Filter Model:

     Donald Broadbent created the filter model based on findings by Colin Cherry about this issue of selective attention. Broadbent used an information processing metaphor to describe human's processing system. His model proposes that stimuli are filtered at an early stage during processing. Here is a diagram of Broadbent's filter model:

By:  Kyle.Farr - Own work, CC BY-SA 3.0   Source:   Wikimedia Commons

By: Kyle.Farr - Own work, CC BY-SA 3.0

Source: Wikimedia Commons

This model is mentioned in Cocktail Party Effect, go check it out!