Purpose-This study examined the relationship between listener comprehension and intelligibility scores for speakers with mild, moderate, severe, and profound dysarthria. Relationships were examined across all speakers and their listeners when severity effects were statistically controlled, within severity groups, and within individual speakers with dysarthria.Method-Speech samples were collected from 12 speakers with dysarthria secondary to cerebral palsy. For each speaker, 12 different listeners completed two tasks (for a total of 144 listeners), one task involved making orthographic transcriptions and one task involved answering comprehension questions. Transcriptions were scored for the number of words transcribed correctly; comprehension questions were scored on a 3-point scale according to their accuracy.Results-Across all speakers, the correlation between comprehension and intelligibility scores was non-significant when the effects of severity were factored out and residual scores were examined. Within severity groups, the relationship was significant only for the mild group. Within individual speaker groups, the relationship was non-significant for all but two speakers with dysarthria.Conclusions-Findings suggest that transcription intelligibility scores do not accurately reflect listener comprehension scores. Measures of both intelligibility and listener comprehension may provide a more complete description of the information-bearing capability of dysarthric speech than either measure alone. Keywords speech intelligibility; speech perception; dysarthria; cerebral palsy; comprehensibilityThe characterization of dysarthric speech is a topic of both clinical and theoretical importance. Although the dysarthrias are a heterogeneous group of speech disorders, one common characteristic is reduced intelligibility (Duffy, 2005; Yorkston, Beukelman, Strand, & Bell, 1999). Reduced intelligibility can have a critical impact on communication abilities, and may limit vocational, educational, and social participation. As a result, quality of life may be greatly diminished.Intelligibility refers to how well a speaker's acoustic signal can be accurately recovered by a listener. Although this definition seems simple, there are many speaker-related and listenerrelated variables that can impact how well a speech signal is deciphered. For example, research has shown that message predictability (Garcia & Cannito, 1996), message length Portions of these data were presented at the American Speech Language and Hearing Association Annual Convention, Chicago, IL (November, 2003).
NIH Public AccessAuthor Manuscript J Speech Lang Hear Res. Author manuscript; available in PMC 2011 January 5.
NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript (Yorkston & Beukelman, 1981), contextual cues (Hunter, Pring & Martin, 1991), visualfacial information (Hustad & Cahill, 2003), and listener experience (Tjaden & Liss, 1995) each have the potential to affect intelligibility in significant ways. Thus, intelligibili...