In AOS, which error types are more characteristic than phoneme insertions?

• A. Substitutions and distortions are more characteristic of AOS than phoneme insertions
• B. Phoneme insertions are more characteristic than substitutions
• C. Tremor and dysarthric-type weakness define AOS
• D. Rate and rhythm errors are unrelated

Answer: (D)

In apraxia of speech, the kinds of errors you see most often are substitutions and distortions of phonemes, rather than adding extra phonemes. This happens because the speech planning and programming processes struggle to select and sequence the correct articulatory plans, leading to phoneme substitutions (you hear one sound replace another) and distortions (sounds that are misproduced or imprecise). Occasional phoneme insertions can occur, but they are not the hallmark pattern of AOS.

Tremor and weakness are features more typical of dysarthria, a different motor speech disorder, so they don’t define AOS. Rate and rhythm abnormalities, reflecting timing and prosodic planning difficulties, can appear in AOS as well, so saying rate/rhythm errors are unrelated wouldn’t be accurate.