Relationships between speech intelligibility and the slope of second-formant transitions in dysarthric subjects

Abstract

The relationship between speech intelligibility on a single-word identification test and the average second-formant (F2) slope of selected test words was examined for a group of 25 men and ten women with amyotrophic lateral sclerosis (ALS). A Spearman rank-order correlation coefficient greater than 0.80 was obtained for both the male and female subjects. This moderately high correlation indicates that the F2 slope index is a useful acoustic measure of speech proficiency in ALS. F2 slope indices are reported for normal control populations of geriatric men and women. In addition, progressive deterioration of the F2 slope index is illustrated in a case study of one woman with ALS.