A Public Address or "PA" System is an electronic amplification system with a Controller, Mixer, Amplifier, Router and Loudspeakers, used to reinforce a given sound and distributing the sound throughout a venue or a building. It is a centralized amplifier based system that is designed such, to provide voice paging and to broadcast alarm tone during emergencies.
The system can transmit alarm tone and routine voice messages, from a central location, to all or selected areas of the facility, in a reliable and safe manner, by the use of loudspeakers. 
Simple PA systems are often used in small venues such as school auditoriums etc. PA systems with a larger number of speakers are widely used in institutional and commercial buildings, to read announcements or declare states of emergency.

A Public Address or "PA" System is an electronic amplification system with a Controller, Mixer, Amplifier, Router and Loudspeakers, used to reinforce a given sound and distributing the sound throughout a venue or a building. It is a centralized amplifier based system that is designed such, to provide voice paging and to broadcast alarm tone during emergencies.
The system can transmit alarm tone and routine voice messages, from a central location, to all or selected areas of the facility, in a reliable and safe manner, by the use of loudspeakers. 
Simple PA systems are often used in small venues such as school auditoriums etc. PA systems with a larger number of speakers are widely used in institutional and commercial buildings, to read announcements or declare states of emergency.