Let's take the final /b/ sound as a example. An SLP has two apraxic children both of whom are struggling with the final /b/ sound. That SLP also has a set of cards that focuses on the final /b/ sound. For Child A, using that card deck would be very appropriate, and for Child B it would not be her best choice. Why?
Child A: Child A is 2 1/2 years old. She isn't really talking at all and has only two "words" in her vocabulary /ma/ for "more" and /da/ for "that" which she uses for everything else. She struggles to even imitate sounds. Through informal assessment, the SLP has determined that /b/ is one of the only sounds that Child A is stimulable for. Child A has an easier time imitating /b/ in final position than in initial position. This would be a perfect time to work on the final /b/ sound and using a final /b/ card deck would be one way to work on it.
Child B: Child B is also 2 1/2 years old. Child B is doing a lot of talking, but it is difficult to understand anything she says because of the high numbers of speech errors. Child B can make most of the early emerging consonant sounds (/p, b, t, d, m, n, h/) and a few of the sounds that tend to emerge next (/s, sh, w/). One of the speech errors that is having the biggest impact on this child's speech is her tendency to leave final consonants off of words. With this child the final /b/ is not going to the the therapist's top priority. She would probably focus on final consonant production using voiceless, early emerging consonants because those specific sounds are the least complex in terms of motor processing. Final /b/ would not be included because it is a voiced sound.
Summary An SLP working with a child who has a severe speech disorder has more potential targets than there is time to work on. The SLP will use her expertise, professional judgement, and assessment of the child's current skill level and needs to determine which targets are most important at any given time.
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