Correlation of Orofacial Speeds with Voice Acoustic Measures in Persons Who Stutter
M McClean, S Tasko
Stuttering is often viewed as a problem in coordinating the movements of different speech muscle subsystems. From this perspective, it is logical that efforts be made to compare the strength of neural coupling between muscle subsystems in persons who stutter (PS) and those who do not (NS). This problem was addressed by correlating the speeds of orofacial structures with voice fundamental frequency (F0) and intensity across fluent repetitions of a nonsense phrase in 43 NS and 39 PS. It is assumed that resulting correlations indirectly reflect the strength of neural coupling between orofacial structures and the respiratory-laryngeal system. An electromagnetic system was used to record movements of the upper lip, lower lip, tongue, and jaw. Measures of vowel F0 and intensity were obtained from the acoustic signal. For each subject, correlation measures were obtained relating peak orofacial speeds of different structures to F0 and intensity. For lower lip and tongue speed, mean correlations with F0 and intensity were significantly reduced in PS compared to NS. Significant group effects were not observed for the upper lip or jaw. The implications of these results for understanding the mechanisms of speech disfluency will be considered.