A public address system, abbreviated PA system, refers to an audio transmission system used in institutional and commercial buildings, in which input from a microphone or prerecorded music is amplified and sent to speakers throughout the building. These types of PA systems are commonly seen in schools (used to read announcements and summon students) and hospitals (used to summon staff or declare states of emergency). Other examples include airports, airplanes, and drive-through windows at fast food chains. Some systems can address specific rooms and exclude others. Other types of PA systems, called intercom systems, also have microphones in each room so that the occupants can reply to the central office. These systems are brought to you in collaboration with Global Manufacturers.