Abstract: A laser doppler vibrometer was used to measure the motion of a simple middle ear model and tympanic membrane vibrations of human temporal bone specimen. Different pathological conditions were simulated: Increasing or decreasing middle ear pressure to defined levels create a situation similar to a barootitis. Additionally the middle ear cavities were partially or totally filled with fluids of different viscosities. Characteristic changes of the vibration patterns were detected: With increasing pressure difference between middle ear and atmosphere the vibration amplitudes decreased. In middle ear effusions diminished amplitudes were obtained, depending on the fluid- occupied volume within the tympanic cavity. The vibration pattern was not influenced by differences in the viscosity of the effusion. Therefore a preoperative examination of a patient with middle ear effusions by laser doppler vibrometer offers no predictive aspect to the decision whether a ventilation tube should be inserted or not.!3
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