What is a distinguishing feature of 'dyskinetic' speech sound disorders?

A distinguishing feature of dyskinetic speech sound disorders is the presence of involuntary movements that affect speech production. Individuals with dyskinetic speech often struggle with control over their vocal tract and articulators, leading to irregular rhythms, unpredictable fluctuations in speech, and difficulties in coordinating the complex movements required for clear articulation. This disorder is typically associated with a neurological condition that impacts motor control, resulting in speech that may be slurred, jerky, or unintelligible due to inconsistent muscle contractions.

In contrast to the other options, the presence of consistent sound production is not characteristic of dyskinetic disorders; rather, dyskinetic speech is marked by variability and lack of control. Clear and rapid speech production would suggest good motor control, which is not the case in dyskinetic conditions, as speech is often disrupted. Lastly, a difficulty with speech rate only would imply a more specific issue that doesn't encompass the broader range of involuntary movement and control disturbances seen in dyskinetic disorders. Thus, the involuntary movements that directly interfere with speech are what distinctly define dyskinetic speech sound disorders.