Quantifying perturbations in temporal dynamics for automated assessment of spastic dysarthric speech intelligibility

Spastic dysarthric speech is often associated with imprecise placement of articulators which, in turn, cause perturbations in speech temporal dynamics, such as unclear distinctions between adjacent phonemes. While these perturbations can lead to a significant reduction in intelligibility, measures to objectively assess their detrimental effect on intelligibility are lacking. In this paper, short- and long-term temporal dynamics measures are proposed and evaluated as correlates of subjective intelligibility. The former is based on log-energy temporal dynamics information, whereas the latter is based on an auditory-inspired modulation spectral signal representation. A composite measure is also developed based on linearly combining the proposed measures with a tone-unit duration parameter. Experiments with the publicly-available 'Universal Access' database of spastic dysarthric speech show that the proposed composite measure can achieve rank correlations with subjective ratings as high as 0.87, thus providing a tool to automatically diagnose speech disorder severity and to evaluate dysarthria treatment outcomes.