Wall of Silence – a spell outline

Wall of Silence
A magical barrier which is inpenetrable to sound and which blocks any sound-based damage.
The exact game stats depend on the rules system used, but this should be easy enough to implement in any of the games which already have some sort of magical barrier in them (and if you prefer a more technological bend, I am sure some technobabble will allow a specialised anti-sound generator to achieve the same results).