Silent magic?

[vidar_fe]

No: HPFGUIDX 110233

Already in the first book we were told how important it is to 
pronounce the spells in the exactly right way (everybody remembers 
Win-GAR-dium Levi-O-sa? :-)). But then, if you look in Fantastic 
Beasts, in the description of Lethifolds, there is a description of a 
lethifold attack. In this description the unlucky victim uses three 
different spells, the Stupefying Charm, the Impediment Hex and the 
Patronus Charm, without uttering one singel word. We know for sure 
that he didn`t speak because the Lethifold covered his mouth, trying 
to suffocate him. How is this possible?

Sorry if this already has been throughoutly discussed. I`m new on 
this list, and don`t quite have the time to look through all 
prprevious postings. :-)

By the way: English is not my native language, so please bear with 
any misspellings.