Neff D L, Dethlefs T M, Jesteadt W
Boys Town National Research Hospital, Omaha, Nebraska 68131.
J Acoust Soc Am. 1993 Dec;94(6):3112-26. doi: 10.1121/1.407217.
Simultaneous maskers comprised of a few random-frequency sinusoids can produce considerable informational (uncertainty-based) masking if the component frequencies are drawn from a wide range and changed with each stimulus presentation. The present experiments examined the effect on informational masking of removing masker energy from large frequency regions around the signal. Threshold for a 1000-Hz signal was measured in the presence of maskers comprised of 2, 4, 6, 10, 50, or 100 random-frequency sinusoids, notched-noise, or two fixed-frequency sinusoids. The multicomponent maskers had a maximum frequency range of 300-3000 Hz, typically excluding a 160-Hz band around the signal. In comparison conditions, masker frequencies were limited to the high or low side of the signal, or the gap around the signal was progressively widened. Four listeners showed substantial informational masking which was not eliminated even by extreme spectral gaps in the maskers. Four other listeners showed much smaller effects of masker uncertainty across all conditions. Notched-noise measures of auditory-filter width did not distinguish the two subject groups, but indices of processing efficiency were typically poorer for the high-threshold listeners, as were measures of both the width and processing efficiency of presumed "attentional filters" under conditions of masker-frequency uncertainty.
由少数随机频率正弦波组成的同时掩蔽器，如果其成分频率取自较宽范围且每次刺激呈现时都发生变化，就会产生相当大的信息性（基于不确定性的）掩蔽。本实验研究了从信号周围的大频率区域去除掩蔽器能量对信息掩蔽的影响。在由2、4、6、10、50或100个随机频率正弦波、带阻噪声或两个固定频率正弦波组成的掩蔽器存在的情况下，测量1000赫兹信号的阈值。多成分掩蔽器的最大频率范围为300 - 3000赫兹，通常排除信号周围160赫兹的频段。在比较条件下，掩蔽器频率被限制在信号的高频或低频侧，或者信号周围的间隙逐渐变宽。四名听众表现出大量的信息掩蔽，即使掩蔽器中存在极端的频谱间隙也无法消除。另外四名听众在所有条件下表现出的掩蔽器不确定性影响要小得多。听觉滤波器宽度的带阻噪声测量无法区分这两组受试者，但对于高阈值听众，处理效率指标通常较差，在掩蔽器频率不确定的条件下，假定的“注意力滤波器”的宽度和处理效率测量结果也是如此。
