Only had this issue since a few days ago after downloading descent, all of my audio is fine except anything relating to the inquisitor, all speech and sfx originating from her makes it seem like the focus is far away from her resulting in almost inaudible speech, sfx, etc.
edit: to be more specific, the bug is always on the focused character.
Do you have a surround sound setup? If not, make sure dynamic range is set to headphones in the audio settings.
Normally the issue with muffled voices is when the game outputs dialog through the central speaker which is either missing or not working.
Is it only the main character, or also other characters in cutscenes? Have you tested your speaker configuration in Windows to confirm the central speaker is working?
It could also just be an issue with the game, in which case you should try repairing it by right clicking DAI and clicking 'repair game'.
