When I presented British /ӕ/ sound to three Korean English-familiar persons online – they are doing answering English-related questions activities [case 1; case 2], and asked what sound it’s like /ӕ/ or /ɑ/, astonishingly all three of them without hesitation checked out /ɑ/. That shows how difficult it is to differentiate the two sounds for Koreans.
I can perceive both British and American /ӕ/ are made at the front. But the former sound is far more similar to Korean’s “ㅏ” sound. That’s why the Koreans all hear /ɑ/. And this definitely shows, I wonder, that there’s some difference between British and American /ӕ/. Would you let me know the difference?
Best Answer
The complete story is too complex to fit into an answer here.
The short story is that there are many accents in America, and there are many, many, many accents in Britain, and just exactly what happens to phonemic /ӕ/ and to phonemic /ɑ/ varies incredibly in many of them, so much so that things can sound like different words.
The thing you were probably noticing was the TRAP–BATH split, which occurs on both sides of the Altantic but moreso in Britain than America. However, there are quite a few other factors, too; it is by no means the only one affecting any of this. Some of those accents can even seem comical to those who don’t have it, and vice versa.
The medium story can be found here in the Wikipedia article on the “phonological history of English short a. I strongly suggest that you read it in full. It can be quite subtle, and perhaps surprising. I think you may be astonished at all the variants.
The long story can perhaps be found by chasing the bibliographic references provided there.