Biting your tongue in order to speak. The bite marks of dental fricatives.

If you know this:θand this: ð 

You're good, go on with your life. If not, consider reading this post.

English pronunciation can be pretty difficult if your first language doesn't have the same sounds. A lot of muscles need to be used(sometimes for the first time) and trained to produce a new sound.  Your tongue needs to get used to the exercise too, you just need to see all the bite marks on your tongue and mouth from the time you started practicing English.

These two sounds: θ and ð(in IPA phonetic notation), can be quite difficult for English learners. This might be especially true when you read them, because they are written the same way in English with the consonants "th".

Let's see the difference between these two sounds.

Voiceless Dental Fricative θ

Dental, as you might have guessed, means that you use your teeth to make this sound. You need to put your tongue between your teeth, some people say that you need to "bite" your tongue, that's good too, just remember not to do it too hard or you are going to look like a snake with a fork tongue.

Fricative means that you force air through the center of the tongue, the same way your force air when you pronounce the "S" sound in "sound". 💨

And finally, voiceless means that when pronounce this consonant your vocal cords are resting, the sound comes from the front of your mouth not from your throat.

Now combine all of these features together, and you can boast to your friends that you can pronounce The Voiceless Dental Fricative.

Here are some words that have this pronunciation:

Thing, think, thought, earth, lethal, tooth, thunder, authority, thread, three, tenth, math, breath, strength...

FYI: For all the Spanish speakers out there, this might come in handy. What we normally call the español de España, has exactly this sound. When you think of a Spanish accent normally you pronounce "S" and "C"(also "Z") differently, like in Corazón, Zapato, Cisne... This is what we call the voiceless dental fricative. 

Voiced Dental Fricative ð

Same exercise, put your teeth and tongue in the same place, is exactly the same. The only difference is that it is voiced. This means that you use your vocal cords to pronounce it.

There's something that might help you master this new sound. Try to pronounce a "D" in this position. 

Here are some words that have this sound:
Though, that, this, they, them, within, leather, feather, gather, mother, there, another, brother, father, neither, either...

Of course you can check with a native speaker if you're pronouncing it correctly, but this should help you understand what's behind the sound.

I hope this little article helped you in pronouncing these two sounds. Feel free to comment any ideas, suggestions, and... corrections? yeah, corrections, if you want.

Stay cool,

Mark