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 speak to a large public.
In many cases ,the system is integrated into the building’s safety Protocol such as automatic vice evacuation message in emergency situation.
Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars. PA systems with
many speakers are widely used to make announcements in public, institutional and commercial buildings and locations,
such as schools, stadiums and large passenger vessels and aircraft.