Inaccurate?

Resounding Thunder

(Complete Mage)

Evocation [Sonic]
Level: Bard 4, Sorcerer 5, Wizard 5,
Components: V, S,
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: 20-ft.-radius spread
Duration: 5 rounds (D)
Saving Throw: Fortitude partial
Spell Resistance: Yes

Waves of sound crash continuously upon the ears of those in the area.
You fill the area with discordant crashes of sonic energy that deal 4d6 points of sonic damage per round to creatures within the area.
Furthermore, any creature within or entering the area becomes deafened as long as it remains within and for 1 round thereafter.
A successful Fortitude save halves the damage and negates the deafened effect.
The clamorous sound in the area also interferes with all sonic spells and effects.
Any such spell or effect has only a 50% chance to affect a creature within the area of resounding thunder.