The next sounds that we are going to look at are /θ/ as in thistle and /ð/ as in this,

We looked at these before, and saw that one is voiced and the other is unvoiced. These are notoriously difficult sounds for learners of English, as many languages do not use these sounds. 

How do we make the /θ/ sound?

Lift your tongue so that the tip makes gentle contact with underneath your upper front teeth. It doesn’t matter if the bottom of your tongue touches your bottom teeth - you won’t be pushing air through there. Relax your tongue so that the sides touch the sides of your upper teeth, and breathe out. If your tongue is tensed and narrow, the air will blow into your cheeks, rather than out between the tip of your tongue and your front teeth. 

The /ð/ sound is formed in the same way as the /θ/ sound, but with voice. 

Many students will try to substitute these sounds with alternative sounds that do exist in their language. Check that you are not doing this. 

/θ/ is often substituted with the voiceless sounds /t/ /f/ and /s/

‘I think’ turns into ‘I tink’, ‘I fink’ or ‘I sink’. You might hear young British children, who are still learning to speak, also make these mistakes. Some dialects also make these sounds. We all go through this process at some stage!

/ð/ is often substituted with the voiced sounds /d/ /v/ or /z/.

‘In this’ turns into ‘in dis’, ‘in vis’ or ‘in zis’.

Go back and rewatch the part where I describe how to form these sounds if you think you are making any of these mistakes. 

Let’s have a look at some words with the /θ/ sound

/θ/ is commonly spelt using:

1. th - thanks, both, healthy

/θ/ is often found in these clusters:

/θr/ - through, thread, three

/θw/ - thwart

Let’s practice the /θ/ sound in these sentences: 

Repeat after me:

1. I think Bertha is going to turn thirty-three on Thursday.
2. She thanked him for strengthening her teeth with tooth therapy.
3. Thirteen thirsty maths students celebrated Martha’s birth of a healthy baby.
4. Author Dorothy Beckworth wrote a thesis on ethical wealth growth.
5. Hypothetically, monthly baths reduce death threats.

Let’s have a look at some words with the /ð/ sound

/ð/ is usually spelt using:

th - the, father, smooth

Both /θ/ and /ð/ are only really spelt using th, but the th spelling doesn’t always represent these sounds - look at thyme and Thailand. It’s important that you bear this in mind.

Let’s practice the /ð/ sound in these sentences: 

Repeat after me:

1. Even though their team was the best they tried to go further.
2. Their mother was from the Netherlands, where the weather is rather rainy.
3. She breathed in the smooth southern air without a bother in the world.
4. His other brother wore the same leather clothing as their father.
5. These feathers were gathered by girls in bathing suits. 

Let’s have a look at some minimal pairs

/θ/ /ð/

ether either

mouth mouth

teeth teethe

loath loathe

And finally, let’s practice some sentences with both sounds.

1. If you have a bathing suit you can take a bath in one of the baths.
2. Thelma thanked the mother of the bride a thousand times.
3. This author’s method of soothing her brother causes bother.
4. There is no such thing as something for nothing in this world.
5. The athlete's enthusiasm brought everything together in the end.