acoustic vs vocative

acoustic

noun
  • A medicine or other agent to assist hearing. 

  • The properties or qualities of a room or building that determine how sound is transmitted in it. 

adj
  • Utilizing sound energy in its operation. 

  • (of building materials) Used for soundproofing or modifying sound. 

  • (of an explosive mine or other weapon) Able to be set off by sound waves. 

  • Naturally producing or produced by an instrument without electrical amplification or the need thereof. 

vocative

noun
  • A word in the vocative case 

  • The vocative case 

  • Something said to (or as though to) a particular person or thing; an entreaty, an invocation. 

adj
  • Of or pertaining to calling; used in calling or vocation. 

  • Used in address; appellative (said of that case or form of the noun, pronoun, or adjective, in which a person or thing is addressed). For example "Domine, O Lord" 

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