Vowel merging problems

I'm sure this has been asked before, but basically my variety of English does not distinguish between the "ä" of calm, the "ŏ" of rot, and the "aw" of raw. They have all merged.

What is the recommended practice for people like me? Use the "a" or the "o" symbol for this vowel?

I also find the grouping of the diphthong of "tame" with the a-group rather strange. It's based on written English, but not phonetics. Same goes for including the vowel of "cut" in the u-group. I wish there were a fix or tweak for these inconsistencies that bug my inner phonetician. :)


(by sonjachick for everyone)