Analyses of sustained vowels in Down Syndrome (DS): a case study using spectrograms and perturbation data to investigate voice quality in 4 adults with DS.Objectives. Automatic acoustic measures of voice quality in people with Down Syndrome (DS) do not reliably reflect perceived voice qualities. This study used acoustic data and visual spectral data to investigate the relationship between perceived voice qualities and acoustic measures.Study design. Participants were 4 young adults (2 male, 2 female; mean age 23;8 years) with DS and SevereLearning Disabilities (SLD), at least one of whom had a hearing impairment (HI).Methods. Participants imitated sustained /i/, /u/ and /a/ vowels at pre-determined target pitches within their vocal range. Medial portions of vowels were analysed, using Praat, for Fundamental frequency (f0), HNR, jitter and shimmer. Spectrograms were used to identify the presence and the duration of subharmonics at onset and offset, and mid-vowel. The presence of diplophonia was assessed by auditory evaluation.Results. Perturbation data were highest for /a/ vowels and lowest for /u/ vowels. Intermittent productions of subharmonics were evident in spectrograms, some of which coincided with perceived diplophonia. The incidence, location, duration and intensity of subharmonics differed between the four participants. Conclusions.Although the acoustic data do not clearly indicate atypical phonation, diplophonia and subharmonics reflect nonmodal phonation. The findings suggest that these may contribute to different perceived voice qualities in the study group and that these qualities may result from intermittent involvement of supraglottal structures. Further research is required to confirm the findings in the wider DS population, and to assess the relationships between voice quality, vowel type and physiological measures.

The musical rhythmic abilities of people with Down Syndrome (DS) reportedly exceed their general cognitive abilities. Although they display atypical rhythmic production in musical motor tasks, little is known about how their developmental and cognitive differences affect temporal perception or production. Additionally, hearing impairment often excludes potential participants from studies, further limiting our understanding. This case study examined the rhythmic ability of one young adult with DS and moderate-severe hearing impairment when producing limb-motor movements to music in auditory-only and auditory-visual conditions. His temporal accuracy was observed for gross-motor movements to music. Measurements were made of his temporal accuracy and stability when tapping on a drum at three tempi, and when tapping to non-isochronous rhythms. Results revealed temporal deficits in all tasks. However, production improved in tasks that were augmented with visuo-spatial stimuli, and in isochronous beat entrainment at the fastest tempo. Findings were compared to the participant’s cognitive and perceptual profile. Results suggest that his production was limited by developmental factors, but that auditory memory deficits and hearing may account for instability in isochronous entrainment tasks and delayed onset of timing. Recommendations are made for supporting skills in production and perception of auditory rhythms within the DS population.

No abstract