How to pronounce the TH sound in English (θ and ð), with a five-minute drill

TH is the sound English learners complain about most, and for a good structural reason: the two dental fricatives written "th" are rare across the world's languages. Most languages have no sound made by putting the tongue between the teeth, so when your mouth meets one it substitutes the nearest thing it already owns — a /t/, a /d/, an /s/, a /z/ or an /f/.

That substitution is not laziness and it is not an accent flaw. It is your motor system doing exactly what it was trained to do. Retraining it takes about a week of deliberate practice, and it starts with knowing that there are two TH sounds, not one.

The two sounds

Put two fingers on your throat, just below the jaw. Say a long "sss" — no vibration. Say a long "zzz" — vibration. That vibration is voicing, and it is the only difference between /θ/ and /ð/. Everything your tongue and lips do is identical.

The spelling gives you no help at all: th is written the same way for both. There is a rough pattern — the small grammatical words (the, this, that, these, those, them, then, there, though, than) take voiced /ð/, while most content words take voiceless /θ/ — but there are enough exceptions (mother, brother, weather, together, breathe) that the pattern is a hint, not a rule. Learn the frequent words individually.

Tongue position, in one sentence

Tip of the tongue lightly between the teeth, air flowing continuously over the top of it, lips doing nothing.

Three details decide whether it works:

• Light contact. The tongue touches the teeth; it does not push through them. If it feels like you are biting your tongue, you have gone too far, and it will show up in fast speech as a stumble.
• Continuous air. TH is a fricative — friction, not a blockage. If the air stops and then bursts out, you have made a /t/ or /d/ instead.
• No lips. If the lower lip moves toward the upper teeth, you have made /f/ or /v/.

The mirror test: say think in a mirror. You should see the tip of your tongue. If you see only lips and teeth, you are producing something else.

What your first language pushes you toward

These are the standard, well-documented substitutions. Find your row and the minimal pair that exposes it.

Arabic speakers are the lucky exception: Modern Standard Arabic has both dental fricatives, so the sounds already exist in your inventory and it is only a matter of using them in English words.

Two things are worth saying plainly. First, some of these swaps are meaning-changing and some are not. Think becoming sink changes the word and will cause real misunderstandings. A slightly dental /t/ in place of /θ/ at the end of month rarely does. Fix the meaning-changing ones first. Second, native speakers substitute too — th-fronting (think as fink) is standard in much of London and Essex, and th-stopping (this as dis) is standard in Irish English and parts of New York. The goal is being understood, not erasing where you are from. That distinction is the whole argument in accent-tolerant scoring.

The five-minute drill

Do all three blocks in order. Blocks 1 and 2 are ear and mouth training; block 3 is where the habit either survives or collapses.

Block 1 — words in isolation (90 seconds). Voiceless first, then voiced. Exaggerate the tongue position; you can pull it back later.

/θ/: think · thank · three · thin · thirty · path · month · bath · health · nothing

/ð/: this · that · they · then · there · mother · brother · weather · other · breathe

Block 2 — minimal pairs (90 seconds). Say both, then have someone else guess which you said. If they cannot tell, the contrast has not landed yet.

Block 3 — sentences (2 minutes). Isolated words are easy. TH inside a phrase, at speed, is the real test.

• Record: "Think about this thing for three months."
• Record: "My brother and mother think the weather is healthy."
• Record: "There are thirty-three paths through the northern field."

The second sentence alternates voiced and voiceless TH, which is where most people discover they have been producing only one of the two.

Three mistakes that show up on a recording

Over-biting. Beginners push the tongue far out between the teeth, which is fine for a slow drill and impossible at conversational speed. Once the sound is reliable, pull the tongue back until only the very tip touches. The sound survives; the effort disappears.

Dropping /θ/ at the end of a word. Month becomes mon, health becomes hell, sixth becomes six. Word-final TH after a consonant is genuinely hard, and it is the position learners abandon first. It is also grammatically loaded — six and sixth are different words. Practise final TH separately from initial TH.

Voicing the wrong one. Saying thing with a voiced /ð/, or this with a voiceless /θ/. This is subtler than a full substitution and native listeners often register it as "something slightly odd" rather than a specific error, which makes it hard to self-diagnose. The throat-finger test during practice is the fix.

Tracking whether it is actually improving

Self-assessment on TH is unreliable, because if your ear files /θ/ and /s/ in the same category you cannot hear whether you just succeeded. You need feedback from outside your own head: a teacher, a patient friend, or a tool that inspects the phoneme rather than the word.

If you record the drill sentences in sayit, the useful signal is not the overall score — it is the per-word breakdown. Each word gets a clarity verdict, and opening a flagged word shows the target pronunciation in IPA next to the phonemes that were actually detected. A row reading /θ/ replaced by /s/ on think is a completely different problem from think simply being unclear, and it tells you which drill to run.

Two practical notes. Because the analysis works from the sounds rather than from a transcript, it does not quietly repair sink into think the way a dictation model would — that failure mode is explained in the autocorrect problem. And when the same substitution shows up across several words in one take, it appears in the focus areas list, which is a more honest read on your week than any single recording.

Move on to the next sound when TH is landing cleanly in block 3 sentences, not when it is landing in block 1 words. Isolated-word success is a false summit.

Questions people actually ask

Do native speakers always pronounce TH? No. Whole regions of the English-speaking world systematically use /f/ or /t/ instead. What native speakers do reliably is stay consistent, so listeners tune to their pattern within a sentence. The reason to learn /θ/ and /ð/ anyway is that they are the internationally neutral forms and the ones exam rubrics are written against.

Is TH ever stressed? TH is a consonant, so it does not carry stress itself, but it appears in both stressed syllables (THINK, THIR-ty) and completely unreduced-proof positions in function words (the, that), where the vowel reduces to a schwa but the /ð/ stays. See the schwa for what happens to the vowel next to it.

How long does it take to fix? For most people, a few days to make the sound reliably in isolation and one to three weeks to stop losing it inside fast sentences. The sentence stage is where nearly all the time goes, and it is the stage most learners skip.

Should I fix /θ/ or /ð/ first? /θ/, because it appears in more content words and its substitutions (sink, tin, free) collide with more real English words. /ð/ mostly appears in function words that context rescues.

Where to go next

TH is one entry in a longer list — the sounds that are hard for almost everyone are catalogued in the hardest English sounds, and the general method behind the drill above is set out in minimal pairs practice.

To find out whether TH is actually your bottleneck rather than the sound you have been told to worry about, record one sentence for free and look at which phonemes were flagged. It takes about ten seconds and needs no install and no card.