Dirckx J J, Decraemer W F, von Unge M, Larsson C
Laboratory of Biomedical Physics, University of Antwerp-RUCA, Groenenborgerlaan, Belgium.
Hear Res. 1997 Sep;111(1-2):153-64. doi: 10.1016/s0378-5955(97)00108-1.
The shape of the pars flaccida (PF) boundary and its pressure induced deformation was measured in five Mongolian gerbil ears, using an opto-electronic moiré interferometer. To determine the PF boundary, membranes were deformed by middle ear (ME) pressures of -2 kPa and +2 kPa. The boundary of the PF was defined as the locus of points where the pressure induced deformation begins. To a very high precision, this boundary was found to be a circle with the same radius for both over- and underpressure deformations. Between animals the radius varied from 0.760 mm to 0.778 mm. We show that the shape of the PF, while being deformed by static pressure in the ME, can be modeled as part of a sphere. Volume displacement can then be calculated as the volume enclosed by the sphere cap, delimited by the circular PF boundary plane. Volume displacement was calculated for membranes deformed by 400 Pa ME overpressure and -400 Pa ME underpressure. The agreement of the experimental data with the sphere cap model is shown to be very good, and results in a volume displacement measuring accuracy which is better than 10%.
使用光电莫尔干涉仪，在五只蒙古沙鼠的耳朵中测量了松弛部（PF）边界的形状及其压力诱导变形。为了确定PF边界，通过-2 kPa和+2 kPa的中耳（ME）压力使鼓膜变形。PF的边界被定义为压力诱导变形开始的点的轨迹。非常精确地发现，该边界是一个对于过压和负压变形具有相同半径的圆。不同动物之间，半径在0.760毫米至0.778毫米之间变化。我们表明，PF的形状在受到中耳静态压力变形时，可以被建模为球体的一部分。然后，体积位移可以计算为球体帽所包围的体积，该球体帽由圆形PF边界平面界定。计算了由400 Pa中耳过压和-400 Pa中耳负压变形的鼓膜的体积位移。实验数据与球体帽模型的一致性非常好，并且体积位移测量精度优于10%。
