Ah, Sound Off!—the annual underage battle of the bands that has been at least partially responsible for the early discovery of now-glamorous music-scene veterans such as the Schoolyard Heroes, the Lonely H, the Lonely Forest, Mon Frere, Idiot Pilot, and the Hollowpoints. Now in its sixth year, Sound Off! ups the ante by choosing 12 finalists instead of 8. Tonight's first round of semifinals features Don't Tell Sophie, For Years Blue, Halfbreed, and the Oregon Donor. One of them could very well be the next great thing. (EMP, 325 Fifth Ave N, 877-EMP-LIVE. 8 pm, $7/$10, all ages.)