Abstract
In order to increase the usefulness of and obtain safer judging of tympanometry, experimental studies were performed on human temporal bones. The aim was to find out how the appearance of the tympanogram is affected by different water levels in the middle ear as well as by variations in the volume of the middle ear. The aim was also to evaluate how the actual middle ear air-pressure corresponds to the tympanometrically measured middle ear air-pressure. Investigation of 8 human temporal bones shows that the tympanogram maintains its original appearance when the water level is low in the middle ear, while a higher water level gives rise to a pathologic tympanogram. Compliance increased in all cases and the width of the tympanogram was reduced in 5 out of 6 investigated human temporal bones during volume increase. Results from 6 human tempral bones demonstrate a discrepancy between tympanometrically, indirectly recorded middle ear air-pressure and middle ear air-pressure as measured manometrically, directly from the middle ear. The findings in the recorded tympanogram variations are discussed.