Figure 1.

Lip Contour and Acoustic Speech Envelope

(A) The time series of the lip contour (area defined by the light blue points measured in square pixels) with the corresponding video frames is displayed together with the audio signal and the acoustic speech envelope [6] for a 2-s forward section. For the coherence analyses, the lip contour and the acoustic speech envelope were used.

(B) The coherence spectrum (averaged across stimuli) between lip contour and acoustic speech envelope is plotted peaking at 5 Hz, the rhythm of the syllables, for both forward and backward speech. The shaded area reflects the SD across stimuli. No difference between forward and backward speech occurred. For stimulus examples, see Videos S1 and S2.