If there is one sound that reliably marks a speaker as non-native, it is the English 'th'. Knowing how to pronounce the th sound in English matters not because of accent purity, but because getting it wrong often replaces one word with a completely different one — and the listener has to do repair work to understand you. This guide covers both versions of the sound, explains exactly what your tongue should be doing, and gives you the kind of deliberate practice that actually changes a habit.
There Are Two 'th' Sounds, Not One
Most learners treat 'th' as a single target. It isn't. English has two distinct sounds that share the same spelling:
- Voiceless 'th' — as in think, three, bath, author, method. Your vocal cords do not vibrate. It is a pure breath sound.
- Voiced 'th' — as in the, this, that, those, brother, breathe. Your vocal cords do vibrate. It has a slight hum beneath it.
The tongue position is identical for both. Only the voicing changes. If you can make one, you are already most of the way to the other.
Where the Tongue Actually Goes
The sound is a dental fricative. 'Dental' means involving the teeth; 'fricative' means air is squeezed through a narrow gap, creating friction rather than a full stop.
Here is what to do:
- Part your lips slightly.
- Place the tip of your tongue lightly against the back of your upper front teeth — or let it protrude just a little between your upper and lower teeth. Both positions work. Neither is more correct than the other.
- Push air over the top of your tongue and through the gap. You should feel the air on your tongue.
- For the voiceless version, that is all — pure moving air.
- For the voiced version, add your voice at the same time. Put two fingers lightly on your throat and feel the vibration begin.
If you say think correctly, your larynx is quiet. If you say the correctly, your larynx hums. That is the entire physical difference.
The Mirror Test
Hold a small mirror in front of your mouth. When you say the voiceless 'th' (as in thin), you should see a faint cloud of condensation on the glass — the escaping air. When you say it as 't' or 'd', you will not see that cloud because the air is released in a burst rather than a flow. This is one of the few cases where watching yourself in a mirror gives you genuinely useful feedback.
The Most Common Substitutions
Depending on your first language, you will likely replace 'th' with one of these sounds:
| What you say | What the listener hears | Example |
|---|---|---|
| /d/ for voiced 'th' | "dis" for this, "dey" for they | Common in many languages |
| /t/ for voiceless 'th' | "tink" for think, "tree" for three | Common in Irish English, some Asian Englishes |
| /s/ for voiceless 'th' | "sree" for three, "sofa" for author | Common in Greek, some Spanish varieties |
| /z/ for voiced 'th' | "ze" for the, "zis" for this | Common in French, German, Italian |
| /f/ for voiceless 'th' | "fink" for think, "baf" for bath | Common in some British regional accents and certain African Englishes |
None of these substitutions are shameful — they are simply what happens when a language does not contain a dental fricative and your tongue has never had to do this before. The task is not to feel self-conscious about it but to practise until the new movement becomes automatic.
Practise the Voiceless 'th' First
Because it contains no voice, the voiceless sound is easier to isolate. Start here.
Say the following words slowly, making sure you feel air flowing over the front of your tongue:
think — three — through — thank — thin — tenth — truth — method — author — teeth
Now say this sentence aloud: "I think the earth is three thousand times thicker than the crust."
There are six voiceless 'th' sounds in that sentence. Go slowly. Feel each one. If any of them collapses into a 't' or 's', stop, reset your tongue position, and try the word again in isolation before returning to the full sentence.
Now Add the Voiced 'th'
Once the voiceless version feels more reliable, add voicing.
Say these words: the — this — that — those — then — though — there — brother — weather — breathe — smooth
Now say this sentence: "This is the path they chose, though the weather threatened their plans."
That sentence contains both voiced and voiceless 'th' sounds. Read it slowly once, identifying which is which, then read it again at a natural pace.
- Voiced: this, the, they, though, the, their
- Voiceless: path, threatened, plans — note that plans contains no 'th' at all, which is a useful reminder to check your own perception and not over-apply the rule.
The Word 'The': A Special Case
'The' is the most frequently spoken word in English, and it has two pronunciations depending on what follows it.
- Before a consonant sound: the book, the car, the night — rhymes loosely with uh, said quickly.
- Before a vowel sound: the apple, the egg, the hour — rhymes with thee, said with a slightly longer vowel.
Both versions use the voiced 'th'. Because you say 'the' dozens of times in any conversation, getting the voiced 'th' right in this single word pays dividends immediately.
Building the Habit in Real Speech
Isolated word drills are necessary but not sufficient. The sound has to become automatic in connected speech, which means practising at speed.
A useful approach: pick three or four 'th' words that appear constantly in your domain — if you work in finance, that might be think, therefore, the, through. For a teacher, it might be this, that, the, three. Read one paragraph aloud each day from something you would actually say at work or in conversation. Mark the 'th' sounds in advance if it helps. Record yourself on your phone and listen back.
The gap between how you think you sound and how you actually sound is often large at first. That gap is not discouraging — it is information. Closing it is exactly what deliberate practice is for. If you want to understand more about how feedback-driven practice works, the how it works page explains the approach ummute takes.
A Note on Perfectionism
You do not need a perfect dental fricative every single time to be understood clearly. Native English speakers vary enormously — regional British accents, Irish English, and many varieties of American English have their own 'th' patterns. What you are aiming for is consistent enough that a listener never has to pause and decode whether you said three or free, think or tink, this or dis.
Those moments of decoding have a cost: they break the listener's attention, they slow down an interview or a presentation, and over time they can make you seem less confident than you are. See the benefits of working on individual sounds for a clearer picture of what consistent pronunciation actually does for how people receive you.
The 'th' sound is awkward because it is genuinely strange — very few of the world's languages use it. But it responds well to patient, physical practice. Put your tongue on your teeth, push air through, add your voice when required, and repeat until your mouth does it without asking permission.