Can I spell a voiced "th" without using IPA?
Solution 1:
This list of pronunciation respelling systems on Wikipedia gives a good idea as to what's used in various systems.
Here is a screenshot (irrelevant rows removed):
So, /θ/ (unvoiced th) is usually written as "th", while /ð/ (voiced th) has more variation:
- "dh"
- underlined t̲h̲
- capitalized TH
- italic th
- various strikethroughs (th̸, t̷h,
TH)
Solution 2:
The American Heritage Dictionary uses:
- 'th' for unvoiced th /θ/
- 'th' (italicized) for voiced th /ð/.
Reference (PDF).