By Kim Dillon, M.A., CCC-SLP · The Speech Source
Your child says "pup" when they mean "pop." "Bee" comes out as "bih," and "boat" sounds more like "but." If your child has childhood apraxia of speech (CAS) or another motor speech planning disorder, you may have heard errors like these, and they can be hard to put a finger on.
Most speech therapy talk focuses on consonants: the /k/ sounds, the /s/ sounds, the sounds a child leaves off the ends of words. But when the challenge is motor planning, the vowels matter just as much. Here's why vowel errors happen in CAS, what they sound like, and how SLPs work on them.
Why vowels matter in CAS and motor speech planning disorders
Childhood apraxia of speech is a motor planning disorder. A child knows what they want to say, but the brain has trouble planning and sequencing the movements of the lips, jaw and tongue to say it. CAS is the best-known motor speech planning disorder in children, and the same vowel challenges can show up in any child whose speech difficulty involves motor planning.
The American Speech-Language-Hearing Association (ASHA) names three features that experts agree are common in CAS. One of them is inconsistent errors on consonants and vowels when a child repeats the same syllables or words (ASHA, 2007). In other words, vowel errors aren't a side note in apraxia. They're one of the hallmarks.
Vowels also carry a lot of how well we understand a word. Change the vowel and you change the word: "pop" becomes "pup," "bead" becomes "bid." When vowels are off, even a child with good consonants can be hard to understand (Kent, 2020).
What vowel errors sound like
Every child is different, but parents and SLPs often notice patterns like these:
Vowels that drift toward "uh." Many vowels collapse into a relaxed, middle sound, so "pop," "pep" and "pup" all sound alike.
Mouth shapes that don't go far enough. The jaw doesn't drop enough for "ah," or the lips don't round enough for "oo."
Two-part vowels that lose a part. Vowels like the ones in "pie," "cow" and "boy" need two mouth shapes in a row (these are called diphthongs). A child may say only one, so "pie" sounds like "pa."
The same word said differently each time. "Boat" may be clear once and come out as "bot" or "but" the next time. This inconsistency is typical of apraxia.
A vowel can also sound right in a short word like "bee" and then fall apart in a longer one like "beehive." That's a clue that the challenge is motor planning, not just knowing the sound.
How SLPs treat vowels in apraxia and motor speech planning disorders
Because these are motor planning disorders, treatment is motor-based: it practices the movements of speech, not just the sounds. For CAS, the two approaches with the most research support are Dynamic Temporal and Tactile Cueing (DTTC) and Rapid Syllable Transition Treatment (ReST) (Morgan et al., 2018; McCabe et al., 2024). Here's how vowels fit into that kind of therapy.
Practice in real words, not just sounds. Strand (2020) recommends choosing distorted vowels as early targets and practicing them inside words. The goal is a movement plan for the whole word, not a vowel said by itself.
Build up the syllable shape. A vowel that's easy in "bee" (consonant-vowel, or CV) gets harder in "beet" (CVC) and harder again in "teepee" (CVCV). Therapy climbs that ladder one step at a time as the child's accuracy grows.
Fade the support. In DTTC, the SLP starts by saying the word together with the child, then has the child copy right after, then after a short pause, and finally say it on their own (Strand, 2020). Cues like slowing down, touch cues and showing the mouth shape are added or faded as needed.
Mix it up as skills improve. Motor learning research supports moving from practicing one target over and over (blocked practice) to mixing targets together (random practice) as accuracy improves (Maas et al., 2008). Mixed practice feels harder, but it helps the new movements stick.
Tips for practicing vowels at home
Ask your child's SLP which vowels and words to work on, then use these ideas to practice between sessions:
Name the mouth shapes. Simple words help: a smile for "ee," open for "ah," round for "oo." Point to your own mouth as you say them.
Use a mirror. Sit side by side so your child can see both your mouth and theirs.
Keep it short and frequent. Five minutes a day does more than one long session a week.
Practice the words, not just the sounds. Use the real words your SLP gives you, like bee, moon or pop, in play and daily routines.
Slow down. Say the word slowly and clearly, and let your child say it with you before trying it alone.
Celebrate effort. Motor planning practice is hard work. Praise trying, not just getting it right.
Home practice works best as a team effort with your child's SLP. They can choose the right targets and cues for your child and adjust as skills grow.
A ready-made path for vowel practice
We built the Motor Speech Vowel Kit to make this kind of vowel practice easy to plan and easy to print. It follows the path above: 14 vowels across 4 levels, from corner vowels to glides. Each vowel has a real child's-mouth photo cue, word lists that climb from CV to CVCV, photo flashcards, contrast pairs and a cueing data grid based on the DTTC steps.
It's designed for SLPs working with children who have CAS or other motor speech planning disorders, and parents are welcome to bring it to their child's therapy sessions.
See what's inside the Motor Speech Vowel Kit →
This article is for general information. It isn't a substitute for an evaluation or treatment by a licensed speech-language pathologist.
References
American Speech-Language-Hearing Association. (2007). Childhood apraxia of speech [Position statement]. https://doi.org/10.1044/policy.PS2007-00277
Kent, R. D. (2020). What acoustic studies tell us about vowels in developing and disordered speech. American Journal of Speech-Language Pathology, 29(3), 1749–1778. https://doi.org/10.1044/2020_AJSLP-19-00178
Maas, E., Robin, D. A., Austermann Hula, S. N., Freedman, S. E., Wulf, G., Ballard, K. J., & Schmidt, R. A. (2008). Principles of motor learning in treatment of motor speech disorders. American Journal of Speech-Language Pathology, 17(3), 277–298. https://doi.org/10.1044/1058-0360(2008/025)
McCabe, P., Murray, E., & Thomas, D. (2024). Evidence summary: Childhood apraxia of speech. The University of Sydney.
Morgan, A. T., Murray, E., & Liégeois, F. J. (2018). Interventions for childhood apraxia of speech. Cochrane Database of Systematic Reviews, 2018(5), CD006278. https://doi.org/10.1002/14651858.CD006278.pub3
Strand, E. A. (2020). Dynamic temporal and tactile cueing: A treatment strategy for childhood apraxia of speech. American Journal of Speech-Language Pathology, 29(1), 30–48. https://doi.org/10.1044/2019_AJSLP-19-0005