This is to figure out whether it’s a dialect difference or whether I’m just really unobservant about pronunciations (I pronounced ‘dull’ as homophonous with ‘dole’ for years; apparently this is weird).
So for me, ‘am’ (first person singular form of ‘to be’) is [ɛm] and so is the letter M.
For my friend who has a contrast, it’s M = [ɛm] and am = [æm].
Or to put it simply, I am rhymes with hem, not with Sam.
I don’t think I’ve ever heard anyone pronounce them the same…and am and Sam are definitely much closer than am and hem. Are you southern?
I’m from the Virginia suburbs of DC.
Depends on context, “am” and “M” can be the same sound in some cases, but generally I’d say they’re different.
In before guizot makes his traditional post about the uselessness of self-reporting on things like this. I never thought about it until now but I’ll wager big money I pronounce am and M the same unless I’m emphasizing am for some reason.
“Am” rhymes with “ham.”
“M” rhymes with “hem.”
Now I suppose you’re gonna tell me “ham” rhymes with “hem.”
Different. But how often does one really say “am”? Is it ever used except following “I”, and then isn’t it almost always said “I’m” (which, for me anyway, rhymes with “lime”)?
It depends. If I answer “I am.”, it rhymes with ham. If it’s spoken quickly in the middle of a sentence, it sounds like “m”.
“Am I?”
I said “differently”, but that’s if I’m paying attention. In casual speech I doubt you’d hear any difference when listening to me.
I used to say it the same, when I still had a Michigan accent. Now I don’t.
I’d say I pronounce am “em” (like the letter m) about 75% of the time so I put that I pronounce them the same.
Differently for sure.
Am I saying ‘M’ the same? No.
Very differently.
One of my friends in high school said “I em!” all the time (it bugged me, she said melk instead of milk too, and aygs instead of eggs). I believe her mom was from the south, but I don’t know which state.
“Are you hungry?” “Yes, I am.”
Am rhymes with Sam
M rhymes with hem.
(I’m rhymes with lime).
I don’t even do it when speaking “lazily,” as /æ/ before nasals gets fronted in my dialect, but /ɛ/ does not. So even if I get lazy and open my mouth the same amount, they still sound distinct.
BTW, OP: which of dole and dull were you said to have pronouncing incorrectly? Am I right in thinking it was dole?
Ha, you funny Americans with your vowel rationing.
We’ve got bucketloads over here in England. Sometimes we even shove two into one syllable just for the diphthongised heck of it. Perhaps we should ship a few containers of them over, and you can finally distinguish between Mary, merry and marry; or Aaron and Erin; or cot and caught; and all those other words of ours that you mangle 
Do you like green eggs and ham?