A public address system (PA system) is an electronic system that comprises microphones, amplifiers, loudspeakers, and related equipment. It is used to increase the apparent volume of a human voice, musical instrument, or other acoustic sound source or recorded sound or music. PA systems are used in any public venue that requires that an announcer, performer, etc. be sufficiently audible at a distance or over a large area. Some typical applications include sports stadiums, public transportation vehicles and facilities, and live or recorded music venues and events.

A PA system may include multiple microphones or other sound sources, a mixing console to combine and modify multiple sources, and multiple amplifiers and loudspeakers for louder volume or wider distribution. 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 passenger vessels and aircraft. Intercom systems, installed in many buildings, have both speakers throughout a building and microphones in many rooms so occupants can respond to announcements. PA and intercom systems are commonly used as part of an emergency communication system.

A PA system is used to project sounds from instruments, voices, and other acoustic sources. It comprises microphones, mixers, amplifiers, and loudspeakers. Front of house (FOH) speakers point towards the audience, while monitors are directed to the performers. PA systems usually consist of two loudspeaker cabinets, each of which usually contains one large speaker and a smaller “tweeter” speaker or horn for higher frequencies. They’re typically passive speakers, which means they require amplification. PA systems also include a powered mixer, which is like the central nervous system of your PA (similar to a receiver in a stereo system). It will have between four and 24 inputs or channels, and controls for tone, volume, and maybe some echo effects.

In summary, a PA system is a sound reinforcement system used to amplify sound sources to a large group of people in public venues. It is composed of microphones, mixers, amplifiers, and loudspeakers. PA systems are used in various settings such as sports stadiums, public transportation vehicles and facilities, and live or recorded music venues and events[[1]](https://en.wikipedia.org/wiki/Public_address_s...