sound out vs want to know

sound out

verb
  • To question and listen attentively in order to discover a person's opinion, intent, or preference, especially by using indirect conversational remarks. 

  • To pronounce a word or phrase by articulating each of its letters or syllables slowly in sequence. 

  • To speak or sing loudly, to call out. 

want to know

verb
  • To ask (used as a dialogue marker or introductory statement). 

How often have the words sound out and want to know occurred in a corpus of books? (source: Google Ngram Viewer )