鼓膜 == komaku == (noun) tympanic membrane/eardrum
Left radical is 'flesh/of the body' (肉). Right
a Non-General Use character meaning 'sun sinking among plants', here
acting phonetically to express 'wrap'. A membrane is something that
wraps around flesh. Henshall
suggests taking the right radical as 'grass', 'sun' (日), and 'big' (大),
and as a
mnemonic: ' Big fleshy membrane stretched over sunny grass.' Ewww.