Giant Voice…

https://military.technomad.com/products/giant-voice-mass-notification-system/

http://www.frontlinewarningsystems.com/military-giant-voice-systems

'Giant Voice systems are mass notification equipment that sends warning tones, music such as bugle calls and reveille through Radio, Wireless, Ethernet or landline systems to permanently installed arrays. In addition, this system is capable of broadcasting voice messages that are prerecorded and live public address in real-world force protection applications. '