Bauer J W
Sens Processes. 1978 Jun;2(2):156-72.
Single units of the auditory nerve are maximally sensitive to a given frequency, the so-called characteristic frequency (CF). Tuning curves (functions relating the "threshold" for such units to the frequency of a sinusoidal stimulus) have inspired psychophysical measurements of masked thresholds in humans. At low levels, the results bear a striking resemblance to neural tuning curves, suggesting that a small, homogeneous group of units determine the so-called psychophysical tuning curves. This paper describes physiological measurements modeled after the psychophysical forward-masking paradigm. A masking tone was used to reduce the response in auditory-nerve fibers elicited by a probe tone that followed the masker. The level of the masking tone was varied to maintain a criterion level of responding to the probe. Plotting level of the masker as a function of its frequency yields a fiber-masking function. For low probe-tone levels, fiber-masking functions of low CF fibers and the tips of functions from high CF fibers were similar in shape to tuning curves obtained with single tone bursts. The fiber-masking function depends upon the response criterion and upon the level, duration, and frequency of the probe. Varying the level of the probe can also alter the shape of the fiber-masking function. These results have implications for interpreting psychophysical masking functions.
听神经的单个单元对特定频率（即所谓的特征频率，CF）最为敏感。调谐曲线（将此类单元的“阈值”与正弦刺激频率相关联的函数）启发了人类对掩蔽阈值的心理物理学测量。在低强度水平下，结果与神经调谐曲线惊人地相似，这表明一小群同质的单元决定了所谓的心理物理学调谐曲线。本文描述了以心理物理学前掩蔽范式为模型的生理学测量。使用一个掩蔽音来降低在掩蔽音之后出现的探测音所诱发的听神经纤维的反应。改变掩蔽音的强度以维持对探测音反应的标准水平。将掩蔽音的强度作为其频率的函数进行绘图，可得到纤维掩蔽函数。对于低探测音强度，低CF纤维的纤维掩蔽函数以及高CF纤维函数的峰值在形状上与用单音爆获得的调谐曲线相似。纤维掩蔽函数取决于反应标准以及探测音的强度、持续时间和频率。改变探测音的强度也会改变纤维掩蔽函数的形状。这些结果对解释心理物理学掩蔽函数具有启示意义。
