Public address systems incorporate essential functions such as broadcasting announcements or music distribution, but they also add many others depending on the needs of the installation and the performance of the chosen equipment.
One of the unique features of public address systems is speech priority, a function performed by preamplifiers that attenuates or inhibits the music signal when an announcement is broadcast, whether live or prerecorded. Another associated function is the paging security, which prevents attenuators from cutting or reducing the volume of messages.
Defining speaker groups allows announcements to be directed to the appropriate zones. This involves the use of zone microphone desks and independent zone selectors or amplifiers.
Sound sources include microphones or microphone desks, music sources, pre-recorded messages on specific devices or on a computer, or telephones via a telephone access point.
The location of control and power can also be defined, often centralized with equipment arranged in a rack, but also distributed in cases such as railway station networks. In this case, we can talk about local sound sources, computer control, audio transmission over a TCP/IP network, etc.
Finally, the PA system communicates with external equipment, such as noise sensors, and with external systems, such as fire safety systems, which send commands to activate evacuation messages.
