Communication remains one of the vital and critical aspects of the human race. However, effective communication comes with being in consensus with your listener as far as your information is concerned.
According to Merriam Webster, Listening is defined as the ability to hear something with thoughtful attention.
However, Speaking is the act of denoting information or rather reflecting one's feelings toward another person through speech.
Thus, these two definitions affirm the prerequisites of communication. Although, meeting the prerequisites of communication doesn't necessarily mean that the demand for effective communication is met.
Here are few reasons why people don't listen to you while you're in conversation with them.
They have their own version of truth
Most people tend to wriggle your conversation with them whenever they have a particular truth they've submitted to already.This mostly happens during an argument. When you get into an argument or a dialogue with someone and you're trying to buttress a point in context of the argument. People by default tend to turn dead ears to your perspective and opinions based on the fact that your truth might be ugly to them.
This would mostly factor misconception of your thoughts in the cause of arguing with them.
Anticipating to talk
When you have a conversation with people and they find it difficult to give you the room to speak, this would by default refrain them from giving you an effective listening and this is because they simply want to take the position of talking rather than listening.This mostly happen when you're talking to them and they've noted few of your words and trying to think and reflect of the best reply or approach for the noted words, this made them loose track of the rest of your conversation simply because they try to review their responses and expecting when to seize the conversation from the current speaker.
In that respect, the criteria for meeting effective communication is deficient.
Not being objective
Objectivity simply means an act of not being incited by emotions or prejudices towards another person's thoughts.Hence, when having a conversation with someone and such a person refuses to be objective towards your thoughts and opinions, they tend to sway away from the truth even when it's so flashing which will in turn make them feel nonchalant towards listen to you effectively.
Ignorance
There's a popular quotes that says "It is always futile to talk facts with someone who enjoy sense of superiority in ignorance". Although, it seems as a waste of precious time talking to someone who doesn't reflect to your level of thinking or not even close to your thinking aptitude.An example of this case is when a vast and sophisticated medical doctor is going into an arguments with an home based native doctor about some crucial diseases in the body system. This kind of arguments and conversation can never come into conclusion because the native doctor is clearly confined to an obsolete medical knowledge which is out of vogue.