01 / 06
What the ⟨th⟩ spelling actually hides
In English, ⟨th⟩ is not a letter pair with a single value; it is a spelling that hides two different sounds. Both are dental fricatives: the tongue tip touches the edge of the upper front teeth lightly, and the air flows continuously between tongue and teeth. The first is voiceless /θ/, called "theta" in phonetic notation, as in think, three, thanks, month and third. The second is voiced /ð/, called "eth", as in the, this, they, with and other. The only difference between them is voicing: with /ð/ the vocal cords vibrate, with /θ/ they do not. Tongue position, airflow and lips stay identical. That is good news, because you only have to learn one movement and then decide whether to add a buzz to it. Just as importantly: each of these is a single sound, not a combination of t plus h. Anyone who says ⟨t⟩ and then ⟨h⟩ produces something that is not an English ⟨th⟩ at all. The symbols /θ/ and /ð/ come back on several slides in this lesson — learn them now, because they are the shortest way to talk about the difference.
02 / 06
How to produce the two sounds mechanically
The solution lives in your tongue tip, not in your ear. Place it lightly against the edge of your upper front teeth — some speakers push it a tiny way between the teeth, which is equally correct. What matters is that the contact stays light. Press too hard and you seal the mouth, the air backs up, and releasing it gives you a /t/ instead of a fricative. The contact has to be loose enough for air to escape the whole time. Now hold up a mirror: if you can see the tip of your tongue before the word starts, the sound can no longer come out as /s/. For /θ/ you simply blow — no tone, only air, like a very soft, lisped s. For /ð/ you add a finger on your throat and switch the voice on until you feel the buzz. Cover your ears and /ð/ hums inside your head while /θ/ does not. Practise the sound on its own first, then in a syllable, then in the whole word. Only once the tongue finds its way by itself should you add speed. That order — position, then voice, then speed — is the fastest route to a stable TH.
03 / 06
Which words take which sound
There are three environments in which ⟨th⟩ appears, and one workable rule of thumb for each. First, at the start of content words: there you almost always get voiceless /θ/ — think, thing, three, thanks, Thursday, third, thirty, thousand, through. Second, at the start of little function words: there you get voiced /ð/ — the, this, that, these, those, they, them, then, there, than, though. Third, in the middle and at the end of a word. Between vowels, ⟨th⟩ is voiced in old Germanic words: mother, brother, other, weather, together. In later learned borrowings, many of them Greek, it is voiceless: method, mathematics, sympathy, theory. Word-finally it is usually voiceless — month, both, north, health — but voiced in the verbs breathe and bathe, and in with for many speakers. In this lesson the reading tabs are deliberately ordered by how often you meet each sound in running speech, which is why voiced /ð/ comes first: words like the, this and they turn up in almost every English sentence. These notes, by contrast, open with /θ/, because that is the harder sound for German speakers to produce.
04 / 06
The typical mistakes German speakers make
German has neither dental fricative, so the mouth automatically reaches for the nearest sound in its own inventory. Five patterns come up again and again. First, /s/ for /θ/ — I think becomes "I sink", thanks becomes "sanks", three becomes "sree". Second, /z/ for /ð/ — this, that, the, they become "zis, zat, ze, zey". Third, the stops /t/ and /d/ — "tink" for think, "dis" for this. This repair shows up especially in emphatic, careful speech, and it produces a closure where English needs continuous airflow. Fourth, final devoicing, known in German as Auslautverhärtung: German neutralises voicing at the end of a word, and the habit travels into English. breathe then comes out as /briːθ/ or /briːt/, clothes as /kləʊθs/, and with ends hard. In English, a word-final /ð/ has to keep buzzing. Fifth, over-correction once the rule lands: suddenly Thomas /ˈtɒməs/, Thames /temz/ and Thailand get a TH, even though ⟨th⟩ there simply spells /t/ — or the article the gets devoiced, although it is always /ðə/ or /ði/. On top of that come two purely motor problems: the /θr/ cluster in three, throw, through, which easily collapses into "free" or "tree", and the /θs/ cluster in months, sixths, lengths, which even native speakers simplify. You should be able to produce it fully at slow speed, but you do not need to treat the reduced form as an error.
05 / 06
/θ/ versus /ð/: minimal pairs and the breath–breathe pair
The fastest way to keep the two sounds apart is minimal pairs — word pairs that differ in one sound only. On the voiceless side, drill think–sink, thing–sing, thick–sick and three–free–tree. Most learners already know these. The voiced half tends to get skipped, even though that is where the most frequent errors live: they–day exposes the "dis" error, breathe–breeze exposes the "zis" error, and then–den and worthy–wordy belong in the same set. Say each pair slowly first, then at normal speed, and have someone listen whose only job is to say which of the two words they heard. One especially instructive case is the pair breath and breathe. The noun breath is /breθ/, short vowel, voiceless ending; the verb breathe is /briːð/, long vowel, voiced ending. English has a small family of such pairs where vowel and voicing shift together: bath /bɑːθ/ – bathe /beɪð/, cloth /klɒθ/ – clothe /kləʊð/. The silent ⟨e⟩ at the end is the spelling clue. This is exactly where German final devoicing bites, because breathe has to keep buzzing right to the end.
06 / 06
The TH sound at work
In working English, only a handful of words demand this sound again and again — and they turn up precisely in the situations where you are under time pressure. Thanks and thank you appear in nearly every email and every conversation. Third is what you need for dates and for ordering points on an agenda. Thousand comes up in figures and budgets, month in deadlines and reporting periods, and this Thursday is the standard phrasing when you confirm an appointment. These words run through the whole lesson, from the opening sentence to the final quiz. On the phone the difference matters even more, because the other person cannot see your lips and has only the sound to go on: three and free then separate a quantity from a price. So take the sentences you use habitually and say them aloud before you need them — for instance "Thanks, I think the third meeting is this Thursday". Once your tongue knows that sentence, it will find the sound even while you are busy thinking about something else. Pronunciation does not improve by listening alone; it improves through repeated speaking aloud with a conscious tongue position.