Public address system

professional electronic acoustic system for delivering live or recorded music and speech to a larger audience; has larger and stronger amplifiers and speakers than a home audio 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.

PA system