Public Address (PA) System

A PA system is an electronic sound amplification and distribution system with a microphone, amplifier and loudspeaker, used to allow a person to speak to a large audience.  It is used for announcements in large air and rail terminals, sports stadiums and used to amplify other audio content, such as recorded music or the live sound of a band.

The term is also used for systems that may additionally have a mixing console, amplifiers and loudspeakers suitable for music as well as speech used to reinforce a sound source, such as recorded music or a person giving a speech or distributing the sound throughout a venue, building or area.

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. Intercom systems, installed in many buildings, have both speakers throughout a building, and microphones in many rooms allowing the occupants to respond to announcements.