Do you have to understand a language to recognize an accent?

I agree with you, someone can understand that a person is pronouncing a word one way and another is pronouncing it differently without speaking the language. now, you would not know which pronunciation was correct, but you would be able to tell it was different.

I think both of your are correct. Strictly speaking you don't need to understand a language to recognize an accent, BUT this would only happen IF 2 or more people keep on repeating the same word or few words before you for so many times you could recognize the difference. But once people start talking about other things, you would not be able to tell. On the other hand if you know a language well enough, you could tell the differences between accents right away no matter what people talk about.

When you don't understand a language but recognize it, it only means you could identify the language, but it's almost impossible to identify an accent. If one does not understand English, how can this person know what is a Brooklyn, Texas, North Carolina accent?

Your friend's correct, sorry. I almost wish I could record myself for you to try and find out what accent I'm speaking with LOL.

I agrre with you. Some languages I do not understand but can recognose when I hear them.

You are correct.