out of tune vs unnatural

out of tune

prep
  • Not in agreement or in harmony (with something). 

  • Not in the correct musical pitch. 

unnatural

adj
  • Going against nature; perverse. 

  • Not occurring in nature, the environment or atmosphere 

  • Not natural. 

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