fricative vs sibilation

fricative

noun
  • Any of several sounds produced by air flowing through a constriction in the oral cavity and typically producing a sibilant, hissing, or buzzing quality; a fricative consonant. 

adj
  • produced by air flowing through a restriction in the oral cavity. 

sibilation

noun
  • A hissing sound. 

  • From the shadows emanated a hushed sibilation. 

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