I have a friend who was complaining today about the pen pin merger, which he says he has been encountering more on national media.
Well, the population has been moving south, and that's the locus of pin pen merger!
'This is another academic term for something you’ll recognize the second you hear it. In this merger, words that end in -en or -en merge with the vowel in words like pin or Tim. So, for example, my own name, Ben, sounds more like “bin,” and hem sounds a bit like “him.”'
You hear it in Chicago from people whose recent ancestors came from down South - which includes a large proportion of African Americans here. I remember a nun in elementary school - she was from Massachusetts - trying to get a black student to say "pen" not "pin". He didn't seem to be able to.
I'm guessing he just needed more specific instruction, and probably a lot of practice, to master speaking consistently with the distinction:
"It's absolutely normal not to be able to reliably hear or pronounce a distinction that not part of your native phonological system. This is an experience that I've had every time I've encountered a new language, or a new variant of English. But usually people can hear that a minimal pair, performed side-by-side in the over-distinct facultative style of such productions, is in fact different; and usually it's fairly easy to learn to identify which member of such a pair is which."
I hear them as different, personally.
Pin does not rhyme with pen
Pin rhymes with been
And pen with again.