baritone vs bass guitar

baritone

noun
  • The musical range between tenor and bass 

  • a brass instrument similar to the euphonium, but with a cylindrical bore instead of a conical one; a baritone saxhorn 

  • The male voice between tenor and bass 

  • A person, instrument, or group that performs in the range between tenor and bass 

bass guitar

noun
  • A long-necked and solid-bodied stringed instrument (chordophone), tuned to produce bass or low notes, usually with a fretted fingerboard and four thick strings, and requiring the use of an amplifier. 

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