timpanum vs tympanic cavity

timpanum

noun
  • The middle ear. 

  • A kettledrum. 

  • The diaphragm of a telephone. 

  • An external hearing organ in some insects. 

  • An ornamental panel in any triangular space. 

  • The eardrum. 

tympanic cavity

noun
  • A small cavity surrounding the bones of the middle ear. 

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