Articulatory characteristics of sibilant production in young people with Down's syndrome
Timmins, C. (2014) Articulatory characteristics of sibilant production in young people with Down's syndrome, no. 338.
Speech production in children with Down’s syndrome (DS) has been found to be variable and inconsistent. Errors are concentrated in consonants that are typically late developing, such as fricatives. It has been suggested that inconsistency in speech production in DS is a result of a motor speech deficit but there is little detailed articulatory evidence to support this claim. This study (with data from MRC grant ‘Assessment and Treatment of Impaired Speech Motor Control in Children with Down's syndrome’ (G0401388)) provides a detailed phonetic analysis of the voiceless sibilants /s/ and /ʃ/, in a group of young people with DS, by means of auditory and articulatory analysis. The aim of the study is to assess fine motor ability and articulation variability at word level production in a group of speakers with well-established difficulties in speech articulation. The study analysed data from 25 children with DS, 10 typically developing children and 8 adult speakers, recorded using EPG. Perceptual measures were compared with quantitative analyses of EPG data, along with visual analysis of articulation patterns based on a new set of articulation taxonomies. The data is presented by group and in the form of 5 case studies. The case studies provide a means to analyse the relationship between articulation and auditory information in detail and to compare these with supplementary motor control measures. The results show presence of atypical articulation patterns for speakers with DS for both perceptually acceptable tokens, and those in error. Higher levels of within-speaker articulation variability are presented in comparison to the TD control group. Further findings suggest presence of articulation patterns in the TD speakers previously unidentified in EPG studies. Similar to previous studies, the results find that speakers with DS are a highly variable group and that speakers display a combination of typical and atypical speech patterns, influenced by speech motor control difficulties.