communicator vs public address system

communicator

noun
  • A usually portable communications device. 

  • Any of several electronic devices that allow people with various disabilities to communicate via displays or artificial speech. 

  • Someone who, or something that communicates. 

public address system

noun
  • An electronic voice-amplification apparatus, usually containing a set of two loudspeakers and a central control unit, used for singing, giving a speech, play-by-play commentary at events, or broadcasting in public areas like in airports or stations. 

How often have the words communicator and public address system occurred in a corpus of books? (source: Google Ngram Viewer )