I have a friend who pronounces the vowel in plague, vague, and bagel as
[æ] instead of the standard
[eɪ] (so plague rhymes with flag, for instance). Interestingly, he apparently can't tell the difference between the vowel sounds (i.e. even when I say
[væg] back-to-back, he can't tell me which pronunciation is the one he uses and which is the one I use).
I had at first assumed it was a regional pronunciation, but his wife is from the same relatively small (35k) town in western Michigan, and she uses the standard pronunciation.
Is this shift common in his region (or any other region, for that matter)? Is it otherwise explainable? Any insight would be appreciated.