The 'th' sound in English: /θ/ and /ð/ without stress.

The English 'th' has two faces. One is voiceless, the other vibrates. If your tongue never makes this gesture in other languages, the trap is inevitable… but the mechanics can be mastered quickly with two simple references and a mirror.

The two sounds of 'th'

In English, 'th' is written for two different consonants: the voiceless '/θ/' (no vibration) as in "think", and the voiced '/ð/' (with vibration) as in "this". In both cases, the tongue lightly touches the teeth: tip against the edge of the upper incisors or very slightly between the teeth. The air rubs around the tongue: it’s a fricative. These two sounds are described as interdental fricatives in standard English according to the article "Dental fricative" on Wikipedia.

Voiceless vs voiced: the throat test

Place two fingers on your throat and say '/θ/' then '/ð/'. For '/θ/', nothing vibrates; for '/ð/', you feel the buzzing. Keep a steady stream of air and your tongue relaxed: the key is the friction (a breath), not a sharp hit like '/t/' or '/d/'.

Common pitfalls

Many learners replace '/θ/' with '/s/' or '/t/', and '/ð/' by '/z/' or '/d/'. Or '/θ/' and '/ð/' are interdental fricatives: air must flow continuously with a slight hissing sound. Two other useful details: the determiner "the" has a weak form '/ðə/' and a strong form '/ðiː/' depending on the rhythm, and words ending in 'th' vary according to the accent ("with" is often pronounced '/wɪθ/' or '/wɪð/').

• Minimal pair t/θ: "tin" /tɪn/ vs "thin" /θɪn/ — keep the friction sound for '/θ/', don't snap like '/t/'.
• Minimal pair d/ð: "den" /dɛn/ vs "then" /ðɛn/ — vibrate for '/ð/', without blocking the air like '/d/'.
• End of word: "with" '/wɪθ/' or '/wɪð/' (both exist). "clothes" '/kloʊðz/' often simplifies to '/kloʊz/' in quick conversation.
• Don't press too hard: keep your tongue relaxed, light contact. Pressing too much cuts off the air and turns '/θ/' into '/t/'.

My experience

At first, I thought I was doing the right thing… until the day I filmed my mouth. I saw my tongue staying behind my teeth: naturally, it sounded like a '/s/'. The breakthrough came with a simple exercise: mirror, regular breathing, and a tiny bit of tongue visible. I also learned not to force my jaw: when I'm tense, the '/θ/' becomes a '/t/'. Since then, I've been practicing with short sets: five 'think', five 'this', then pairs 'thin–then'. It's repetitive… and it works.

How to train

Structure your sessions: breath first, voice next, then string together words and phrases. If you like to see phonetics, display the IPA to check the targeted sound — it's available in Discus: you can request the IPA word by word and activate a global display preference. Details here: IPA and pronunciation.

1. Friction first: make a long '/θ…/' without voice, then add the vibration for a '/ð…/' stable. 3 sets of 10 seconds.
2. Minimal pairs: slowly say "thin–then", "thought–though", "three–tree". Keep your tongue against your teeth at the beginning of the word.
3. Function words: link "the, this, that, these, those, there, they" in rhythm. Switch from the weak form '/ðə/' to the strong form '/ðiː/' for "the".
4. Record yourself: 30 seconds of reading aloud with "with, both, breathe, smooth". Listen again: do you hear the friction?

Progressive word list

Practice from the simplest to the most challenging. Keep your breath steady and maintain light contact between your tongue and teeth.

• /θ/ initial: think, thin, three, thank, theory.
• /ð/ initial (function words): the, this, that, these, those, they, there.
• Word final: with, both, bath, breath /brɛθ/, breathe /briːð/, smooth.
• Groups and phrases: "thank you", "this thing", "see you there", "my brother and mother".

To go further

In terms of terminology, '/θ/' and '/ð/' are interdental fricatives, one voiceless (without voicing), the other voiced. Their distribution in modern English follows a useful trend: many grammatical words (determiners, pronouns, adverbs like "the, this, that, these, those, there, they, thus") carry '/ð/' in initial position, while many content words start with '/θ/' ("think, three, thousand"). Morphologically, observe the pairs "breath" '/brɛθ/' (noun) vs "breathe" '/briːð/' (verb) or "bath" '/bæθ/' vs "bathe" '/beɪð/': the alternation of voicing often marks derivation. Historical context: English used to denote these sounds with the letters thorn (þ) and eth (ð) before the generalization of the digraph "th" in modern spelling. If you analyze your accent, identify where you neutralize the frication (stops instead of fricatives) and work on coarticulation: start the interdental gesture.before the next vowel to stabilize the contrast.