The opposite of muffling a sound would be amplifying.
Muffling what? Muffling screams in your basement? Soundproofed walls. Muffling somebody's snoring in bed? A sturdy pillow over their face, held firmly, until subject is no longer moving or breathing noticeably.
He walked through the forest, the thick fog muffling the sound of his footsteps.
it is when you can not hear anything
yes
muffling
A muffling device
carpets, curtains and wood are best at muffling sound carpets, curtains and wood are best at muffling sound
A muffling device
Most states do require a muffling device on boats. Most states do have exceptions like the age of the boat, but may have to be under a decibel level or if it is a racing competition, there are other requirements for those.
A muffled sound. To muffle means to wrap with something to deaden sound (you know, for example, a girl is kidnapped by a gang and they put a handkerchief on her mouth. When she goes "Mmmph!", that's what muffling sounds like).
"Muffling" or "Baffling". To be academic: "Attenuation".
A muffling device