The Th Sound
The th sound combines two sounds: the / T / and / D /. When two sounds come together to make a distinctive sound, it is called a digraph.
The th Consonant Sounds: / D / and / T /
The / T / sound involves passing air through the mouth while the / D / sound involves vibrating the vocal folds of your throat. However, the / D / sound only vibrates a little.
Making the th Sound
Both sounds require you to block air flow out of the mouth by your tongue and then releasing it. Let's practice this:
1) Bring your teeth together;
2) Move your tongue so that it comes in between the front teeth;
3) Relax your tongue and let the air flow out.
For step two, the tongue does not always come through the front teeth if one is talking fast of there are other complex sounds close to the th sound. The difference between the / D / and / T / is made in step three. For / T /, the vocal folds are at rest while they vibrate for / D /.
Words with the / T / Sound
/ T / sounds are commonly used in content words. Remember, this sound is not voiced, meaning the vocal folds do not vibrate. This includes, but is not limited to, north, both, three, through, thief, thin, thorn, thorough, thumb, Thursday.
Words with the / D / Sound
/ D / sounds are commonly used in function words. Remember, this sound is voiced, meaning the vocal folds vibrate a little. This includes, but it is not limited to, them, themselves, these, there, then, this, those, and together.
Say these / T / words: north, both, three, through, thief, thin, thorn, thorough, thumb, Thursday.
Say these / D / words: them, themselves, these, there, then, this, those, together and with.