Visual Analog Scale Ratings and Orthographic Transcription Measures of Sentence Intelligibility in Parkinson's Disease With Variable Listener Exposure

Abstract

Purpose While orthographic transcription (OT) is the gold standard for measures of intelligibility, it is relatively inaccessible to clinicians. This study investigates the relationship between visual analog scale (VAS) ratings and OT measures of intelligibility for speakers with Parkinson's disease (PD), with the eventual goal of developing more clinically feasible assessments of intelligibility. Method Twenty speakers with PD and 5 controls read 11 sentences. First, 33 listeners completed an OT task using 1 sentence from each speaker. An additional 33 listeners rated the intelligibility of 1 sentence from each speaker using a VAS, reflecting a minimized exposure VAS (MEV) task. Lastly, 14 additional listeners each rated the intelligibility of all 11 sentences produced by all speakers using a VAS, reflecting an extended exposure VAS (EEV) task. Smaller listener groups were simulated from each VAS task for comparison to scores from the OT task. Results There was a strong relationship between OT and both MEV and EEV. This relationship remained strong ( R 2 ≥ .82) even when only 1 listener in MEV and 2 listeners in EEV were simulated per sentence. Conclusions VAS ratings may be a suitable alternative to OT measures of sentence intelligibility for PD using listeners with both minimal and extended exposure to the stimuli.

Intelligibility in Down syndrome: Effect of measurement method and listener experience

“…In relation to the method used to measure speech intelligibility, the findings of this study are in agreement with several previous studies (Abur et al 2019, Stipancic et al 2016, Yorkston and Beukelman 1978. Differences in the intelligibility scores measured by the two methods may be related to the fact that measurement involving orthographic transcription provides a score reflecting only the number of spoken words recognised by the listener, whereas a rating task may also be sensitive to additional subjective listener judgements of speech features (Tjaden et al 2014a).…”

“…The intelligibility scores in the current study were found to be highly correlated across both orthographic transcription and VAS tasks. These findings agree with those of Abur et al (2019) and Stipancic et al (2016). The strong positive correlation across tasks indicates that while scores differed, the general pattern of scores was similar.…”

“…It also examines the relationship across the speech intelligibility scores by comparing the correlation between the two listener groups in the orthographic transcription and VAS tasks; and the correlation between the two tasks within the experienced listeners and within the naïve listeners. As previous studies (Abur et al 2019, Stipancic et al 2016 have reported a significant correlation between speech intelligibility scores obtained from orthographic transcription and VAS despite the significant difference in the intelligibility scores, this study also examined this aspect in speakers with DS. VAS and orthographic transcription were chosen as the methods of measurement for comparison.…”

“…The previous studies reviewed so far show that the way in which speech intelligibility is measured can influence assessment outcomes and this should be considered when interpreting and comparing findings. In particular, speech intelligibility scores tend to be lower when scaling methods, such as VAS, are used compared with orthographic transcription (Stipancic et al 2016, Abur et al 2019, Tjaden et al, 2014a.…”

“…A more recent study by Abur et al . (2019) used a group of naïve listeners to directly compare the speech intelligibility scores measured using orthographic transcription and VAS for a group of speakers with PD and typical speakers. The results also showed that the scores from orthographic transcription were higher than the scores obtained from VAS.…”