There's a parameter that controls sound:
pagesound (see Wiki).
With

pagesound="false"

no sound will be played while dragging and turning pages.

Another approach with finer tuning options is soundcount (see Wiki).
With

soundcount="0,0,0,0,0"

no sound will be loaded at all. And you could enable/disable drag, turn, dragstiff, dragturn and restore individually.

BTW: Deleting the sound files would work, but is NOT a good idea because MegaZine3 still will try to load and get unnecessary time outs. Which will negatively impact performance.
You could substitute the sound files with your own sounds also.
And then there is the button to mute the sounds...