A little "thun" for "sun" can sound sweet in a preschooler. But as kids get older, many parents start to wonder: is this lisp something my child will grow out of, or something to check on? This post summarizes what speech-language research and the American Speech-Language-Hearing Association (ASHA) say about lisps: what they are, when the "s" sound usually develops, and when it makes sense to talk with a speech-language pathologist (SLP).
What exactly is a lisp?
A lisp is a kind of speech sound error that mostly affects "s" and "z" (and sometimes related sounds like "sh").[3] Speech-language pathologists call this kind of error a distortion. ASHA describes distortions as sounds that "are altered or changed," and gives "a lateral /s/" as its example.[1] In other words, the child is trying to say the right sound, but it doesn't come out quite clear.
Speech researchers and ASHA name a few common kinds of "s" errors:[2, 3, 4]
- Interdental lisp. The tongue tip comes forward between the front teeth. This is the lisp most parents picture.
- Dentalized "s." The tongue is placed against the teeth rather than just behind them.
- Lateral lisp (lateralized "s"). "Lateral" means "to the side": the air for "s" flows out over the side of the tongue instead of down the middle.
Only an SLP can tell you which kind your child has, since some differences are hard to hear and see at home.
Lisps are a type of speech sound disorder. ASHA explains that articulation disorders focus on "the motor production of speech sounds," and notes that speech sound disorders more broadly can involve perception and motor production as well as the sound system of a language.[1] If you'd like more background on that difference, see our post on articulation vs. phonological disorders.
How common are lisps in young children?
Quite common, especially among kids whose speech has caught an adult's attention. In a community study of 4- to 5-year-olds, researchers assessed 143 children whose parents or teachers had concerns about their speech. "Interdental lisps on /s/ and /z/ were produced by 39.9% of the children," along with "dentalization of other sibilants by 17.5%, and lateral lisps by 13.3%."[3] Because those children were chosen for concerns about their speech, the figures describe that group, not all preschoolers.
The same study found that "despite parent/teacher concern, only 41/109 children had contact with an SLP."[3] That's a reminder that it's okay to ask questions early rather than wait and wonder.
At what age should my child say "s" clearly?
There's no single magic birthday, and "s" is one of the more variable sounds. A 2020 review pooled 15 studies covering 18,907 children learning English in the United States. It found that "most consonants were acquired by 5;0 (years;months)," and that "s" and "z" were in the group typically acquired between 4;0 and 4;11, using a standard where 90% of children in a study said the sound correctly.[2]
That review also found that "s" and "r" had the widest spread of ages across studies, with a standard deviation of about 20 months.[2] The authors note that these two sounds are commonly reported as "residual errors" and "common clinical distortions" for children whose speech sound difficulties persist.[2] They also caution that "age of acquisition data are not enough for clinical decision making or to determine eligibility for services."[2]
For a broader picture, the Communication Health Support Association, which describes itself as powered by ASHA's expertise, says that "most children can say almost all speech sounds correctly by 4 years old," and that "other sounds can take longer to learn—like z, v, or th."[5]
Good to know: Missing front teeth can change how "s" sounds. One analysis of typical speech development, described in the 2020 review, found that "s" errors shift with age: often replaced with "t" or "d" in younger children, then sometimes dentalized or lateralized in older children, and "impacted by the loss of the upper incisors."[2] If your 6-year-old's lisp showed up along with a gap-toothed grin, that may be part of the story. An SLP can help you sort out what's what.
What causes a lisp? Is it tongue-tie or a tongue thrust?
Often there's no single clear cause. Parents frequently ask about tongue position, swallowing habits, and tongue-tie, and the honest answer is that the research is still sorting this out.
ASHA's guidance on orofacial myofunctional disorders (patterns of how the tongue, lips, and jaw rest and move) lists "distorted productions of /s, z/, often with an interdental lisp" among the possible signs.[4] ASHA notes that "tongue thrusting, or protrusion of the tongue between the teeth, may impact swallowing and articulation," and that "children with speech sound disorders are more likely to exhibit a tongue thrust swallow."[4] But ASHA is careful to add that the limited research "shows possible correlations between OMD characteristics and symptoms but does not indicate causation."[4]
On tongue-tie (ankyloglossia), ASHA says it "might also coexist with speech sound errors, but the evidence regarding the impact of ankyloglossia … and tongue-tie release on speech sound errors is debated."[4] If someone suggests a procedure to fix a lisp, it's reasonable to ask your pediatrician and an SLP about the evidence for your child specifically.
