troubadour vs yodeler

troubadour

noun
  • An itinerant composer and performer of songs in medieval Europe; a jongleur or travelling minstrel. 

yodeler

noun
  • One who sings so that their voice fluctuates rapidly between their normal chest voice and a falsetto, one who yodels. 

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