If someone hears an illusion with visual component (such as ventriloquism) and disbelieves it, does it sound different to them? I imagine the voice would sound distorted in some way that would make it obvious it was fake.
I think you meant audio component, not visual, as for how does it sound. That's left up to the GM, but no matter what if you've successfully made the save you should know it's not real.
Since illusions that are disbelieved "leave an outline" according to some source in the rules (I can't recall where) I imagine you still hear the verbal illusion but recognize it as fake.
With respect to such voices and sounds, anyone who hears the sound and rolls a successful save recognizes it as illusory (but still hears it).
Since this is in the spirit of how disbelieving visual illusions works, I'd extend this to cover other nonvisual figments and phantasms.
Yes I meant to say WITHOUT a visual component
Since illusions that are disbelieved "leave an outline" according to some source in the rules (I can't recall where) I imagine you still hear the verbal illusion but recognize it as fake.
It is here
A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.
Illusions of the Glammer, Pattern, and Shadow type do not leave a translucent outline.
/cevah