Holographic interferometry applied to the investigation of tympanic-membrane displacements in guinea pig ears subjected to acoustic impulses

Abstract

The displacements of the tympanum of guinea pigs undergoing the action of acoustic impulses were investigated using holographic interferometry. The motion of the umbilicus is approximately 7.5 times smaller than that of the maximum elongation point of the tympanic membrane located between the umbilicus and the annulus fibrocartilagineus in the prolongation of the manubrium mallei. The results attempt to explain why tympanic lesions originated under the action of acoustic impulses frequently appear in the lower area of the pars tensa in the case of guinea pigs, The holographic visualization of tympanic-membrane displacements appears to offer a number of practical applications allowing to throw light into the transmission of acoustic energy at the level of the tympanic membrane. Subject Classification: 65.24; 35.65; 80.50.

A fibrous dynamic continuum model of the tympanic membrane

“…At later times the position of maximum deflection moves posteriorly. Although no experimental vibrational shapes have been reported for the cat eardrum exposed to an impulse, the calculated response does have some characteristics similar to the impulse response recorded for guinea pigs (Dancer et al, 1975). The model results also display a resonance-type behavior consistent with results of Svane-Knudsen and Michelsen (1985) for humans.…”

The effect of increased inner ear pressure on tympanic membrane vibration

“…However, multifrequency tympanometry is a measure of the average motion of the entire tympanic membrane and does not distinguish the differential motion of different locations on the membrane. Using holographic interferometry, Dancer et al [20] investigated tympanic membrane displacement in the guinea pig subjected to acoustic impulses. A vibration amplitude smaller than 100 nm, however, is not obtainable with the use of this technique.…”

Biomechanics of the tympanic membrane

“…For these reasons most detailed descriptions of the motion of the mammalian TM were obtained by means of time-averaged holograms Lokberg and Hogmonen, 1976;Tonndorf and Khanna, 1972;Wada et al, 2002). Time-averaged holography and holographic interferometry enable to record the complete vibration pattern of a surface within several seconds (Dancer et al, 1975;Khanna and Tonndorf, 1972;Saldner, 1996;Tonndorf and Khanna, 1972).…”