Cacophonous Alarm(Complete Mage, p. 98)
Level: Bard 2,
Components: V, S, AF, DF,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Area: 20-ft.-radius emanation centered on a point in space
Duration: 2 hours/level (D)
Saving Throw: None
Spell Resistance: No
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-foot radius spread).