英语词源字典 - 在线词源网站

crackle (v.)[crackle 词源字典]: mid-15c., crackelen, frequentative of cracken "to crack" (see crack (v.)). Related: Crackled; crackling. The noun is recorded from 1833.[crackle etymology, crackle origin, 英语词源]
murmur (n.): late 14c., "expression of discontent by grumbling," from Old French murmure "murmur, sound of human voices; trouble, argument" (12c.), noun of action from murmurer "to murmur," from Latin murmurare "to murmur, mutter," from murmur (n.) "a hum, muttering, rushing," probably from a PIE reduplicative base *mor-mor, of imitative origin (cognates: Sanskrit murmurah "crackling fire," Greek mormyrein "to roar, boil," Lithuanian murmlenti "to murmur"). Meaning "softly spoken words" is from 1670s.
crepitate: "Make a crackling sound", Early 17th century (in the sense 'break wind'): from Latin crepitat- 'crackled, rustled', from the verb crepitare, from crepare 'to rattle'.