clank vs clunk

clank

verb
  • To make a clanking sound 

  • To cause to sound with a clank. 

noun
  • A loud, hard sound of metal hitting metal. 

clunk

verb
  • to make such a sound 

noun
  • A dull, metallic sound, especially one made by two bodies coming into contact. 

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