Stability of speech intelligibility measures (Vitti et al., 2021)

Purpose: The purpose of this investigation was to measure the test–retest stability of single-word intelligibility in a group of 28 speakers with chronic apraxia of speech and aphasia.

Method: The Assessment of Intelligibility of Dysarthric Speech was administered twice to each participant, with samples separated by 1 week. Scoring of recorded samples was completed independently by three expert listeners using transcription and multiple-choice scoring formats.

Results: Percent intelligible words was very similar for the group over the two sampling times for both scoring formats (i.e., within 1.5%), with no statistically significant differences found between times. Statistically significant, very strong, positive correlations were found between sampling times for intelligibility scores. Transcription and multiple-choice scores were strongly, positively correlated, with multiple-choice scores being statistically higher. There was a statistically significant difference between mean transcription and multiple-choice scores for the group at Time 1 and Time 2. Individual performance was similar to group performance for the majority of participants.

Conclusions: These findings indicate that single-word intelligibility measures are stable over repeated sampling occasions. Stability was evident for transcription and multiple-choice scoring methods.

Supplemental Material S1. Scores for each participant for each rater.

Supplemental Material S2. Differences in raters’ intelligibility scores.

Vitti, E., Mauszycki, S., Bunker, L., & Wambaugh, J. (2021). Stability of speech intelligibility measures over repeated sampling times in speakers with acquired apraxia of speech. American Journal of Speech-Language Pathology. Advance online publication. https://doi.org/10.1044/2020_AJSLP-20-00135

Publisher Note: This article is part of the Special Issue: Select Papers From the 2020 Conference on Motor Speech.