Is this a standard Northern accent? No matter how many times I listen, I hear "Muộn câu hỏi đặc biệt", not một. Does this sound natural to a native Northern speaker?
It's something you'll encounter in songs too. Words ending in -t often sound like -n while you drag the sound on. Similarly -c sounds like -ng.
I confirm it did sound like that because the voice talent briefly pauses after "một", causing a sudden dropping in his tone. Unfortunately, we cannot have this re-record.
I heard it on several occasions here in the course that the speaker inserts an "n" in-between some words. According to my native VN friend this is common to make the sentence more fluent.
...and very distinct in traditional singing too, like adding „nn“ after every word.
It's been recorded by a native speaker, not a robot, so I suppose, it sounds natural.