Teeth and bite matter too. ASHA gives the example that "an orthodontist may need to treat a child's open bite before the clinician provides interventions for a tongue thrust and/or an interdental lisp."[4] And because hearing affects speech, ASHA notes that "a hearing screening is conducted during the comprehensive speech sound assessment."[1]
When should we talk to a speech-language pathologist?
You don't need a perfect cutoff to ask a question. The Communication Health Support Association puts it simply: "If you're concerned about your child's speech development, consult a speech-language pathologist (SLP)."[5] Things worth mentioning to an SLP or your pediatrician include:
- A lisp that's still there as your child moves past the preschool years, given the age ranges above.[2]
- An "s" that sounds like air is escaping out the side, since ASHA uses "a lateral /s/" as its example of a distortion.[1]
- A tongue that often rests forward or between the teeth, or a mouth that's often open at rest. ASHA lists a forward or interdental tongue resting posture among the signs of orofacial myofunctional disorders.[4]
- Your child noticing, feeling self-conscious, or talking less. ASHA notes that persisting speech difficulties may be linked to psychosocial problems such as "low self-esteem" and an "increased risk of bullying," and that a speech sound disorder can affect "the child's ability or willingness to communicate in the classroom."[1]
ASHA also notes that "speech difficulties sometimes persist throughout the school years and into adulthood," and that "1%–2%" of young adults "exhibit residual or persistent speech errors."[1]
A speech-language evaluation looks at more than one sound. As the 2020 review explains, a fuller picture considers things like a child's speech production and perception, intelligibility, stimulability, phonological awareness, spelling, reading, and "academic and social impact," along with input from the child and family.[2]
How do SLPs help with lisps?
Treatment is individual. ASHA says that "treatment selection depends on several factors, including the child's age, the type of speech sound errors," and that "a particular strategy may not be appropriate for all children."[1] In general terms, SLPs help children "learn the correct way to make sounds," "recognize when sounds are correct or incorrect," "practice sounds in different words, sentences, or stories," and "use sounds in conversations."[5]
Where tongue posture is part of the picture, ASHA says SLPs "exercise caution before using OMT as a standalone approach to address speech sound errors and may need to consider combining OMT and articulation interventions."[4] (OMT is orofacial myofunctional therapy, which works on how the tongue and lips rest and move.) How any one child progresses varies, so goals and next steps belong with your child's SLP.
Our speech therapy services work on speech sound errors like these, and Arizona families outside the Phoenix area can ask about telehealth.
The bottom line
Lisps are common in young children, and "s" has one of the widest ranges of typical ages, with "s" and "z" usually acquired between about 4 and 5 years old in U.S. studies.[2, 3] Missing front teeth, tongue posture, and bite can all play a part, while the evidence on tongue-tie and speech is still debated.[2, 4] If your child's lisp is sticking around, sounds lateral, or is bothering them, it's reasonable to check in with an SLP or your pediatrician. You don't need to wait for a certain birthday to ask.
Sources
- American Speech-Language-Hearing Association (n.d.). Speech Sound Disorders: Articulation and Phonology (Practice Portal). ASHA.
- Crowe, K., & McLeod, S. (2020). Children's English consonant acquisition in the United States: A review. American Journal of Speech-Language Pathology, 29(4), 2155–2169.
- McLeod, S., Harrison, L. J., McAllister, L., & McCormack, J. (2013). Speech sound disorders in a community study of preschool children. American Journal of Speech-Language Pathology, 22(3), 503–522.
- American Speech-Language-Hearing Association (n.d.). Orofacial Myofunctional Disorders (Practice Portal). ASHA.
- Communication Health Support Association (n.d.). Speech Sound Disorders. HelpingYouCommunicate.org (powered by the expertise of ASHA).
Articles from Speech Me Therapy, a pediatric speech-language therapy practice in North Phoenix serving Scottsdale, Paradise Valley, and families across Arizona by telehealth. Our posts summarize published guidance from professional and public health organizations; sources are listed at the end of every article.