Ishihara M
Nihon Jibiinkoka Gakkai Kaiho. 1989 May;92(5):726-35. doi: 10.3950/jibiinkoka.92.726.
To aid in the establishment of optimum conditions for postoperative function of the tympanic membrane, a model of the middle ear was experimentally prepared, the cross-sectioned area of aditus ad antrum was altered and the effects on the tympanic membrane vibrational characteristics were observed using the holographic interference method. The following results were obtained. 1) At the low frequencies below 2 kHz, the vibration mode of tympanic membrane was concentric on the whole, but the vibration pattern became fractionated at 4 kHz and above. The frequency of onset of the fractionated vibration pattern was changed only by the conditions of the membrane itself and was not affected much by the sound pressure, the volume of the middle ear cavity and the cross-sectioned area of aditus ad antrum. 2) There were resonance and anti-resonance points in the tympanic vibration pattern. These resonance and anti-resonance frequencies became higher as the diameter of aditus increased until eventually a constant value was reached. At diameters in excess of this constant value, the resonance frequency tended to fall and the anti-resonance frequency tended to rise. 3) The tympanic vibration in the middle ear cavity was not influenced very much by the diameter of aditus at 250Hz. Vibration decreased when aditus was blocked at 500Hz and the opening diameter had a major influence at 1kHz. Vibration was maximum at a diameter of about 2mm and a minimum when aditus was blocked. At 2 to 3kHz, the effects on vibration increased when aditus was blocked. 4) When aditus ad antrum was blocked, the vibration frequency characteristics of tympanic membrane deteriorated at under 1kHz and improved at 2 to 3kHz. When a comparison was made between the case with opened aditus, (which was considered to be equivalent to the closed method of tympano-plasty), and the case with closed aditus, (considered to be equivalent to the open method), the vibration frequency characteristics of the tympanic membrane improved in the low sound region up to 2kHz when the diameter was 4mm.
为了帮助确定鼓膜术后功能的最佳条件，通过实验制备了中耳模型，改变鼓窦入口的横截面积，并使用全息干涉法观察其对鼓膜振动特性的影响。获得了以下结果。1）在2kHz以下的低频时，鼓膜的振动模式整体上是同心的，但在4kHz及以上时振动模式变得分散。分散振动模式开始的频率仅受鼓膜本身条件的影响，而受声压、中耳腔体积和鼓窦入口横截面积的影响不大。2）鼓膜振动模式中存在共振点和反共振点。随着鼓窦入口直径的增加，这些共振和反共振频率会升高，直到最终达到一个恒定值。当直径超过这个恒定值时，共振频率趋于下降，反共振频率趋于上升。3）在250Hz时，中耳腔内的鼓膜振动受鼓窦入口直径的影响不大。在500Hz时，当鼓窦入口被堵塞时振动减弱，开口直径在1kHz时有主要影响。在直径约为2mm时振动最大，鼓窦入口被堵塞时振动最小。在2至3kHz时，鼓窦入口被堵塞时对振动的影响增加。4）当鼓窦入口被堵塞时，鼓膜的振动频率特性在1kHz以下恶化，在2至3kHz时改善。当比较鼓窦入口开放的情况（被认为等同于鼓膜成形术的封闭方法）和鼓窦入口封闭的情况（被认为等同于开放方法）时，当直径为4mm时，在高达2kHz的低声区域鼓膜的振动频率特性得到改善。
