churr vs roop

churr

verb
  • To make the low vocal sound of some birds. 

noun
  • A low vocal sound made by some birds. 

roop

verb
  • To make hoarse. 

  • To roar; make a great noise. 

  • To cry; shout. 

noun
  • Hoarseness. 

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