chirl vs duet

chirl

noun
  • A kind of musical warble. 

verb
  • To emit a low sound; to warble. 

duet

noun
  • A song composed for and/or performed by a duo. 

  • A musical composition in two parts, each performed by a single voice (singer, instrument or univoce ensemble). 

  • A pair or couple, especially one that is harmonious or elegant. 

verb
  • To perform (sing, play, etc.) as a duet. 

  • (of two people) To say at the same time, to chorus. 

  • To perform a duet. 

  • To communicate (warnings, mating calls, etc.) through song. 

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