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

Abstract

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.

Figure 1.

An adaptive shift-up perturbation was applied to the f_o of auditory feedback (black dotted line), with a maximum perturbation of 100 cents. The 95% confidence intervals of the adaptive responses in the speakers with typical voices (n = 9; in blue) are negative, compensating for the direction of the perturbation. Individual adaptive responses of nine speakers with hyperfunctional voice disorders (in orange for individuals with accompanying vocal fold lesions and in magenta for those without) are more variable, with many speakers showing a distinct following response (positive changes, in the direction of the perturbation). Adaptive responses are plotted as the mean across five-trial blocks.

Figure 2.

Average adaptive responses of each group as a function of experimental phase. Error bars: 95% confidence intervals. Speakers with hyperfunctional voice disorders had significantly higher adaptive responses (p _adj ≤ .001) than speakers with typical voices.