Public address system
（重定向自P.A. System）
![Horn loudspeakers are often used to broadcast sound in outdoor locations](/Images/godic/202502/01/Hornloudspeaker3251.jpg")
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![Early public-address system from around 1920 using a Magnavox speaker. The microphone (then called a](/Images/godic/202502/01/Early_vacuum_tube_public_address_system3251.jpg")
![Public address system in a school](/Images/godic/202502/01/Pa_system3251.jpg")
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 for announcements of movements at large and noisy air and rail terminals or at a sports stadium. The term is also used for systems which may additionally have a mixing console, and 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 or building.