A public address system (PA system) is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeakers, used to allow a person to address a large public, for example for announcements of movements at large and noisy air.  

It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound source or recorded sound or music. PA systems are used in any public venue, Office that requires that an announcer, performer, etc. be sufficiently audible at a distance or over a large area. 

The goal of a PA system is to provide “public address”, or a way to transmit audio communication to a group.