sibilant vs sibilating

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. 

sibilating

noun

  • A hissing sound 

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