dulcimer vs santur

dulcimer

noun
  • A stringed instrument, with strings stretched across a sounding board, usually trapezoidal, played by plucking on the strings (traditionally with a quill) or by tapping on them (in the case of the hammer dulcimers). 

santur

noun
  • A type of hammered dulcimer played in Persian music 

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