Think about last time when you were in a concert ,party or social gathering with your friends . Most probably a full volumed music was playing in the background continuously and screaming notoriously. Yet your communication capability with your friends were good and you may heared them clear. Why? Because filtering of the sounds were processing so perfectly and sharply even when the background music was dancing in your eardrums. However, suddenly your attention of listening might have shifted because you heared another group or individual calling your name.What kind of processing took place in this matter? How you were able to filter your name even in a condition where the voice was loud and the conversation that mentioned your name was irrelevantly low? Why your mind caught the conversation that time even though you were not intentionally or unintentionally listening to them? This ability to focus on one out of different volumed voices and to concentrate on stimulus (in this case- auditory) is one of the most striking phenomena in cognitive psychology known as “cocktail party effect”.