refrain vs sound off

refrain

verb
  • To stop oneself from some action or interference; to abstain. 

  • To abstain from (food or drink). 

noun
  • The chorus or burden of a song repeated at the end of each verse or stanza. 

  • A much repeated comment, complaint, or saying. 

sound off

verb
  • To hold forth about something in an opinionated manner. 

  • Command instructing a person to confirm that they are present or that some other objective has been met. 

  • Command instructing a person to speak up or acknowledge something. 

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