listening vs opus

listening

adj
  • Of an action that is performed with caution and attention to sounds. 

  • Of something that is used in order to hear or to improve the ability to hear. 

  • Of something or someone that listens. 

noun
  • Skill or ability of perceiving spoken language. 

  • Action of the verb listening 

  • An educational exercise involving listening 

opus

noun
  • A work of music or set of works with a specified rank in an ordering of a composer's complete published works. 

  • A work, especially of art. 

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