Stopping Prevocalic Sibilants

By Pam Marshalla

Q: I work with a first grade student with multiple articulation errors. He inserts /t/ after /s/ and /sh/ words. For example he says “stay” for “say” and “shtirt” for “shirt.” We’ve slowed the production down to the point of an actual pause between the /s/ and the proceeding vowel and he is 100% accurate. But how do we speed up the motor movement while keeping the production accurate?

I have found that the insertion of /t/ before or after /s/ and /sh/ is a developmental skill kids use to help them add a continuant sibilant to a syllable when their oral movement skills are immature. I would recommend that you try the following:

  • Switch to the postvocalic /ts/ cluster for a while. Use simple words like hats, boats, lights, and so forth. The word-final position cluster can be easier than the initial cluster, and its practice will allow the client to insert the /t/ for a while.
  • Switch to prevocalic /s/-clusters including /sp/, /st/, /sk/, /sm/, /sn/, /sl/ and /sw/. Find one that he can do well, and then branch out from there. /st/ may be his best, but you will not know until you try.
  • Instead of a pause, teach him to insert an /h/ in place of the /t/. E.g., practice “soap” as “s-hhh-oap.” This keeps his airflow going from the sibilant to the vowel.

The reason many children insert /t/ is because they cannot maintain continuous air stream during voice onset. E.g., the voice turns on when he moves from /s/ to /o/ in a word like “soap.” It seems to be easier for kids to initiating voice when airflow is stopped in the oral cavity.

In motor terms, we note that ADDUCTING simultaneously in two places is easier than ADDUCTING in one place while ABDUCTING in another. Movements develop from gross to fine, therefore, adducting simultaneously in two places is a more gross movement pattern. As such, it is more primitive to adduct the vocal folds (bring them together, initiate voicing) while adducting in the oral cavity (occluding). Initiating voice (adducting) while maintaining continuous airflow (abducting) is motorically a more advanced speech movement skill.

Over time your client will learn to refine this process. The insertion of /h/ allows him time to hear this voice onset. It allows him to learn how to adduct the vocal folds while abducting the oral cavity.

P.S. If you can follow this line of thinking, you are engaging in advanced oral-motor concepts and therapy. If you can’t follow it, don’t worry about it. Continue to think in terms of phonemes, and simply recognize that inserting /h/ can help many clients learn to sequence from /s/ to the adjacent vowel.

1 thought on “Stopping Prevocalic Sibilants”

  1. After an initial unvoiced consonant, a fellow SL P’s Grade 1 student adds /h/ before the following vowel once he tries to blend the unvoiced consonant with a vowel at the syllable or 1 syllable word level, ie: /khop/. He can produce the unvoiced consonant when it is separated from the following vowel, but adds the /h/ as soon as he attempts to blend the onset to the rime. He also adds a glottal stop before the vowel. He still omits most initial consonants in connected speech. He either has a severe phonological disorder or dyspraxia. How can we move to accurately blending unvoiced consonants with vowels without adding /h/.

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