Stimulability: Where to Start?

Blog #13 in the Phonology Means Nothing and Other Astounding and Very Practical Facts about Speech Sound Disorders Blog Series

For more information about this series, see the Phonology Means Nothing Series welcome page.

By Ken Bleile, PhD
February 12, 2021

Treatment sounds are the speech elements (vowels, consonants, consonant clusters, syllables, prosody, etc.) through which a clinician facilitates speech change. Another (more widely used) word for treatment sound is treatment target. I prefer treatment sound because target suggests a clinician is shooting something. In children from toddlers through high school, treatment sounds (or treatment targets, if you prefer) are a pivot on which treatment turns. Infant attention and focus abilities are such that developmental treatment goals seldom benefit from focus on a specific treatment sound. The same may be true for some toddlers and some older children with cognitive disabilities. 


A first question arising in selecting a treatment sound is, should you select one that a child demonstrates some capacity to produce or one that a child cannot produce under any circumstance? If you select one a child demonstrates some capacity to pronounce, you have selected a stimulable treatment sound. If you select one a child has no capacity to pronounce, you have selected a nonstimulable treatment sound. Since at least the last 50 years, researchers have argued the stimulable versus nonstimulable question, sometimes with near religious fervor. I do not think we will resolve the controversy here, but we can strive to achieve the lesser goal of giving the topic a little clarity.

The Logic of the Positions

The logic behind selecting a stimulable treatment sound is that children experience less frustration because they have some capacity to pronounce it. Another reason to select a stimulable sound is that because children can already pronounce it correctly, during treatment, they are practicing success. The logic behind selecting a nonstimulable sound is that children already are occasionally pronouncing a stimulable sound correctly and may not require treatment to complete its acquisition.

The reason the stimulable versus nonstimulable debate has continued so long is that research supports both positions. Studies indicate some children self-correct a stimulable sound without treatment, and others indicate some children do not self-correct (Diedrich, 1983; Powell, 1991; Powell, Elbert, & Dinnsen, 1991; Shine, 1989). Sometimes in the same study, some children self-correct and others do not.

Usually people groan when they hear the sentence: Research supports both positions. The groan is because we want research to answer questions, and we are disappointed when it doesn’t. However, in this case, I believe the research, if not giving us an answer, is pointing toward one. The direction it points toward is the need to understand why some children self-correct while others require professional assistance to achieve that goal. That is, children are diverse learners—why should we expect them all to generalize stimulable sounds in the same way?

Stimulable or Nonstimulable?

In the meantime, an element of trial and error exists in stimulability.

Selecting Stimulable Sounds

Relying on experience and intuition, most clinicians select a stimulable treatment sound with a younger child and those with less tolerance for failure. Because capacity to produce the treatment sound already exists, the clinician can more quickly generalize success to other words or phonetic environments, rather than focusing treatment on the possibly frustrating and time-consuming task of teaching a treatment sound that a person shows no capacity to produce in any circumstance.  

Selecting Nonstimulable Sounds

Selecting a stimulable sound may not be an option for an older student or an adult learning a second language. In such situations, per force a clinician selects a nonstimulable sound. With later preschoolers (approximately 3;6 to 5;0) with both stimulable and nonstimulable speech errors, a clinician often first treats a stimulable sound to build a child’s confidence and sense of success and later works on nonstimulable sounds on a trial basis.


Diedrich, W. (1983). Stimulability and articulation disorders. In J. Locke (Ed.), Seminars in Speech and Language, 4, 297-311.

Powell, T. (1991). Planning for phonological generalization: An approach to treatment target selection. American Journal of Speech-Language Pathology, 1, 21–27.

Powell, T., Elbert, M., & Dinnsen, D. (1991). Stimulability as a factor in phonological generalization of misarticulating preschool children. Journal of Speech and Hearing Research, 34, 1318–1328.

Shine, R. (1989). Articulatory production training: A sensory-motor approach. In N. Creag-head, P. Newman, & W. Secord (Eds.), Assessment and remediation of articulatory and phonological disorders (pp. 355–359). Columbus, OH: Charles E. Merrill.