Changes Over Time in Dysarthric Patients with Amyotrophic Lateral Sclerosis (ALS): I. A Study of Changes in Articulatory Function

Abstract

Changes in articulatory function over time, from a point when speech intelligibility is still at a high level until oral communication becomes almost impossible, were studied perceptually and acoustically in two dysarthric patients with amyotrophic lateral sclerosis (ALS). The following results were obtained. 1) In analysis according to manner of articulation, accuracy scores for nasals maintained a high level and a trend towards global nasalization of articulation was observed. 2) For vowels, accuracy scores tended to be high for /a/ and low for /i/. 3) In accuracy scores for consonants according to phonemes also, a certain degree of communality between the two patients was observed; also, phonemes which decreased in accuracy scores from the mild period tended to become more difficult to produce as the disease progressed. 4) Acoustic analysis revealed a reduction in the transition rate of both the first and second formants accompanying a decrease in speech intelligibility for all speech samples. It also showed a strong correlation with speech intelligibility. These results suggest that this acoustic parameter is a sensitive index which objectively and quantitatively reflects changes in articulatory function. © 1998, The Japan Society of Logopedics and Phoniatrics. All rights reserved.