Zhang Yuxuan, Wright Beverly A
Department of Communication Sciences and Disorders and Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL 60208, USA.
J Acoust Soc Am. 2009 Sep;126(3):1349-58. doi: 10.1121/1.3177267.
Humans rely on interaural level differences (ILDs) to determine the location of sound sources, particularly for high-frequency sounds. Previously, ILD-discrimination performance with a 4-kHz pure tone was reported to improve with multi-hour training. Here the effect of the same training regimen on ILD discrimination with a 4-kHz tone sinusoidally amplitude modulated (SAM) at 0.3 kHz was examined. Ten of the 16 trained listeners improved more than untrained controls, demonstrating training-induced learning. However, compared to the learning previously obtained with the 4-kHz pure tone, learning with the SAM tone was less predictable based on starting performance, took longer to complete, and was characterized by specificity to stimulus type (SAM vs pure tones) rather than stimulus frequency. These differences demonstrate an influence of amplitude modulation on learning of ILD discrimination. This influence suggests that the auditory system makes use of amplitude envelope information in determining ILD-discrimination performance, a form of interaction between time and level processing in the binaural system.
人类依靠双耳声级差（ILD）来确定声源的位置，尤其是对于高频声音。此前有报道称，经过数小时的训练，对4千赫纯音的ILD辨别能力会有所提高。在此，研究了相同训练方案对以0.3千赫进行正弦幅度调制（SAM）的4千赫纯音的ILD辨别的影响。16名经过训练的听众中有10名的改善程度超过了未经训练的对照组，这表明了训练诱导的学习效果。然而，与之前用4千赫纯音获得的学习效果相比，用SAM音进行的学习基于起始表现的可预测性较低，完成所需时间更长，并且具有对刺激类型（SAM与纯音）而非刺激频率的特异性。这些差异表明幅度调制对ILD辨别学习有影响。这种影响表明，听觉系统在确定ILD辨别性能时利用了幅度包络信息，这是双耳系统中时间和强度处理之间的一种相互作用形式。
