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- TH has two sounds: voiceless TH (think) and voiced TH (this).
- Both are made with the tongue lightly between or behind the teeth.
- The difference is voicing: voiced TH uses the voice, voiceless TH does not.
- Common substitutions are s, z, t, d and f sounds — avoid these.
- Voiced TH often appears in common function words like the, this, that.
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The English TH spelling represents two sounds that do not exist in many languages: the voiceless TH in think and the voiced TH in this. Both are made by placing the tongue between the teeth, which is why learners often replace them with s, z, t, d or f sounds. This guide explains the tongue position, gives word lists and shows you how to practise both sounds.
Two TH Sounds
The single spelling TH stands for two different sounds. The difference is whether you use your voice.
Voiceless TH: think, three, bath, mouth
Voiced TH: this, that, mother, breathe
Tongue Position
For both sounds, place the tip of your tongue lightly between or just behind your top and bottom front teeth, then push air through the small gap. The only difference is that the voiced TH adds vibration from the vocal cords.
The Voiceless TH Sound
The voiceless TH uses no voice — just air pushed past the tongue. It often appears at the start of content words and in many ordinal numbers.
think, thing, thank, three, thirty
both, month, north, fourth, fifth
The Voiced TH Sound
The voiced TH adds vocal-cord vibration. It is extremely common because it appears in many short function words.
the, this, that, these, those
they, them, then, mother, father, weather
Minimal Pairs
Practising minimal pairs — words that differ by only one sound — trains your ear and mouth to keep TH distinct from common substitutes.
TH Minimal Pairs
| TH word | Substitute |
|---|---|
| think (voiceless TH) | sink (s) |
| three (voiceless TH) | tree (t) |
| they (voiced TH) | day (d) |
| then (voiced TH) | den (d) |
Common Mistakes
The most common mistake is replacing TH with another sound: s or z (so think becomes sink), t or d (they becomes day), or f (three becomes free). The cause is usually keeping the tongue behind the teeth rather than between them. Slowing down and consciously placing the tongue, then practising minimal pairs, fixes the problem over time.
Sentences for Practice
Once you can produce both sounds in single words, the next challenge is keeping them clear in connected speech, where TH appears very often. Practise the sentences below slowly, then at a natural speed.
Voiceless TH: I think Thursday is the third of the month.
Voiced TH: They thought that this was their mother's.
Both: The three brothers breathe through their mouths.
Sentences like these are demanding because the voiced TH words — the, they, this, their — come thick and fast, while the voiceless TH words such as think and third need clear airflow without voice. Record yourself and listen back, checking that think does not turn into sink and they does not become day. Regular practice with sentences, not just isolated words, is what carries your improved TH sounds into real, flowing speech.
Do not be discouraged if the TH sounds feel awkward at first — they are among the last sounds that even native-speaking children master, so they genuinely are difficult. The key is little and often: a few minutes of focused practice every day will improve your TH far more than one long session a week. Start slowly and exaggerate the tongue position so you can feel exactly where it goes, then gradually speed up until the sounds fit naturally into ordinary words. With patience, the movement becomes automatic, and you will produce clear TH sounds without having to think about your tongue at all.
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