On the Great Journey, the Shipmaster, Johnson, Miranda, and 343 are all inaudible during gameplay (Not cutscenes). When you have the wraith, the music is too loud or the dialogue is too low to be audible (this is not the case when you switch to classic). This is also true during the fight with Tartarus; you can just barely make out the end of one of Johnson’s lines during the fight while the rest are inaudible (drowned out by the music, it seems). Again, the issue isn’t present in classic presentation mode.
Hopefully someone can up the dialogue volume in this level!
Thanks!
There were also, on occasion, points during the campaign when the music stopped (but again, not in classic mode). I noticed this the most on the ghost section of the level Uprising.