"Th" sound:
* The most common way to spell this sound is "th". Examples: think, thank, thumb, thin, father, mother.
* There are some exceptions with words of Greek origin where "ph" represents the "th" sound: Examples: phone, phantom, photograph.
"Dh" sound:
* The "dh" sound is rare in English. It's primarily found in:
* Words of Indian origin like "dharma" and "Dhanush".
* Some borrowed words from other languages where the spelling "dh" is kept.
* Occasionally in dialectal pronunciations.
In practice:
* You'll rarely encounter "dh" in English. The sound "th" is far more prevalent.
* Pay attention to the context of the word to determine the correct sound when you see "th" or "ph". For example, "thin" has a different sound than "phone".
Let me know if you have any more questions about English sounds!