At the school pep rally, you are able to hear the cheerleaders on the field, hold a conversation with your friend next to you, and pay attention when the announcer says your name. This kind of attention is known as inattention blindness.
selective inattention.
cocktail party effect.
change blindness.
choice blindness.

cocktail party effect

Explanation:

This is the cocktail party effect and similar to its name the phenomenon usually occurs when you are able to focus your auditory attention to one stimulus and filter the rest. So for this example, the person can talk with his/her friend even when he/she can hear the cheer leader. They can also turn their attention to announcer when they call their name.