Acoustic analysis of dysarthria associated with multiple sclerosis

Approximately 40% of all individuals with multiple sclerosis (MS) present some degree of speech impairment. MS speakers with dysarthria are a heterogeneous group and the speech disorder is characterized by disturbances of the temporal patterning of speech as well as articulatory and phonatory symptoms. Previous research also indicates that the neuromotor dysfunction manifests itself in the fundamental frequency of sustained phonation, even in the absence of other speech symptoms. The present study was designed with the specific purpose of exploring the temporal, spectral and phonatory acoustic features of five MS speakers as compared to those of two normal controls. It was found that the dysarthric symptoms of these MS speakers largely mirror their different underlying neuromotor dysfunctions, and that they exhibit temporal and articulatory deviation when compared to the normal speakers. It is also suggested that a Fourier spectrum analysis of the derived pitch of the sustained phonation in MS speakers is particularly valuable in characterizing an important but often subtle symptom of their illness. © 1995 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Long-term phonatory instability in individuals with multiple sclerosis

This paper uses a new approach to describe and quantify the long-term phonatory instability of speakers with MS. Sustained vowel phonations of 20 individuals with a definite diagnosis of multiple sclerosis (MS) and 20 age- and gender-matched individuals with normal speech were recorded. The phonations were f0 and intensity analyzed and subjected to spectral analysis using the Fast Fourier Transform. Three methods for analyzing the instabilities are presented, compared, and related to perceptual judgments: (a) coefficients of variation, (b) magnitude-based analysis of spectral energy, and (c) frequency-based analysis of spectral components. All measures reliably distinguished between individuals with MS and persons with normal speech. A single factor based on a linear discriminant analysis of the frequency-based measures was especially useful in distinguishing these groups. Critical frequency bands of instability, corresponding to wow (1-2 Hz), tremor (around 8 Hz), and flutter (17-18 Hz), distinguished the MS group from those of the control group