For full context, see here: https://www.docdroid.net/5vuuiCe/img-20170821-0002-new.pdf
The sentence in question (last line): 今、カラオケは単なる機械ではなく、日本が世界中に誇る文化なのである。
First, my attempt at translation: "Now, Karaoke is not (just) a mere machine and japan is a culture holding proud in the world."
I just translated the sentence as if なの wasn't present in the respective phrase because I don't know what to with it here. I also must say that I wonder wether my interpretation of the second part of this sentence ("Japan is...") is correct at all. It seems a bit far fetched to me to make Karaoke representative of the whole japanese culture xD At least this sentence sounds to me like it does so...^^ That said, maybe japanese people themselves think so. I don't know, I don't have that much insight into japanese people's heads :D