This advice-column-style blog for SLPs was authored by Pam Marshalla from 2006 to 2015, the archives of which can be explored here. Use the extensive keywords list found in the right-hand column (on mobile: at the bottom of the page) to browse specific topics, or use the search feature to locate specific words or phrases throughout the entire blog.
A high-pitched “whistled S” is the result of an airway space in the mouth that simply is too narrow causing whistling instead of true frication.
All you have to do is get him in front of a mirror and have him start experimenting with how much air he is letting out. He may need to pull the tip of his tongue back a little, or adjust the jaw downward a millimeter or two, or pull the lower lip out of the way, or other things.
His whistle is the result of what HE is doing slightly wrong, so there is no way to tell you exactly what to do until you experiment with it a little. This is all about trial-and-error.
Once he produces a better sound with you, it’s all a matter of ear training. Help him hear the difference between the two sounds (basic auditory discrimination work) and teach him which one sounds better. I usually tell my clients, “This is what you are saying… And this is how most kids say it…”
In my studies of articulation therapy, I found the best description of the whistled S in the reference named below.
- Berry, M. F., & Eisenson, J. (1956) Speech Disorders: Principles and Practices of Therapy. NY: Appleton-Century-Crofts.