The English TH sounds are some of the most challenging for non-native speakers. English has two distinct TH sounds, and mixing them up or replacing them with other sounds can cause real misunderstandings. The good news is that once you understand how they work, you can train your mouth to produce them correctly.
The Two TH Sounds
Both sounds are made by placing the tip of your tongue between your upper and lower teeth (or lightly against the back of your upper teeth) and pushing air through. The difference between them is voicing.
- /θ/ (voiceless): Air flows through without vibrating your vocal cords. Words: think, three, bath, math, author
- /ð/ (voiced): Your vocal cords vibrate as air passes through. Words: this, that, the, mother, weather
How to Tell Them Apart
Place your fingers on your throat. Say "think" slowly. You should feel no vibration on the TH. Now say "this" slowly. You should feel a buzzing vibration on the TH. That vibration is the difference between /θ/ and /ð/.
Why These Sounds Are Hard
Most languages do not have dental fricatives. Speakers of different languages tend to substitute them with different sounds:
- Spanish speakers often say /t/ or /s/ for /θ/, and /d/ for /ð/ ("tink" or "sink" for "think", "dis" for "this")
- Portuguese speakers often say /f/ or /t/ for /θ/, and /d/ or /v/ for /ð/ ("fink" for "think", "brover" for "brother")
- French speakers often say /s/ or /f/ for /θ/, and /z/ for /ð/ ("sink" for "think", "zis" for "this")
Tongue Position Guide
- Open your mouth slightly.
- Place the tip of your tongue between your upper and lower front teeth. Your tongue should be visible if you look in a mirror.
- For /θ/: blow air gently through the gap. Do NOT vibrate your vocal cords.
- For /ð/: blow air gently AND vibrate your vocal cords at the same time. You should feel a buzz in your throat.
A common mistake is pulling the tongue back too far. If your tongue is behind your teeth (like for /t/ or /d/), you will produce the wrong sound. Keep it forward, touching or between the teeth.
Practice: Voiceless /θ/ Words
Focus on keeping your vocal cords still. Only air should pass through.
Practice: Voiced /ð/ Words
Same tongue position, but now add voice. Feel the vibration in your throat.
Minimal Pairs: Train Your Ear
These word pairs show how replacing /θ/ or /ð/ with a different sound changes the meaning entirely.
/θ/ vs /t/
- three /θriː/ vs tree /triː/
- thick /θɪk/ vs tick /tɪk/
- thin /θɪn/ vs tin /tɪn/
- bath /bæθ/ vs bat /bæt/
/θ/ vs /f/
- three /θriː/ vs free /friː/
- thought /θɑːt/ vs fought /fɑːt/
- thin /θɪn/ vs fin /fɪn/
- throw /θroʊ/ vs fro /froʊ/
/ð/ vs /d/
- they /ðeɪ/ vs day /deɪ/
- then /ðɛn/ vs den /dɛn/
- those /ðoʊz/ vs doze /doʊz/
Practice Sentences
Try these sentences that mix both TH sounds. Go slowly at first, then build up speed.
- "I think that the weather will be warm this Thursday."
- "The three brothers went through the tunnel together."
- "My mother and father think this is their best theater show."
Tips by Language
For Spanish Speakers
You already make a sound close to /ð/ when you say the "d" in words like "cada" or "nada" between vowels. That soft, relaxed "d" is very similar to English /ð/. Try isolating it and using it in English words like "this" and "mother".
For Portuguese Speakers
The biggest trap is substituting /θ/ with /f/. Both are voiceless fricatives, so they feel similar, but the tongue position is completely different. For /f/, your lower lip touches your upper teeth. For /θ/, your tongue tip touches your upper teeth. Practice in front of a mirror to make sure your lip is not moving up.
For French Speakers
You tend to use /s/ and /z/ instead of /θ/ and /ð/. The fix: move your tongue forward. For /s/, your tongue is behind your teeth (alveolar position). For /θ/, push it forward until the tip is between your teeth (dental position). It is a small physical shift, but it makes a big difference in sound.
Key Takeaways
- English has two TH sounds: voiceless /θ/ (think) and voiced /ð/ (this).
- Both require the tongue tip between or touching the upper teeth.
- Check with the "throat test": /ð/ vibrates, /θ/ does not.
- Use a mirror to confirm your tongue is visible between your teeth.
- Practice minimal pairs to hear and feel the difference from /t/, /f/, /s/, /d/, and /z/.