Middle-Ear Sound Transmission 
    Investigations of middle-ear structure and function have been undertaken in the Auditory Laboratory for over 15 years.  Most of the effort during the last decade has been directed toward understanding the contribution of middle-ear maturation on the overall maturation of hearing capacity.  These investigations studied the changing structure of the conductive apparatus during development in various laboratory animals.  Functional development was traced by using laser interferometry to measure the magnitude of tympanic membrane (the eardrum) motion at various test frequencies when the membrane was acoustically stimulated at a constant sound pressure level (i. e. 100 dB SPL). 
     The current middle-ear work is oriented toward the changes that occur to the conductive apparatus in the aging middle ear.  The tympanic membrane contain collagen fibers which impart to the membrane structural properties that are important to its function.  Collagen is known to break down with aging.  If collagen in the tympanic membrane changes with age it may contribute to a reduction in the efficiency of sound transmission through the conductive system.  This possibility is presently being explored.