listen vs overhear

listen

verb
  • To expect or wait for a sound, such as a signal. 

  • To pay attention to a sound or speech. 

  • To accept advice or obey instruction; to agree or assent. 

noun
  • An instance of listening. 

overhear

verb
  • To hear something that was not meant for one's ears. 

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