earphones vs listener

earphones

noun
  • A pair of small loudspeakers worn inside each outer ear or covering all or part of the ear, without a connecting band worn over head. 

listener

noun
  • A person's ear. 

  • Someone who listens, especially to a speech or a broadcast. 

  • A musical anthology. 

  • A function that runs in response to an event; an event handler. 

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