play by ear vs rehearse

play by ear

verb
  • To play guided by one's musical ear, rather than from a written score. 

  • To do by guessing, intuition, or trial and error; to react to events as they occur; improvise 

rehearse

verb
  • To narrate; to relate; to tell. 

  • To contrive and carefully prepare (a story, etc.) to offer consistency. 

  • To repeat, as what has been already said; to tell over again; to recite. 

  • To practise by recitation or repetition in private for experiment and improvement, prior to a public representation, especially in theater 

  • To cause to rehearse; to instruct by rehearsal. 

How often have the words play by ear and rehearse occurred in a corpus of books? (source: Google Ngram Viewer )