Fig. 8.

LFO and HFA effects when participants spontaneously report their perception of the speech sequences. A: phase differences of the 3-Hz response contrasting the perceived speech utterances. Polar plots report the 3-Hz phase difference between the 2 perceptual outcomes (top, in the left hemispheric sensors; bottom, in the right hemispheric sensors). Each gray bar is an individual's phase difference between the 2 perceptual outcomes in a given condition. The black bar corresponds to the mean average phase difference across all participants. Red arcs are 95% CI. As during the volitional task, we observed significant phase shifts of −8° for the contrast ”plan“–”lampe.“ The contrast ”pse“–”sep“ was not clearly interpretable in the spontaneous task due to a high rejection rate of participants' data. B: phase differences of the 1.5-Hz response contrasting perceived words in the bisyllabic sequences. As in the volitional task, the 1.5-Hz phase did not significantly differ between percept conditions. C: cross-correlations between the speech envelope and brain activity during the ”lampe“ sequences for 2 participants in the spontaneous task. Each plot shows the difference in cross-correlation between ”plan“ and ”lampe“ percept conditions. Significant differences are indicated by any patch not colored green.