How can clinicians differentiate AOS from a phonological disorder?

• A. AOS shows motor-based planning errors with groping and inconsistent articulations; phonological disorders involve errors in sound structure but preserved motor planning and sequencing.
• B. AOS shows only language comprehension deficits.
• C. Phonological disorders involve motor planning deficits only.
• D. AOS is characterized by no speech errors.

Answer: (A)

The main idea is to separate problems with planning and programming movements for speech from problems with knowledge of sound patterns. In apraxia of speech, the challenge is motor-based planning. People with AOS try to assemble the precise movements of the lips, tongue, and jaw needed for each sound and sequence, but this planning is faulty. You often see groping, trial-and-error articulations, and the same word produced in different ways on different attempts. Because the motor plan can vary from attempt to attempt, articulations are inconsistently realized, especially on longer or more complex sequences.

In a phonological disorder, the issue is linguistic rather than motor. The person’s knowledge of how sounds combine into words is affected, so errors reflect systematic phonological processes (like substituting one sound for another, deleting a final consonant, or simplifying a cluster). The motor system can typically execute the sounds correctly; the problem lies in how speech sounds are organized and applied across contexts. These errors tend to be more predictable and stable across attempts.

So, you differentiate them by looking at variability and signs of motor planning difficulty. AOS shows motor planning errors with groping and inconsistent articulations, while a phonological disorder shows errors in sound structure that align with phonological patterns and relatively preserved motor planning and sequencing.