sibilant vs whirring

sibilant

noun
  • A consonant having a hissing or hushing sound such as the s or sh in sack or shack. 

adj
  • Characterized by a hissing or hushing sound such as the s or sh in sack or shack. 

whirring

noun
  • A whirr, the sounds of a whirr. 

adj
  • Producing a whirr; giving off a whirring noise. 

  • Spinning rapidly. 

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