Cacophonous Alarm

(Complete Mage)

Level: Bard 2,

Your magic causes the surrounding region to vibrate briefly with a deep rumble.
This spell functions like alarm, although you can only set it to produce an audible result, not a mental one.
Furthermore, an effect equivalent to a sound burst spell affects the first creature to violate the warded area (only this creature is affected, not a 10-footradius spread).