There is a major difference between listening and hearing.
Hearing is the mechanical process of sounds entering your ears. A sound within hearing distance will enter your ear canal and stimulate the eardrum unless something is blocking the sound such as earmuffs or earplugs.
Scientific research has been dedicated to trying to understand what people choose to listen to. Findings show we listen to what we want to hear (the enjoyable message) and tune out what we don't want to hear (the unenjoyable message) The next time you are talking to your child and they only get part of the message you now know why.