Does anyone have any ideas on how we could mute the dialogue volume of NPCs while keeping the overhead volume switched on, and vice versa?

DOS:2 implemented a dialogue/overhead volume slider in the options menu for this but DOS:1 doesn't have it.

My assumption is that you'd need to unpack the dialogue audio files from the sound bank and either edit or delete them, but I'm not sure how to do this or if it would actually work.