churr vs clangour

churr

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

noun
  • A low vocal sound made by some birds. 

clangour

verb
  • To make a clanging sound. 

noun
  • A loud, repeating clanging sound; a loud racket; a din. 

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