heN-a isn’t used as a tag though is it?
Hannes’ “shi-ou” occured to me too, it gets truncated to “hioh” a lot and is used as a tag but the sound is not the same as what Chris seems to be hearing.
Could it be there as in: in cu ehiah? (At their house, there).
I thought of that as well, but can you see (or rather hear 
) it being tacked onto a Mandarin sentence?