A closer look at transcription intelligibility for speakers with dysarthria: evaluation of scoring paradigms and linguistic errors made by listeners.

PURPOSE: This study addressed the effects of 3 different paradigms for scoring orthographic transcriptions of dysarthric speech on intelligibility scores. The study also examined whether there were differences in transcription accuracy among words from different linguistic classes.
METHOD: Speech samples were collected from 12 speakers with dysarthria of varying severity. Twelve different listeners made orthographic transcriptions of each speaker, for a total of 144 listeners. Transcriptions were scored using 3 different paradigms: total word phonemic match, informational word phonemic match, and informational word semantic match. Transcriptions were also coded into 3 linguistic categories: content words, modifiers, and functors. The number of words that each listener transcribed correctly within each category was tallied.
RESULTS: There were significant differences among the 3 scoring paradigms. However, the magnitude of differences was relatively small. In addition, listeners transcribed functor words more accurately than content words or modifiers. They also transcribed free morphemes more accurately than bound morphemes.
CONCLUSIONS: The specific scoring paradigm that clinicians employ for measuring speech intelligibility appears to be relatively inconsequential as long as consistent procedures are used. Analyses of the kinds of words that listeners transcribe correctly suggest that interventions focusing on listener processing strategies should be considered for enhancing intelligibility of speakers with chronic dysarthria.