Introduction
As speech-language pathologists, one of the most common goals we work on with both children and adults involves refining the /s/ and /z/ sounds. These sounds might seem simple, but producing them clearly and consistently depends on precise tongue placement, airflow, and muscle coordination.
When something isn’t quite right, like when the tongue slips too far forward or air escapes from the sides, speech can start to sound “slushy” or unclear. This is often described as a lisp.
What Is a Lisp?
A lisp occurs when someone incorrectly produces the /s/ or /z/ sounds due to incorrect tongue placement or airflow direction. Instead of the airflow being directed neatly down the center of the tongue and out between the teeth, it either escapes out the sides or is blocked altogether, distorting the sound. For tongue placement, the tongue will sit in the incorrect position when the /s/ is produced.
For example, when someone says “sun” and it sounds closer to “thun,” that’s a sign of an interdental lisp, the tongue is coming too far forward between the teeth. On the other hand, if the sound seems “wet” or “slushy,” with air escaping along the sides of the tongue, it’s likely a lateral lisp.
While many children go through a phase where they have a lisp, most outgrow it as their oral motor skills develop. However, for others, the pattern becomes habitual and carries into adulthood. The good news? It’s never too late to fix a lisp.
Lisp Correction in Adults
Many adults come to speech therapy because they’ve had a lingering lisp since childhood, or they’ve recently become more aware of it in professional or social situations. The misconception that “it’s too late to change” is common, but research and clinical experience show that with the right techniques, adults can make significant improvement, often faster than they expect.
In many cases, once an adult learns the correct tongue placement and airflow pattern, they begin to hear a difference immediately. For others, it might take a few sessions for their muscles and motor patterns to adapt to the new placement. Everyone progresses at their own pace, what matters most is consistency, motivation, and guided feedback.
Two Most Common Types of Lisps
There are several types of lisps, but the interdental and lateral varieties are the most common. Understanding the difference helps tailor the right therapy approach.
- Interdental Lisp:
This is when the tongue pushes forward and slightly out between the front teeth, producing a “th” sound instead of /s/ or /z/. For instance, “sun” sounds like “thun,” and “zoo” might sound like “thoo.” - Lateral Lisp:
In a lateral lisp, the air escapes along one or both sides of the tongue, giving the sound a “slushy” quality. The central airflow needed for a crisp /s/ or /z/ is missing.
In both cases, therapy focuses on retraining the tongue to stay inside the mouth and directing airflow down the midline of the tongue, not out the sides or between the teeth.
Tongue Placement: Dipper or Tipper?
Now here’s where things get interesting, and where the “Dipper or Tipper” question comes in.
When I work with clients on correcting a lisp, one of the first things we explore is where the tip of the tongue should rest during production of the /s/ and /z/ sounds.
There are two common positions, and both can produce a correct, clear sound:
- Dipper Position:
The tongue tip points down, resting gently on or behind the lower teeth or gums. The sides of the tongue lift slightly against the upper molars to help direct airflow down the middle. - Tipper Position:
The tongue tip points up, hovering just below or lightly touching the alveolar ridge (the bumpy ridge just behind the upper front teeth).
Both positions can produce an accurate /s/ and /z/—what matters most is that the airflow is steady and centered.
Finding What Works Best
Every person’s oral anatomy, comfort level, and speech habits are a little different. That’s why I always let clients experiment with both positions.
Some clients feel immediately comfortable as “dippers,” while others find it easier to stabilize their tongue in the “tipper” position. There’s no universal “right” way, it’s all about discovering what feels natural and produces a clear sound.
Interestingly, I’ve had several clients tell me they previously worked on their /s/ and /z/ sounds in therapy but never quite achieved success. Once they tried the alternative tongue position (for instance, switching from tipper to dipper), the sound “clicked” for them, sometimes even within the first session.
This reinforces an important point: small physical adjustments can make a big difference. Speech therapy isn’t about forcing one “correct” placement; it’s about finding the most efficient, consistent way for each individual to produce their clearest speech.
Patience, Practice, and Progress
Correcting a lisp, especially one that’s been present for years, takes time and consistent practice. Some clients start to notice improvement within a few sessions; for others, it can take several weeks before a notable improvement is seen.
The key is to practice regularly, even for short bursts each day, and to record yourself periodically to track changes. Listening to your own progress can be incredibly motivating and reinforces the correct sound. Especially with the subtle adjustments required to correct a lisp.
Final Thoughts
Whether you’re a dipper or a tipper, the ultimate goal is the same: clear, confident, and natural-sounding speech. Discovering the tongue position that works best for you is just one part of the process, but it can be a game-changer.
If you’ve struggled with a lisp or unclear /s/ and /z/ sounds, whether since childhood or more recently, it’s never too late to make a change. With professional guidance, practice, and a bit of curiosity, you can retrain your speech patterns and experience the confidence that comes with crisp, precise articulation.
