Source: The Half-Blood Prince
Fills the ears of target persons near the caster with an unidentifiable buzzing, so that the caster can hold lengthy conversations without being overheard.
References from the canon
- One of the spells Harry learned from the Half-Blood Prince's notes. Hermione disapproved of it and would refuse to talk at all if Harry had cast the spell on anyone in the vicinity (HBP12)
- Ron wished Harry had used this when Sprout caught the trio talking in class during their sixth year (HBP14)
- Cast by Hermione to help cover up her conversation with Harry and Ron on the night of Harry's seventeenth birthday (DH7).
- The corridors at the Ministry of Magic were as hushed as though the Muffliato charm had been cast over the place (DH13).
- One of the protective charms cast by Hermione on the campsite (DH14).
"muffle" Eng. to deaden a sound, making it more difficult to hear