Henry K R, Price J M
Department of Psychology, University of California, Davis 95616.
Hear Res. 1992 Nov;63(1-2):90-6. doi: 10.1016/0378-5955(92)90077-z.
The Derived cochlear nerve compound action potential (CAP) and the Enhanced CAP are both measures which demonstrate the ability of a forward masker to increase the amplitude of the CAP produced by a probe stimulus. Enhancement occurs whenever the amplitude of a masked CAP is larger than that of a nonmasked CAP, whereas the derived CAP is produced by the subtraction of the entire masked CAP waveform from that of the nonmasked waveform. Therefore, a derived CAP is created whenever the masker produces a difference of amplitude, latency, and/or waveform shape. The present experiments compare these two measures by observing the effects of 13 kHz maskers varying from levels of -10 to +70 db SPL on CAPs produced by 50 or 60 dB SPL, 13 kHz probe stimuli. Enhancement is characterized by a nonmonotonic increase of CAP amplitude (and sometimes a decrease of latency) as a function of increasing levels of the forward masker, whereas this pattern seldom occurs with the derived CAP. Enhancement is typically seen with forward making, but seldom seen with simultaneous masking, whereas the derived CAP is very similar under these two types of masking.
衍生耳蜗神经复合动作电位（CAP）和增强型CAP都是用于衡量正向掩蔽声增加探测刺激所产生CAP幅度能力的指标。只要掩蔽CAP的幅度大于非掩蔽CAP的幅度，就会出现增强现象，而衍生CAP是通过从非掩蔽波形中减去整个掩蔽CAP波形而产生的。因此，只要掩蔽声产生幅度、潜伏期和/或波形形状的差异，就会产生衍生CAP。本实验通过观察13千赫掩蔽声，其声压级从-10到+70分贝声压级变化，对由50或60分贝声压级、13千赫探测刺激所产生的CAP的影响，来比较这两种指标。增强的特征是CAP幅度非单调增加（有时潜伏期缩短），这是正向掩蔽声声压级增加的函数，而这种模式在衍生CAP中很少出现。增强通常在正向掩蔽时出现，但在同时掩蔽时很少出现，而衍生CAP在这两种掩蔽类型下非常相似。
