1. Voiced "th"
* Sound: A soft, breathy sound similar to the "d" in "this" or the "z" in "zoo."
* Example words: this, that, then, father, brother, with, both, athlete
2. Unvoiced "th"
* Sound: A sharp, hissing sound similar to the "s" in "sin."
* Example words: thin, thing, three, math, cloth, bath, south, mother
How to distinguish them:
* Place your finger lightly on your throat. You'll feel a vibration with the voiced "th" sound, but not with the unvoiced "th" sound.
* Listen carefully to the sounds. The voiced "th" is softer and more breathy, while the unvoiced "th" is sharper and more hissing.
Let me know if you have any other questions about English pronunciation!