Dye R H, Stellmack M A, Grange A N, Yost W A
Department of Psychology, Loyola University, Chicago, Illinois 60626, USA.
J Acoust Soc Am. 1996 Feb;99(2):1096-107. doi: 10.1121/1.414670.
A two-dimensional stimulus-classification paradigm was used to examine the ability of listeners to judge the laterality of an interaurally delayed low-frequency target component presented concurrently with a distractor component. Of primary interest was the effect on performance of the frequency difference (Delta f) between the target and distractor. In one set of conditions, the target was fixed at 753 Hz and the distractor was 353, 553, 653, 703, 803, 853, 953, or 1153 Hz (fixed within a block of trails). In a second set of conditions, the distractor was fixed at 753 Hz and the target frequency was 353, 553, 653, 703, 803, 953, or 1153 Hz. The listeners were presented with a target component with an interaural delay that varied from trial to trial, taking on one of ten values, five leading to the left ear and five leading to the right. A distractor component was simultaneously presented with an interaural delay that also took on one of the same ten values. Delays ranged from -90 to (+)90 microseconds in 20-microsecond steps. during a block of 100 trials, each of the possible combinations of target and distractor delay was presented once and only once in a random order. Listeners were instructed to make left-right judgments based on the target delay. Each condition was repeated ten times, and the slopes of the best linear boundaries between left and right responses were used to derive the relative weights given to the target and distractor. The duration of the signals was 200 microseconds. Two of the eight listeners weighted the target heavily when the target and distractor were spectrally remote but gave the two components equal weight when the different in frequency was small. These two listeners yielded similar target weights regardless of which component was designated as the target. One listener gave nearly equal weight to the target and the distractor regardless of Delta f. Five of the listeners gave greater weight to the higher of the two frequencies regardless of which was assigned as the target. This high-frequency dominance is explained in terms of cross-correlation functions based on the composite two-tone waveforms.
采用二维刺激分类范式来检验听众判断与干扰成分同时呈现的耳间延迟低频目标成分的侧向性的能力。主要关注的是目标与干扰成分之间的频率差（Δf）对表现的影响。在一组条件下，目标固定为753赫兹，干扰成分分别为353、553、653、703、803、853、953或1153赫兹（在一组试验中固定）。在第二组条件下，干扰成分固定为753赫兹，目标频率为353、553、653、703、803、953或1153赫兹。向听众呈现一个耳间延迟逐次变化的目标成分，延迟有十个值，其中五个导致左耳，五个导致右耳。同时呈现一个干扰成分，其耳间延迟也取相同的十个值之一。延迟范围从 -90到（+）90微秒，以20微秒为步长。在100次试验的一组中，目标和干扰成分延迟的每种可能组合以随机顺序呈现一次且仅一次。听众被指示根据目标延迟做出左右判断。每个条件重复十次，使用左右反应之间最佳线性边界的斜率来得出赋予目标和干扰成分的相对权重。信号持续时间为200微秒。八位听众中有两位在目标和干扰成分频谱距离较远时给予目标很大权重，但当频率差异较小时给予两个成分相等的权重。无论将哪个成分指定为目标，这两位听众产生的目标权重相似。一位听众无论Δf如何，都给予目标和干扰成分几乎相等的权重。五位听众无论将哪个指定为目标，都给予两个频率中较高的频率更大的权重。基于复合双音波形的互相关函数对这种高频优势进行了解释。
