falsetto vs piercing tone

falsetto

verb
  • To sing or utter in falsetto. 

noun
  • A person who sings in falsetto. 

  • 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. 

piercing tone

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