Longitudinal Assessment of Early Premature Infant Skills for Audiovisual Speech Perception

From birth, babies perceive speech face to face with their interlocutors in audiovisual situations (AV): in addition to hearing them (auditory speech), they will also, in most cases, be able to observe their speaking faces (ex: mouth movements, lips, tongue etc.) . However, the ability to associate visual speech (ex: the movement of the lips of a speaking face) with auditory speech (ex: sound information) to which it corresponds is one of the earliest signs of language development. This ability to audiovisual association is present from the age of 2.5 months in infants with Typical Development and notably allows predicting the subsequent acquisition of vocabulary from the age of 12 months. This skill allows infants to access redundant AV cues between auditory and visual speech. However this redundancy is a key piece of information allowing them, compared to an auditory situation alone, to focus their attention longer on the speech signal compared to the surrounding noises. This mechanism facilitates their subsequent language learning (identification of sounds, recognition and memorization of vocabulary, etc.) Alternatively, several studies show that children with atypical development of language and communication (e.g., Autistic Spectrum Disorder (ASD)), present clear difficulties in AV association, which may be, at least in part, at the origin of their subsequent linguistic and communicative difficulties. On the other hand, children born prematurely have a higher risk of language disorders and ASD. Furthermore, some research shows that infants born prematurely exhibit an atypical exploration of speaking faces. This atypicity could explain the subsequent language difficulties observed in these populations. Currently, we do not know at what age this ability develops in premature children and if it may be the cause of a language development disorder. The hypothesis would be that premature children develop this capacity later than full-term children. This could be o