diapason vs level set

diapason

noun
  • A harmonious outpouring of sound. 

  • The range or scope of something, especially of notes in a scale, or of a particular musical instrument. 

  • A tonal grouping of the flue pipes of a pipe organ. 

  • The musical octave. 

level set

noun
  • An event consisting of level setting 

  • The set of values x for which a real-valued function f(x) is equal to a given constant. 

  • A state of mutual understanding among parties 

verb
  • To establish a baseline of mutual understanding 

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