When listening to a speaker which four styles of is not defined?

The prompt seems to be missing some information. There isn't a universally recognized set of "four styles" when it comes to listening.

To help me understand your question better, could you please clarify:

* What specific context are you referring to? Are you talking about a specific type of listening (e.g., active listening, empathetic listening), or a general framework for understanding how people listen?

* What do you mean by "not defined"? Are you looking for styles that haven't been formally named, or styles that are commonly used but not clearly explained?

Once I have this information, I can better assist you with your request.