Focus on the pronunciation of muffle
English definition of “muffle”
/ˈmʌf·əl/ v [T]
› to make a sound quieter and less clear: Ted and I looked at each other with open mouths and muffled our laughs in our sleeves. muffled
/ˈmʌf·əld/ adj [not gradable] › I could hear muffled voices next door, but couldn’t make out any words.