Quote Originally Posted by Curmudgeon View Post
I'm certainly not trying to contest these modifiers; however, those apply to any Listen check, and have no particular significance to hearing a spell's verbal component. The answer about the base DC to hear a spellcaster (without situational modifiers) being 0 or less is correct, though. How much less than 0 is dependent on the extent to which an individual DM calculates someone using a strong voice is easier to hear than a voice at a normal conversational level.
Yes, this was the problem I had.