falsetto vs stammer

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. 

stammer

noun
  • A speech defect whereby someone speaks with a stammer 

  • The involuntary repetition of a sound in speech. 

verb
  • To utter with a stammer, or with timid hesitancy. 

  • To keep repeating a particular sound involuntarily during speech. 

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