Lisp in Adults and Teens: Why It Stays, and Whether It Can Be Fixed

✓ Reviewed against Flipsen (2015), Lipetz & Bernhardt (2013), ASHA Practice Portal, NIDCDEvidence level BLast reviewed October 14, 2026Published October 14, 2026

An adult lisp is usually a childhood S or Z error that never resolved — a residual speech error, estimated to persist in 1–2% of young adults. It can still improve: teens and adults respond to direct practice and SLP techniques such as visual feedback. A lisp that appears suddenly in adulthood needs a medical check.

Why a lisp can last into adulthood

Most lisps fade in childhood, but not all. A 2015 review estimates that 1–2% of young adults still have residual or persistent speech errors — most often distortions of S, Z, or R. It describes two routes: residual errors, the more common, which appear to be leftovers of an earlier speech delay that gradually migrated into distortions; and persistent errors, distortions present from an early age that reflect long-instantiated habits.¹

1–2%of young adults are estimated to have residual or persistent speech errors (Flipsen, 2015).¹

The same review estimates that up to 75% of these errors may resolve on their own between about age 9 and the end of high school — so a lisp at 10 has a real chance of fading, while one still present in the late teens is less likely to.¹

Can a teen or adult lisp be fixed?

The evidence is small but consistent: older speakers can learn new S placement. In a case study, an adolescent with a persistent frontal lisp showed no change after a phase of general awareness training, but notable improvement on S, Z, SH, and CH after a phase of direct articulation training with online visual-acoustic biofeedback — gains largely maintained four months later.²

In a preliminary study of 18 children aged 6;9 to 11;10 with dentalized or interdental S and Z, once-weekly 10-minute sessions produced significant gains in spontaneous speech, and most children kept them two years later. The authors note that traditional methods for distortion errors in older school-age children have had mixed success, which is why structured, well-targeted practice matters.³

ASHA’s Practice Portal, which covers speech sound disorders in ages 3 to 21, notes its information may be relevant for speech sound disorders persisting into adulthood, and lists techniques such as ultrasound and spectral biofeedback that give older learners a picture of what their tongue and voice are doing.⁵

A lisp that appears suddenly is different

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New speech changes need a medical check

If a lisp or any other change in speech appears suddenly in an adult, see a doctor promptly. Speech problems that begin in adulthood can have medical causes.

NIDCD explains that acquired apraxia of speech, which most typically occurs in adults, is caused by damage to the parts of the brain involved in speaking and may result from a stroke, head injury, tumor, or other illness affecting the brain. A long-standing childhood lisp is not this — but a new one should not be assumed to be harmless.⁶

What to do next

1Check yourself: record S and Z words and listen back, or use the free lisp test.
2Identify the type: TH-like (frontal), dull (dentalized), wet and slushy (lateral), or hissy and SH-like (palatal).
3Try structured practice for a frontal lisp; see an SLP for lateral or palatal lisps, which are harder to correct by ear.
4Skip oral-motor “tongue workouts” — a systematic review found insufficient evidence that they change speech.

The oral-motor finding comes from a systematic review of 15 studies of nonspeech oral motor exercises.⁸

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Where SpeechStep fits

SpeechStep’s practice is built for children 4–8; teens and young adults can use it, but it was not designed around them. The free lisp test works at any age. For S, practice is listen-and-compare (an instant AI check is offered only for R), and none of it replaces an SLP.

To find a certified speech-language pathologist, use ASHA’s ProFind directory.⁹

Frequently asked questions

Can you fix a lisp as an adult?＋

Often, yes. Residual speech errors are distortions, and older speakers can learn new placements with direct practice. In one case study, an adolescent with a persistent frontal lisp improved notably after 11 sessions of direct articulation training with visual-acoustic biofeedback, and largely kept the gains four months later. Results vary, and a speech-language pathologist can tell you what to expect.

Why do some people still have a lisp as adults?＋

A 2015 review describes two routes. Residual errors (the more common) appear to be leftovers of an earlier speech delay that migrated toward normal and became distortions. Persistent errors appear to be distortions from an early age that reflect long-held habits. Up to 75% of such errors may resolve between about age 9 and the end of high school — but some do not.

Is it normal to develop a lisp as an adult?＋

A lisp that has always been there is a residual childhood error. A lisp or other speech change that appears suddenly in an adult is different: speech problems that begin in adulthood can have medical causes — NIDCD notes that acquired speech disorders can result from a stroke, head injury, or tumor. New, sudden changes in speech need prompt medical attention.

How do I know if I have a lisp?＋

Listen to yourself say words with S and Z at the start, middle, and end (“sun,” “messy,” “bus”), ideally recorded. A TH-like S suggests a frontal lisp; a wet, slushy S suggests a lateral lisp. SpeechStep’s free lisp test walks you through it in about two minutes, but only a speech-language pathologist can diagnose.