I was in Los Angeles last weekend visiting friends, and when we ordered dinner at an Asian restaurant, one of them spoke to the waiter in a language I didn't understand. I asked him if it was Cantonese and I wasn't surprised when it was; whenever I hear a Chinese-sounding language that I think I should understand but don't, it's Cantonese! The next day, I overheard a couple of women speaking a language that sounded Scandinavian, but I couldn't identify it. It was probably Dutch because it sounded a whole lot like German.
These two experiences made me realize that I cannot identify, by sound, very many languages other than the ones I speak. Cantonese is one of them, as well as Vietnamese and Japanese. The rest of them---Taiwanese, Mandarin, Spanish, German, French, and Italian---are languages in which I can recognize specific words, even though it's a stretch to say that I speak the last two. However, I can identify nearly all major European and Asian languages by sight.
I don't know if this is just because I'm a particularly visual person, or if this is common to everyone. I also have trouble remembering music without seeing a score in my head, so it may just be the way my brain stores information that can be represented in multiple ways.