Complexity Approach

Target later developing clusters to improve overall speech intelligibility more efficiently.

Who It's For:

3-6 year old children with phonological disorders. It is important to consider the child’s temperament and persistence during difficult tasks. This approach can be difficult and may become frustrating at times, therefore this approach may not be a good fit for all children.

How It's Practiced:

Focus on later-developing sounds and clusters to create “system wide” change. It can improve intelligibility faster. Children will acquire earlier developing sounds as well as later developing sounds. There are two phases of production training: imitation and spontaneous.

Treatment Steps:

1. Phonological Analysis Baseline

Use a single-word measure to assess productions of all single phonemes and clusters.

2. Imitation phase of treatment

The child imitates the clinician model for 7 sessions or until the child produces targets with 75% accuracy for 2 consecutive sessions. You will provide lots of cueing and feedback as needed. Focus on word level productions at this time.

3. Monitor for Generalization

Check single phonemes and clusters using single-word measures.

4. Spontaneous phases of treatment

The child will produce targets spontaneously with 90% accuracy across 3 consecutive sessions or total of 12 sessions. You can include activities beyond word level in naturalistic play.

5. Monitor for Generalization

Check singletons and onset clusters immediately following treatment, at 2 weeks, and at 2 months using single-word measures.

Treatment targets:

3-element clusters: /str/, /spr/, /skr/, /skw/, /spl/

The child must have the second and third phonemes in their phonemic inventory (it must occur twice on a probe or assessment). Consider these targets for children without /s/, affricates, fricatives, or 2-element clusters as it will help to make most wide-spread change. If the child doesn’t have the second or third phoneme, look at 2-element clusters (focus on clusters with sonority differences of 3 and 4 if possible).

2-element clusters

These clusters are organized by their sonority differences. The more open the vocal tract is the more sonority that the phoneme has. It’s best to avoid adjunct clusters if possible.

-2 /sp/, /st/, /sk/ (adjunct cluster, not as effective as other targets to encourage wide-spread generalization)

+2 /sm/, /sn/, /mj/ (/sm/, /sn/ are adjuct clusters as well)

+3 /fr/, /fl/, /sl/, /thr/, /shr/, /vj/

+4 /bl/, /gl/, /br/, /dr/, /gr/, /sw/, /fj/

+5 /pl/, /kl/, /pr/, /tr/, /kr/, /bj/

+6 /tw/, /kw/, /pj/, /kj/

Note: The numbers listed on the left are related to sonority differences, the more open the vocal tract is the more sonority that the phoneme has.

When gathering baseline data, you will likely need more than what a standardized assessment. Be sure to probe clusters, you can find free probes in the resources section below.

Download the complexity approach handout here


Duration: Varies; 2 times per week for 30 minutes.


Graham, A. (2022). Demystifying the Complexity Approach: Making Theory Practical[PowerPoint Slides]. Bright Ideas Media.

Reinking, R. (2022). Implementing the Complexity Approach[PowerPoint Slides]. Bright Ideas Media.

Morrisette, M. (2021). Complexity Approach. In A.L. Williams, S. McLeod, & R. J. McCauley (Eds.) Interventions for Speech Sound Disorders in Children (2nd ed., pp. 91–110). essay, Paul H. Brookes Publishing Co. .

Storkel, H. L. (2018). The Complexity approach to phonological treatment: How to select treatment targets. Language, Speech & Hearing Services in Schools, 49, 463-481