falsetto vs sough

falsetto

noun
  • The "false" (singing) voice in any human, usually airy and lacking a purity of vowels; created by utilizing the next highest vocal folds above those used for speech and normal range singing. It is commonly confused with the head voice register. 

  • A person who sings in falsetto. 

verb
  • To sing or utter in falsetto. 

sough

noun
  • A murmuring sound; rushing, rustling, or whistling sound. 

  • A gentle breeze; a waft; a breath. 

  • A (deep) sigh. 

  • A small drain; an adit. 

verb
  • To make a soft rustling or murmuring sound. 

  • To drain. 

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