bass guitar vs woofer

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. 

woofer

noun
  • A loudspeaker that produces low-frequency sound. 

  • A dog. 

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