Rhythmic Disturbance in Ataxic Dysarthria: A Comparison of Different Measures and Speech Tasks‪.‬

A number of rhythm measures have been developed for different speaker groups and speech materials. Not all of these different measures have been applied to speech samples from speakers with ataxic dysarthria, a speech disorder in which a disturbance of rhythm is one of the main characteristics. In this study, a variety of speech samples from six speakers with ataxic dysarthria and from six age and gender matched control speakers were analyzed with four different rhythm measures: the Pairwise Variability Index (PVI), the Proportion of Vocalic Intervals (%V), the Scanning Index (SI), and the Interstress Interval measure (ISI). Perceptual ratings of degree of rhythmic disturbance were also performed. Results varied between different measures and speech tasks, but the PVI and ISI measures seem to be the measures most suitable to characterize rhythmic changes in ataxic dysarthria. These two measures yielded significant differences between the speakers with ataxic dysarthria and the control group, and they also correlated better with the perceptual evaluation of rhythm compared to other measures. Results also indicate that both highly structured as well as spontaneous speech samples were suitable tasks to highlight rhythmic disturbances. **********