Technical Terms

1 Public address (PA)

Sound broadcast that is managed by the user and serves the public within the area occupied by the user. It includes business

announcement, background broadcast, and emergency broadcast.

2 Public address system

A system composed of all public address equipments and facilities serving public address coverage area, as well as the acoustic

environment of this public address coverage area.

3 Public address equipment

A general term for all the equipments in public address system. It includes loudspeakers, power amplifiers, transmission lines

and transmission equipments, management/control equipments, paging equipments, microphones and other signal source

equipments.

4 Emergency broadcast

Broadcast by public address system to its service zone(s) in case of public emergency. For example, alarm signals, guidance

information about public evacuation, and instructions given by relevant departments on the emergency site.

5 Business announcement

An announcement releasedby public address system to its service zone(s) intended for the whole or part of the audience. For

example, notices, news, information, voice files, paging, time tones, etc.

6 Background broadcast

Broadcast by public address system to its service zone(s) to create a certain atmosphere. For example, background music and

background sounds (including environmental simulation sounds) in a variety of occasions, etc.

7 Loudspeakers distribution

To design and allocate loudspeakers in specific area of public address system.

8 Transmission line

Lines that used for transmitting public address signals from signal processing equipment(s) (including amplifiers) or station to

onsite loudspeakers in the service zone(s), including various conductive cables and optic-fiber networks.

9 Transmission distance

Length of the line from the input terminal of public address Transmission line to the load terminal.

10 Rated transmission voltage

Rated voltage of the original terminal of Transmission line. That is, the nominal input voltage of loudspeaker (or some other

terminal devices) connected to the Transmission line.

11 Ensured function

The most basic function that public address system shall provide.

12 Airingpriority

The priority of source signals to be broadcast.

13 Microphone priority

To enable a microphone the highest airing priority.

14 Voice file

The broadcast voice recorded in advance.

15 Dual function system

The standby mode of emergency broadcast system. Normally, the system runs as a business announcement system or

background broadcast system. When triggered by an emergency signal, the system switches automatically to emergency

broadcast system.

16 One touch ready

Makepublic address systemto enter a specified state by one touch.

17 Paging

Broadcast intended for seeking person, things or help, or temporary broadcast to the designated zone(s) as required.

18 Call station

The device that is independent from the broadcast host and can make zone Paging.

19 Override

To Override other signals being on-air with specific contents, or to forcibly awaken the stand-by system in order to release

Emergency broadcast

20 Zone management

To divide public address service area into several broadcast zones and manage them. Broadcasting can be turned on or off

for each zone separately or for all zones.

21 Zoning with matrix mode

To mange broadcast zones in matrix mode. Broadcasting can be turned on or off separately for each zone, and different

signals can be sent to two or more zones simultaneously.

22 Zoning override

To Override one or more broadcast zones selectively without affecting other zones.

23 Remote control and monitor

To monitor and control public address system outside the station (or control center).

24 Ensured sound pressure level

The averaged value of the root-mean-squared (RMS) steady-state sound pressure level that shall be achieved in public

address zone.

25 Sound field irregularity

The maximum difference between Sound Pressure Level (SPL) values measured in public address zone.

26 Leak out acoustic attenuation

The difference between the Ensured sound pressure level of public address system and the SPL30moutside the border of the

service area.

27 System signal-to-noise ratio

The signal-to-noise ratio from the audio signal input terminal of public address system