tympanum
noun [ C ] anatomy specialized uk/ˈtɪm.pə.nəm/ us/ˈtɪm.pə.nəm/ tympana /ˈtɪm.pə.nə/ tympanums
鼓膜
an eardrum (= a thin piece of skin inside the ear that moves backwards and forwards when sound waves reach it, allowing you to hear sounds)