croon vs psalmody

croon

noun
  • A soft or sentimental hum or song. 

verb
  • To make a continuous hollow moan, as cattle do when in pain. 

  • To say softly or gently 

  • To hum or sing softly or in a sentimental manner. 

  • To soothe by singing softly. 

psalmody

noun
  • The singing or the writing of psalms. 

  • A collection of psalms. 

verb
  • To celebrate in psalms. 

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