I talk to myself outloud several times per day, including in public, sometimes. I don't know if it's related to bipolar disorder. I think some people without mental illness do the same, sometimes. I will say that mine increases in public when I am hypomanic and manic. I assume it has to do with disinhibition. Otherwise, I find doing so self-soothing or a tension release. Question is do you care if you do so and/or others hear you? I generally don't, especially when hypomanic or manic. Or, depending on what I say that shouldn't be heard.

In general, I am not worried about judgement from others, unless it's a result of something I said/did that affects them negatively.