Open access funding provided by Medical University of Graz. This study was supported by the Austrian Science Fund (FWF; P25241, KLI811, and TCS24), the Austrian National Bank (OeNB; P16430), and Rett Deutschland e.V.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.Medical University of GrazAustrian Science Fund (FWF) P25241
KLI811
TCS24Austrian National Bank (OeNB) P16430Rett Deutschland e.V