Physiological differences between stutterers and nonstutterers in perceptually fluent speech: EMG amplitude and...

Area of Science:

• Speech motor control
• Neuroscience of speech disorders
• Biomedical engineering

Background:

• Stuttering is a complex speech disorder affecting motor control.
• Previous research on electromyography (EMG) in stutterers has yielded mixed results.
• Understanding muscle activity during speech is crucial for developing effective interventions.

Purpose of the Study:

• To investigate electromyograph (EMG) signals of the orbicularis oris inferior muscle in stutterers during perceptually fluent speech.
• To compare EMG levels and durations between stutterers and non-stutterers.
• To identify the most effective EMG measure for differentiating between stutterers and non-stutterers.

Main Methods:

• Analysis of EMG signals from the m. orbicularis oris inferior during lip-rounding gestures for the Dutch /o/ sound.
• Inclusion of a relatively large group of stutterers (n=15) and age/gender-matched controls (n=20).
• Inclusion of a reaction time experiment with varying verbal item lengths and time-stress conditions, analyzing only perceptually fluent trials.

Main Results:

• Stutterers demonstrated significantly higher EMG levels at speech onset and during speech production compared to non-stutterers.
• A substantial difference was observed in EMG peak latency, a powerful feature for distinguishing stutterers.
• EMG peak latency proved to be a more effective differentiator than EMG levels or durations.

Conclusions:

• Stutterers exhibit distinct patterns of lip muscle activity even during fluent speech.
• EMG peak latency is a highly sensitive measure for identifying stutterers.
• Findings contribute to understanding speech motor control strategies in stuttering and may inform therapeutic approaches.