How to pronounce "th" in English (both of them)

Two sounds, one spelling

Say "think" and put your hand on your throat. You should feel nothing. The air just flows out over your tongue.

Now say "this" the same way. You should feel your throat vibrate. Same tongue, same air, plus voice.

The spelling does not tell you which one a word uses, so you learn it word by word. There is one helpful pattern: the very common grammar words start with the buzzing th — the, this, that, they, them, then, there. Most other words that begin with th use the quiet one: think, thank, three, Thursday.

Between two vowels, the buzzing th is normal: mother, other, weather, brother.

Why it is hard

Very few languages have these sounds, so most learners have never made them. When your mouth meets a sound it does not know, it picks the closest sound it does know. That is why th usually comes out as s, t, f, z, d or v.

Those substitutes are close, and that is the problem. "Think" becomes "sink" or "tink". "They" becomes "day" or "zey". "Three" becomes "tree" or "free". Each of those is a real English word, so listeners hear the wrong word rather than an accent.

There is a second reason. In every substitute sound, your tongue stays behind your teeth. In th, it comes forward and touches them. Your tongue has spent your whole life staying inside your mouth, and this sound asks it to come to the edge.

How to make it

Step one. Open your mouth a little. Put the tip of your tongue against the bottom edge of your top front teeth. Just touching — do not push hard.

Step two. Keep the tongue there and blow gently. The air must escape over the top of your tongue, between the tongue and the teeth. You should feel air on your tongue tip. That is the quiet th, as in think.

Step three. Do exactly the same thing and turn on your voice. Your throat vibrates. That is the buzzing th, as in this.

Two important notes. The tongue does not tap or hit. It rests and the air keeps moving, so you can hold both sounds for several seconds. If you cannot hold the sound, you probably made a t or a d instead.

Also, the tongue can go slightly between the teeth while you learn. That is fine at the start. Later, most speakers just touch the back or bottom edge of the teeth, and you can move to that once the sound is easy.

Words to practice

Hold the sound first, with no word around it. Blow air over your tongue for five seconds. Then add voice for five seconds. Do this ten times.

Now the quiet th: think, three, thank, health, month, both.

Now the buzzing th: this, that, they, mother, weather, other.

Now the pairs that catch learners out. Say them slowly, one after the other: think and sink, three and tree, thin and fin, they and day, breathe and breed.

Then practice th at the end of words, which is where it is easiest to drop: month, both, with, mouth, health. Keep the air flowing until the word is finished.

Finally, use a short sentence that has many of them: "I think this is the third one." Say it slowly five times, then at normal speed. Slow first, always. If the sound falls apart when you speed up, go back to slow — speed comes from the habit being easy, not from trying harder.

What to listen for

Listen for length. A th can be held. A t or a d cannot — they stop the air. If your "think" starts with a short hit instead of a flow of air, it is a t.

Look, do not only listen. Use a mirror or your phone camera. You should be able to see your tongue tip at your teeth. If you cannot see it, it is probably still inside your mouth.

Record yourself saying "think" and "sink" one after the other, then listen. If they sound the same to you, they sound the same to everyone else too.

This is what TonePerfect is for: it scores each sound inside the words you record, so you can see whether your th is one of your weaker sounds, and it gives you the tongue position to fix it.

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