Chiang Y C, Freyman R L
Department of Communication Disorders, University of Massachusetts, Amherst 01003, USA.
J Acoust Soc Am. 1998 Nov;104(5):3039-47. doi: 10.1121/1.423885.
This study examined the influence of background noise on the localization of lead-lag noise-burst pairs and on echo threshold for the same stimuli. Experiments were conducted in an anechoic chamber with a leading stimulus delivered from a loudspeaker at 45 degrees to the right of center and a lagging stimulus from 45 degrees left. Lead and lag stimuli were 4-ms bursts of Gaussian noise. In experiment 1, with lead and lag at equal levels and the lag delay fixed at 2 ms, the perceived location of the image produced by the lead-lag stimulus was estimated from subjects' left/right judgments relative to bursts from a "comparitor" loudspeaker whose position could be adjusted. In experiment 2, the dominance of the leading burst on perceived location was measured by determining the increase in level of the lagging burst necessary to produce an image estimated to be centered at 0 degree azimuth. Experiment 3 was concerned with echo threshold. Subjects reported whether or not they heard a sound in the vicinity of the lagging loudspeaker as the lag-burst delay was varied. In all three experiments, data were obtained for four to five stimulus levels in quiet and for three levels of background white noise from a loudspeaker at 180 degrees. The results revealed a substantial weakening effect of background noise on the precedence effect in experiments 2 and 3, and a nonsignificant effect in experiment 1.
本研究考察了背景噪声对超前-滞后噪声脉冲对定位以及相同刺激回声阈值的影响。实验在消声室内进行，超前刺激由位于中心右侧45度的扬声器发出，滞后刺激由左侧45度的扬声器发出。超前和滞后刺激均为4毫秒的高斯噪声脉冲。在实验1中，超前和滞后处于相同水平，滞后延迟固定为2毫秒，通过受试者相对于“比较”扬声器发出的脉冲的左右判断来估计超前-滞后刺激产生的图像的感知位置，该“比较”扬声器的位置可进行调整。在实验2中，通过确定为使估计图像位于0度方位角中心所需的滞后脉冲电平增加量，来测量超前脉冲对感知位置的主导作用。实验3关注回声阈值。随着滞后脉冲延迟的变化，受试者报告他们是否在滞后扬声器附近听到声音。在所有三个实验中，均获取了安静环境下四到五个刺激电平的数据以及来自180度扬声器的三个背景白噪声电平的数据。结果显示，在实验2和实验3中，背景噪声对优先效应有显著的削弱作用，而在实验1中作用不显著。
