croak vs falsetto

croak

verb
  • To utter in a low, hoarse voice. 

  • To kill someone or something. 

  • To complain; especially, to grumble; to forebode evil; to utter complaints or forebodings habitually. 

  • To die. 

  • To make a croak. 

  • To make its sound. 

noun
  • The call of a frog or toad. (see also ribbit) 

  • A faint, harsh sound made in the throat. 

  • The harsh call of various birds, such as the raven or corncrake, or other creatures. 

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. 

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