The Effectiveness of an Integrated Treatment for Functional Speech Sound Disorders—A Randomized Controlled Trial

Background: The treatment of functional speech sound disorders (SSDs) in children is often lengthy, ill-defined, and without satisfactory evidence of success; effectiveness studies on SSDs are rare. This randomized controlled trial evaluates the effectiveness of the integrated SSD treatment program PhonoSens, which focuses on integrating phonological and phonetic processing according to the Integrated Psycholinguistic Model of Speech Processing (IPMSP). Methods: Thirty-two German-speaking children aged from 3.5 to 5.5 years (median 4.6) with functional SSD were randomly assigned to a treatment or a wait-list control group with 16 children each. All children in the treatment group and, after an average waiting period of 6 months, 12 children in the control group underwent PhonoSens treatment. Results: The treatment group showed more percent correct consonants (PCC) and a greater reduction in phonological processes after 15 therapy sessions than the wait-list control group, both with large effect sizes (Cohen’s d = 0.89 and 1.04). All 28 children treated achieved normal phonological abilities: 21 before entering school and 7 during first grade. The average number of treatment sessions was 28; the average treatment duration was 11.5 months. Conclusion: IPMSP-aligned therapy is effective in the treatment of SSD and is well adaptable for languages other than German.