hammering vs pitter-patter

hammering

noun
  • A heavy defeat. 

  • A period of being beaten or hammered. 

  • A dented appearance on silverware, produced by successive blows of a hammer. 

pitter-patter

noun
  • A soft, percussive sound, as of tiny feet, or of rain on a rooftop. 

How often have the words hammering and pitter-patter occurred in a corpus of books? (source: Google Ngram Viewer )