Phonetic Variability in Flaccid Dysarthric Speech

The purpose of this study was to investigate the presence and nature of phonetic variability in the speech of persons with flaccid dysarthria. Seven adults with facial nerve paralysis and subsequent flaccid dysarthria produced one- and three-syllable words in isolation and embedded in sentences. Responses were perceptually analysed using narrow phonetic transcription supplemented by diacritics. Analysis of consistency of error location and variability of error type yielded a profile of flaccid dysarthria slightly different from the traditionally accepted view. Among the results was a relatively high incidence of inconsistency in error location, with significantly more errors of inconsistency in one-syllable words in isolation compared to one-syllable words embedded in sentences. Results are discussed with reference to a motor planning/programming adaptation to peripheral bio-mechanical limitations caused by the lower motor neuron lesion.