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 2 tasks (for a total of 144 listeners): One task involved making orthographic transcriptions, and 1 task involved answering comprehension questions. Transcriptions were scored for the number of words transcribed correctly. Responses to comprehension questions were scored on a 3-point scale according to their accuracy.Results: Across all speakers, the Pearson product–moment correlation between comprehension and intelligibility scores was nonsignificant when the effects of severity were factored out and residual scores were examined. Within severity groups, the same relationship was significant only for the mild group. Within individual speaker groups, the relationship was nonsignificant for all but 2 speakers with dysarthria. Percentage of correct scores for listener comprehension was descriptively higher than percentage of correct intelligibility scores for all groups.Conclusion: 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.

Purpose: In this study, the authors proposed and tested a preliminary speech and language classification system for children with cerebral palsy.Method: Speech and language assessment data were collected in a laboratory setting from 34 children with cerebral palsy (CP; 18 male, 16 female) with a mean age of 54 months (SD= 1.8). Measures of interest were vowel area, speech rate, language comprehension scores, and speech intelligibility ratings.Results: Canonical discriminant function analysis showed that 3 functions accounted for 100% of the variance among profile groups, with speech variables accounting for 93% of the variance. Classification agreement varied from 74% to 97% based on 4 different classification paradigms.Conclusions: The results of this study provide preliminary support for the classification of speech and language abilities of children with CP into 4 initial profile groups. Further research is necessary to validate the full classification system.

Purpose: Speech acoustic characteristics of children with cerebral palsy (CP) were examined with a multiple speech subsystems approach; speech intelligibility was evaluated using a prediction model in which acoustic measures were selected to represent three speech subsystems. Method: Nine acoustic variables reflecting different subsystems, and speech intelligibility, were measured in 22 children with CP. These children included 13 with a clinical diagnosis of dysarthria (speech motor impairment [SMI] group) and 9 judged to be free of dysarthria (no SMI [NSMI] group). Data from children with CP were compared to data from age-matched typically developing children. Results: Multiple acoustic variables reflecting the articulatory subsystem were different in the SMI group, compared to the NSMI and typically developing groups. A significant speech intelligibility prediction model was obtained with all variables entered into the model (adjusted R ² = .801). The articulatory subsystem showed the most substantial independent contribution (58%) to speech intelligibility. Incremental R ² analyses revealed that any single variable explained less than 9% of speech intelligibility variability. Conclusions: Children in the SMI group had articulatory subsystem problems as indexed by acoustic measures. As in the adult literature, the articulatory subsystem makes the primary contribution to speech intelligibility variance in dysarthria, with minimal or no contribution from other systems.

Clinical measures of speech intelligibility are widely used as one means of characterizing the speech of individuals with dysarthria. Many variables associated with both the speaker and the listener contribute to what is actually measured as intelligibility. The present study explored the effects of presentation modality (audiovisual vs. audio-only information) and the effects of speaker-specific familiarization across 4 trials on the intelligibility of speakers with mild and severe dysarthria associated with cerebral palsy. Results revealed that audiovisual information did not enhance intelligibility relative to audio-only information for 4 of the 5 speakers studied. The one speaker whose intelligibility increased when audiovisual information was presented had the most severe dysarthria and concomitant motor impairments. Results for speaker-specific repeated familiarization were relatively homogeneous across speakers, demonstrating significant intelligibility score improvements across 4 trials and, in particular, a significant improvement in intelligibility between the 1st and 4th trials.

Purpose: The authors examined speech intelligibility in typically developing (TD) children and 3 groups of children with cerebral palsy (CP) who were classified into speech/language profile groups following Hustad, Gorton, and Lee (2010). Questions addressed differences in transcription intelligibility scores among groups, the effects of utterance length on intelligibility, the relationship between ordinal ratings of intelligibility and orthographic transcription intelligibility scores, and the difference between parent and naïve listener ordinal ratings. Method: Speech samples varying in length from 1 to 7 words were elicited from 23 children with CP ( M _age = 54.3 months) and 20 TD children ( M _age = 55.1 months). Two hundred fifteen naïve listeners made orthographic transcriptions and ordinal ratings of intelligibility. Parent ordinal ratings of intelligibility were obtained from a previous study (Hustad et al., 2010). Results: Intelligibility varied with speech/language profile group and utterance length, with different patterns observed by profile group. Ratings of intelligibility by parents and naïve listeners did not differ, and both were highly correlated with transcription intelligibility scores. Conclusion: Intelligibility was reduced for all groups of children with CP relative to TD children, suggesting the importance of speech-language intervention and the need for research investigating variables associated with changes in intelligibility in children.

Many speakers with dysarthria have reduced intelligibility[,] and improving intelligibility is often a primary intervention objective. Consequently, measurement of intelligibility provides important information that is useful for clinical decision-making. The present study compared two different measures of intelligibility obtained in audio-only and audio-visual modalities for 4 different speakers with dysarthria (2 with mild-moderate dysarthria; 2 with severe dysarthria) secondary to cerebral palsy. A total of 80 college-aged listeners provided word-by-word transcriptions and made percent estimates of intelligibility which served as dependent variables. Group results showed that transcription measures were higher than percent estimates of intelligibility overall. There was also an interaction between speakers and measures of intelligibility, indicating that the difference between transcription scores and percent estimates varied among individual speakers. Results revealed a significant main effect for presentation modality, with the audio-visual modality having slightly higher scores than the audio-only modality; however, presentation modality did not interact with speakers or with measures of intelligibility. Results suggest that standard clinical measurement of intelligibility using orthographic transcription may be more consistent than the use of more subjective percent estimates.