Public address system
A public address system, commonly known as a PA system, is a network of sound devices that can play sound to several people. They are often used to make announcements in large buildings or neighbourhoods. In big spaces outdoors, amplifiers and loudspeakers have to be very loud. Otherwise the volume would be too small to be heard by everybody.
Public Address System Media
Horn loudspeakers are often used to broadcast sound in outdoor locations.
A late 19th-century speaking trumpet used by firefighters
A small sports megaphone for cheering at sporting events, next to a 3 in (8 cm) cigarette lighter for scale
A woman using a small handheld electric megaphone at a demonstration in Portugal. Electric megaphones use a type of horn loudspeaker called a reflex or reentrant horn.
Public address system consisting of amplifiers, mixers, and routers for Gatwick Airport in London.
London Underground employee making a Long Line Public Address system announcement using an RPA01 Radio Microphone at Bank station
This small venue's stage shows a typical PA system.
