There is nothing more painful to a communicator than talking to an individual or group and not have their attention. Some people like to talk more than they like to listen, others listen selectively, some may just listen superficially without really bothering about what is being said. All this lead to ineffective listening. Though most times you get people’s attention by saying things that are of value to them.
By default humans have two ears for hearing and one mouth which contains the tongue that aid speech. This may be a deliberate design to make us pay more attention to listening than talking. Hearing is simply the act of perceiving sound by the ear. If you are not hearing-impaired, hearing simply happens. Listening, however, is something you consciously choose to do. Listening requires concentration so that your brain processes meaning from words and sentences. http://www.d.umn.edu/kmc/student/loon/acad/strat/ss_hearing.html
People show different attitudes that are unacceptable when it comes to listening. If the listener is thinking about his reply before the other person has finished, then in all probability he is not listening. Some people listen until they want to say something; then they quit listening, start rehearsing what they will say, and wait for an opportunity to respond. There is another set of people who are not actually listening and are thinking about something else, deliberately try to look as though they were listening thereby faking attention. “Most people do not listen with the intent to understand; they listen with the intent to reply.” –Stephen R. Covey.
In conclusion, when you are listening to somebody, completely, then you are listening not only to the words, but also to the feelings of what is being conveyed, to the whole of it, not part of it.