Purpose: We investigated the specificity of auditory–motor impairment in people with hyperfunctional voice disorders (HVDs) and relationships with dysregulated perilaryngeal muscle activation during voicing by measuring muscle activity during adaptive vocal learning. Method: Fifty-two participants (26 HVDs, 26 controls) completed auditory discrimination and adaptive vocal learning tasks for the vocal parameters intensity and fundamental frequency ( f o ). Surface electromyographic measures were collected from suprahyoid and infrahyoid muscles. We examined the effects of HVD status and singing experience on discrimination and adaptation. The effects of HVD status, vocal parameter, and time on the co-contraction index (CCI), a measure of co-activation of agonist/antagonist muscles, were also investigated. Relationships among dependent variables were examined using a mediation model. Results: There were no significant effects of HVD status or singing on discrimination thresholds. People with HVDs adapted more to intensity perturbations than controls ( p = .050), and singers adapted significantly less than nonsingers ( p = .018). For f o adaptation, significantly more participants with HVDs produced large following responses than controls ( p = .017). There were no significant effects of time, vocal parameter, or HVD status on CCI. However, significant moderate relationships were found between discrimination threshold, CCI, and adaptation responses for f o . Participants with better discrimination compensated less or followed the perturbation and co-contracted more. Participants who co-contracted more also compensated less or followed the perturbation. No significant relationships were found for vocal intensity. Conclusions: People with HVDs demonstrated different impairments in auditory feedback integration for f o versus intensity. This dissociation suggests an independence of the underlying control mechanisms. Preliminary evidence suggests a laryngeal stabilization response may occur when a speaker perceives a feedback mismatch to be externally generated. Supplemental Material: https://doi.org/10.23641/asha.32114905
Kapsner-Smith et al. (Thu,) studied this question.