Toddler Puts Tongue Between Teeth for S Sound
The short answer
An interdental or frontal lisp, where the tongue slides between the teeth during S and Z sounds (making them sound like TH), is a common developmental pattern in young children. Most children outgrow this by age 4.5. If the lisp persists past this age, speech therapy can help your child learn correct tongue placement.
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By Age
What to expect by age
S sounds are just beginning to develop. Lisping is not a concern at this age as children are still learning how to position their tongue for different sounds. Many toddlers do not yet produce S sounds at all.
An interdental lisp is very common and completely normal during this period. Many children naturally place their tongue between their teeth when attempting S and Z. This usually resolves as oral motor control improves.
A frontal lisp is still considered normal at this age. Many preschoolers lisp and most will outgrow it. Correct S production typically emerges between ages 3.5 and 4.5. No intervention is usually needed yet.
By age 4.5, the frontal lisp should be resolving. If it persists, speech therapy may be recommended. Some speech-language pathologists prefer to wait until age 5 before beginning treatment, as many children self-correct during this period.
A frontal lisp that persists past age 5 is unlikely to resolve on its own and speech therapy is recommended. Treatment is typically effective and straightforward, teaching the child to keep their tongue behind their teeth.
What Should You Do?
When to take action
- Your child is under 4.5 years and places their tongue between their teeth for S and Z sounds
- Your child's lisp is consistent, not something that appeared suddenly
- Your child's other speech development is on track aside from the lisp
- Your child is not frustrated or self-conscious about their speech
- Your child is over 4.5 years and still has a consistent frontal lisp
- Your child's lisp is accompanied by other speech sound errors
- Your child is starting school and is self-conscious about lisping
- Your child suddenly developed a lisp they did not have before, which could indicate dental or oral changes
- Your child is over 5 years and the lisp is affecting their confidence or willingness to speak
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Related Speech Concerns
My Toddler Has a Lisp
Lisps are very common in toddlers and preschoolers who are still learning to make certain sounds. Most children don't master the "s" sound until around age 4-5, so a lisp before then is usually developmentally normal. If your child still has a noticeable lisp after age 5, or if it's affecting their confidence, a speech evaluation can help.
Toddler Has a Slushy S Sound (Lateral Lisp)
A lateral lisp produces a "slushy" or wet-sounding S and Z, caused by air escaping over the sides of the tongue rather than through the center. Unlike a frontal lisp (tongue between the teeth), a lateral lisp is not considered a normal developmental pattern and typically requires speech therapy to correct. If you notice this sound quality in your child, a speech-language evaluation is recommended.
Child Cannot Say the S Sound
The S sound is typically mastered between ages 3 and 5. Many young children substitute TH or T for S, which is normal developmental variation. A frontal lisp with S is common and often resolves by age 4.5. If S errors persist past age 5, or if your child has a lateral (slushy) lisp, a speech evaluation is recommended.
Accent vs Speech Disorder in Bilingual Toddlers
When toddlers grow up hearing more than one language, they naturally blend sounds, patterns, and accents from both languages. This is normal and healthy, not a speech disorder. A bilingual child may pronounce some sounds differently than monolingual peers because they are learning the sound systems of two languages simultaneously. True speech disorders affect both languages equally, while accent influence appears only in specific sounds borrowed from one language to another.
Ear Fluid Affecting Baby's Speech Development
Chronic or recurrent middle ear fluid (otitis media with effusion) can temporarily reduce hearing by 15 to 40 decibels, which is like hearing through water. During critical periods of language learning, this muffled hearing can impact speech and language development. If your baby has frequent ear infections or persistent fluid, discuss the potential speech impact with your pediatrician.
Will Ear Tubes Help My Child's Speech?
Ear tubes (tympanostomy tubes) can restore normal hearing by draining persistent fluid from the middle ear. Many children show speech and language improvement within weeks to months after tube placement, particularly if hearing loss from fluid was contributing to their speech delay. However, ear tubes alone may not resolve all speech delays, and some children benefit from speech therapy alongside tube placement.