Speech Sound Guide
The /th/ sound is one of the later sounds children master — typically by age 6. This guide covers when /th/ develops, what typically goes wrong, simple ways to practice it, and over 85 /th/ words organized by position.
Developmental norms — when the /th/ sound typically emerges and is mastered.
Source: McLeod & Crowe (2018); Crowe & McLeod (2020), AJSLP.
A child still substituting or distorting /th/ after age 6 is a good candidate for a speech-language evaluation — earlier if they're hard to understand or frustrated.
Sound Safari's 24-sound screener checks against the McLeod & Crowe norms above.
What typically goes wrong — and whether it's age-appropriate.
/th/ → /d/
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 — /d/ is hidden behind the teeth, voiced /th/ pokes between them. Practice slowly with the tongue visible.
/th/ → /voiceless th/
Typically resolves on its own by around age 4; worth a check-in if it persists.
What helps →
Touch the throat — voiced /th/ (this, that) buzzes; voiceless /th/ (think, thumb) is silent. Compare both side by side.
Practical starting points for parents and SLPs. Always follow your SLP's plan if your child is in therapy.
Every word from the Sound Safari practice library. The /th/ in each word is bolded.
Minimal pairs differ by a single sound — the heart of phonological therapy. Tap a card to hear it, or tap “vs” to hear a pair back-to-back.
More /th/ minimal pairs — tap a contrast to explore
/th/ at the start · 8
/th/ at the end · 4
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."
Sound Safari logs every trial against your goals and writes the SOAP note for you.
Most children produce voiced /th/ correctly by age 6. About half can do it by age 4. Voiced and voiceless /th/ are among the latest English sounds to develop.
Yes — substituting /d/ ("dis" for "this", "dem" for "them") is developmentally typical up to about age 5–6. If it persists past age 6, it's worth a check-in.
Both use the same tongue-between-teeth position. Voiceless /th/ (think, thumb, math) is silent — just air. Voiced /th/ (this, that, mother) buzzes — the voice is on.
Show the tongue position in a mirror, touch the throat to feel the buzz, and use contrast pairs (they/day, those/doze). Practice with everyday words like "this", "that", "mother".
If voiced /th/ is still being replaced with /d/ past age 6, see an SLP. (Note: voiced /th/ is one of the latest sounds and many adults keep some "d-ish" quality casually.)
Yes — /th/ is treatable at any age. The tongue position is visible, and once voiceless /th/ is in place, adding voicing is straightforward.
Sounds that pair, contrast, or are commonly confused with /th/.
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