Abstract
The main principle of this new impedance method is a continuous recording of changes in tympanic membrane compliance in relation to its neutral position during changes in pressure, using a small pressure chamber. The subject sitting in the chamber can be placed in the recumbent position by rotation of the chamber. The working principles of the impedance method are: a servosystem regulates displacement of the loudspeaker membrane in order to keep the sound pressure in the external ear canal constant, independent of tympanic membrane compliance. From this recording it is possible to isolate tympanic membrane compliance during changes in intratympanic pressure as well as during ambient pressure changes. The results indicate that the new regulated impedance method combined with the small pressure chamber should be useful in routine clinical examination of middle ear mechanics and eustachian tube function.
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