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February 1958

Post-Stimulatory Fatigue in Diagnosis

Author Affiliations

Turku, Finland
From the Department of Otolaryngology, University of Turku, Finland.

AMA Arch Otolaryngol. 1958;67(2):228-238. doi:10.1001/archotol.1958.00730010234018


The classification of hard of hearing persons into conductively and perceptively deaf groups can generally be done with the ordinary pure-tone audiogram when bone-conduction values are related to air-conduction figures. Their difference shows the amount of the conductive component, whereas the gap between bone-conduction thresholds and zero line indicates the perceptive component. However, there are cases in which these criteria do not strictly apply, viz., patients in whom the normal balance between inertia and compression bone conduction is disturbed, or both mechanisms are suppressed. Examples of these are otosclerotic ears with fixed stapedial footplate, and patients with some hindrance in the middle ear limiting the movements of both windows at the same time.1 In these cases lowered bone-conduction values are found also in conduction deafness.

If the tympanic membrane and the middle ear are otoscopically normal, bone-conduction measurements almost without exception classify the subjects into

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