airing vs phone-in

airing

noun
  • The broadcast of a television or radio show. 

  • A public expression of an opinion or discussion of a subject. 

  • An exposure to warm or fresh air. 

phone-in

noun
  • A show requiring members of the public to telephone the studio. 

How often have the words airing and phone-in occurred in a corpus of books? (source: Google Ngram Viewer )