The influence of severity of speech involvement on acoustic measures in dysarthria

Abstract

Several different acoustic measures have described the articulatory deficit and predicted the overall speech intelligibility deficit in speakers with dysarthria. The articulatory basis of acoustic variables that predict speech intelligibility variations across speakers have been thought to be the ones that should be manipulated clinically for maximum therapeutic effect. For example, F2 extent and slope are known to have strong correlations with speech intelligibility measures, across dysarthric speakers. This may suggest that within-speaker manipulation of magnitude and/or speed of articulatory movements will, if successful, result in improved speech intelligibility. Some of our previous work [Weismer et al., 2001, Folia Phoniat. Logopaed.] indicates, however, that these measures may not be predictive of within-speaker fluctuations in intelligibility, but rather are indices only of across-speaker variation in severity. The large data base of dysarthric speakers at UW-Madison permits us to begin to determine how much variability exists for measures like F2 slope in a relatively large group of speakers with homogeneous speech severity. This paper will report results of F2 extent and slope measures for speakers with relatively mild speech involvement. If the measures are primarily tied to severity, they should not vary much within a homogeneous group of speakers. [Work supported by DC00319.]