Evidence for Auditory-Motor Impairment in Individuals With Hyperfunctional Voice Disorders.

Purpose The vocal auditory-motor control of individuals with hyperfunctional voice disorders was examined using a sensorimotor adaptation paradigm. Method Nine individuals with hyperfunctional voice disorders and 9 individuals with typical voices produced sustained vowels over 160 trials in 2 separate conditions: (a) while experiencing gradual upward perturbations in the fundamental frequency (fo) of their auditory feedback (shift-up) and (b) under no auditory perturbation (control). The shift-up condition consisted of 4 ordered (fixed) phases: baseline (no perturbation), ramp (gradual increases in heard fo), hold (a consistently higher heard fo), and after-effect (no perturbation). Adaptive responses were defined as the difference in produced fo during control and shift-up conditions. Results Adaptive responses were significantly different between groups. Individuals with typical voices generally showed compensatory adaptive responses, with decreased fo during the ramp and hold phases. Conversely, many individuals with hyperfunctional voice disorders instead displayed the opposite effect by following the direction of the perturbation. When fo was experimentally increased, speakers further increased their fo. Conclusion Results indicate that some individuals diagnosed with hyperfunctional voice disorders have disrupted auditory-motor control, suggesting atypical neurological function. These findings may eventually allow for the development of new interventions for hyperfunctional voice disorders.