Sentence/vowel correlation in the evaluation of dysphonia

Considering the widespread use of the sustained vowel in the evaluation of voice disorders, our objective was to study the degree to which the vowel is representative of voice in continuous speech. Phonatory samples were recorded from 20 normal subjects and 60 patients representing commonly occurring voice problems (nodules, unilateral paralysis, and functional). The phonatory samples were evaluated by 25 listeners on the basis of 12 bipolar, semantic differential scales. Factor analysis produced two perceptual dimensions with similar loadings for both vowels and sentences. A correlation of 0.78 was obtained between vowels and sentences on factor 1 scores, "vocal severity," and a correlation of 0.77 was obtained between vowels and sentences on factor 2 scores, "pitch/quality." Six of the 80 pairs of sentences and vowels differed by two scale points or more on vocal severity. Results suggest that although a relatively strong relationship exists between the two measures, sustained vowel sounds may not be an adequate clinical index to the dysphonic severity of continuous speech.