1994 Volume 37 Issue 6 Pages 732-740
Fluid loading audiometry, a diagnostic method to determine ossicular function or stapes mobility, is based on the threshold difference (TD) between bone conductions when fluid is present or not in the external ear canal, reflecting the mobility of the stapes foot plate. For the purpose of utilizing this testing method for evaluating ossicular mobility, we first investigated and confirmed the utility and reliability of this testing method. From 34 notmal ears we obtained normal range of TD at 250, 500, 800 and 1000Hz, each mean value of which was only about 2.5-7.5dB less than that obtained by Tsunoda, who has proposed this method. In 256 ears classified into 5 groups with nonperforated ear drums and 3 groups with perforated ones, mean TD value for each group of each frequency was obtained. From these results we obtained diagnostic value of more than 20dB and less than 10dB at 250Hz for ossicular function and that of more than 10dB and less than 5dB at 1000Hz for situation of middle ear cleft under the condition that TD at 250Hz is more than 20dB. Mechanism of threshold difference was also discussed.
