Purpose: The aim was to evaluate the effect of a motor-based, hierarchically structured intervention directed at active nasal fricatives substituting /s/ in young children with normal palatal function.

Method: An experimental single-subject design was replicated across three children, aged 4–6 years, with normal palatal function, who substituted oral /s/ with active nasal fricatives. Treatment was performed weekly by a speech-language pathologist and included home training conducted by parents. Audio documented probes were registered regularly and /s/-production evaluated as oral or nasal.

Result: All children achieved 98–100% oral production of /s/ in six probed linguistic contexts at treatment end and exhibited good maintenance at follow-up. The four-year-olds showed gradual or inconsistent response and slower progress, the six-year-old direct response and faster progress.

Conclusion: The study provides preliminary evidence suggesting positive intervention effects for treating active nasal fricatives in children with normal palatal function. However, possible confounding effects such as maturation or repeated testing could not be ruled out; thus, results need to be replicated with increased experimental control. Nevertheless, the study adds to the currently meagre empirical evidence-base for the population. Individual treatment response and progress patterns were found and data suggests that the intervention may be beneficial from age 4.