Post-hoc results. ERP analyses at all electrodes for the speech and non-speech vocal sounds comparisons. The color code is shown on the right side. Electrodes are stacked along the vertical axis. The horizontal black lines separate the different groups of electrodes organised in frontal, fronto-central and occipital electrodes. Gray areas were not significant. Significant ERP differences (amplitude difference in μV averaged across subjects) are represented in an increasing gradient from blue to red (jet64). Bootstrap analyses revealed significant amplitude differences between (a) speech sounds and the two non-voice categories grouped together in a conjunction test, (b) non-speech vocal sounds and the two non-voice categories grouped together in a conjunction test, c) the conjunction of a) and b), and d) the speech vs. non-speech vocal sounds test.