Lutfi R A, Patterson R D
J Acoust Soc Am. 1984 Sep;76(3):739-45. doi: 10.1121/1.391260.
Masking asymmetry was investigated over a wide range of stimulus intensities for two signal frequencies, fo = 1.0 and 4.0 kHz, using both fixed-masker and fixed-signal paradigms. The masker was a notched noise with the upper and lower edges of the notch, fu and fl, respectively, placed asymmetrically about fo. For various notch widths, the asymmetry of masking was measured as the difference between the masked threshold obtained when fl was nearer fo and that obtained when fu was nearer fo. For maskers with wide notches, (fu - fl)/fo greater than 0.15, masking asymmetry changed with stimulus level; at the highest level, masked threshold was greatest when fl was nearer fo, and, at the lowest level the asymmetry reversed slightly for fo = 1.0 kHz so that masked threshold was actually greater when fu was nearer fo. Nonparallel growth of masking functions reveal changes in masking asymmetry with signal level as well as with masker level. It is concluded that the nonlinear growth of masking with level is due primarily to changes in the auditory filter, rather than changes in the detector following the filter.
使用固定掩蔽器和固定信号范式，在1.0千赫和4.0千赫这两个信号频率的广泛刺激强度范围内研究了掩蔽不对称性。掩蔽器是一个带凹口的噪声，凹口的上边缘和下边缘分别为fu和fl，它们围绕fo不对称放置。对于各种凹口宽度，掩蔽不对称性通过fl更接近fo时获得的掩蔽阈值与fu更接近fo时获得的掩蔽阈值之间的差异来衡量。对于宽凹口的掩蔽器，(fu - fl)/fo大于0.15，掩蔽不对称性随刺激水平而变化；在最高水平时，当fl更接近fo时掩蔽阈值最大，而在最低水平时，对于fo = 1.0千赫，不对称性略有反转，以至于当fu更接近fo时掩蔽阈值实际上更大。掩蔽函数的非平行增长揭示了掩蔽不对称性随信号水平以及掩蔽器水平的变化。得出的结论是，掩蔽随水平的非线性增长主要是由于听觉滤波器的变化，而不是滤波器之后探测器的变化。
