Sound Safari
Speech Sound Guide
The Voiceless TH Sound: Norms, Challenges & Word Lists
The /th/ sound is one of the later sounds children master — typically by age 8. This guide covers when /th/ develops, what typically goes wrong, simple ways to practice it, and over 90 /th/ words organized by position.
When should a child say /th/?
Developmental norms — when the /th/ sound typically emerges and is mastered.
Source: McLeod & Crowe (2018), AJSLP.
A child still substituting or distorting /th/ after age 8 is a good candidate for a speech-language evaluation — earlier if they're hard to understand or frustrated.
Find out where /th/ stands — in 5 minutes
Sound Safari's 23-sound screener checks against the McLeod & Crowe norms above.
Common challenges with /th/
What typically goes wrong — and whether it's age-appropriate.
Stopping
/th/ → /t/
Typically resolves on its own by around age 4; worth a check-in if it persists.
What helps →
Show the tongue position in a mirror — /t/ is hidden behind the teeth, /th/ pokes between them. Practice slowly with a mirror.
How to practice the /th/ sound
Practical starting points for parents and SLPs. Always follow your SLP's plan if your child is in therapy.
- 1 Tongue between the teeth. /th/ is made with the tongue gently between the top and bottom teeth — not biting, just resting. Have your child practice the position in a mirror before adding any sound.
- 2 Blow gently. /th/ is a quiet fricative — just air passing over the tongue. No voice, no buzz. Have your child blow softly while the tongue is between the teeth.
- 3 Feel the air on a finger. Hold a finger just in front of your child's mouth. They should feel a faint stream of air with each /th/ — confirms the sound is air, not a /t/ stop.
- 4 Contrast pairs — /th/ vs. /f/ and /s/. /th/ is often replaced with /f/ (think → fink) or /s/ (think → sink). Use pairs like thin/fin, thank/sank to train the ear and the mouth.
- 5 Start with words that show the tongue. Use a mirror and start with words that begin with /th/ (think, thumb, three) so the tongue position is visible the whole time.
/th/ word lists by position over 90 words
Every word from the Sound Safari practice library. The /th/ in each word is bolded.
Initial — /th/ at the start of the word (30)
Medial — /th/ in the middle of the word (30)
Final — /th/ at the end of the word (30)
IEP goals for /th/
A starting point for SLPs writing articulation goals — across the six therapy levels.
Goal progression — tap a level to see the goal
Sample goal — word level
"Given a verbal model, [student] will produce /th/ in the initial position of words with 80% accuracy across 3 consecutive sessions."
Track /th/ progress automatically
Sound Safari logs every trial against your goals and writes the SOAP note for you.
/th/ sound — frequently asked questions
At what age should my child say the /th/ sound? +
Most children produce /th/ correctly by age 8. About half can do it by age 6. /th/ is one of the latest English sounds to develop.
Is it normal for my child to say "f" or "s" for "th"? +
Yes — substituting /f/ ("fink" for "think") or /s/ ("sink") for /th/ is developmentally typical up to about age 7. If it persists past age 8, it's worth a check-in.
Why is the /th/ sound so hard? +
/th/ requires the tongue to sit between the teeth — a position most other English sounds avoid. It also has very little airflow, so the sound is quiet and easy to confuse with /f/ or /s/.
How can I help my child practice /th/ at home? +
Use a mirror so the child can see the tongue between the teeth, practice blowing gently, and use contrast pairs (thin/fin) to train the ear. See "How to practice" above.
When should we see a speech therapist about /th/? +
If /th/ is still being replaced with /f/, /s/, or /t/ after age 8, or sooner if your child is frustrated or hard to understand.
Can older children and adults still correct /th/? +
Yes. /th/ is treatable at any age. The tongue position is visible and easy to demonstrate, so most older learners make steady progress.
Related sounds
Sounds that pair, contrast, or are commonly confused with /th/.
