外耳道の狭窄または閉塞と聴力との関係について

概要

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The audiological study for ears with aural stenosis and atresia was performed. The hearing level of ears with three types of ear plugs (with the hole of 1, 1mm, with the hole of q63mm and without the hole) was tested experimentaly by 10 normal hearing subjects in pure tone audiometry, and the audiograms of congenital and acquired aural stenosis and atresia were investigated statisti- cally. And then following results were obtained. 1) The air conduction levels were higher, as the diameter of ear plugs hole got shorter in normal hearing subjects. And the shape of their audiograms was gradual sloping type. 2) The air conduction levels of ears with congenital aural stenosis and atresia were almost from 60 to 70 dB, and the levels were almost same throughout 7 frequencies. But the audiograms of ears with acquired aural stenosis and atresia showed conductive and gradual sloping type. 3) From the results mentioned above, the reason why the hearing loss of ears with aural stenosis and atresia showed conductive hearing loss limitted to low and middle frequencies was considered to depend on the abnormality of the middle ear. 4) An average value of hearing threshold level in bone conduction among normal hearing subjects with three types of ear plugs was almost -7.8dB. There was no relation between the size of ear plugs hole and the shift of bone conduction level.