Wall of Silence

Area 
Surrounds the affected area with a wall that sounds will not pass. Those within it cannot hear outside sounds, or be heard by those outside. Casting of spoken spells is unaffected.

Duration: 1 minute. 
Base cost: 2 to cast. 1 to maintain. 
Prerequisite: Silence.

Item 
As for Silence, but the cost is 100 per yard radius.