The word 눈 is pronounced differently to what I expect it would, with regards to the first consonant. Fluent Forever mentions that pronunciation rules for Korean are fairly complex, but I don't understand this particular case, and I couldn't find anything by doing a search. What rule explains its pronunciation?
Link to krdict entry, where the first consonant sounds more like a "d" sound rather than an "n". Some entries on forvo also have this pronunciation.