motet vs psalmody

motet

noun
  • A composition adapted to sacred words in the elaborate polyphonic church style; an anthem. 

psalmody

noun
  • The singing or the writing of psalms. 

  • A collection of psalms. 

verb
  • To celebrate in psalms. 

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