Speech sound guide · /s/ as in “sun”
My child has a lisp on the S sound
Published · Updated
The short answer
In a large review of US studies, 90% of children said S correctly by about 4 years 3 months. A “th” lisp (“thun” for sun) is common in younger children. A lisp that continues past the early school years, or a “slushy” lisp where air escapes out of the sides, is worth checking with a speech-language pathologist.
Most children say it by about 4¼ (90% by 4 years 3 months)
How the S sound is made
S is made with the tongue tip just behind the top front teeth, sending a narrow stream of air down the middle of the tongue and out over the teeth. Small changes in where the tongue sits change the sound a lot.
Common ways children say it differently
- Frontal lisp (“th” sound)
- “thun” for sun, “yeth” for yes. The tongue pushes forward between the teeth. Common in young children.
- Lateral lisp (“slushy” sound)
- Air escapes over the sides of the tongue, so S sounds wet or slushy. This isn’t a usual stage of development, so it’s worth asking an SLP early.
What the age means, and what it doesn’t
“90% by 4 years 3 months” means that in the pooled studies, nine in ten children said S correctly by that age. About one in ten children who are developing typically get there later, so it’s a guide for when to ask, not a deadline. Ages come from US children learning English.
When to ask a speech therapist about S
- Your child is past about about 4¼ and still swaps or distorts S.
- People outside the family often find your child hard to understand, or your child is frustrated or teased about how they talk.
- You’re worried. You don’t need to wait for a set age to ask.
More signs: Does my child need speech therapy? In the US, you can ask for a free speech evaluation, or find a certified SLP through ASHA ProFind.
S practice words
At the start
sun, sock, soap, seal
In the middle
messy, pencil, bicycle, baseball
At the end
bus, horse, ice, yes
Use the words your child’s SLP picks first. For keeping practice low-pressure, see how to help at home, and for why a sound can work in sessions before it shows up in conversation, see carryover.
Questions parents ask about S
At what age should a lisp go away?
Most children say S correctly by about age 4 (90% by 4 years 3 months in the 2020 review). If a lisp continues into the school years, ask an SLP.
Is a lateral lisp normal?
A lateral, “slushy” lisp isn’t a usual part of development, so it’s a good idea to ask an SLP rather than wait.
Can missing front teeth cause a lisp?
Losing front teeth can change how S sounds for a while. If a lisp continues once adult teeth are in, ask an SLP.