timpanum vs tympanic membrane

timpanum

noun
  • The eardrum. 

  • A kettledrum. 

  • The diaphragm of a telephone. 

  • The middle ear. 

  • An external hearing organ in some insects. 

  • An ornamental panel in any triangular space. 

tympanic membrane

noun
  • Synonym of eardrum. 

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