Preparing an E-learning-based Speech Therapy (EST) efficacy study: Identifying suitable outcome measures to detect within-subject changes of speech intelligibility in dysarthric speakers

Abstract

We explored the suitability of perceptual and acoustic outcome measures to prepare E-learning based Speech Therapy (EST) efficacy tests regarding speech intelligibility in dysarthric speakers. Eight speakers with stroke (n = 3), Parkinson’s disease (n = 4) and traumatic brain injury (n = 1) participated in a 4 weeks EST trial. A repeated measures design was employed. Perceptual measures were (a) scale ratings for “ease of intelligibility” and “pleasantness” in continuous speech and (b) orthographic transcription scores of semantically unpredictable sentences. Acoustic measures were (c) “intensity during closure” (ΔIDC) in the occlusion phase of voiceless plosives, (d) changes in the vowel space of /a/, /e/ and /o/ and (e) the F0 variability in semantically unpredictable sentences. The only consistent finding concerned an increased (instead of the expected decreased) ΔIDC after EST, possibly caused by increased speech intensity without articulatory adjustments. The importance of suitable perceptual and acoustic measures for efficacy research is discussed.

• Clinical outcome research
• dysarthria
• outcome measures
• speech intelligibility
• web-based training

Acknowledgements

The authors wish to thank Joop Kerkhoff, Anke van Stiphout, Gerna Scholte and Sonja Peters for their assistance in performing the experiments and collecting the data in this study.

Notes

¹Available on demand.