THE INFLUENCE OF SIMULATED MIDDLE-EAR PAT HOLOGIES BY A TEMPORAL BONEPREPARATION ON EAR CANAL RESONANCE

By means of a model of the external and the middle ear it is possible to simulate various, exactly defined pathological conditions of the mi ddle ear and to describe their influence on ear canal resonance. Start ing point of the investigations are fresh postmortem preparations of 8 human temporal bones with an intact ear drum and a retained skin of t he ear canal. The compliance of the middle ear does not significantly differ from the clinical data of probands with healthy ears. After ant rotomy it is possible to simulate pathological conditions of the middl e ear one after the other at the same temporal bone. The influence of the changed middle ear conditions on ear drum compliance, ear canal vo lume and on the resonance curve of the external ear canal was investig ated. For example, the middle ear was filled with water to create appr oximately the same conditions as in acute serous otitis media. In this middle ear condition a significant increase of the sound pressure amp lification was found, on an average by 4 decibels compared to the unch anged temporal bone model. A small increase in resonance frequency was also measured. The advantages of this model are the approximately phy siological conditions and the constant dimensions of the external and middle ear.