Henry K R
Department of Psychology, University of California, Davis 95616.
Hear Res. 1992 Nov;63(1-2):12-8. doi: 10.1016/0378-5955(92)90068-x.
The amplitude of a cochlear nerve compound action potential (CAP) can be increased by forward maskers having levels close to the visual detection threshold of the CAP. This effect, termed enhancement, varies as a function of the frequency of the masker and probe stimulus, and is nonmonotonic with respect to the level of the masker. Other studies using the derived CAP have used a subtraction technique to evaluate the ability of simultaneous maskers having levels near the CAP visual detection threshold to influence the CAP produced by an above threshold tone. The present paper compares audiograms produced by the conventional nonmasked CAP visual detection threshold technique with audiograms produced by both forward masked derived CAPs and forward masked enhanced CAPs. In response to low and middle frequency stimuli, both masked CAP measures produce more sensitive audiograms than does the conventional nonmasking method. Forward masked amplitude tuning curves (TCs) were also produced, comparing the conventional 50% amplitude reduction and 20 microV amplitude reduction methods with TCs obtained with derived and enhanced CAPs. When the same criteria are used, both masked CAP measures result in sharply tuned amplitude TCs that are approximately 60 dB more sensitive than the conventional CAP technique. At near-threshold levels, the properties of forward masked enhanced and derived CAPs appear to be similar.
具有接近耳蜗神经复合动作电位（CAP）视觉检测阈值水平的前向掩蔽器可增加CAP的幅度。这种效应被称为增强，它随掩蔽器和探测刺激的频率而变化，并且相对于掩蔽器的水平是非单调的。其他使用衍生CAP的研究采用减法技术来评估具有接近CAP视觉检测阈值水平的同时掩蔽器影响高于阈值音调产生的CAP的能力。本文比较了传统的非掩蔽CAP视觉检测阈值技术产生的听力图与前向掩蔽衍生CAP和前向掩蔽增强CAP产生的听力图。对于低频和中频刺激，两种掩蔽CAP测量方法产生的听力图都比传统的非掩蔽方法更敏感。还生成了前向掩蔽幅度调谐曲线（TCs），将传统的50%幅度降低和20微伏幅度降低方法与通过衍生和增强CAP获得的TCs进行比较。当使用相同标准时，两种掩蔽CAP测量方法都会产生尖锐调谐的幅度TCs，其灵敏度比传统CAP技术高约60分贝。在接近阈值水平时，前向掩蔽增强和衍生CAP的特性似乎相似。
