Rate Modulation Abilities in Acquired Motor Speech Disorders

Area of Science:

• Speech-Language Pathology
• Neurolinguistics
• Motor Speech Disorders

Background:

• Motor speech disorders (MSDs) encompass a range of conditions affecting the motor planning, programming, and execution of speech.
• Understanding speech modulation capabilities is crucial for accurate diagnosis and treatment of MSDs.

Purpose of the Study:

• To compare speech rate modulation abilities in patients with different types of motor speech disorders.
• To investigate the impact of stimuli complexity on speech rate modulation.
• To assess the relationship between speech modulation and articulatory accuracy in MSDs.

Main Methods:

• Twenty-nine patients with apraxia of speech (AOS) or dysarthria, and nine controls, performed speech tasks at natural, fast, and slow rates.
• Speech rate was manipulated using varying complexity stimuli (words, sentences).
• Word durations, interword intervals, and articulatory accuracy were measured and analyzed using linear mixed-effects models.

Main Results:

• Patients with prosodic AOS exhibited reduced capacity to increase speech rate and increased articulatory errors.
• Spastic dysarthria patients showed some rate modulation capacity, particularly in sentence repetition.
• Apraxia of speech patients generally made more articulatory errors, which decreased with slower speech rates.

Conclusions:

• Speech rate modulation capacity and its effect on articulatory accuracy can help differentiate between healthy speech and various MSD subtypes.
• Further validation in larger, diverse cohorts is needed to confirm these findings.