Haunting Melody( Heroes of Horror, p. 123)
You can use your music to inspire fear.
Perform 9 ranks, Bardic music,
When you sing or use some other Perform skill, you can inspire fear in enemies within 30 feet of you. Any opponent in range must succeed on a Will saving throw (DC 10 + 1/2 your bard level + your Cha modifier) or become shaken for a number of rounds equal to your ranks in the Perform skill. This is a mind-affecting fear effect.
Using this ability counts as one of your daily uses of bardic music.