I have hallucinations both visual and auditory when in psychosis, that is when they bring on the antipsychotics. Usually this is during mania, or med withdrawl. Paranoia overlaps it.
I recently read an article on the web , whether it is clinically true I can't say, but it said that mj can cause psychosis in the bipolar individual. I think it meant a habitual user, not just smoking a joint.
schizophrenia and schizoaffective disorders might be a trouble causer here, otherwise. In this case conversations can take place, or seem to , such as a voice telling you to do something.
Delusions are much different than hallucinations. Delusions are false beliefs, rather than a manifestation of false images or sounds. Bipolar can cause delusions of grandeur, one of the main sx's of bipolar.
http://bipolar.about.com/cs/psychoticfe ... cinate.htm