This article says "Hallucinations are more likely to be auditory than visual in people with bipolar disorder."

Does anyone know why someone with bipolar is more likely to have auditory hallucinations rather than visual? I'm just curious about the science of it. Or is it presently unknown why? It only says more likely. So it does not mean you will hear anything. For me that's true. I hear a lot of voices, but only on rare occasion will see something.

Do People with Bipolar Disorder Have Hallucinations?