The mechanical reaction of the pars flaccida of the eardrum to rapid air pressure oscillations modeling different levels of atmospheric disturbances.
Atmospheric pressure fluctuations (APF) might induce mechanical effects in the pars flaccida (PF) of the eardrum. To clarify these effects, different kinds of pressure oscillations (PO), chosen within the range of naturally occurring APF, were applied to the middle ears (ME) of gerbils. The linear displacement of the PF during a PO in the ME was measured by laser interferometry. The compliance of the PF to PO was calculated as the ratio of the amplitude of a PF oscillation to the amplitude of a PO. The displacement of the PF traced the PO in the entire range of frequencies (from 10mHz to 200mHz) and amplitudes (from 10Pa to 110Pa) applied to the ME. Moreover, the PF is found to be displaced by pressure pulses of a few pascals only using a PO with a complex shape. The differences found in the compliance of the PF due to PO with low (less than 20Pa) and high (more than 90Pa) amplitude point out that the mechanism of pressure regulation in the ME through the mechanical reaction of the PF in gerbil ears is better adapted to ordinary levels of natural APF than to extraordinary levels. The implications of these findings for the physiology of the human ME with respect to adaptation to natural APF are discussed.
Didyk
L A
LA
Institute of Physics of National Academy of Sciences of Ukraine, Pr. Nauki 46, Kiev 03028, Ukraine. didyk@iop.kiev.ua
Dirckx
J J J
JJ
Bogdanov
V B
VB
Lysenko
V A
VA
Gorgo
Yu P
YP
D000818:Animals; D001274:Atmospheric Pressure; D001696:Biomechanical Phenomena; D004432:Ear, Middle / Q000502:physiology; D005849:Gerbillinae; D066298:In Vitro Techniques; D007368:Interferometry; D011311:Pressoreceptors / Q000502:physiology; D014432:Tympanic Membrane / Q000502:physiology*