"그 여자는 누구입니까?"
Translation:Who is that woman?
Yes. A lot of the time when a word starts with ㄴ, it sounds similar to an English "D". Try this. When you say "Nine", feel that your vocal chords vibrate as you say the "N" sound. In Korean, that doesn't happen. So saying a "N" sound sounds like a "D", the ㅁ sounds a little like a "B", etc, etc.
Here's a video about it. https://www.youtube.com/watch?v=zhf9NWKHjqE
It is not uncommon for beginning learners to hear 누구 as "dugu" or 뭐 as "bwo". This arises because these nasal consonants are often "denasalized" when they are initial consonants. When pronouncing these consonants there is little to no "wind-up" of air in the nose, no air resonating in your nasal cavity. You can simulate this by pinching your nose and pronunciating 누나 or 뭐.