Henry K R
Department of Psychology, University of California, Davis 95616.
Hear Res. 1991 Nov;56(1-2):197-202. doi: 10.1016/0378-5955(91)90170-e.
Under restricted frequency and intensity conditions, forward masking can result in the amplitude of the CAP being increased above its unmasked value (Henry, 1991). The present study provides a quantitative analysis of this enhancement effect. In response to forward maskers having the same frequency as the probe stimulus, central frequency (CF) enhancement varies as a function of the level of the forward masker: the lowest masker level at which it can reliably be detected is often well below the visual detection threshold of the CAP generated by the unmasked probe stimulus; the highest masker level at which it can reliably be detected corresponds to approximately 10 dB above the probe stimulus CAP threshold. A second low frequency (LF) enhancement region also exists, encompassing a narrow range of more intense maskers. CF enhancement can double the amplitude of the CAP, whereas LF enhancement is less pronounced. The magnitude of CF enhancement varies as a function of the duration of the forward masker, with longer durations generally increasing the magnitude of the effect. This duration effect, however, interacts with the level of the stimulus. Decreasing the interval between the end of the forward masker and the beginning of the probe increases the magnitude of CF enhancement.
在受限的频率和强度条件下，前掩蔽可导致复合动作电位（CAP）的幅度增加到其未掩蔽时的值之上（亨利，1991年）。本研究对这种增强效应进行了定量分析。对于与探测刺激频率相同的前掩蔽刺激，中心频率（CF）增强随前掩蔽刺激的强度而变化：能够可靠检测到CF增强的最低掩蔽强度通常远低于未掩蔽探测刺激产生的CAP的可见检测阈值；能够可靠检测到CF增强的最高掩蔽强度大约比探测刺激的CAP阈值高10分贝。还存在第二个低频（LF）增强区域，涵盖了范围较窄的更强掩蔽刺激。CF增强可使CAP的幅度加倍，而LF增强则不太明显。CF增强的幅度随前掩蔽刺激的持续时间而变化，持续时间越长，通常效应幅度越大。然而，这种持续时间效应与刺激强度相互作用。缩短前掩蔽刺激结束与探测刺激开始之间的间隔会增加CF增强的幅度。
