EXPERIMENTAL STUDY ON THE LESION OF MIDDLE EAR APPARATUS BY ELECTRORIC COCHLEAR RESPONSE

Abstract

What infuence could investigate to cochlear response when the middle ear apparatus were given the impairment and its repairment in free system? The results were as follows; 1) On the experiment regarding the degree of loss and the location of the perforation in tympanic menbrane, some increase of loss was seen in the post-inferior perforation of the ear drum, but there was no remarkable difference between this and the other portions, and con-sequently, it was proved in the relation between size of the perforation of tympanic menbrane and cochesar response that the response had decreased in proportion to the size of the perfora-tion. Next, when these perforations were closed by the artificial ear drum, there was scarcely any response in the small perforation, but in the middle and large perforations some effects of the response could be observed. The increase of the response in its efficacy was maximum at 800 cps; in general, the increase of the response in the lower and middle part of sound wass higher than that in the high part of sound. Moreover it was recognized definitely that the difference of effect depended upon the materials used for the artificial ear drum. 2) On the occasion that the function of facial nerves was paralized, a little increase of res-ponse could be observed at 2000 cps but in other frequencies the loss did not fall more than 5 db in the response. When the function was stimulated, the increase of response would be observed just after the impetus; The response began to decrease as the time went on but the decrease stopped within 10 db in degree of the hearing loss. 3) In the case that the ossicular chain was fixed, two different phenomena appeared; when that fixation was incomplete, the impairment was observed in the low-middle part of sound, while it became perfect, the loss appeared running parallel with the fiducial line in all parts of sound. Again, on the occasion that the ossicular chain was blocked, the impairment appeared in rather than high part of sound showing 50 db in an average. 4) In the case that a continuous manipulations were done upon the middle ear apparatus, a definite change was observed in cochlear response every time the manipulation was done. When the middle ear apparatus was repair using the artificial ear drum, the response inc reased 5-15 db in all cases.With removal of ear drum and malleus after the opening of epitympanum, In the other cases which had been repaired, no effect by artificial ear drum was observed.