interlocutor vs mouthpiece

interlocutor

noun
  • A person who takes part in dialogue or conversation. 

  • A man in the middle of the line in a minstrel show who questions the end men and acts as leader. 

  • A decree of a court. 

  • An interlocutory judgement or sentence. 

mouthpiece

noun
  • A spokesman; one who speaks on behalf of someone else. 

  • The part of a wind instrument that is held in or against the mouth. 

  • A lawyer for the defense. 

  • The part of a telephone that is held close to the mouth. 

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