It's true that we stop discerning differences between sounds that don't carry meaning in our native languages, as you said, but I think it's possible to regain the ability later in life if you become very accustomed to the language and you find those differences mattering in your every day linguistic environment.
I gradually became fluent in Japanese over the 6 years I lived in Japan, and just last year I realized the way I had been pronouncing ん "n" in some contexts was wrong, but I only realized because I first noticed the way a native speaker was saying 千円 "sen-en" (the way I'd been saying it) was something more like se-yen (which maybe explains why in English we call it yen instead of 円 "en").
There were other pronunciation things I realized over time like this. So it takes a long time, but in my experience you can re-learn to make differentiation like that, and you really do start hearing things you couldn't before.
magifool t1_j4k5ebn wrote
Reply to comment by percautio in What it means to “know” a language by thenousman
It's true that we stop discerning differences between sounds that don't carry meaning in our native languages, as you said, but I think it's possible to regain the ability later in life if you become very accustomed to the language and you find those differences mattering in your every day linguistic environment.
I gradually became fluent in Japanese over the 6 years I lived in Japan, and just last year I realized the way I had been pronouncing ん "n" in some contexts was wrong, but I only realized because I first noticed the way a native speaker was saying 千円 "sen-en" (the way I'd been saying it) was something more like se-yen (which maybe explains why in English we call it yen instead of 円 "en").
There were other pronunciation things I realized over time like this. So it takes a long time, but in my experience you can re-learn to make differentiation like that, and you really do start hearing things you couldn't before.