扩声 meaning in English

pa public address
sound reinforcement

General specification for annoucing equipment on shipboard
舰船扩声设备通用规范
What is disadvantage of traditionary teaching
传统的教学扩声有什么弱点？
Ds - 80 - 120 - 200 - 2300 digital shift frequency sires
:反馈消除教学扩声器
General specification for power supplies of annoucing system on shipboard
舰船扩声系统电源通用规范
Jhs - d shift frequency aptitude transmitter mixer : system introduction
海之升数字移频扩声系统简介：

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