Auditory-Motor Control of Fundamental Frequency in Essential Vocal Tremor

Area of Science:

• Speech and Hearing Sciences
• Neuroscience
• Biomedical Engineering

Background:

• Essential vocal tremor (EVT) is a neurological disorder affecting voice production.
• Understanding vocal control mechanisms in EVT is crucial for developing effective interventions.
• Both feedforward and feedback control systems contribute to stable voice production.

Purpose of the Study:

• To assess feedforward voice control in EVT by measuring adaptive responses to gradual auditory pitch perturbation.
• To assess feedback voice control in EVT by measuring reflexive responses to sudden auditory pitch perturbation.

Main Methods:

• Ten participants with EVT and 10 controls produced sustained vowels with pitch-perturbed auditory feedback.
• Adaptive responses to gradual pitch changes and reflexive responses to sudden pitch changes were measured.
• Acoustical analyses quantified fundamental frequency (f₀) responses; comprehensive assessments aided interpretation.

Main Results:

• Both EVT participants and controls exhibited compensatory responses to pitch perturbations.
• No significant differences in the magnitude of adaptive or reflexive responses were found between groups.
• EVT participants showed significantly lower variability in adaptive responses compared to controls.

Conclusions:

• Speakers with EVT appear to have typical feedforward and feedback control of voice pitch.
• The reduced variability in adaptive responses in EVT warrants further investigation.
• The underlying reasons for altered adaptive response variability in EVT remain unclear.