If you’re convinced you can belt it out with the best of ’em, crank up your volume and submit an a cappella audition video for the “Star-Spangled Sing-Off” sponsored by San Francisco Opera and Classical 102.1 KDFC.

Three finalists of the online contest, selected by KDFC listeners voting during the week of Aug. 24, will be posted on the station Web site Aug. 31. David Gockley and Nicola Luisotti, general director and music director of S.F. Opera respectively, and KDFC program director Bill Leuth will then pick the winner, to be announced the morning of Sept. 8 by radio host Hoyt Smith.

RTWT