If you are not sure what you heard or even if you wonder if
it is a hallucination,
it is not a hallucination. A hallucinator
is absolutely positive (though they may have their doubts later on). So, during a psychotic episode, you usually "hear voices."
2. Delusions: believing something is true that couldn't possibly be true. I'm not talking about believing that Bill Clinton never had sex with Monica Lewinsky.