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 : announcements of movements at large and noisy air and rail
terminals or at a sports stadium.
PA systems are often used in small venues such as school auditoriums, churches
etc. PA systems with many speakers are widely used to make announcements in
public, institutional and commercial buildings and locations. Intercom systems,
installed in many buildings, have microphones in many rooms allowing the
occupants to respond to announcements.
