Vocalisation Repertoire at the End of the First Year of Life: An Exploratory Comparison of Rett Syndrome and Typical Development

Abstract

Rett syndrome (RTT) is a rare, late detected developmental disorder associated with severe deficits in the speech-language domain. Despite a few reports about atypicalities in the speech-language development of infants and toddlers with RTT, a detailed analysis of the pre-linguistic vocalisation repertoire of infants with RTT is yet missing. Based on home video recordings, we analysed the vocalisations between 9 and 11 months of age of three female infants with typical RTT and compared them to three age-matched typically developing (TD) female controls. The video material of the infants had a total duration of 424 min with 1655 infant vocalisations. For each month, we (1) calculated the infants’ canonical babbling ratios with CBRUTTER, i.e., the ratio of number of utterances containing canonical syllables to total number of utterances, and (2) classified their pre-linguistic vocalisations in three non-canonical and four canonical vocalisation subtypes. All infants achieved the milestone of canonical babbling at 9 months of age according to their canonical babbling ratios, i.e. CBRUTTER ≥ 0.15. We revealed overall lower CBRsUTTER and a lower proportion of canonical pre-linguistic vocalisations consisting of well-formed sounds that could serve as parts of target-language words for the RTT group compared to the TD group. Further studies with more data from individuals with RTT are needed to study the atypicalities in the pre-linguistic vocalisation repertoire which may portend the later deficits in spoken language that are characteristic features of RTT.

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“…By nature of their symptomatology, these diseases are prototypical examples of ones that manifest in auditory biomarkers. Thus, different signals have been used to detect their presence, such as speech (60), breathing and coughing (61,62), or sustained vowels (63). The most exemplary of those is COVID-19, whose devastating impact was felt around the world since its emergence in late 2019 and has led to a wave of renewed interest in computer audition for healthcare applications.…”

Automatic vocalisation-based detection of fragile X syndrome and Rett syndrome

“…Deficits in the speech-language domain are a core characteristic of both RTT 29 , 30 and FXS 20 , 31 , 32 . Nevertheless, there is limited knowledge of early verbal capacities of individuals with FXS or RTT, i.e., of verbal behaviour from the prodromal period 33 – 36 . In a study comparing the (pre-)linguistic development of 10 individuals with FXS and 14 typically developing (TD) individuals at 9–12 months of age, Belardi and colleagues 37 reported a reduced number of produced syllables per time and a reduced proportion of produced canonical syllables for the individuals with FXS.…”

Emerging Verbal Functions in Early Infancy: Lessons from Observational and Computational Approaches on Typical Development and Neurodevelopmental Disorders

“…For example, some infants with late detected developmental disorders (LDDDs such as ASD, RTT, FXS) exhibited a delayed onset of canonical babbling whereas others have reached this milestone at an adequate age, i.e. between 5 and 10 months ( Bartl-Pokorny et al, 2022 ; Lang et al, 2019 ; Marschik et al, 2013 ; Yankowitz et al, 2019 , 2022 ).…”