Greenfield D G, Wiley T L, Block M G
J Speech Hear Disord. 1985 Feb;50(1):14-20. doi: 10.1044/jshd.5001.14.
Acoustic-reflex growth functions and Loudness-Discomfort Level (LDL) measures were obtained for 15 normal-hearing subjects. The hypothesis that signals considered uncomfortably loud occur at intensity levels that produce proportionately equal acoustic-reflex magnitudes was evaluated. Individual reflex growth functions were measured as a function of activator SPL for a 1000-Hz tone, a 4000-Hz tone, and a broadband noise. These growth functions were measured within subjects (two trials) and across subjects in terms of (a) percentage acoustic-impedance change at LDL, (b) percentage acoustic-reactance change at LDL, (c) acoustic impedance at LDL, (d) relative change in acoustic impedance at LDL, and (e) ratio of static acoustic impedance to change in acoustic impedance at LDL. Although the loudness and acoustic-reflex measures demonstrated good reliability across trials, the data showed large variability across subjects and did not support the experimental hypothesis. It was concluded, therefore, that the use of acoustic-reflex measures in the estimation of an individual's LDL is unwarranted.
对15名听力正常的受试者进行了声反射增长函数和响度不适阈（LDL）测量。评估了这样一种假设，即被认为响度不适的信号出现在产生成比例相等声反射幅度的强度水平上。针对1000赫兹纯音、4000赫兹纯音和宽带噪声，测量了个体声反射增长函数随激活声压级的变化。这些增长函数在受试者内部（两次试验）以及在受试者之间进行了测量，测量指标包括：（a）LDL时声阻抗变化百分比；（b）LDL时声抗变化百分比；（c）LDL时的声阻抗；（d）LDL时声阻抗的相对变化；（e）静态声阻抗与LDL时声阻抗变化的比值。尽管响度和声反射测量在各次试验中显示出良好的可靠性，但数据表明受试者之间存在很大差异，且不支持实验假设。因此得出结论，在估计个体的LDL时使用声反射测量是没有必要的。
