Strike up the band! The 31st annual Bix Biederbecke Memorial Jazz Festival is only a chorus away.People from all over the world are converging on Davenport, the hometown of Bix Biederbecke, the late cornetist, pianist and composer. And they’ll pay tribute to his memory by listening to bands from California to Australia in concert tonight through Sunday. Eleven bands will celebrate this year’s theme, “Jazz, the Sound of America,” in nearly 20 concerts at seven different venues, including the banks of the Mississippi. A downtown street fest and Saturday’s Bix 7-mile run also take place in conjunction with the festival.