holler vs speak out

holler

verb
  • To call out one or more words 

  • To yell or shout. 

  • To complain, gripe 

noun
  • A field holler. 

  • Any communication to get somebody's attention. 

  • A yell, shout. 

speak out

verb
  • To assert or promote one's opinion; to make one's thoughts known. 

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