DL Difference Test に関する臨床的研究

第1編 検査方法と正常耳の検査成績

抄録

Among recruitment tests the author selected DL difference (DL.D) test and studied it for dete-rmining the presence or absence of recruitment. Namely, this selected DL difference is the rema-inder obtained after subtracting DL at 40db over the threshold from DL at 10db over the threshold, and examined 50 ears of 25 persons with normal hearing on the basis of this DL.D test using Maico MA-I.
1. DL's at 10db over the threshold show slight individual differences, but DL's at 40db over the threshold and DL. D's hardly show any individual difference.
2. The minimal limits of DL. D's in the normal ears. were 250cps. 0.6db; 500cps. 0.6db; 1000cps. 0.6db; 2000cps. 0.5db; and 4000cps. 0.5db.
3. The standard deviation of DL. D's by the frequency is small compaired with DL's, showing the least standard deviation at 1000cps. In selecting one frequency for the testing sound, the freq-uency at 1000cps is the most suitable one.
4. DL will yield different values according to different examiners and to the measuring methods, especially the way how the testing sound is given. Therefore, unless the determination of recruit-ment is conducted under the same conditions, the measured values will be meaningless and the actual determination of the presence or absence of recruitment will become difficult.