I'm not buying that explanation. Hearing, just like seeing, is something that you need to practice. If it's the first time you're hearing a specific sound then

I'm not buying that explanation. Hearing, just like seeing, is something that you need to practice. If it's the first time you're hearing a specific sound then you might not notice the intricate details in it. If you stick around those sounds for long enough then you'll hear the details as well. When I was younger I knew a girl whose voice I did not understand when I first met her. It took me some time before I was able to understand what she was saying, because I hadn't heard a voice like that before. Based on that event, I think that the reason people can't hear the specific details of pronunciation is because they're not used to it, but they can learn with more experience.