Validation of Articulatory Rate and Imprecision Judgments in Speech of Individuals With Amyotrophic Lateral Sclerosis

Abstract

Purpose Perceptual judgments of articulatory function are commonly used by speech-language pathologists to evaluate articulatory performance in individuals with amyotrophic lateral sclerosis (ALS). The goal of this study was to evaluate the psychometric properties (e.g., reliability, validity) of these perceptual measures to inform their application as part of a comprehensive bulbar assessment tool in ALS. Method Preexisting data from 51 individuals with ALS were obtained from a larger longitudinal study. Five independent raters provided perceptual judgments of articulatory rate and imprecision in a sentence task. Inter- and intrarater reliability of these judgments were assessed. Perceptual ratings were correlated with an acoustic measure of articulatory rate, in syllables per second, obtained from passage-reading recordings. Both perceptual and acoustic measures were correlated with gold-standard kinematic tongue and jaw movement measures, recorded from sentences using electromagnetic articulography. Results The results revealed good inter- and intrarater reliability of perceptual judgments of articulatory function. Strong correlations were observed between perceptual ratings of articulatory rate and imprecision and acoustic measures of articulatory rate and kinematic measures of tongue speed. Conclusions These findings support the clinical application of perceptual judgments of articulatory function as valid and reliable measures of underlying articulatory changes in bulbar ALS. Additional research is needed to understand the responsiveness of these measures to clinical changes in articulatory function in ALS.