chirl vs strum

chirl

noun
  • A kind of musical warble. 

verb
  • To emit a low sound; to warble. 

strum

noun
  • The sound made by playing various strings of a stringed instrument simultaneously. 

  • The act of strumming. 

verb
  • To play (a guitar or other stringed instrument) using various strings simultaneously. 

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