choir vs vocalize

choir

verb
  • To sing in concert. 

noun
  • A group of people who sing together; a company of people who are trained to sing together. 

  • The part of a church where the choir assembles for song. 

  • One of the nine ranks or orders of angels. 

  • Set of strings (one per note) for a harpsichord. 

vocalize

verb
  • To sing without using words. 

  • To produce noises or calls from the throat. 

  • To add vowel points to a consonantal script (e.g. niqqud in Hebrew) 

  • To express with the voice, to utter. 

  • To turn a consonant into a vowel. 

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