Audiovisual production and perception of contrastive focus in French: a multispeaker study

This study examines the visual cues to prosodic contrastive focus in Hexagonal French and their role in visual speech perception. Two audiovisual corpora were recorded (from two male native speakers of French) consisting of sentences with a subject-verb-object (SVO) syntactic structure. Four conditions were studied: focus on each phrase (S,V,O) and broad focus. The corpora were first acoustically validated. Then lip area and jaw opening were extracted from the video. For each speaker, we identified a set of visible correlates of contrastive focus. The combined results showed that there were consistent visible articulatory correlates of contrastive focus across speakers: a) an increase in lip area and its first derivative on the focused item b) a lengthening of the focal syllables. There were also speaker-specific strategies in the amount of a) prefocal anticipation or b) post-focal hypo-articulation. Visual only perception tests were then conducted to see if the identified correlates were valid cues in perception. They showed that contrastive focus was well perceived visually for both speakers. The scores were better for the first speaker who displayed greater focal hyper-articulation. We also found that presence and salience of the visual cues enhances perception.