Categorization of Extremely Brief Auditory Stimuli: Domain-Specific or Domain-General Processes?

The present study investigated the minimum amount of auditory stimulation that allows differentiation of spoken voices, instrumental music, and environmental sounds. Three new findings were reported. 1) All stimuli were categorized above chance level with 50 ms-segments. 2) When a peak-level normalization was applied, music and voices started to be accurately categorized with 20 ms-segments. When the root-mean-square (RMS) energy of the stimuli was equalized, voice stimuli were better recognized than music and environmental sounds. 3) Further psychoacoustical analyses suggest that the categorization of extremely brief auditory stimuli depends on the variability of their spectral envelope in the used set. These last two findings challenge the interpretation of the voice superiority effect reported in previously published studies and propose a more parsimonious interpretation in terms of an emerging property of auditory categorization processes.本研究旨在探明可实现语音、器乐与环境声区分的最小听觉刺激量。本研究报告了三项新发现：1）所有刺激在50毫秒片段条件下的分类准确率均高于随机猜测水平；2）采用峰值归一化（peak-level normalization）处理后，音乐与语音仅需20毫秒片段即可实现精准分类；当刺激的均方根（RMS）能量被均衡化后，语音刺激的识别效果优于音乐与环境声；3）进一步的心理声学分析表明，极短听觉刺激的分类效果取决于本次实验所用刺激集合中其频谱包络的变异性。上述后两项发现对既往已发表研究中报道的语音优势效应（voice superiority effect）的传统解释提出了挑战，并基于听觉分类过程的涌现属性提出了更为简约的新解释。