Abstract
The diagnosis of the ossicular condition such as ixation or dislocation may often not be achieved by the routine tympanogram. This might be due to the facts that the routine tympanogram figurizes the impedance of the middle ear as an equivalent air volume without phase measurement, and frequency of the probe tone is quite tow and mostly 220 Hz. A new technique has been developed in our department in order to improve the diagnostic value.
The method was consisted of the followings: (1) Frequency of probe tone was changed continuously from 45 Hz to 2500Hz. (2) The changes in sound pressure and in phase were measured continuously at the external meatus, as the frequency of the tone changed. (3) These values were figurized in a kind of polar notation as the difference between conditions of -200mmH2O and 0mmH2O, by the aid of a microcomputer.
This system was applied for normal subjects and patients of otosclerosis and traumatic ossicular dislocation. Pre- and post-operative diagnosis agreed with each other.
The authors feel that this new system should be routinely applied because of it's validity in clinical use.
