cantillate vs croon

cantillate

verb
  • To chant, or to recite musically (especially in a synagogue). 

croon

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

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

  • To say softly or gently 

  • To soothe by singing softly. 

noun
  • A soft or sentimental hum or song. 

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