Feedback delays eliminate auditory-motor learning in speech production

Area of Science:

• Neuroscience
• Motor Control
• Speech Science

Background:

• Neurologically healthy individuals adapt movements using sensory feedback to update internal models.
• Sensorimotor adaptation adjusts movement planning when sensory feedback (visual, auditory) is perturbed.
• Limb motor learning is robust to sensory feedback delays, attributing delayed input to external factors.

Purpose of the Study:

• To investigate the effect of auditory feedback delays on speech motor learning.
• To compare speech motor adaptation with limb motor adaptation under delayed sensory feedback conditions.
• To determine the critical timing of auditory feedback for speech articulation control.

Main Methods:

• Participants performed speech tasks with formant-shifted auditory feedback.
• Auditory feedback was experimentally delayed by varying durations (e.g., 100ms, 5000ms).
• The degree of auditory-motor adaptation was measured under different delay conditions.

Main Results:

• Auditory-motor adaptation for speech articulation was completely eliminated with feedback delays of 100ms or more.
• Limb motor adaptation showed only moderate effects with similar delays, remaining largely intact.
• Speech motor learning critically depends on real-time auditory feedback, unlike limb motor learning.

Conclusions:

• Real-time auditory feedback is essential for speech motor learning and adaptation.
• Delayed auditory feedback disrupts the sensorimotor control of speech articulation.
• Findings have implications for understanding human motor control and treating speech disorders.