How to pronounce the “th” sound (θ and ð)

English spells two different sounds with the same two letters: th. They trip up learners from almost every language background, because many languages do not use them at all. The good news is that both are made the same way — once your tongue knows the position, the rest is practice.

The two “th” sounds

There are two of them, and the International Phonetic Alphabet (IPA) gives each its own symbol:

• Voiceless θ — as in think, bath, three. Your vocal cords do not vibrate.
• Voiced ð — as in this, mother, breathe. Your vocal cords do vibrate.

Try it: put a hand on your throat. Say a long thhh as in think — no buzz. Now say the th in this — you should feel a buzz. That buzz is the only difference between the two sounds; the tongue does exactly the same thing for both.

What your tongue actually does

The “th” sounds are dental fricatives. That means:

1. The tip of your tongue rests lightly against the back of your top front teeth — or just peeks between the teeth.
2. You push air through the narrow gap. The friction of that air is the sound.
3. For ð, you add voice; for θ, you don’t.

There is no need to stick your tongue out dramatically. A light contact is enough, and it keeps the sound quick and natural.

Why learners get it wrong

Because “th” is rare across languages, most people borrow the closest sound they already have. The usual substitutions are:

You might say	Instead of	Example
s / z	θ / ð	sink for think
t / d	θ / ð	dis for this
f / v	θ / ð	free for three

None of these are wrong in your first language — they are just different sounds. The fix is the same in every case: move the friction from your lips or the ridge behind your teeth forward to the teeth themselves.

Quick check: if you can feel air on the underside of your tongue near your top teeth, you’re in the right place. If the air is escaping past your lips, you’ve drifted toward /f/.

A short practice routine

Minimal pairs — words that differ by a single sound — are the fastest way to train the contrast:

• θ vs s: think / sink, thick / sick, path / pass
• ð vs d: they / day, though / dough, breathe / breed
• θ vs f: three / free, thought / fought, deaf / death

Say each pair slowly, exaggerating the tongue position at first, then speed up until it feels natural in a full sentence.

Practising with Phonym

Reading about a sound only gets you so far — you have to hear yourself. The fastest way in is shadowing: play the native model, say it straight back, and repeat. Phonym listens to your attempt, lines it up against a native reference, and marks each sound as correct, close, wrong, or missing, so you can see at a glance whether your “th” landed or slid toward /s/ — the one thing plain shadowing can’t tell you on its own. The tricky words come back on a schedule until the new tongue position is automatic. The “th” contrast is a great place to start, in either British RP or General American — the sounds are the same in both accents.