The TH Sound in English: A Complete Guide to /θ/ and /ð/
English has two TH sounds, both made by placing your tongue between your teeth. Here is how to produce the voiceless /θ/ and the voiced /ð/ accurately.
By the Ledoly team
The TH sound is produced by placing the tip of your tongue lightly between your upper and lower front teeth and pushing air through the gap. There are two versions: the voiceless /θ/ as in think, and the voiced /ð/ as in this. The only difference between them is whether your vocal cords are vibrating.
Vietnamese has neither sound, which is why TH is one of the clearest markers of a Vietnamese accent. Most speakers replace /θ/ with /t/ and /ð/ with /d/, so think becomes "tink" and this becomes "dis." Native listeners notice this instantly. The good news is that TH is a visible, mechanical sound — once you place the tongue correctly, it is one of the more reliable sounds to fix.
The two TH sounds
Both TH sounds are interdental fricatives. "Interdental" means the tongue sits between the teeth. "Fricative" means the sound is made by friction — air squeezing through a narrow gap.
Voiceless TH — /θ/
This is the TH in think, three, thank, month, bath, and healthy. Your vocal cords do not vibrate. The sound is just air friction — like a soft, quiet hiss.
Voiced TH — /ð/
This is the TH in this, that, the, they, mother, and breathe. Your vocal cords vibrate while air passes the tongue. It carries a soft buzz.
Here is the useful pattern: the voiced /ð/ appears mostly in short, high-frequency grammar words — the, this, that, these, those, they, them, there, then. The voiceless /θ/ appears in most content words. If you can pronounce the small set of /ð/ grammar words, you have covered the majority of voiced TH you will ever use.
Put your hand flat on your throat. Say a long think — no vibration in your hand. Now say a long this — you should feel a buzz. That buzz is the only difference between /θ/ and /ð/. The tongue position is identical for both.
How to produce TH correctly
Step 1: Stick the tongue tip out. The tip of your tongue should poke very slightly past your front teeth. You should be able to see a small amount of tongue in a mirror. This visual check is the fastest way to confirm you are doing it right.
Step 2: Keep the contact light. The tongue rests gently between the teeth. Do not bite it or press hard. There must be a thin gap for air.
Step 3: Push air through. For /θ/, blow gentle air with no voice. For /ð/, do the same while voicing.
Step 4: Retract slightly for fast speech. Once the sound is reliable, you can pull the tongue back so the tip just touches the back of the upper teeth. Native speakers in fast speech often use this near-dental version. Learn the fully interdental form first — it builds the correct habit.
Why Vietnamese speakers substitute T and D
Vietnamese has /t/ and /d/, which are stops — the tongue fully blocks the airflow behind the teeth, then releases. TH is a fricative — the airflow never stops; it just narrows. When you produce "tink" instead of "think," you are blocking air where you should be flowing it. The mental shift is from "block and release" to "narrow and hiss." If you hear a sharp little burst, you made a stop; if you hear continuous friction, you made the fricative.
Drill these minimal pairs slowly: think / sink, thin / tin, three / tree, thank / tank, they / day, then / den. Hold the TH friction for a full second each time so your ear learns the contrast. Then say them at normal speed.
TH in tricky combinations
TH gets harder in clusters. Two cases catch Vietnamese speakers most often.
TH plus R
The word three contains /θ/ followed immediately by /r/ — two sounds Vietnamese lacks, in a row. Practice the TH first, then glide into the R. If the R itself is shaky, work through our guide to the American R sound before combining them.
TH at the end of words and in clusters
Final TH is easy to drop, and months (/nθs/), sixths, and clothes are genuinely demanding. Vietnamese syllables rarely end in clusters, so endings tend to vanish. Slow each word into separate beats — "mon-th-s" — then speed up. This overlaps with a broader pattern covered in our article on final consonants and consonant clusters.
A practice plan
Spend the first week producing /θ/ and /ð/ in isolation and at the start of words, checking the mirror for visible tongue. In the second week, move to minimal pairs and final position. In the third week, practice full sentences such as "I think this is the third month" and record yourself. For target words with instant feedback, use the TH sound practice page, and explore the broader set of minimal pairs to sharpen your ear.
Frequently asked questions
What is the difference between /θ/ and /ð/?
The tongue position is identical — tip between the teeth, air flowing through. The only difference is voicing. /θ/ (as in think) is voiceless, with no vocal cord vibration. /ð/ (as in this) is voiced, with vibration. Put a hand on your throat to feel the buzz that marks /ð/.
Why do Vietnamese speakers say "tink" instead of "think"?
Vietnamese has /t/ and /d/ but no TH. Speakers substitute the nearest familiar sounds. Crucially, /t/ and /d/ are stops that block airflow, while TH is a fricative that lets air flow continuously, so the substitution changes the manner of the sound, not just its location.
Is it okay if my tongue touches my teeth instead of going between them?
For learning, push the tongue tip slightly between the teeth so you can see it in a mirror — this guarantees the correct sound. Native speakers in fast speech sometimes use a near-dental version with the tongue just behind the upper teeth, but you should master the clearly interdental form first.
Which TH words should I prioritize?
Master the small set of voiced /ð/ grammar words first — the, this, that, these, those, they, them, there, then — because they appear constantly. Then drill voiceless /θ/ in common content words like think, three, thank, and month.
Want to know if TH is your biggest accent giveaway? Take the 60-second pronunciation check and get a phonetic heatmap showing exactly which sounds to work on first.