An investigation into the influences of age, pathology, and cognition on speech production

Changes in speech rate have long been identified as a prominent sign of dysarthria. At the same time, such changes have been reported in the literature on normal ageing. This study aimed to provide information on the speech rate behaviour in the three participant groups, comprising speakers with Parkinson's Disease (PD), healthy age matched control speakers (CON), and an older non-dysarthric group with mild cognitive decline (DEM). The analysis revealed that the CON and PD group performed similarly for articulation rate whereas the DEM speakers spoke significantly more slowly. This relationship was reversed for pausing behaviour, where the DEM and CON groups performed similarly whilst the PD speakers produced a higher degree of pause time. All groups could change their articulation rate significantly from habitual to slow and fast conditions. However, the groups differed in the amount of change, with CON speakers showing the greatest and DEM the smallest amount of differences in articulation rate. The data did not identify clear performance predictors. However, there was a suggestion that the speakers' cognitive skills had an impact on their speech performance