canticle vs tenson

canticle

noun
  • A chant, hymn or song, especially a nonmetrical one, with words from a biblical text. 

tenson

noun
  • A form of lyric poem used by troubadours in Provençal in which two voices present different sides of an argument, in alternate stanzas, lines, or groups of lines with identical structure. 

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