Patterns of perceptual features in speakers with ALS: A preliminary study of prominence and intelligibility considerations

This study examined the pattern of prominent perceptual features in dysarthria for a group of speakers with amyotrophic lateral sclerosis (ALS), described changes in these features over time, and began to identify the perceptual features that may contribute to reduced speech intelligibility. Three women and three men with ALS were recorded as they read a series of sentences on two occasions at least 2 months apart. During Phase 1, samples were perceptually rated for the prominence of seven broad features of speech, including differences in vowels, voicing feature, nasality, pressure consonants, breath groups, vocal quality, and intonational envelope. Results indicated that the pattern of perceptual features tended to be consistent for five of the six speakers over time. However, each speaker exhibited a different pattern of prominent features. During Phase 2, researchers (authors) rated features to identify which feature(s) may have contributed to the reduced speech intelligibility in each speaker. Some prominent features such as nasality, were judged to contribute minimally to reduced intelligibility, whereas other less prominent features, such as voicing, were judged to contribute extensively to changes in intelligibility. Use of perceptual features as a measure of progression of dysarthria in ALS are discussed.