SOUNDS

Williams syndrome (WS) is a neurodevelopmental disease characterized by mild to moderate intellectual disability (ID), a heterogeneous cognitive profile, an atypical social behavior, and an unusual acoustic hypersensitivity to noise. The very specific profile of people with WS is probably at least partly attributable to the inherent characteristics of the pathology: their sounds hypersensitivity could lead to high-level Phonological Short Term Memory (PSTM). Unfortunately, the impact of the acoustic hypersensitivity on language development is difficult to establish. The hyperacousis is clearly more subjective experience than scientific evidence: most studies used questionnaires to probe the auditory experiences of people with WS and too few used physiological measurements. Therefore, it is important to conduct new studies to determine possible relationships between hyperacusis, linguistic and non-linguistic skills (such as PSTM). A way to test these hypotheses is to conduct cross-syndrome studies. In the literature, WS is often compared to Down syndrome (DS) because both of these neurodevelopmental diseases are characterized by an equivalent moderate ID level. All studies appear to show that structural aspects of language in people with WS are definitely at a higher level than in people with DS. The strong mastery of these structural aspects of language could be due to the very good PSTM present in WS. Moreover, the excessive reliance on PSTM could explain that people with WS produce more words than they comprehend as if they were only memorizing and using phonological forms without their semantic underpinnings. Specifically, there would be an abnormal imbalance between phonological and semantic processing in people with WS. Language development would rely more on PSTM and less on lexical-semantics. This phonology-semantics imbalance hypothesis contrasts with the conservative hypothesis which argues that language skills are simply in line with developmental age. In compliance with these two hypotheses, the present project aim at investigating a possible effect of hyperacusis on language development of individuals with WS. We hypothesize that their acoustic particularities could increase their interest on phonology and then lead to a high level of PSTM. To test this hypothesis, we will assess objectively their hyperacusis creating appropriate tools including physiological measures (EEG-NIRS protocol), questionnaires, and psychometric measures (prosody, phonological awareness). We will use various standardized tests and original experimental tasks to assess cognitive development (verbal and non-verbal) and language (receptive vocabulary, qualitative aspects of language). To better understand the link between acoustic hypersensitivity and PSTM, a full assessment of PSTM skills (nonword repetition task, serial order STM) will be conducted. Finally, we will specifically test the link between phonology and semantic skills via a minimally verbal task using a priming paradigm. The performance of people with WS will be compared to those of participants with DS and TD participants of same developmental age. Our study will provide new additional support on WS and DS phenotype and will allow us to characterize the disorder group’s trajectory. It will also contribute to better understand the impact of acoustic sensitivity on language development of people with WS. For clinicians, families and children, these issues are particularly important: language and communicative skills are crucial in the development of subsequent cognitive and social abilities.