Voicing Duration and Vocal SPL Changes Associated with Stuttering Reduction During Singing

This study was conducted to determine if stuttering reduction during singing is associated with increased voicing duration and increased vocal SPL. Eight moderate to severe stutterers comprised the experimental group. Eight normal speakers, matched pairwise with the stutterers for sex and age, served as controls. Pre-experimental testing indicated that all subjects knew from memory the melody of the well-known song "Home on the Range." Subsequently, subjects were asked to read aloud and sing altered lyrics of this song to the conventional melody. Results showed that from reading to singing, disfluency frequency decreased significantly among the stutterers. Both groups of subjects significantly increased voicing durations across the two conditions, but only the normal speakers increased vocal SPL during song. These results indicated that the reduction in stutterers' disfluency (stutterings included) during singing was attended by an altered pattern of vocalization that included an increase in voicing duration, but no significant change in vocal SPL. These findings are discussed with reference to vocal tract dynamics, especially those that might promote higher levels of fluency among stutterers.