COBEM99

S2 Bioengenharia e Qualidade de Vida

Title:

VIBRATION IN THE CAT MIDDLE EAR

Summary :

THE ACOUSTICAL ENERGY IS TRANSMITTED FROM THE TYMPANIC MEMBRANE TO THE INNER EAR BY THE MIDDLE EAR OSSICLES. IT IS ACCEPTED THAT THE OSSICLES ROTATE AROUND A FIXED AXIS AND FUNCTION AS MECHANICAL LEVERS. MEASUREMENTS OF MALLEUS VIBRATION HAS CLEARLY SHOWN THAT ITS MOTION IS NOT A ROTATION ABOUT A FIXED SUSPENSION AXIS BUT THAT TRANSLATION AND ROTATION COMPONENTS IN ALL THREE DIMENSIONS ARE PRESENT AND CHANGE DRAMATICALLY OVER THE FREQUENCY OF HEARING. THE QUESTION ARISES HOW COMPLEX IS THE MOTION OF THE STAPES? THE MOTION OF THE STAPES HAS BEEN DIFFICULT TO MEASURE BECAUSE ACCESS IS LIMITED AND THE CRURA CAN ONLY BE SEEN PARTIALLY. IN ORDER TO GET A BETTER ACCESS A NOVEL TEMPORAL BONE PREPARATION WAS UTILIZED. THE VIBRATION OF THE STAPES WAS MEASURED WITH A CONFOCAL HETERODYNE INTERFEROMETER AT THREE POINTS FROM DIFFERENT VIEWING ANGLES. ITS GEOMETRY WAS ALSO MEASURED. RIGID BODY MOTION CAN BE DECOMPOSED IN A GLOBAL TRANSLATION AND A ROTATION ABOUT AN IMMEDIATE ROTATION AXIS. THE THREE DIMENSIONAL COMPONENTS OF THE STAPES MOTION ARE PRESENTED IN THIS PAPER. OUR RESULTS SHOW THAT THE MOTION IS LARGELY PISTON-LIKE, BUT OTHER, SMALL, COMPONENTS THAT WILL CAUSE TILTING OF THE FOOTPLATE ARE ALSO PRESENT. KEYWORDS: MIDDLE EAR, MECHANICS, OSSICLES, VIBRATION, INTERFEROMETER

Author :

Decraemer, Willem Firmin
Funnell, Robert W
Khanna, Shyam Mohan

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