Age-related differences in repetition variability : Analysis of lip movements using functional data analysis
Susanne Schötz, Johan Frid, Anders Löfqvist · Lund University Publications (Lund University) · 2011
This study examined repetition variability of lip movements as a function of age in Swedish speakers. A number of studies, using acoustic analysis and movement recordings, have shown that variability decreases with age until adolescence. The purpose of the present study was to apply functional data analysis (FDA, e.g., Ramsay et al. 1998) to lip movements. Our aim was to extend earlier findings of decreasing variability with age to see if both amplitude and phase change together, or only one of them. Previous studies have used the Spatiotemporal Index (STI, Smith et al. 1995), which only provides a single metric of variability (cf., Lucero et al. 1995), incorporating both amplitude and phase. Our long-term objective is to examine (1) if children with atypical language development differ from typically developing children in terms of articulatory variability and (2) the possible relationship with cerebellar function as assessed by the blink reflex.