eavesdrop vs tune in on

eavesdrop

verb
  • To hear a conversation one is not intended to hear; to listen in. 

  • To listen for another organism's calls, so as to exploit them. 

noun
  • The act of intentionally hearing a conversation not intended to be heard. 

  • A concealed aperture through which an occupant of a building can surreptitiously listen to people talking at an entrance to the building. 

  • The dripping of rain from the eaves of a house. 

  • The space around a house on which such water drips. 

tune in on

How often have the words eavesdrop and tune in on occurred in a corpus of books? (source: Google Ngram Viewer )