But the reason "silence" prevents spells is that in many magic traditions, Magic spells required a vocal component. Think harry potter or some similar magic story. Words are said a certain way to activate the spell. That is why the removal of sound prevents magic spells from being cast.
Shockwaves may cause a sound. and sound travels through the air. So I think its a good contender. Im just not sure because there arent any sound based spells currently in game. Shockwave in my mind refers to the force, not the sound. and silence is a lack of sound, not sound itself.