The audio here is generated speech. A recorded human voice for this lesson is on the way.
The two sounds
TH is the sound most learners find hardest, because very few languages have it. Put the tip of your tongue lightly between your front teeth, or just behind them, and push air through the tiny gap. That's it. There are two versions. The voiceless one, in "think", "three" and "thank", is a soft hiss. The voiced one, in "this", "the" and "mother", adds a buzz.
The common substitutes are S, T, F, D and Z: "sink" for "think", "tree" for "three", "dis" for "this". People will usually understand you, but TH is one of the quickest ways to sound clearer. Seeing your tongue tip in a mirror is the whole trick.
Hear the difference
Tap each word. Then test your ear.
Voiced TH, as in "this", against D and Z below.
Say it out loud
Tap a sentence to hear it. Say it after the voice.
Practice · 3 min
Say each sentence slowly with a mirror, showing your tongue tip on every TH. Then say it at normal speed. Record the second sentence and count the TH sounds you hear: there should be seven, including the one at the end of "month".
Say it today
Use it once in a real conversation before tomorrow. Out loud counts, even to yourself.