a cappella vs yammer

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. 

yammer

noun
  • A loud noise. 

  • One who yammers. 

  • The act or noise of yammering. 

verb
  • To complain peevishly. 

  • To repeat on and on, usually loudly or in complaint. 

  • To make an outcry; to clamor. 

  • To talk loudly and persistently. 

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