a cappella vs utterance

a cappella

noun
  • A vocal performance with no instrumental accompaniment. 

adj
  • Singing solely or mainly without instrumental accompaniment. 

  • Related to a form of purely vocal music mostly associated with American college performance groups. 

adv
  • In a manner of a choir with no instrumental accompaniment; literally, "in the style of the (Sistine) Chapel (in Rome)", such as a musical Mass done a cappella. 

utterance

noun
  • Something spoken. 

  • The ability to speak. 

  • A manner of speaking. 

  • An act of uttering. 

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