Bending of the manubrium in cat under normal sound stimulation

摘要

It is generally considered that in coupling the motion of the tympanic membrane to the incus, the malleus behaves as a rigid body. To investigate the bending of the manubrium, its vibrations were measured with an interferometer in response to sound applied to the ear at a large number of observation points along its center line. Measurements at an arbitrary position are now possible due to high interferometer sensitivity. The x, y, and z coordinates of the observation points were measured with optical scales incorporated in the positioning system. The displacements are plotted as a function of position along the manubrium at seven phases (30$DGR apart throughout a half cycle). At low frequencies the bending is moderate and near the tip. In portions in the mid and high frequencies the bending is quite strong and extends to the middle region of the manubrium or is absent and the extreme lower edge of the malleus tip does not seem to vibrate solidly with the rest of the manubrium.