It's human nature to have an agenda when it comes to communication. We get so preoccupied with what we are going to say next that we fail to pay attention to the here and now. Pre-existing conditions are another major cause of how we become afflicted by the Passive Listening plague. Pre-existing conditions are things that have gotten into our mind prior to the conversation. This takes our attention away from the current conversation and puts us in passive listening.
Impressions are another passive listening trap.
People get caught up in how their impression is being received or vice versa how they are receiving the other person they forget to listen. A big part of the answer is awareness. Being aware that we will inevitably fall victim to Passive Listening is key. Awareness will also lead you to better understand what causes you to fall into Passive Listening. Listening is a learned skill, which requires discipline.