mike vs public address system

mike

noun
  • A microphone. 

  • A minute. 

verb
  • To microphone; to place one or more microphones (mikes) on. 

  • To measure using a micrometer. 

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 mike and public address system occurred in a corpus of books? (source: Google Ngram Viewer )