜像一个柔顺的膜而非刚性的隔膜的作用是一致的，也与由于鼓膜的弯曲形状而产生的悬链线行为是一致的。（C）2019美国声学学会